Since its inception in 1992, laparoscopic liver resection (LLR) has been increasingly employed as the new alternative to open liver resection.1 Over 3000 cases of LLRs have been reported worldwide.2 The safety and efficacy of the procedure have been shown in recent evidence to be comparable with open surgery. The advantages of LLR over traditional open surgery are less analgesic requirements, less operative blood loss, shorter hospital stay, accompanied with a low operative mortality and morbidity of 0.3% and 11%, respectively.3 4 5 6 Laparoscopic left lateral sectionectomies and wedge resections are now considered standardised operations performed routinely in dedicated centres.7

Laparoscopic hepatectomy is considered to be a complicated laparoscopic procedure. The surgeon should be experienced in both laparoscopic and liver surgery. Most of the studies on the learning curve effect show improved outcome with experience.8 9 10 11 However, LLR is not a single procedure and the complexity of operation ranges from wedge resections to major hepatectomies involving anatomical resection of three or more segments. Experience in the complexity of procedure performed has not been adequately studied. In Kwong Wah Hospital, our experience with laparoscopic liver surgery commenced in 2006, and since then the procedure has been performed in an increasing number of patients. Here we report our experience with the first 100 cases of LLR and the learning curve effect through the series of cases.

All data including patient demographics, tumour characteristics, operative procedures, and outcomes were prospectively collected. All patients underwent chest radiography and contrast computed tomography (CT) of the abdomen. Magnetic resonance imaging and lipiodol arteriogram were performed in selected patients. Patients’ preoperative liver function was assessed according to the Child-Pugh classification,12 and with indocyanine green retention test and CT volumetric analysis, if necessary. Patients were selected for laparoscopic liver surgery if they were medically fit for the major operation, Child-Pugh class A or B liver cirrhosis with adequate liver remnant after resection. Our centre adopted a less stringent criterion in terms of patient selection; hence, patients were included if LLR was considered technically feasible after evaluating patients’ history of surgical operations, tumour size, and location. In the later years, indications were expanded to include resection of more benign pathologies and cholangiocarcinoma, wherein resection was anticipated to be more difficult.13 14

All patients were operated on by specialist hepatobiliary surgeons with expertise in laparoscopic surgery. Hand-assisted or laparoscopic-assisted approaches were employed in the earlier period; however, the approach changed into total laparoscopy in the later period. Patient was put in Lloyd-Davis position for left hepatectomies and in semi-left lateral or left lateral position for right-sided lesion. Intra-operative laparoscopic ultrasound was used routinely. Five ports were used and placed according to tumour location. Parenchymal dissection was performed by Cavitron ultrasonic surgical aspirator (Valleylab Inc, Boulder [CO], US), Harmonic Scalpel (Harmonic ACE; Ethicon Endosurgery, Johnson & Johnson, Langhorne [PA], US) or LigaSure (Valleylab). Methods employed for haemostasis included bipolar diathermy, metal clips, Hem-o-lok (Weck Surgical Instruments, Teleflex Medical, Durham [NC], US) or endovascular staplers; the Pringle manoeuvre was not used routinely. Specimen was put inside a plastic bag and retrieved via a Pfannenstiel incision if the specimen was large or by extension of one of the port sites if the specimen was small. Pneumoperitoneum was re-established after specimen retrieval at a pressure of 6 to 8 mm Hg to check for haemostasis. Tissue glue (Tisseel; Baxter, Vienna, Austria) was applied selectively. Abdominal drains were inserted as needed.

Patients who underwent laparoscopic hepatectomies were divided chronologically into two periods for comparison. Those performed from March 2006 to May 2010 were classified into the ‘early group’ while those performed from June 2010 to October 2012 were classified into the ‘late group’. All data including patient demographics, operative and postoperative parameters were retrieved from a prospectively collected database. Operative parameters included operation type, conversion, operating time, blood loss, transfusion requirement, duration of Pringle manoeuvre, and intra-operative complications. The postoperative parameters included resection margin, staging, medical and surgical complications, length of hospital stay, and operative mortality. Complications were recorded and classified according to the Clavien-Dindo classification.15 Postoperative survival was measured using Kaplan-Meier estimates.

Statistical analyses were performed with the Statistical Package for the Social Sciences (Windows version 16.0; SPSS Inc, Chicago [IL], US). Numerical data were expressed as the median value. Mann-Whitney U test was used for comparing continuous variables. Chi squared test and Fisher’s exact test were used for comparing categorical variables. Statistical significance was set at a P value of less than 0.05.

From March 2006 to October 2012, our unit performed a total of 212 hepatectomies. A laparoscopic approach was employed in 98 patients. The proportion of LLRs performed increased from 40% in the early group to 58% in the late group. There was an increasing proportion of laparoscopic major hepatectomies and anatomical resections in the late group versus the early group (Table 1).

A total of 98 patients who underwent LLRs were recruited during this study period. There were 69 (70%) male and 29 (30%) female patients; the median age was 65 years. Of the 98 patients, two underwent a second LLR, giving a total of 100 LLRs. Some of these patients had previously undergone conventional hepatectomy. The Eastern Cooperative Oncology Group status was 0 for all patients. The demographic data and tumour characteristics of the two groups are shown in Table 2. There were significantly more patients with cirrhosis in the early group (P=0.016), and more patients had segment 7 tumour in the late group (P=0.017).

Indications for liver resection are shown in Table 2. Overall, 72% of LLRs were performed for hepatocellular carcinoma, whereas benign pathologies accounted for 10% of all LLRs. There was an increase in the number of LLRs performed for benign pathologies and cholangiocarcinomas in the late versus the early period. The types of resection performed are listed in Table 3. The proportion of anatomical resections increased from 50% in the early period to 62% in the late period, including predominantly right hepatectomies (6% vs 16%) and right posterior sectionectomies (2% vs 8%). An increasing proportion of major hepatectomies, including right and left hepatectomies, as well as right posterior sectionectomies, were performed in the late period (20% vs 32%). In addition, more resections involving the posterosuperior segments (including segments 7 and 8) were performed in the late period (34% vs 26%); these are considered to be anatomically more difficult resections. Pure laparoscopic approach was employed in the majority of LLRs, and more LLRs were performed with a pure laparoscopic approach in the late period than in the early period (98% vs 88%) [Table 3].

A number of procedures were performed alongside with LLRs. These included two laparoscopic colectomies, two closures of ileostomies, one hepaticojejunostomy, one small bowel resection, and three radiofrequency ablation–assisted LLRs.

Table 4 shows the intra-operative results, postoperative complications, status of margin involvement, and hospital stay. Conversion rates were higher in the late period than in the early period (14% vs 2%) but did not reach statistical significance. Among the operations that required conversion to a standard approach (n=8), three were due to haemorrhage, and the rest were due to poor exposure, dense adhesions with resultant small bowel injury, anatomical limitations at posterior segment, and doubtful tumour margin during resection. There was no mortality in the early group and one in the late group. Complications were classified according to the Clavien-Dindo classification and are shown in Table 4. One patient in the early group who had situs inversus experienced complications in the form of bile leakage from a segment 4 branch after an anatomical right hepatectomy; this patient required laparotomy with T-tube insertion. One patient in the late group was found to have extensive bowel ischaemia on postoperative day 2 after a laparoscopic right hepatectomy; this patient required reoperation but did not survive. Two patients, one each from the early and late groups, developed bile leak postoperatively after laparoscopic right hepatectomies; they were managed with image-guided drainage and endobiliary stenting.

A subgroup analysis was conducted for patients receiving laparoscopic right hepatectomies. Between the early and late period, a total of 11 laparoscopic right hepatectomies were performed. Table 5 shows the peri-operative results of these patients. With increasing experience, the operating time, blood loss, transfusion rate and volume, as well as duration of hospital stay were significantly reduced.

The 2-year survival, according to Kaplan-Meier survival analysis, showed an overall survival of 89.1% in the early group versus 96.9% in the late group (log rank P=0.593; Fig). Since the majority of the study population were recruited after 2008, 5-year survival data from this main bulk of patients were not available for this analysis.

Laparoscopic hepatectomies are technically demanding.16 17 The difficulty lies in parenchymal transection with limited exposure and traction, thus requiring proficiency in both laparoscopic and liver surgery. The reproducibility and feasibility of the procedure have been questioned, preventing the procedure from being widely employed. Our current study demonstrated that, with growing experience, we could perform LLR safely, as demonstrated by the favourable overall outcome of LLR. The rates of overall mortality and major morbidity were 1% and 5%, respectively. Reoperation was required in two (2%) patients. For malignant indications, R0 resection rate (complete resection with no microscopic residual tumour) was 94% (85/90). The overall results are in accordance with reports in the literature.2 5

Blood transfusion was required in 21% of our patients and the conversion rate was 8%. We did not use the Pringle manoeuvre frequently because most of the bleeding occurred from hepatic veins. Among these eight patients requiring conversion, three quarters were related to bleeding from branches of the hepatic vein. We preferred a pure laparoscopic approach because the use of a hand port caused interference with laparoscopic trocars and instruments.18 It has been suggested that hand-assisted or hybrid approach offers speedy haemostasis but there is no solid evidence to support which single method is superior. We did not consider conversion to be a failure and hence, a higher conversion rate (14% vs 2%, P=0.06) was observed with a lower blood transfusion rate (16% vs 26%, P=0.22) in the late versus the early period. No strict transfusion criteria were implemented. The decision of blood transfusion was mostly made by individual anaesthetist intra-operatively. Early in our series, we tended to initiate transfusion early because we anticipated bleeding during LLR to be more difficult to control. With gaining experience, transfusion was given more judiciously. Thus, with similar median blood loss, there was a trend towards lower transfusion rate in the late group as compared with the early group.

We further analysed the outcomes of the LLRs performed in the early and late periods. The overall outcome parameters were comparable with no significant learning curve effect observed. We observed a slight increase in operating time (263 vs 240 mins, P=0.40) and duration of hospital stay (6 vs 5 days, P=0.41) during the later period, and we believe that this was probably related to the increasing number of laparoscopic major hepatectomies and anatomical resections of right-sided lesions, as well as posterior segment LLRs performed in the later period.

With increasing experience in performing LLRs, we extended our indications of LLR from peripherally located tumours to posterosuperior lesions and from wedge resections to major resections, all reflecting an improvement in our techniques of performing LLR. However, we believe that we are still on the learning curve for the more difficult LLRs because the operative outcomes did not improve much. We managed to perform more anatomical resections with time in order to secure oncological safety. However, 5-year survival and recurrence results of our patients are not available for comparison between these two study groups.

