Use of non-invasive positive-pressure ventilation for acute respiratory failure: prospective study

MT Cheung, LYC Yam, CW Lau, CK Ching, CH Lee
Department of Medicine, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong

OBJECTIVE. To study the effectiveness and safety of non-invasive positive-pressure ventilation in the management of acute respiratory failure.

DESIGN. Prospective study.

SETTING. Regional public hospital, Hong Kong.

PATIENTS. One hundred and eighty-nine haemodynamically stable adult Chinese patients with acute respiratory failure (119 men and 70 women; mean age, 71.2 years [range, 18-92 years]) who were treated with non-invasive positive-pressure ventilation as the primary mode of ventilatory assistance from 1 January 1996 to 31 December 1998.

MAIN OUTCOME MEASURES. Arterial blood gas measurements, respiratory rate, airway pressures used, use of endotracheal intubation, and standardised mortality ratio.

RESULTS. Fifty-two patients had hypoxaemic respiratory failure (group I); 97 had hypercapnic respiratory failure (group II); and 40 had either type with advanced co-morbidities and were not planned to receive endotracheal intubation (group III). For groups I and II, the overall mean duration of non-invasive positive-pressure ventilation was 56.2 hours. Improvements in gas exchange were seen in approximately 71% of these patients, endotracheal intubation was not needed for 82%, and the standardised mortality ratio was 0.86. The hospital survival rate was approximately 93% in non-intubated patients and 41% in intubated patients. Predictors of success were reduction in respiratory rate within 6 hours (P<0.005), and (for hypercapnic respiratory failure) increased pH and reduced arterial carbon dioxide tension within 24 hours (P<0.005). Patients with pneumonia had significantly higher failure rates (P<0.05). Group III patients were older, had higher Acute Physiology and Chronic Health Evaluation II scores, and required longer ventilatory support, but their gas exchange response rate was 68%. The only complication of treatment was minor facial skin abrasions.

CONCLUSION. Non-invasive positive-pressure ventilation is effective in treating haemodynamically stable patients with acute respiratory failure and causes few and minor complications.

Hong Kong Med J 2000;6:361-7

Key words: Intubation, intratracheal; Lung disease, obstructive; Positive-pressure respiration; Respiratory distress syndrome, adult; Treatment outcome