Outcome predictors of non-invasive positive pressure ventilation in acute respiratory failure.

BACKGROUND Noninvasive positive pressure ventilation (NIPPV) has emerged as a significant advancement in the management of acute respiratory failure. OBJECTIVE To identify factors, based on clinical and laboratory parameters, for predicting the outcome of NIPPV in patients with acute respiratory failure. MATERIALS AND METHODS Fifty patients were included in the study. Inclusion criteria were RR>30 breaths/ min, PaO2<60mmHg, PaO2/FiO2<300, pCO2< or = 45mmHg and signs of increased work of breathing. Baseline clinical parameters and arterial blood gas (ABG) were recorded before initiating NIPPV. Clinical parameters including heart rate, respiratory rate, oxygen saturation and ABG was revaluated at 1, 4, 12, 24 hrs after initiation of NIPPV. Change in these parameters and need for intubation was evaluated. RESULTS Of the 50 patients, 37 (74%) showed clinical and ABG improvement. Out of 13 (26%) patients who failed to respond, 7 (52%) needed endotracheal intubation within 1 hr. There was significant improvement in clinical and ABG parameters within 1st hr in success group and these parameters continues to improve even after 4 hrs of NIPPV treatment (p<0.05). Failure group had higher baseline heart rate than success group (p<0.05). CONCLUSION Determination of baseline clinical factors such as heart rate and respiratory rate, available at the time of initiation and after a short period, can predict the likelihood of success or failure of NIPPV. As a result, delay in intubation can be avoided which itself is associated with significant mortality.