The subject of learning curve effect of laparoscopic hepatectomy has been investigated by several authors in the literature. Many studies attempted to identify the number of hepatectomies required to overcome the learning curve effect.8 9 10 11 The 12-year experience of Vigano et al9 demonstrated that after performing 60 consecutive cases of laparoscopic hepatectomies, operative outcomes in three consecutive periods in terms of conversion rate (15.5%, 10.3%, and 3.4%; P<0.05), operating time (210, 180, and 150 mins; P<0.05), blood loss (300, 200, and 200 mL; P<0.05), and morbidity (17.2%, 22.4%, and 3.4%; P<0.05) improved. They reported a steady increase in the proportion of LLRs and a statistically significant increment in major and right hepatectomies in the later period of the study. The cumulative analysis of conversion rates in minor hepatectomies showed that at the 60th consecutive case, the conversion rate reached the average value and improved thereafter. A Korean group examined the results from their first 100 cases of laparoscopic liver surgery.8 Their mean operating time was 220 minutes and the overall morbidity was 11%. They demonstrated a decrease in the volume of blood transfusion in the latter half of patients operated with a malignant pathology. Kluger et al11 investigated the learning curve effect in laparoscopic major hepatectomy. Dividing their study results chronologically into three phases, they showed a steady increase in the proportion of major LLRs (1% vs 9%, P<0.05) and malignant lesions being resected at a later stage in the study period. Median operating time (150 vs 210 mins, P<0.05), blood loss (200 vs 300 mL, P<0.05), and clamping time (20 vs 45 mins, P<0.05) were significantly lower in the later study period. Morbidity rates also improved significantly with time (3% vs 17%, P<0.05). Their group concluded that a learning curve existed for both the operator and the institution, and a high-volume environment enables overcoming of the learning curve. The latest experience in the attempt to identify a learning curve came from a UK group.10 Analysing their 37 LLRs, the researchers concluded that their results followed a learning curve whereby more complicated procedures could be performed in the latter part of their experience. They also emphasised the importance of achieving proficiency in laparoscopic hepatectomies via simulation and wet laboratories. From our experience, we agree that we could safely expand our indications from wedge resection of small tumours at anterior and superior liver segments to major resections and posterosuperior lesions. However, the technical demand and learning path for wedge resections are entirely different from those of anatomical hemihepatectomies or monosegmentectomies. The training for LLR and learning curve issue is still an important unresolved topic that needs to be investigated further.

Laparoscopic hepatectomies are feasible and safe with favourable patient outcomes. A learning curve is present and could be overcome with increasing experience. However, the long-term outcomes associated with the procedure require further study with longer follow-up.

The survival rate of out-of-hospital cardiac arrest (OHCA) is low in Hong Kong. The reported overall survival-to-admission rate in recent local studies ranged from 12.7% to 14.6%, while the survival-to-discharge rate ranged from 1.25% to 3.0%.1 2 3 4 5 In the first few minutes after OHCA, rapid implementation of five critical actions including early access, early cardiopulmonary resuscitation (CPR), rapid and effective defibrillation, early advanced life support, and comprehensive post-cardiac arrest care can strengthen the “chain of survival”.6 7 A study including 1737 patients found that, within 4 minutes of collapse, approximately 53% of patients were in ventricular fibrillation/tachycardia.8 Many studies have already shown that rapid defibrillation with automated external defibrillators (AEDs) by non-paramedics can improve survival.9 10 11 12 In public access defibrillation (PAD), laypersons can have access to AED so that defibrillation can be delivered at the earliest before ambulance arrival. The concept of PAD has been well adopted in basic life support (BLS) training. However, the utilisation rate of AED was low in Hong Kong in a previous study.13 With the undoubtful benefit of PAD on the outcome of OHCA, it is invaluable to explore the reasons behind low PAD rate.

The successful delivery of PAD for cardiac arrest patients outside hospitals depends on a chain of factors including adequate number of AEDs in the community, close proximity of the AED to the site of OHCA (satisfactory matching of site of AED and OHCA), knowledge of bystanders and laypersons in BLS and how to use AED and, eventually, willingness of bystanders to use AED. Minimising mismatch between the site of AED placement and the site of OHCA would maximise the chances of PAD and improve the outcomes of OHCA. A significant association has been demonstrated between the matching and cost-effectiveness of AED placement.14

The objective of our study was to evaluate the availability and accessibility of AEDs in a territory in Hong Kong. We evaluated the total number of AEDs in the community and their geographical distribution throughout the territory. In addition, we assessed the matching of AED placement site and the site of OHCA.

This was a cross-sectional study performed in the New Territories West region of Hong Kong. The region includes urban town area and rural area in the districts of Yuen Long, Tin Shui Wai, and Tuen Mun. According to data from the 2011 Census, the residential population of the region was 1 066 07515 and the area of the territory was 223 km².16 17 There were only two hospitals with acute emergency services in the territory. All OHCAs were delivered to either hospital.

Data on all OHCAs in the territory were obtained from the local cardiac arrest registry which prospectively collects data on all OHCA cases managed in the emergency departments of the two hospitals. All data were recorded in Utstein style. The study period was from August 2010 to September 2013. Patients with traumatic cardiac arrest and deaths with postmortem changes were excluded. A total of 1936 cases were retrieved. Within those, 20 cases were excluded because these were in-hospital cardiac arrests in mental hospitals; 53 cases were excluded because of non-traceable site of arrest; 78 cases were excluded because of incomplete address. Overall, 1785 cases were included in the analysis. For OHCAs occurring at home or in institutions, the sites of arrest information were retrieved from the hospital database in the admission office. For OHCAs occurring outside home or institutions, data were traced from either the hospital records or ambulance records. Moreover, the PAD rate was retrieved from the registry, and double-checked with the hospital medical records and ambulance record. Public access defibrillation rate was defined as the rate of pre-hospital defibrillations performed by laypersons in patients with OHCA. It was calculated by dividing the total number of PAD cases by the total number of OHCAs.

According to the American Heart Association (AHA) recommendation, a community AED is regarded as accessible if it can be transported to the patient by a layperson by brisk walking within 1 to 1.5 minutes.14 For human beings, the average speed of brisk walking is around 8 km per hour, ie 2.2 m per second. A layperson can travel 200 m within 1.5 minutes. So, an AED is defined as being accessible if it is located within 100 m of a cardiac arrest patient (layperson travels 100 m to get the AED and travels 100 m to save the victim).18 Accessibility of AED in an arrest episode was also reported with various timeframes from 1 to 5 minutes of brisk walking speed.

Since there was no AED registry in Hong Kong, obtaining the data on the site of AED was difficult. We exhausted all methods to trace all AEDs in the community throughout the territory. There were two sources of data on the locations of AEDs. Firstly, we searched all AEDs in the community as per the information from the suppliers. All suppliers registered on the Medical Device Control Office of the Department of Health for external defibrillators were contacted for purchase records. Other brands of AEDs were traced from contacts with BLS training centres. Data about the locations of AEDs were obtained from sales registers of suppliers. In total, five brands of AED suppliers were contacted including Cardio Science, Physio-control, Laerdal, Philips, and Metrax. The second source was through community search. Staff at all schools, sport facilities, swimming pools, old-age homes and other hostels, shopping malls, housing estates, and public facilities in the territory were contacted by emails, telephone calls, or personal visits to confirm the existence of AEDs. The list of public facilities was found by Internet search and included government webpages. The information of locations of community AEDs was obtained for the period from September to December 2013.

The numbers of AEDs located in the searched facilities were reported as percentages. For all AEDs located in different facilities, we evaluated the number of OHCAs that occurred within 100 m throughout the study period, and calculated the average number of OHCAs that occurred around the AED per year.

According to AHA recommendation, AED should be placed where there is likely one cardiac arrest within 100 m in 5 years.14 In other words, the AED installation was regarded as cost-effective if there were more than 0.2 OHCA per AED per year within 100 m.

The availability of AED can be reflected by the AED density and the number of AEDs per 10 000 population. The AED density was calculated by dividing the total number of AEDs by the area of the territory. The number of AEDs per 10 000 population was calculated with the data of residential population from the Census data. We searched the literature to obtain similar data from studies in other countries, including Japan, Singapore, Denmark, Austria, and the US for comparison and illustration.

Locations of all cardiac arrests in this cluster were geographically coded by the Google Map (http://maps.google.com.hk) to longitudes and latitudes. The longitudes and latitudes of the centre of the corresponding building were coded. The precision was up to 6 decimal degrees which implies a maximum error of coordinate of 11.3 cm. For OHCAs that occurred in an open area, the geocoding was performed with best achievable precision according to information from the ambulance record or hospital record. The sites of AEDs in this cluster were also located and geographically coded. The distance between each case of OHCA and AED was calculated using the Haversine formula.18 Geographical mapping was performed using scripts with Google Map.

Statistical analysis was performed with IBM SPSS 20. Categorical variables were shown in proportions and percentages. Continuous variables of distance were presented as medians and interquartile ranges for data with skewed distribution. Categorical data were compared using Chi squared test. Distances were compared with independent sample median test. P values of less than 0.05 were regarded as significant.

The research was approved by the Cluster Clinical Research and Ethics Committee.

A total of 674 public facilities were found in the search and enquired for the installation of AED (Table 1). The response rate was satisfactory with only two schools failing to respond to our enquiry. A total of 207 community AEDs were found and located. Among them, 180 were identified from the registers of suppliers and 27 through community search. The geographical location of the AEDs in the territory is shown in Figure a.

The characteristics of community AEDs in various types of facilities are shown in Table 1. Schools possessed most of the community AEDs (n=78), followed by sports stadiums (n=35), community clinics (n=30), and hostels (n=16). All major parks and sports stadiums, and nearly half the schools in the territory had installed AEDs. Less than 20% of housing estates and hostels had been equipped with AEDs.

The number of OHCAs occurring per AED per year in various facilities is also shown in Table 1. Hostels or institutions had the most OHCAs per AED per year (2.072), followed by sports stadiums (0.884), shopping malls (0.850), and schools (0.834). All facilities with AEDs in the territory had more than 0.2 OHCA per AED per year within 100 m.

The number of AEDs per 10 000 population was 1.942, and the AED density was 0.928 per km² (Table 2). The number of AEDs per population and density of Singapore, Austria, Japan, Denmark, and the US are also shown in Table 219 20 21 22 23 24 25 26 for comparison.

The geographical distribution of all OHCAs is shown in Figure b. The characteristics of OHCAs in various sites of cardiac arrest are shown in Table 3. More than half of OHCAs occurred at home (53.0%) while one third occurred in the elderly’s home (36.4%) and 8.5% occurred in open areas. More patients with OHCAs in open areas and inside other buildings had received pre-hospital defibrillation versus those occurring in other locations. The median distance from the site of cardiac arrest to the nearest AED was lowest for cardiac arrest occurring in open areas. The proportion of OHCAs in open areas with AEDs in reachable distance was higher compared with those occurring in other sites.

Among all OHCAs, 25.2% could have AEDs reachable within 100 m (1.5 minutes); 59.4% could have AEDs available within 3 minutes (200 m) [Table 4]. For cardiac arrests occurring in open areas, the proportion of cases with AEDs within reachable distance (100 m) was higher than the arrests happening in buildings (37.7% vs 24.0%). The difference was statistically significant (P<0.001). Figure c illustrates the distribution of OHCAs for which AEDs were not accessible within 100 m.

