OBJECTIVE. To review the clinical features and management of patients with injuries related to the Chinese cobra (Naja atra).

DESIGN. Retrospective study.

SETTING. Two acute hospitals in Hong Kong.

MAIN OUTCOME MEASURES. The nature of injuries, envenoming features, complications, response to antivenom therapy, and outcome.

RESULTS. Eighteen patients were recruited during the 5-year study period. Fifteen of them were snake-bitten, the remaining three suffered ocular injuries. Of the 15 patients with cobra bites, 14 (93%) presented with local swelling. No patient developed severe neurotoxic symptoms. Two patients had laboratory features of haemolysis. Fourteen patients received antivenom therapy and five of them subsequently underwent surgical interventions for extensive local tissue damage and necrosis. There was no fatality.

CONCLUSION. Bites from Chinese cobra result in serious local complications with extensive tissue necrosis and minimal neurotoxic symptoms. There is an apparent trend of favourable outcomes following the early administration of antivenom to patients without early signs of irreversible tissue damage. Further research is needed to evaluate the effectiveness of early antivenom use in Chinese cobra bites in order to minimise extent of tissue damage.

Key words: Antivenins; Cobra venoms; Emergency treatment; Necrosis; Snake bites

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OBJECTIVE. To evaluate the results of pulmonary valve replacement in patients with severe pulmonary regurgitation after tetralogy of Fallot repair in Hong Kong.

DESIGN. Retrospective review.

SETTING. University teaching hospital, Hong Kong.

PATIENTS. Consecutive patients undergoing pulmonary valve replacement after repair of tetralogy of Fallot between August 2002 and December 2008.

MAIN OUTCOME MEASURES. Magnetic resonance imaging of right ventricular volume and cardiopulmonary exercise test data before and after the operation were documented and compared.

RESULTS. Over a 6-year period, 16 patients underwent pulmonary valve replacement for severe pulmonary regurgitation after prior complete repair for tetralogy of Fallot. There was no in-hospital mortality. The mean time interval between the initial repair and pulmonary valve replacement was 19 (standard deviation, 9) years. In three patients, the indication for pulmonary valve replacement was symptomatic severe pulmonary regurgitation, and asymptomatic progressive right ventricular dilatation in the remaining 13 patients. After pulmonary valve replacement, there was a significant decrease in the mean indexed right ventricular end-diastolic volume from 173 (standard deviation, 44) mL/m(2) to 103 (19) mL/m(2) (P=0.043). After the operation, there was also a tendency for improvement of the right ventricular ejection fraction and the maximum oxygen consumption: from 42% (standard deviation, 9%) to 47% (6%) [P=0.173], and 27 (4) mL/kg/min to 29 (4) mL/kg/min (P=0.208), respectively.

CONCLUSION. Pulmonary valve replacement for severe pulmonary regurgitation after tetralogy of Fallot repair is a safe procedure. However, the indications for such an operation in asymptomatic patients remain controversial. Further studies are required to better delineate the timing of pulmonary valve replacement in this patient group.

Key words: Heart valve prosthesis implantation; Pulmonary valve insufficiency; Tetralogy of Fallot; Treatment outcome

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OBJECTIVE. To audit the appendectomies at our institute, and summarise atypical pathological results with a discussion of appropriate management.

DESIGN. Retrospective study.

SETTING. Regional hospital, Hong Kong.

PATIENTS. All patients who underwent appendectomy for presumed acute appendicitis from June 2003 to June 2008 were recruited. Incidental appendectomy was excluded. Patient demographics, pathological findings, and surgical outcomes were analysed.

RESULTS. The overall negative appendectomy rate was 18.2%. Female patients of reproductive age (11-50 years) conferred an independent risk for a higher negative appendectomy rate than other females (28.7% vs 11.5%; P<0.001). The overall perforation rate was 22.5%; the extremes of age (<11 or >70 years) conferred an independent risk of perforated appendicitis (25.2% vs 16.3%; P=0.002). Preoperative imaging was not associated with a lower negative appendectomy rate or rate for perforated appendicitis (P=0.205 and 0.218, respectively). Multivariate analysis suggested that a preoperative white cell count of less than 13.5 x 10(9) /L was an independent predictor of negative appendectomy (P<0.001); the body temperature and pulse rate of the patients with perforated appendicitis were higher than in those without perforation (P=0.004 and 0.003, respectively). Only 4.0% of the appendectomy specimens contained other appendiceal pathologies. Appendiceal diverticulitis was the most common inflammatory pathology, contributing to 2.7% of all appendectomies, followed by granulomatous appendicitis. In this series there were eight carcinoid tumours, three adenocarcinomas, two mucinous cystadenomas; tubular adenoma, metastatic deposition, mucinous cystadenocarcinoma and pseudomyxoma peritonei each occurred in one patient only.