From the cardiac arrest registry, 23 out of 1785 OHCAs had documented PAD. However, with confirmation from hospital and pre-hospital records, 20 were performed by ambulance crew or other pre-hospital personnel. Only three (0.168%) out of 1785 had genuine PAD.

Of the 650 OHCAs occurring in old-age homes, 81 cases happened in hostels equipped with AEDs. Public access defibrillation was delivered in only one case. A total of 80 (98.8%) cases of cardiac arrest events in hostels equipped with AEDs were not defibrillated. Cases where AED was applied but no shock delivered were not considered for calculating PAD rate.

The number of AEDs per 10 000 population in our study (1.942) was comparable to that in Singapore (1.971) and Austria (2.218), but far behind that in Copenhagen (9.200), Japan (6.978), and the US (6.956).

Nearly half of the schools were equipped with AEDs. The high equipment rate was because of the ‘Heart-safe School’ project organised by the Hong Kong College of Cardiology. The project aimed to install AEDs in over 1000 primary, secondary, and special schools in Hong Kong. It also provided training on CPR and the operation of AEDs to school staff.27 In our community survey, among schools not equipped with AEDs, at least 12 had joined the project and would receive AED installation in coming years. Thus, in the coming years, most of the schools would be equipped with AEDs.

All facilities with AEDs in this territory had more than 0.2 OHCA per AED per year within 100 m (Table 1). Thus, the cost-effectiveness of AEDs located in various types of facilities was satisfactory.

More patients with OHCAs in open areas and inside other buildings had pre-hospital defibrillation, ie shockable rhythm (Table 3). The median distance from the site of arrest to the nearest AED was lowest for cardiac arrests occurring in open areas and the proportion of OHCAs in open areas with AEDs within reachable distance was higher. It implies that the accessibility of AEDs in OHCAs occurring in open areas was higher. This group of patients should benefit most from community AEDs.

The average number of OHCA events per AED was highest in old-age homes installed with AEDs (more than two events per AED per year), which was far higher than the recommended threshold of cost-effective AED by AHA (0.2 event per AED per year). However, only 16 (19.3%) out of 83 old-age homes in our study were installed with AEDs. Although there was high incidence of OHCAs, the proportion of patients with shockable rhythm in pre-hospital stage remained low (4.6%) [Table 3]; consequently, the cost-effectiveness of placement of AEDs in old-age homes could not be concluded. In old-age homes with AED equipment, old-age home staff may be unable or reluctant to use AEDs. In our study, 98.8% of cardiac arrests in old-age homes equipped with AEDs received no PAD. This suggests that apart from installing AEDs, BLS training and education should be provided to the old-age home staff to increase the PAD rate.

In our study, most OHCAs (53%) occurred at home. However, OHCAs within coverage of AEDs (100 m) in housing estates was 0.364 event/AED/year, which was lower than that in schools, shopping malls, and sports stadiums. This was related to the large area of the housing estates versus that in hostels or other public facilities. To improve the AED coverage, more AEDs are required to be installed in housing estates. Another alternative would be consideration of home AEDs in families with high-risk residents. However, the benefit of home AEDs remains doubtful. A randomised controlled trial from 2003 to 2005 has shown that home AEDs offered no benefit to high-risk residents.28 The study recruited 7001 survivors of anterior myocardial infarction who were not candidates for an implantable cardioverter-defibrillator. They were randomised to either calling emergency medical services (EMS) and performing CPR, or using AEDs, calling EMS and performing CPR. It was found that there was no significant reduction in mortality in the AED group despite most of the arrests occurring at home. The authors concluded that it was due to low event rate, high proportion of unwitnessed events, and underuse of AEDs.

Only 13 (26%) of 50 shopping malls were equipped with AEDs, while the average event/AED/year was high (0.850) for AEDs installed in this location. This implied that more AEDs should be installed in these buildings. With surge in tourism and increase in people flow in shopping malls, the incidence of OHCAs in shopping malls would be expected to be increased over time. Shopping malls should be encouraged to install AEDs and the staff should be provided with relevant training and education.

For the matching of locations of AEDs and OHCAs, 25.2% of OHCAs occurred with accessible AEDs within 100 m. This was slightly lower than that observed in a study in Copenhagen in 2011 (28.8%) with the same definition.23 With the timeframe of 3 minutes, up to nearly 60% of OHCA events had AEDs within accessible distance of around 200 m.

However, the PAD rate in our cluster was extremely low (0.168%). The PAD rate is low all over the world; it is at most 2.11% in previous studies (Table 5).19 26 29 30 A study in Copenhagen found that no AED was ever used during the study period from 1994 to 2005.29 The authors attributed this to the recent installation of AEDs (predominantly in 2005) and low annual incidence of cardiac arrests near AEDs. There is no local study on this issue. The low usage rate might have several reasons. People might not know there is an AED nearby. There is no central registration of community AEDs in Hong Kong. Automated external defibrillators could be accessible but might not be visible. It is difficult for a bystander to find a community AED if he/she is not a staff of that community facility. Certainly, central registration of community AEDs could improve the problem. Bystanders could be informed how to access the nearest community AED after calling 999 if all community AED sites were registered. A study in the US showed that such emergency dispatch systems could improve the PAD rate.31 With sophistication in mobile technology, it is not difficult to develop softwares or Apps in mobile devices which could firstly provide the current location of the BLS provider by GPS (Global Positioning System), and then automatically locate the nearest reachable AED. The location of AEDs in the territory could be continuously updated with the central AED registry through the Internet. Furthermore, central mandatory AED registry could facilitate researches and auditing, which could provide insight on the PAD situation throughout the Hong Kong territories.

People may be reluctant to use community AEDs even if these are available. In a survey conducted in a shopping mall with AEDs in the US in 2001, it was found that the most common concern with using community AEDs was ‘fear of using the machine incorrectly’. The second most common concern was ‘fear of legal liability’.32 Education of the public and providing legal support may help to change their belief. Lo et al33 suggested that a law offering ‘Good Samaritan’ protection against liability rescuers in Hong Kong could alleviate the uncertainties and increase the benefits of the PAD programme. However, such legal proceeding has not been carried forward in Hong Kong. Lack of explicit and clear legislation certainly decreases the willingness to use AEDs. Without law protection, rescuers may be afraid of being sued by the victims’ families in case of failed resuscitation. As a result, it is no surprise that ‘do no harm without any action including CPR’ is the choice of most bystanders.4 34

Central AED registry for optimising placement of AED, education of laypersons, and legal support for bystanders providing CPR and using AED may be important for improving PAD rate and outcomes of OHCA. Further study on evaluation of laypersons’ attitude towards AED use could provide more insights on this problem.

Without central registry, the list of community AEDs obtained from suppliers and through community search may not be exhaustive. The actual number of community AEDs might be underestimated. Information about PAD delivery was obtained predominantly from the registry and pre-hospital records. The number of OHCAs with AEDs applied but not defibrillated was not traceable. Automated external defibrillators might have been used but PAD not delivered in non-shockable rhythm. The rate of AED use might be underestimated. However, all studies on PAD had the same assumption and bias. There was potential time bias in that the installation time of community AED was unknown. Out-of-hospital cardiac arrests that occurred from August 2010 to September 2013 were included in the study. The cardiac events of patients might have occurred prior to AED installation.

The distance calculated in our study was the shortest distance. In-building travel time was not incorporated. There are plenty of buildings within in a housing estate, especially in urban areas, in Hong Kong. The distance of vertical lift was also not taken into account. The actual time and distance might be underestimated. Furthermore, the accuracy of geographical mapping was up to the level of the building, and there would be bias between the geographical coordinates and the exact location of AEDs. Furthermore, for those OHCAs that happened in open areas, the geocoding was performed at the best achievable precision according to the available information from the ambulance and hospital records; this might have been associated with information bias.

In the New Territories West region of Hong Kong, the number of AEDs per 10 000 population was 1.942 and the accessibility within 100 m of OHCA was 25.2%, both being comparable to those from other developed countries. Although the placement site of community AED was cost-effective, PAD rate at 0.168% was low.

We would like to thank Mr John Kit-shing Wong, Trauma Nurse Coordinator of Tuen Mun Hospital for his invaluable help on the data search.

Click here to watch a video of different intubation techniques

Airway management may be required urgently when a patient deteriorates in an ambulance during interhospital transfer or in a prehospital setting. En-route intubation in an ambulance is challenging due to patient and environmental factors.1 These may include inadequate or over-exposed lighting, limited access to the patient, a continuously moving environment, confined space, and unanticipated patient deterioration. The success rate of en-route intubation (89.6%) is lower than that of hospital intubation (98.8%) and intubation-on-scene (94.9%) in air medical transport.2 Intubation success is more likely in a hospital setting (odds ratio [OR]=8.70) or at the scene (OR=2.3) compared with en-route intubation.2

Some studies3 4 suggest using inverse intubation in an entrapped or confined environment. In inverse intubation, the intubator crouches or kneels near the patient’s right side, while holding the laryngoscope in the right hand. Patient’s mouth is opened with the intubator’s left hand. The laryngoscope blade is gently pulled up and towards the patient’s feet at a 45° angle. The endotracheal tube is passed between the visualised vocal cords. The success rate and time of intubation of using inverse intubation in air transport were not significantly different from those with conventional intubation in air transport.5 Inverse intubation is particularly useful in circumstances where the cephalad access to the patient is limited. In addition, the mechanical advantages of pulling up the larynx with the dominant hand may, theoretically, facilitate visualisation of vocal cords of patients with difficult airways.

In recent years, portable video laryngoscope (GlideScope; Verathon Inc, Bothell [WA], US) was introduced to facilitate airway management in the prehospital setting.6 7 GlideScope was the first commercially available video laryngoscope. It uses a high-resolution camera embedded into a plastic laryngoscope blade, and a LED light for illumination. The distal angulation makes it ideally suitable for visualising and intubating over the anterior larynx. The endotracheal tube has to be used with a special stylet to match the gentle curve of 60° of the GlideScope blade. It has been proven to be a useful adjunct for intubation in both normal and difficult airways in selected settings.8 9 10

The objectives of our experimental study were: (1) to compare the effectiveness of conventional intubation by Macintosh laryngoscope in a moving ambulance versus that in a static ambulance; (2) to compare the effectiveness of inverse intubation and GlideScope laryngoscopy (model: GVL 4) with conventional intubation inside a moving ambulance.

This was a comparative experimental study conducted from June to October 2012. Altogether, 22 doctors—including emergency medicine trainees, members, and fellows—were recruited to participate voluntarily in the study. All participants were working in the accident and emergency department (AED) and had been practising emergency medicine for at least 2 months. All of them had experience in performing endotracheal intubation in patients. The approval of ethics committee was considered waived as the study was performed on manikins and did not involve patients.

Demographic data of the participating doctors including age, gender, AED working experience, previous attendance of advanced airway training workshop, past experience of using inverse intubation and GlideScope on living or dead patients were collected. Advanced airway training workshop is a full-day course organised by the Hong Kong College of Emergency Medicine. Course attendants learn the basic skills of endotracheal intubation. Various airway adjuncts such as GlideScope are demonstrated and opportunities provided for participants to practise intubation with these during the course.

The use of conventional Macintosh laryngoscopy, inverse intubation with Macintosh laryngoscope and GlideScope laryngoscopy were demonstrated to participants individually by the experiment conductor using an “AIRSIM” manikin at least 1 week before the study. The participants were allowed hands-on practice of the techniques and devices, freely, in a training room before the experiment.

The experiment was conducted in an ambulance provided by the Auxiliary Medical Service. The ambulance we used was Mercedes-Benz 516CDI measuring approximately 1.6 m in width and 2.2 m in length. The stretcher, together with the manikin, was locked on the right side of the ambulance, as in real life. The intubator would have limited room to kneel down at the vertex of the patient to perform conventional Macintosh and GlideScope intubations (Fig 1). Inverse intubation was performed on the right side of the manikin (Fig 2). The ambulance was moving at a speed of 20 km/hour, following a fixed route chosen before the experiment within the hospital compound. Moving at this relatively slow speed was only possible on the chosen route as there were a number of turnarounds and road bumpers.

The Laerdal “Adult Basic” manikin was used in the study. A neck collar was applied to the manikin to restrict the neck mobility and simulate a difficult airway. Size-3 blade was used for conventional Macintosh and inverse intubations. All intubations were performed with a 7.5-mm cuffed endotracheal tube. All participants performed intubations on the manikin in both normal and difficult airways inside a static ambulance and moving ambulance. Participants performed the conventional Macintosh, inverse Macintosh and GlideScope intubations in both normal and simulated difficult airways inside the moving ambulance in the same sequence. Neither external manipulation of the larynx nor airway management adjunct was allowed in the study.

The time required for intubation was recorded with electronic stopwatch and corrected to one decimal place. The start time was defined when the participant was asked to begin while sitting on the couch, approximately 1 metre from the manikin, with the equipment in hands. The end of the procedure was defined when the participant verbally stated that the airway was secured with inflation of the cuffed balloon of the endotracheal tube. The verification of the endotracheal tube placement was performed by direct visualisation and inflation of the artificial lung, with no air leakage from the manikin. Both oesophageal intubation and intubation with time taken longer than 60 seconds were considered to be unsuccessful procedures. Incisor breakage was reported by the participants when a “click” sound was heard during intubation; however, it was not considered an unsuccessful intubation. Participants also reported the Cormack-Lehane laryngoscopic grading system (C&L grade; grade 1-4) and their preferences for intubation techniques and devices. Eventful intubation was defined as incisor break, oesophageal intubation, or intubation taking longer than 60 seconds.

We used SPSS version 16.0 for Windows for statistical analysis. Rates of successful intubation and incisor breakage were presented in percentage. The working experience of participants and time spent on intubation were described by median and interquartile range as the data showed skewed distribution. The time required for intubation by different intubation techniques and devices were analysed by Wilcoxon signed rank test for paired data. The rates of successful intubation, complications including oesophageal intubation, incisor breakage and the subjective visualisation grading system among different intubation techniques and devices were compared using Fisher’s exact test with or without Freeman-Halton extension. Spearman’s correlation was employed to show the relationship between time of intubation and AED experience. The results were regarded as statistically significant if P<0.05.

A total of 22 AED (17 male and 5 female) doctors participated in the experiment. The median age of the participants was 30.5 years. The mean AED working experience of the participants was 4.9 years. As the technique and devices were demonstrated by the experiment conductor before beginning the experiment, all doctors had experience with using inverse intubation and GlideScope in a manikin. The details are shown in Table 1. All participants performed intubations in the eight scenarios and the success rate of each scenario was summarised in Figure 3.

The percentage of successful and unsuccessful intubations, time required for intubation, subjective glottis visualisation score, and complication rates using conventional Macintosh intubation in static and moving ambulance are shown in Table 2. In normal airways, the intubation success rates in both static (95.5%) and moving ambulances (95.5%) were high. The median intubation times for intubation in static and moving ambulances were 21.2 seconds and 26.5 seconds, respectively (P=0.268). In difficult airways, the intubation success rates in static and moving ambulances were 86.4% and 90.9%, respectively. The median intubation times in static and moving ambulances were 22.6 seconds and 20.6 seconds, respectively (P=0.488). There was no significant difference in the Cormack-Lehane grades and incidence of eventful intubation between the two groups.

The intubation performance using the conventional Macintosh laryngoscopy and inverse Macintosh intubation in a moving ambulance is shown in Table 3. In normal airways, the success rate of conventional intubation (95.5%) was significantly higher than that of inverse intubation (54.5%; P=0.004). The median intubation time with the conventional technique (26.5 seconds) was shorter than that with inverse intubation (37.8 seconds; P=0.043). The number of difficult laryngeal visualisation (ie Cormack-Lehane grade ≥3) was significantly higher with inverse intubation technique (n=8; 36.4%) versus the conventional technique (0%; P<0.001). The incidence of eventful intubation with inverse intubation (81.8%) was significantly greater than that with conventional intubation (13.6%; P<0.001). In difficult airways, the intubation success rate of conventional technique (90.9%) was also significantly higher than that of inverse intubation (40.9%; P=0.034). The median intubation time required for conventional intubation technique (20.6 seconds) was significantly shorter than that for inverse intubation (51.3 seconds; P=0.002). The number of difficult airway intubations was significantly higher with inverse technique (n=12; 54.5%) than with conventional technique (13.6%; P=0.003). The incidence of eventful intubation was significantly higher in the inverse intubation group (81.8%) than that in the conventional intubation group (36.4%; P=0.002).

The intubation performance using conventional Macintosh and GlideScope laryngoscopes in a moving ambulance is summarised in Table 4. In normal airways, the conventional intubation technique (95.5%) and GlideScope laryngoscopy (95.5%) were associated with high success rates. The median intubation time with conventional technique (26.5 seconds) was shorter than that with GlideScope (31.0 seconds; P=0.012). In difficult airways, both conventional technique (90.9%) and GlideScope (100%) were associated with high success rates. The median intubation time with conventional technique (20.6 seconds) was significantly shorter than that with GlideScope (32.4 seconds; P<0.001). None of the intubations with GlideScope in both normal and difficult airways was given Cormack-Lehane grade of ≥3 but no statistical difference could be demonstrated in the grades when compared with conventional intubation in both normal (P=0.721) and difficult airways (P=0.180). There was an obvious trend for less eventful intubation with GlideScope (9.1%) versus the conventional intubation group (36.4%; P=0.069).

The relationship between the time required for intubation and AED experience is presented in Figure 4. An experienced doctor in AED required less time for conventional intubation in both normal (P=0.043) and difficult airways (P=0.019) in a static ambulance. Also, experienced doctors did better with conventional intubation than inverse intubation in normal airways in a moving ambulance (P=0.019).

Data on the doctors' perception of the new technique and device were also collected. Overall, two (9.1%) and 17 (77.3%) doctors thought that inverse intubation and GlideScope were, respectively, useful as adjuncts in normal airways, while one (4.5%) and 19 (86.4%) thought that inverse intubation and GlideScope were, respectively, useful in difficult airways.

Previous studies found a 7% to 10% incidence of difficult intubation in prehospital emergency en-route intubations.11 12 A number of patient and environmental factors contribute towards the difficulty in en-route intubation.1 Environmental factors including restricted space, continuous movement of the ambulance, and inadequate lighting are believed to adversely affect the en-route intubation compared with intubation in a controlled hospital setting. In our study, we found that the success rates of conventional Macintosh intubation in normal and difficult airways were high in static and moving ambulances. There was no significant difference in oesophageal intubation rate, intubation time, laryngeal visualisation scores, and incisor breakage rate with conventional Macintosh intubation in static and moving ambulances. The environment of a moving ambulance did not appear to hinder the ability of conventional Macintosh intubation in our experiment. Gough et al13 also recruited 20 emergency medical technicians at the advanced-intermediate level of EMT (Emergency Medical Technician) to perform intubation on a manikin in a moving ambulance and static station. They also found no significant difference in the success rates and time required for intubation between the two groups. Stopping an ambulance or a helicopter for en-route intubation may be impossible or dangerous in real life. Our study suggests that en-route intubation is feasible in an ambulance moving at a speed of 20 km/hour.

Inverse intubation has been proposed by Hilker and Genzwuerker3 as “an important alternative for intubation in the street”. The technique was proven to be useful as adjunct in failed conventional intubation and an important backup position if access from behind the patient’s head is impossible.4 5 14 In our study, we found that inverse intubation in an ambulance was associated with higher failure rate, prolonged intubation, and more complication rates versus conventional intubation. The clinical usefulness of this technique in a moving ambulance was not established in our study. Besides, one of the reported complications of inverse intubation is pharyngeal laceration.15 If this complication is not recognised, it could result in significant haemorrhage or potentially lethal infection. Individual experience is a significant determining factor for the success of the technique. During the experiment, we also found that it was quite inconvenient for the intubators who wore spectacles to perform inverse intubation as the spectacles were likely to fall off due to the peculiar posture required when performing the procedure. Inverse intubation would be a reasonable choice for trained rescuer who cannot position himself/herself to the space above the victim’s (eg entrapment).

GlideScope has been shown to facilitate tracheal intubation by improving the laryngeal view in manikin studies,7 8 9 emergency settings,16 17 18 and a wide spectrum of selective surgeries.19 20 21 Struck et al6 conducted a retrospective observational study and survey of experiences in prehospital intubation for a 3-year period. Around 15% of the patients presented with multiple traumas or failed intubation with conventional laryngoscopy and required intubation by GlideScope. In our study, we demonstrated high intubation success and low failure rates with GlideScope laryngoscopy, but the median time for intubation was slightly longer versus that with the conventional Macintosh laryngoscopy in normal airways (P=0.012) and difficult airways (P<0.001). The finding of longer intubation time with GlideScope was also demonstrated in previous studies.16 19 20 However, some studies found no difference in the intubation time.7 22 One study8 even found that GlideScope enables faster intubation in patients with cervical spine immobilisation. The wide range of results may be attributed to the differences in experience with using GlideScope, different study settings (manikin vs real patient), and different study scenarios (normal vs difficult airway). Piepho et al23 conducted a study among paramedics who used the Macintosh and GlideScope video laryngoscopes for intubating manikins. They found that the intubation time with GlideScope was longer than that with Macintosh in the first and second attempts of intubation. However, no significant difference in time required for intubation was observed in the subsequent attempts. This confirms a rapid learning curve for intubation with GlideScope. In another manikin study with 60 anaesthetists, GlideScope was found to have a steep learning curve for intubation but, after five attempts, differences in terms of time of endotracheal intubation persisted when compared with the Macintosh laryngoscopy.24 In our study, there was a trend for less eventful intubation with GlideScope (P=0.069) in the setting of difficult airways. Thus, we recommend its use as a backup for en-route intubation, especially in difficult airway settings. In real-life practice of using GlideScope, the passage of endotracheal tube through the deeply curved and rigid stylet may be hindered. An assistant is required to thread the endotracheal tube into the trachea while the intubator holds the GlideScope in position. This is expected to be more difficult in an ambulance because of limited space.