CONCLUSIONS. A more focused utilisation of preoperative imaging in females of reproductive age and patients at the extremes of age is suggested. Long-term follow-up should be offered to patients with granulomatous appendicitis and neoplastic appendiceal diseases.

Key words: Appendectomy; Appendicitis; Diagnostic errors; Diagnostic imaging; Granuloma

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OBJECTIVES. To evaluate the efficacy of microsurgical vasoepididymostomy for patients with obstructive azoospermia attending our institutions.

DESIGN. Retrospective study.

SETTING. Division of Urology, Department of Surgery, Queen Mary and Tung Wah hospitals, Hong Kong.

PATIENTS. All patients with obstructive azoospermia due to epididymal obstruction who had undergone microsurgical vasoepididymostomy in the study hospitals from July 2001 to November 2007.

MAIN OUTCOME MEASURES. Causes of epididymal obstruction, operative techniques, patency rates, and pregnancy outcomes of their female partners.

RESULTS. Twenty-two patients with obstructive azoospermia due to epididymal obstruction had undergone 23 microsurgical vasoepididymostomy procedures. The mean age of patients and their female partners was 36 and 30 years, respectively. Six procedures were performed by the Berger's triangulation intussusception technique and 17 by Marmar or Chan's two-suture intussusception techniques. The mean operating time of unilateral and bilateral procedures was 164 and 203 minutes, respectively. The median follow-up duration was 15 months. The overall patency rate was 57%; being 50% and 64% for unilateral and bilateral procedures, respectively. The patency rate of patients with epididymal fluid positive for sperm was 71%. The mean best sperm count was 23.1 million/mL, with forward motility of 19% and normal morphology of 7%. The overall paternity rate was 32%. Natural pregnancy was achieved in three cases and assisted reproduction was used in four.

CONCLUSIONS. Microsurgical intussusception vasoepididymostomy is a viable option for couples with male factor infertility due to obstructive azoospermia. Reasonable patency outcomes were achieved in the present series of cases. Individualised counselling, with expectations based on anticipated surgical outcomes, should be offered to couples before resorting to assisted reproduction.

Key words: Anastomosis, surgical; Azoospermia; Epididymis; Microsurgery; Vasovasostomy

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OBJECTIVE. To explore the correlation and concordance between end-tidal carbon dioxide and arterial carbon dioxide partial pressure, and confirm the experience of the general consensus among service environments.

DESIGN. A prospective cross-sectional analysis.

SETTING. Two respiratory service units in Hong Kong.

PARTICIPANTS. Two hundred respiratory patients were recruited, in whom 219 sets of observations were recorded. Patients deemed to require arterial blood gas determination also had their end-tidal carbon dioxide partial pressure measured at that time, using two LifeSense LS1-9R Capnometers.

MAIN OUTCOME MEASURES. The agreement of end-tidal carbon dioxide partial pressure and arterial carbon dioxide partial pressure was studied by correlation coefficients, mean and standard deviation of their difference, and the Bland-Altman plot.

RESULTS. Overall, the correlation was low and insignificant (r=0.1185, P=0.0801). The mean of the difference was 7.2 torr (95% confidence interval, 5.5-8.9) and significant (P<0.001). The limits of agreement by Bland-Altman analysis were -18.1 to 32.5 torr, which were too large to be acceptable. In the sub-group on room air, the mean difference was reduced to 2.26 torr, the correlation between end-tidal carbon dioxide partial pressure and arterial carbon dioxide partial pressure was 0.2194 (P=0.0068), though statistically significant, the extent of correlation was still low.

CONCLUSION. End-tidal carbon dioxide partial pressure did not show significant correlation or concordance with arterial carbon dioxide partial pressure, especially when supplemental oxygen was used. End-tidal carbon dioxide partial pressure currently cannot replace arterial blood gas measurement as a tool for monitoring arterial carbon dioxide partial pressure. Possible reasons for the discrepancy with previous studies include small sample size in previous studies, lack of research facilities in service settings, and publication bias against negative studies.

Key words: Blood gas monitoring, transcutaneous; Capnography; Critical care; Monitoring, physiologic; Respiratory insufficiency

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