This study had several limitations. Firstly, we used a manikin in our study rather than a real patient; thus, the results may not be transferrable to real patients. However, we believe that the use of new techniques and devices in airway management is not ethical in clinically unstable and emergency patients. A well-designed manikin-based study would be an acceptable choice for the aforementioned reasons. Secondly, only one of the difficult airway situations was tested in our study. Other difficult airway situations in daily practice such as limited mouth opening, tongue oedema, and presence of blood/vomitus were not studied. Thirdly, there was the issue of learning curve associated with new techniques and devices. Overall, one (4.5%) and eight (36.4%) of the participants had previous experience of using inverse intubation and GlideScope in clinical settings, respectively. Although we demonstrated the use of inverse intubation and GlideScope and allowed participants to practise freely at least 1 week before the experiment, we cannot demonstrate the non-inferior result associated with the use of inverse intubation in a previous study.5 We also observed that the intubation time for difficult airways in a moving ambulance was shorter than that for normal airways. The most likely explanation is the learning effect and intubation experience. The participants performed different intubation techniques in normal airways followed by the same techniques in difficult airways in a moving ambulance. The participants may have gained experience from working in a continuously moving environment. We suggest further studies with inverse intubation and GlideScope after a longer period of training and practice to examine for the reproducibility of these results. Fourthly, the study was performed inside our hospital which has imposed speed limits on vehicles moving on the road. Moving at a relatively slow speed of 20 km/hour was only possible in the chosen route as there were a number of turnarounds and road bumpers. Moreover, we limited the speed in order to avoid any danger to or fall of participants. Fifthly, GlideScope (model: GVL 4) for the experiment was chosen because it was the only model available in our hospital. Other models that are specifically designed for prehospital use such as Glidescope Ranger may be a better choice, if available. Lastly, the sample size of the study was relatively small and could have inadequate power to detect real differences between some comparison, for example, comparison of the eventful intubation rate between GlideScope and conventional intubation.

Our study demonstrates an overall high intubation success rate with conventional Macintosh and GlideScope laryngoscopes in a moving ambulance. The time required for intubation with GlideScope was longer than that with conventional laryngoscope. Application of GlideScope should be suggested as an adjunct for intubation in an ambulance in the presence of adequately trained staff. The high failure rate and prolonged time associated with the inverse intubation technique make it less useful than conventional intubation and GlideScope intubation unless the cranial access of the patient is restricted.

We would like to thank the Auxiliary Medical Service, the Hong Kong SAR Government for providing the ambulance and all physicians who participated in this experimental study.

1. Helm M, Hossfeld B, Schäfer, Hoitz J, Lampl L. Factors influencing emergency intubation in the pre-hospital setting—a multicentre study in the German Helicopter Emergency Medical Service. Br J Anaesth 2006;96:67-71. CrossRef

2. McIntosh SE, Swanson ER, McKeone A, Barton ED. Location of airway management in air medical transport. Prehosp Emerg Care 2008;12:438-42. CrossRef

3. Hilker T, Genzwuerker HV. Inverse intubation: an important alternative for intubation in the streets. Prehosp Emerg Care 1999;3:74-6. CrossRef

4. Hoyle JD Jr, Jones JS, Deibel M, Lock DT, Reischman D. Comparative study of airway management techniques with restricted access to patient airway. Prehosp Emerg Care 2007;11:330-6. CrossRef

5. Robinson K, Donaghy K, Katz R. Inverse intubation in air medical transport. Air Med J 2004;23:40-3. CrossRef

6. Struck MF, Wittrock M, Nowak A. Prehospital Glidescope video laryngoscopy for difficult airway management in a helicopter rescue program with anaesthetists. Eur J Emerg Med 2011;18:282-4. CrossRef

7. Nakstad AR, Sandberg M. The GlideScope Ranger video laryngoscope can be useful in airway management of entrapped patients. Acta Anaesthesiol Scand 2009;53:1257-61. CrossRef

8. Lim TJ, Lim Y, Liu EH. Evaluation of ease of intubation with the GlideScope or Macintosh laryngoscope by anaesthetists in simulated easy and difficult laryngoscopy. Anaesthesia 2005;60:180-3. CrossRef

9. Benjamin FJ, Boon D, French RA. An evaluation of the GlideScope, a new video laryngoscope for difficult airways: a manikin study. Eur J Anaesthesiol 2006;23:517-21. CrossRef

10. Cooper RM, Pacey JA, Bishop MJ, McCluskey SA. Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anaesth 2005;52:191-8. CrossRef

11. Adnet F, Jouriles NJ, Le Toumelin P, et al. Survey of out-of-hospital emergency intubations in the French prehospital medical system: a multicenter study. Ann Emerg Med 1998;32:454-60. CrossRef

12. Combes X, Jabre P, Jbeili C, at al. Prehospital standardization of medical airway management: incidence and risk factors of difficult airway. Acad Emerg Med 2006;13:828-34. CrossRef

13. Gough JE, Thomas SH, Brown LH, Reese JE, Stone CK. Does the ambulance environment adversely affect the ability to perform oral endotracheal intubation? Prehosp Disaster Med 1996;11:141-3.

14. Koetter KP, Hilker T, Genzwuerker HV, et al. A randomized comparison of rescuer positions for intubation on the ground. Prehosp Emerg Care 1997;1:96-9. CrossRef

15. Smally AJ, Dufel S, Beckham J, Cortes V. Inverse intubation: potential for complications. J Trauma 2002;52:1005-7. CrossRef

16. Platts-Mills TF, Campagne D, Chinnock B, Snowden B, Glickman LT, Hendey GW. A comparison of GlideScope video laryngoscope versus direct laryngoscopy intubation in the emergency department. Acad Emerg Med 2009;16:866-71. CrossRef

17. Mosier JM, Stolz U, Chiu S, Sakles JC. Difficult airway management in the emergency department: GlideScope videolaryngoscopy compared to direct laryngoscopy. J Emerg Med 2012;42:629-34. CrossRef

18. Sakles JC, Mosier JM, Chiu S, Keim SM. Tracheal intubation in the emergency department: a comparison of GlideScope® video laryngoscopy to direct laryngoscopy in 822 intubations. J Emerg Med 2012;42:400-5. CrossRef

19. Kim JT, Na HS, Bae JY, et al. GlideScope video laryngoscope: a randomized clinical trial in 203 paediatric patients. Br J Anaesth 2008;101:531-4. CrossRef

20. Andersen LH, Rovsing L, Olsen KS. GlideScope videolaryngoscope vs. Macintosh direct laryngoscope for intubation of morbidly obese patients: a randomized trial. Acta Anaesthesiol Scand 2011;55:1090-7. CrossRef

21. Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope® video-laryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Can J Anaesth 2012;59:41-52. CrossRef

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Obesity was formally recognised as a global epidemic by the World Health Organization (WHO) in 1997.1 During the past decades, the prevalence of being overweight and obese has increased substantially. In Hong Kong, 17% of children were overweight/obese in 2005/6, which was a 5% increase since 1993, based on International Obesity Task Force cut-offs.2

Overweight/obese children and adolescents are more likely to have hyperinsulinaemia, hypertension, and dyslipidaemia.3 The clustering of cardiometabolic risk factors in these patients tends to track into adult life.3 However, the Diabetes Prevention Program demonstrated that lifestyle interventions could prevent or postpone the onset of type 2 diabetes mellitus (DM) by 58% in adults.4 Thus, identifying at-risk groups may allow early interventions and prevention of potential cardiometabolic complications.

Acanthosis nigricans (AN)—a hyperpigmented, thickened, and velvety dermatosis at the nape of the neck or axilla—is an easily identifiable physical sign.5 The American Diabetes Association includes it as an indicator of DM risk in overweight youths entering puberty.6 Yet, some authors have argued that it is not an independent predictor of insulin resistance (IR) if body mass index (BMI) is controlled for.7

Ethnic differences occur in obesity indices and their associated risk factors include IR.8 Local studies focusing on associations between AN with IR and other cardiometabolic co-morbidities in Chinese paediatric age-groups are sparse. In this regional centre study, we describe the demographic characteristics and IR in obese Chinese children with and without AN, with a focus on exploring the associations of AN with IR and other cardiometabolic co-morbidities.

A retrospective study was conducted by recruiting overweight/obese children and adolescents between 5 and 18 years of age who underwent obesity assessment between January 2006 and December 2010 in a regional hospital in Hong Kong. Patients were excluded if they had underlying metabolic diseases, chronic diseases, or other medical conditions resulting in obesity. Patients taking on medications that would alter metabolic profiles were also excluded.

Anthropometric data and AN status were recorded. Blood samples were collected. Ultrasound liver scans were performed on patients with elevated alanine aminotransferase (ALT) levels. Height was measured to the nearest 0.1 cm using the Harpenden stadiometer (Holtain; Crymych, UK) and body weight to the nearest 0.1 kg with light clothing using an electronic column scale (SECA-780; Seca Ltd, Hamburg, Germany). The BMI (kg/m²) percentiles of 90th and 97th centiles were used to define overweight and obesity, respectively.9 10 Local percentile standards were based on a local population survey conducted in 1993.11 The BMI z-score was calculated using this local age- and gender-specific reference. Blood pressure (BP) was measured using the standard oscillometric method (BP-8800C; Colin Electronics, Komaki, Japan) in the daytime with the children seated and rested. Average BP was obtained from two measurements. The BP z-score was calculated using the local BP reference.12 Participants were considered hypertensive if the mean systolic BP z-score and/or diastolic BP (DBP) z-score was/were greater than or equal to the 95th centiles for age and gender.

The diagnosis of AN was made by paediatricians; additional scoring for this entity was not undertaken as not all authors agreed that specific quantitative scales could improve the accuracy of IR prediction.13

Blood samples for plasma glucose, insulin, lipid profile, and liver enzymes following an overnight fasting were obtained and a standard oral glucose tolerance test (OGTT) was performed. The homeostasis model of assessment (HOMA)–IR value was used to assess IR using the following equation: fasting glucose (mmol/L) x fasting insulin (µU/mL)/22.5.14 Any HOMA value of ≥4 was considered to indicate IR. Glucose abnormalities were defined according to criteria from the WHO.15 Abnormal glucose homeostasis was referred to any combination of impaired fasting glucose, impaired glucose tolerance, or DM on the basis of fasting or 2-hour plasma glucose levels in the OGTT.16 17 Fatty liver was diagnosed by ultrasound scan affirmed by the operational definition of non-alcoholic fatty liver disease in the Asia-Pacific region.18

The statistical analyses were conducted using the Statistical Product and Service Solutions (version 17.0 for Windows 7). Taking P<0.05 as statistically significant, Student’s t test and Wilcoxon rank-sum test were used to compare results with a normal and skewed distribution, respectively. The Chi squared test or Fisher’s exact test as appropriate were used to analyse categorical variables. Multiple logistic regression analysis was then performed to identify independent factors associated with IR. To avoid multicollinearity, body weight and height were not used in the model, since both variables correlated highly with BMI. For the same reason, fasting insulin and glucose levels were not selected for the model as the HOMA-IR was derived from them. The model was simplified in a backward stepwise fashion by removing variables with P values of >0.1. Goodness-of-fit of the regression model was tested with the Hosmer-Lemeshow test.

A total of 543 overweight/obese Chinese patients were included in this study. They had a mean ± standard deviation age of 12 ± 3 years and 64% (n=346) of them were boys. The majority (77%, n=419) were obese with a BMI of >97%. In all, AN was present in 54% (n=295) of the subjects and 29% (n=156) of them had IR. Relevant data are summarised in Table 1.

Table 2 illustrates that adolescents (aged 12-18 years), compared with younger children (aged 5-11 years), were more likely to have AN (63% vs 47%; P<0.001) and IR (37% vs 25%; P=0.005). Obese children, compared with overweight children, were also more likely to have AN (59% vs 44%; P=0.005) and IR (35% vs 19%; P=0.001).

Table 3 shows baseline characteristics and biochemical parameters in children with and without AN. Apart from being older, the group with AN had higher mean 2-hour post-OGTT glucose (P=0.021), fasting insulin (P<0.001), triglyceride (P<0.001), and ALT (P=0.002) levels, but lower mean levels of high-density lipoprotein (HDL) cholesterol (P<0.001). Their BMI (P<0.001), BMI z-score (P<0.001), systolic blood pressure (SBP) [P<0.001], and HOMA-IR values (P<0.001) were also higher. Notably, the higher SBP, when converted to SBP z-score (taking into account age and gender), was no longer significant. Both DBP and DBP z-scores showed no differences between the two groups. The presence of IR and other cardiometabolic co-morbidities in subjects with and without AN are also shown in Table 3. The frequencies of IR, hypertension, fatty liver, and abnormal glucose homeostasis were all significantly higher in subjects with AN.

Further analysis of risk factors for IR using the multiple logistic regression model showed that the presence of AN (odds ratio [OR]=2.36; 95% confidence interval [CI], 1.46-3.80; P<0.001), older age (1.17; 1.07-1.28; P=0.001), higher triglyceride level (1.91; 1.33-2.74; P<0.001), and higher BMI z-score (6.95; 3.40-14.16; P<0.001) were significant independent variables predicting IR (Table 4). However, though HDL and 2-hour post-OGTT glucose level were borderline significant predictors for IR, their effect sizes were small. The Hosmer-Lemeshow test of goodness-of-fit was 0.315, indicating a good logistic regression model fit.

Obesity is a public health problem that has become epidemic worldwide. In the primary care setting, identifying children with AN may allow early implementation of interventions to prevent the development of DM and other cardiometabolic co-morbidities in overweight/obese children.16 Searching for AN over the neck is easy, non-intrusive. and acceptable to the children.19 Presence of AN can also be used as a grounds to initiate and reinforce discussions about lifestyle modification.5 19 20

An observed AN frequency of 54% in our subjects was consistent with data reported in the literature.21 22 Our adolescents were more likely to have AN than younger children, in line with hyperinsulinaemia being more severe among older individuals.22 In our study, development of AN showed no gender preference, as in a study of 1412 unselected children by Stuart et al.23 In our cohort and that in Nsiah-Kumi et al’s study,13 obese children were more likely to have AN than overweight ones.

Whilst IR is a hallmark of obesity, it is also associated with other metabolic derangements and clinical or subclinical cardiovascular diseases.24 We used the HOMA-IR value—a simple, validated, and practical marker of IR in the paediatric population—to give a more physiological estimate of glucose homeostasis,25 that was also shown to correlate well with the hyperinsulinaemic-euglycaemic glucose clamp technique, a gold standard for quantifying insulin sensitivity.24 In a local community-based cross-sectional study, it was shown that the mean HOMA-IR value was lower among Hong Kong Chinese adolescents than subjects in the United States.8 Currently, there is no worldwide consensus on defining IR among children. Some studies have chosen an HOMA-IR value as low as 2.7 while others have shown that a value of 4 can be present in pubertal children (because of the transient physiological IR during puberty).13 Although we do not have data about pubertal stage in our study subjects, an HOMA-IR of ≥4 would be a conservative but reasonable definition of IR, in parallel with the threshold used in a multicentre trial in the United States (Studies to Treat or Prevent Pediatric Type 2 Diabetes—STOPP-T2DM).26

In our study, 29% of our cohort had IR using the cut-off HOMA-IR of ≥4, and the mean value was higher among those with AN present (3.6 vs 2.6; P<0.001). Notably, IR was more common among adolescents than young children (37% vs 25%; P=0.005) as well as among obese than overweight subjects (35% vs 19%; P=0.001). Goran et al27 suggested that long-standing obesity and the physiological IR during puberty accounted for adolescents having more AN and IR. They found that pubertal transition from Tanner I to Tanner III was associated with a 32% reduction in insulin sensitivity across different genders and ethnicities, and proved that body fat was the predominant factor influencing IR whereas total and visceral fat both contributed independently to lower insulin sensitivity.27 Notably, 25% of our young (5-11 years old) overweight/obese subjects already had IR, suggesting that the onset of metabolic derangement might have started long before adolescence and indicates that screening should begin early during childhood.

In our cohort, IR and other cardiometabolic co-morbidities were more prevalent among those with AN. The relationship of AN with hypertension may not be as strong as that with fatty liver and abnormal glucose homeostasis. This might be consistent with hypertension being more closely related to obesity than to AN.28 Nevertheless, studies assessing the relationship of BP and insulin levels are conflicting.29 Some authors postulate that the underlying pathophysiology is a common genetic predisposition to both IR and hypertension, whilst also involving other mechanisms.30

Dyslipidaemia is believed to play a central role in the development of heart diseases. High level of triglyceride and low level of HDL cholesterol are commonly used criteria to define metabolic syndrome both in children and adults.31 High triglyceride levels and the IR index (HOMA-IR) were strong, independent predictors of increased carotid intima-media thickness, which was a non-invasive measure of subclinical atherosclerosis in paediatric research.32 Nevertheless, low HDL cholesterol level carried an even greater relative risk than high triglyceride levels.33 Compared with those without AN, subjects with the condition had a higher mean triglyceride level (P<0.001) but lower HDL level (P<0.001), and hence their future cardiovascular health seems to be of great concern.

Fatty liver, or non-alcoholic fatty liver disease (NAFLD), can be classified into isolated fatty liver in which there is only accumulation of fat, and non-alcoholic steatohepatitis (NASH) in which there is fat accumulation and damage to liver cells. Presence of the latter is associated with raised liver enzymes and more abnormal ultrasound scans. Our subjects with AN had higher levels of ALT (P=0.002) and a higher proportion with fatty livers. In contrast, Uwaifo et al34 reported that AN was not common among a small cohort of 28 subjects with biopsy-proven NASH, despite their high prevalence of IR. These authors therefore questioned the use of AN as an index of IR in patients with NASH. However, in our study liver ultrasounds were only performed in children with raised ALT levels. According to Sartorio et al,35 the ALT level alone was insufficient as a marker of NAFLD and the sensitivity of using its level to predict NAFLD was as low as 41% (depending on the cut-off used). Several prediction scores have been developed for non-invasive liver steatosis screening, but they have insufficient diagnostic accuracy among obese children.36

For DM, incidence, prevalence, and disease progression are believed to vary in different ethnic groups. The overall frequency of abnormal glucose homeostasis of 10% (8% impaired glucose tolerance and 2% with DM; data not shown) was lower than in a recent study by Brickman et al16 who reported a 29% frequency of abnormal glucose homeostasis among a group of 8-to-14 years old, mainly of Hispanic and African American children with AN. Another study from the United Kingdom found a higher frequency of type 2 DM among African-Caribbean and South Asian groups, while the Chinese and white Caucasians had the lowest frequencies.37 The reasons for such inter-ethnic differences are still unclear but do not seem to be solely genetic, as inter-generational social factors may also modify the evolution and biology of the disease.37 Our results, together with the recently reported sharp rise in the incidence of type 2 DM in Hong Kong children aged under 19 years after 2004,38 should alert our health care professionals as to the importance of early detection of potential predictors of abnormal glucose metabolism such as AN.

Recently, the role of IR in cardiometabolic derangements has attracted more attention. Nevertheless, there is no prediction model for IR in our local children and adolescents. Using multivariate analysis, our study demonstrates that age, AN status, triglyceride level, and BMI z-score are significant independent variables associated with IR. Hopefully, a simple and practical prediction model of IR with acceptable sensitivity and specificity can be derived by combining these clinical findings, anthropometric measurements, and biochemical markers.

Important limitations of this study included its retrospective design, being single-centred, and thus not being suitable for calculating population-based rates. In addition, the stage of puberty (not documented) may also influence IR. Moreover, several relevant risk factors (family history of metabolic derangement, maternal gestational DM, duration of obesity, socio-economic status) were not included in the analysis. As in other retrospective studies, it was not possible to retrieve every single item of data. Notably, AN status was unavailable in 11 (2%) patients while HOMA-IR information was absent in 46 (8%) of the subjects, as fasting insulin levels were not checked and might have contributed to selection bias. Our study was clinic-based and not population-based, and so an overestimate of morbidity was a possibility. Besides, establishing a relationship between cause and effect was not possible due to the cross-sectional nature of the study. Growth data collected in 1993 (HK1993) are still widely used locally and seem appropriate in Hong Kong.9 We adopted the operational BMI cut-offs for daily use locally. However, the ideal cut-offs for being overweight and having obesity remain controversial, and various definitions and operational values exist.39 These problems may also limit direct comparisons between different studies using different growth references and cut-offs.39

Local obese Chinese children with AN are at higher risk of IR and cardiometabolic co-morbidities. Primary care physicians should be vigilant for this clinical sign. If present, early attention is necessary to achieve early intervention. Further studies may be necessary to evaluate the longitudinal risk relationship between AN and cardiometabolic outcomes.

1. Caballero B. The global epidemic of obesity: an overview. Epidemiol Rev 2007;29:1-5. CrossRef

2. So HK, Nelson EA, Li AM, et al. Secular changes in height, weight and body mass index in Hong Kong Children. BMC Public Health 2008;8:320. CrossRef

3. Bao W, Srinivasan SR, Wattigney WA, Berenson GS. Persistence of multiple cardiovascular risk clustering related to syndrome X from childhood to young adulthood: the Bogalusa Heart Study. Arch Intern Med 1994;154:1842-7. CrossRef

4. Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393-403. CrossRef

5. Kong AS, Williams RL, Smith M, et al. Acanthosis nigricans and diabetes risk factors: prevalence in young persons seen in southwestern US primary care practices. Ann Fam Med 2007;5:202-8. CrossRef

6. American Diabetes Association. Type 2 diabetes in children and adolescents. Diabetes Care 2000;23:381-9. CrossRef

7. Ice CL, Murphy E, Minor VE, Neal WA. Metabolic syndrome in fifth grade children with acanthosis nigricans: results from the CARDIAC project. World J Pediatr 2009;5:23-30. CrossRef

8. Kong AP, Choi KC, Ko GT, et al. Associations of overweight with insulin resistance, beta-cell function and inflammatory markers in Chinese adolescents. Pediatr Diabetes 2008;9:488-95. CrossRef

9. So HK, Nelson EA, Sung RY, Ng PC. Implications of using World Health Organization growth reference (2007) for identifying growth problems in Hong Kong children aged 6 to 18 years. Hong Kong Med J 2011;17:174-9.

10. Ng DK, Lam YY, Kwok KL, Chow PY. Obstructive sleep apnoea syndrome and obesity in children. Hong Kong Med J 2004;10:44-8.

11. Leung SS, Cole TJ, Tse LY, Lau JT. Body mass index reference curves for Chinese children. Ann Hum Biol 1998;25:169-74. CrossRef

12. Sung RY, Choi KC, So HK, et al. Oscillometrically measured blood pressure in Hong Kong Chinese children and associations with anthropometric parameters. J Hypertens 2008;26:678-84. CrossRef

13. Nsiah-Kumi PA, Beals J, Lasley S, et al. Body mass index percentile more sensitive than acanthosis nigricans for screening Native American children for diabetes risk. J Natl Med Assoc 2010;102:944-9.

14. Matthews D, Hosker J, Rudenski A, Naylor B, Treacher D, Turner R. Homeostasis model assessment: insulin resistance and β-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia 1985;28:412-9. CrossRef

15. Definition, diagnosis and classification of diabetes and its complications: report of a WHO consultation, part 1: diagnosis and classification of diabetes mellitus. Geneva, Switzerland: World Health Organization; 1999.

16. Brickman WJ, Huang J, Silverman BL, Metzger BE. Acanthosis nigricans identifies youth at high risk for metabolic abnormalities. J Pediatr 2010;156:87-92. CrossRef

17. Atabek ME, Pirgon O, Kurtoglu S. Assessment of abnormal glucose homeostasis and insulin resistance in Turkish obese children and adolescents. Diabetes Obes Metab 2007;9:304-10. CrossRef

18. Chitturi S, Farrell GC, Hashimoto E, et al. Non-alcoholic fatty liver disease in the Asia-Pacific region: definitions and overview of proposed guidelines. J Gastroenterol Hepatol 2007;22:778-87. CrossRef

19. Smith WG, Gowanlock W, Babcock K, et al. Prevalence of acanthosis nigricans in First Nations children in Central Ontario, Canada. Can J Diabetes 2004;28:410-4.

20. Kong AS, Williams RL, Rhyne R, et al. Acanthosis nigricans: high prevalence and association with diabetes in a practice-based research network consortium—a PRImary care Multi-Ethnic network (PRIME Net) study. J Am Board Fam Med 2010;23:476-85. CrossRef

21. Shalitin S, Abrahami M, Lilos P, Phillip M. Insulin resistance and impaired glucose tolerance in obese children and adolescents referred to a tertiary-care center in Israel. Int J Obes (Lond) 2005;29:571-8. CrossRef

22. Kluczynik CE, Mariz LS, Souza LC, Solano GB, Albuquerque FC, Medeiros CC. Acanthosis nigricans and insulin resistance in overweight children and adolescents. An Bras Dermatol 2012;87:531-7. CrossRef

23. Stuart CA, Pate CJ, Peters EJ. Prevalence of acanthosis nigricans in an unselected population. Am J Med 1989;87:269-72. CrossRef

24. Singh B, Saxena A. Surrogate markers of insulin resistance: a review. World J Diabetes 2010;1:36-47. CrossRef

25. Keskin M, Kurtoglu S, Kendirci M, Atabek ME, Yazici C. Homeostasis model assessment is more reliable than the fasting glucose/insulin ratio and quantitative insulin sensitivity check index for assessing insulin resistance among obese children and adolescents. Pediatrics 2005;115:e500-3. CrossRef

26. Studies to Treat or Prevent Pediatric Type 2 Diabetes Prevention Study Group. Prevalence of the metabolic syndrome among a racially/ethnically diverse group of U.S. eighth-grade adolescents and associations with fasting insulin and homeostasis model assessment of insulin resistance levels. Diabetes Care 2008;31:2020-5. CrossRef

27. Goran MI, Ball GD, Cruz ML. Obesity and risk of type 2 diabetes and cardiovascular disease in children and adolescents. J Clin Endocrinol Metab 2003;88:1417-27. CrossRef

28. Sorof JM, Lai D, Turner J, Poffenbarger T, Portman RJ. Overweight, ethnicity, and the prevalence of hypertension in school-aged children. Pediatrics 2004;113:475-82. CrossRef

29. Jessup A, Harrell JS. The metabolic syndrome: look for it in children and adolescents, too! Clin Diabetes 2005;23:26-32. CrossRef

30. El-Atat FA, Stas SN, McFarlane SI, Sowers JR. The relationship between hyperinsulinemia, hypertension and progressive renal disease. J Am Soc Nephrol 2004;15:2816-27. CrossRef

31. Reinehr T, de Sousa G, Toschke AM, Andler W. Comparison of metabolic syndrome prevalence using eight different definitions: a critical approach. Arch Dis Child 2007;92:1067-72. CrossRef

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Click here to watch a video of double free-flap reconstruction

The use of microvascular free flaps for the reconstruction of defects following the resection of head and neck cancer is a complex but routine procedure. However, single flaps may not be sufficient for some defects that are either too large or warrant composite tissues. In particular, resection of advanced tumours of the oral cavity results in complex oromandibular defects that often involve bone, oral lining, external skin, and soft tissue. The free fibular osteocutaneous (FO) flap is well established as a workhorse flap for mandible reconstruction,1 which provides 25 to 30 cm of straight bone of good quality that can be contoured, as well as a skin paddle for soft tissue coverage when needed. The pedicle has an acceptable length and its vessels have a good diameter. It is therefore our preferred option for restoring mandibular defects and for lining the oral cavity.

However, the size of the skin paddle is limited1 and may not be supplied by the same vessel as the bone.2 Thus, with larger composite defects, a single fibula flap cannot provide sufficient soft tissue coverage and a second skin flap may be necessary. Some surgeons nevertheless elect to avoid a second free flap by choosing either a pedicled flap or alloplastic material. We therefore set out to demonstrate the feasibility of resorting to double free flap surgery in head and neck reconstruction.

Our choice for additional soft tissue is the anterolateral thigh (ALT) flap that provides up to 630 cm² of skin.3 On occasions when the vascularity of the fibula flap skin paddle is deemed borderline, the ALT can be harvested with multiple skin islands so as to cover both the inner lining and the external skin. Harvest of the FO and ALT flaps can proceed at the same time as tumour excision, without the need for patient re-positioning, which is an important logistical advantage. Like most surgeons, whenever possible we prefer using separate anastomoses for double flaps rather than sequential linking or ‘flow through’,4 5 6 as some studies5 6 suggest that the latter has more complications (possibly due to increased thrombogenicity or a ‘steal’ phenomena).

We conducted a retrospective case review of patients in our institution with head and neck cancer who had reconstruction with planned simultaneous double free flaps over a 2.5-year period (from November 2010 to August 2013). For all cases we deployed two surgical teams; reconstructions were performed (one surgeon) at the same time as tumour excision (other surgeons). Preoperatively, handheld Doppler probes were used to locate the skin perforators for both flaps. The peroneal artery was sacrificed in the harvest of fibula flaps and adequacy of the remaining vessels was screened by palpation of the dorsalis pedis and posterior tibial pulses. An angiogram was used in only one patient with a history of peripheral vascular disease.

The FO flap was harvested first using a lateral approach; a sterile tourniquet was placed on the upper thigh but not inflated. A skin island was harvested in nine out of 10 fibula flaps. In one patient, the skin island was not perfused by the peroneal artery and thus not harvested. In another, the vascularity of the skin island was deemed suboptimal and therefore not used. The fibula flap was kept in situ after isolation of its vascular pedicle while the ALT was harvested. Intramuscular perforators to the thigh skin island were skeletonised in all cases so as to completely visualise the vessels. Once the surgical margins were deemed clear by frozen sections, the final dimensions of the ALT flaps were determined when the final defect was defined.

Whenever possible, intermaxillary fixation was used to hold the mandible and maxilla in an optimal position, and ‘by eye’ the fibula was osteotomised to fit (average 1-2 osteotomies). Two sets of mini-plates were used per osteotomy site so as to maximise rotational stability. The use of 2.5 x or 3.5 x loupes by the reconstructive surgeon allowed micro-anastomoses of the vessels, whilst insetting of the flap was completed.

A 58-year-old man was referred to our centre with a second recurrence of a squamous cell carcinoma of his tongue. Three years earlier, he had had a partial right glossectomy with a selective neck dissection for a pT2N0 lesion. One year later he underwent a complete neck dissection for a right nodal recurrence, and another year later he had had a reconstruction with a pectoralis major myocutaneous flap (PMMF) after total glossectomy for local tumour recurrence. After the tumour was resected, he had a bony defect from one angle of the mandible to the other, and a soft tissue defect that involved the entire inferior oral cavity down to the chin and anterior neck skin, which left a 3-cm rim of lower lip (Fig 1).

We used a fibula flap with its overlying skin island along with a large ALT flap (Fig 2). After anastomosis of the two sets of vessels, bleeding from the edge of the fibula flap skin island appeared rather sluggish. So the ALT was used for both intraoral lining and external skin cover. A strip of the ALT flap was de-epithelialised for suturing to the lower lip remnant (Fig 3). There were no major complications and the patient was discharged on the 14th postoperative day. There was a good contour at follow-up (Fig 4); the patient used a percutaneous endoscopic gastrostomy (PEG) for feeding preoperatively but regrettably could not resume oral feeding after this surgery and therefore remained reliant on the PEG.

All tumours were stage T4a, with nodal status ranging from N0-N3 (Table). During the study period, there were six male and six female patients who had double free flap surgery. Their ages ranged from 31 to 88 (mean, 55) years. In 10 of them, a free fibula flap was combined with an ALT flap harvested from the same limb; in eight of them a skin island was harvested with the bone. One patient had bilateral ALT flaps for reconstruction of an extensive tumour of the tongue and floor of the mouth without bone involvement. Another patient had a free fibula flap combined with an anteromedial thigh flap, due to absence of suitable perforators upon dissecting the ALT flap.

The mean total operating time was 660 minutes, which included the time for frozen section results. Postoperative hospital stays ranged from 11 to 82 days; nine patients were discharged home within 3 weeks. Patient 10 stayed 80 days. She declined further surgery for an intraoral dehiscence, which was therefore treated conservatively. Patient 7 stayed 82 days, as his recovery was complicated by a carotid blowout on the 11th postoperative day for which he had a surgery; subsequently a pseudomonas wound infection was treated with antibiotics. After surgery, seven patients were able to resume oral feeding sufficient to maintain their body weight; the remainder relied on tube feeding. Five patients received adjuvant treatment (4 had chemoradiation and 1 only had radiotherapy).

Minor postoperative complications (fluid collections, fistulae) occurred in 67% of these patients and usually resolved with conservative management. More serious complications occurred in 33% of the patients (carotid blowout, wound dehiscence/infection, and fluid collections treated surgically). In one patient, a haematoma was treated by debridement of the soft tissue portion of the free fibula flap that had been de-epithelialised and ‘buried’. There were no instances of total flap loss; two patients were taken back to theatre for exploration and their flaps were salvaged. One of them (patient 10) had venous congestion of the fibula skin flap (used for intraoral lining), which was salvaged but remained swollen and indurated. In view of a concomitant intraoral wound dehiscence, the swollen skin island was debrided and a pedicled ipsilateral pectoralis major flap was harvested to close the intraoral wound. Regrettably, although the pedicled flap survived, the intraoral wound dehisced again, and the patient declined to have further surgery so her wound was managed with daily dressings (see above).

Two (17%) out of the 12 patients had tumour recurrence during the follow-up period, and a further two (17%) had distant metastases. Survival from the time of surgery ranged from 60 to 303 days. The patient survival rate at 6 months was 91%, and at 1 year was 64%. At the time of writing this paper, only seven of the 12 patients had been followed up for at least 2 years, three (43%) of whom were still alive.

Following resection of advanced oral cancers, it is our standard practice to use double free flaps when needed for reconstruction of complex oromandibular defects, particularly those involving large defects of both bone and soft tissue. In most cases, the indication for double free flaps was the requirement for bone and soft tissue/skin not provided by the skin island of a FO flap. This practice is by no means universal; some surgeons are reluctant to contemplate a second free flap due to the perceived increase in technical complexity, operating time, and risk of complications. Alternative strategies include substitution of the fibular flap with a metal reconstruction plate, combined with a soft tissue flap for resurfacing7; combining a fibular free flap with pedicled regional flaps, such as the deltopectoral flap, PMMF,8 or latissimus dorsi myocutaneous flap. Some centres regard such cases as ‘inoperable’ and offer palliative treatment only.

However, these simpler alternatives have their drawbacks. The problems associated with an alloplastic plate with a soft tissue flap for composite mandible reconstruction are well documented,9 10 11 there being high rates of delayed plate exposure and recourse to salvage procedures.12 In the long term, use of vascularised bone (particularly in the FO flap) is more successful for mandible reconstruction,2 and was our first choice in all cases, with the possible exception of patients with a short life expectancy (<6 months). Recourse to a regional pedicled soft tissue flap instead of a free flap is based on its perceived advantage in being technically easier to harvest and involving shorter operating times.9 13 There is also a perceived lower risk of complications through avoiding a second set of microanastomoses. The PMMF is the most commonly used regional flap,14 but the vascularity of its skin paddle (like that of other regional flaps used in head and neck reconstruction) tends to be suboptimal; if the muscle is too short, more of the skin paddle results in a ‘random-pattern’. Crucially, the skin islands tend to be positioned at the most distal portions and thus have the poorest vascularity in the most critical parts.15 Chen et al16 recommends avoiding PMMFs to line the oral cavity due to a high rate of bone exposure from dehiscence.

On the contrary, surgeons such as Bianchi et al17 have actually demonstrated better outcomes with double free flaps compared to a combination of one free flap with one pedicled flap. The bulk of the muscle pedicle in regional flaps can interfere with the inset and vascularity of a concomitant free flap,13 and the tendency for muscle atrophy and gravitational effects can adversely affect the final results of reconstruction. Chen et al16 demonstrated a lower failure rate with two free flaps (2.8%) compared with the combination of one free and one pedicled flap (9%). They speculated that the bulky PMMF pedicle may actually compress the free flap pedicle, citing the 14% to 33% frequency of internal jugular vein thrombosis after radical neck dissection covered with pedicled flaps.18 19 The skin island of a regional flap also tends to be thicker, less pliable, and thus may interfere with intraoral function. Regional flaps may be limited in other ways (eg lack of necessary tissue components or specific tissue volume), which compromise the final aesthetic and functional outcomes.20

Although on average, a single free flap can take 1.5 hours longer than a PMMF to harvest, Tsue et al21 found that the operating time for double flaps can be 3 hours shorter than for a one free and one pedicled combination. They explained this by citing possible bias by surgeons choosing to use a second pedicled flap, when the resection time was longer, and surgeons working faster whenever two free flaps were anticipated. Guillemaud et al22 found no significant difference in the duration of surgery and complication rate when comparing double free and one free and one pedicled surgeries. In the end, the duration of surgery should not be a factor in determining the type of reconstruction.23

Proposed indications for the use of double free flaps are listed in the Box.20 The reconstruction of defects resulting from tumour resection in the head and neck region is a challenge, particularly when a composite of tissues is required or the defect is too large to cover by a single flap. Recourse to two free flaps allows more versatility and flexibility when reconstructing such complex defects. The best osseous and soft tissue elements may be independently selected, yielding appropriate tissue characteristics for ideal defect reconstruction. Using two separate thin pliable free flaps rather than bulky pedicled flaps may allow easier insetting and better restoration of the 3-dimensional anatomical boundaries,24 and thus both the functional and aesthetic outcomes can be addressed. With free flaps, there is also the potential for including other components such as nerves for sensate flaps.24

Good-quality soft tissue coverage is needed to reduce the risk of plate exposure12; even when the skin component of the FO flap can provide adequate surface cover, there is usually an overall shortage of soft tissue. Soft tissue reconstruction is as important as bone reconstruction25 in determining a satisfactory outcome, as deficiency of the latter tissues is poorly tolerated in the head and neck,26 and may lead to inadequate obliteration of dead spaces (eg from resection of masticators, buccal fat pad, and parotid). This causes accumulation of fluid which may become secondarily infected,16 and threaten micro-anastomoses and lead to contractures, and poor cosmetic outcomes or functionality that can lead to trismus, as well as contraction of the floor of the mouth with tethering of the tongue with difficulties in swallowing and speech.27 Therefore, even in the absence of bone loss, a double free flap reconstruction can be advantageous especially if soft tissue loss is substantial or beyond the reach of pedicled alternatives.

The use of two simultaneous free flaps undoubtedly poses technical difficulties, by increasing potential patient morbidity and is time-consuming. Although it is not our intention to promote double free flap reconstruction as a ‘routine’ reconstruction procedure, we wish to highlight it as an option, at least for tumours that are often deemed ‘inoperable’. Balasubramanian et al28 demonstrated that advanced ‘inoperable’ tumours such as T4b (in 7 of 21 cases) can be safely operated on; having double free flap reconstruction in the armamentarium allows surgeons to be more aggressive with extirpation. With careful patient selection, the duration of surgery, hospital stays, and complications need not be prohibitive compared to single free flap operations.25 Wei et al20 suggest that double free flaps should be restricted to patients with primary cancers, avoiding their use in those with recurrent cancers or second primaries. Nevertheless, in our series three patients presented with recurrent cancer. Individual patients should be assessed on a case-by-case basis—a PMMF could be considered to cover the skin of the neck, whilst reconstruction plates may be used to reconstruct short posterior or lateral mandible defects, particularly in those with a short life expectancy.

Our study shows that double free flap reconstruction can be worthwhile in patients with T4 tumours with a flap survival rate of 100% and a patient survival rate of 64% at the time of going to press. Just over half of our patients were able to resume oral feeding, which is somewhat lower than that in some other studies,28 29 and may be related to the locally advanced extent of their tumours, particularly with regard to tongue involvement.

1. Hidalgo DA, Rekow A. A review of 60 consecutive fibula free flap mandible reconstructions. Plast Reconstr Surg 1995;96:585-96. CrossRef

2. Tan BK, Wong CH. An anomalous septocutaneous perforator to the skin paddle of the fibula osteocutaneous flap originating from the posterior tibial artery. J Plast Reconstr Aesthet Surg 2009;62:690-2. CrossRef

3. Chiu T, Wong EW, Burd A, Vlantis A. Perforator transfer in the antero-lateral thigh flap. J Plast Reconstr Aesthet Surg 2013;66:1012-3. CrossRef

4. Lin PY, Kuo YR, Chien CY, Jeng SF. Reconstruction of head and neck cancer with double flaps: comparison of single and double recipient vessels. J Reconstr Microsurg 2009;25:191-5. CrossRef

5. Wei FC, Demirkan F, Chen HC, Chen IH. Double free flaps in reconstruction of extensive composite mandibular defects in head and neck cancer. Plast Reconstr Surg 1999;103:39-47. CrossRef

6. Wei FC, Celik N, Chen HC, Cheng MH, Huang WC. Combined anterolateral thigh flap and vascularized fibula osteoseptocutaneous flap in reconstruction of extensive composite mandibular defects. Plast Reconstr Surg 2002;109:45-52. CrossRef

7. Boyd JB, Mulholland RS, Davidson J, et al. The free flap and plate in oromandibular reconstruction: long-term review and indications. Plast Reconstr Surg 1995;95:1018-28. CrossRef

8. Ariyan S. The pectoralis major myocutaneous flap. A versatile flap for reconstruction in the head and neck. Plast Reconstr Surg 1979;63:73-81. CrossRef

9. Blackwell KE, Buchbinder D, Urken ML. Lateral mandibular reconstruction using soft-tissue free flap and plates. Arch Otolaryngol Head Neck Surg 1996;122:672-8. CrossRef

10. Cohen M, Schultz RC. Mandibular reconstruction. Clin Plast Surg 1985;12:411-22.

11. Shpitzer T, Gullane PJ, Neligan PC, et al. The free vascularized flap and the flap plate option: comparative results of reconstruction of lateral mandibular defects. Laryngoscope 2000;110:2056-60. CrossRef

12. Wei FC, Celik N, Yang WG, Chen IH, Chang YM, Chen HC. Complications after reconstruction plate and soft-tissue free flap in composite mandibular defects and secondary salvage reconstruction with osteocutaneous flap. Plast Reconstr Surg 2003;112:37-42. CrossRef

13. Blackwell KE, Buchbinder D, Biller HF, Urken ML. Reconstruction of massive defects in the head and neck: the role of simultaneous distant and regional flaps. Head Neck 1997;19:620-8. CrossRef

14. Lerrick AJ, Zak MJ. Oral cavity reconstruction with simultaneous free and pedicled composite flaps. Operat Tech Otolaryngol Head Neck Surg 2000;11:76-89. CrossRef

15. Shah JP, Haribhakti V, Loree TR, Sutaria P. Complications of the pectoralis major myocutaneous flap in head and neck reconstruction. Am J Surg 1990;160:352-5. CrossRef

16. Chen HC, Demirkan F, Wei FC, Cheng SL, Cheng MH, Chen IH. Free fibula osteoseptocutaneous-pedicled pectoralis major myocutaneous flap combination in reconstruction of extensive composite mandibular defects. Plast Reconstr Surg 1999;103:835-45. CrossRef

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