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

Objective

To determine outcome predictors of non-invasive positive pressure ventilation (NIPPV) in patients with hypoxaemic acute respiratory failure (HARF).

Design

Retrospective analysis.

Method

One hundred patients with HARF treated with NIPPV in a 30-bed tertiary care hospital were analysed. A successful outcome of NIPPV was avoiding endotracheal intubation, and failure was considered if intubation was needed. We classified the patients into three etiological subgroups: (1) acute cardiogenic pulmonary edema (ACPE), (2) acute respiratory distress syndrome (ARDS) secondary to sepsis, and (3) miscellaneous group including pulmonary embolism, bronchial asthma exacerbation, postoperative respiratory failure, status post-extubation, etc. We compared various patient variables and parameters among successful and failure groups.

Results

The overall success rate of NIPPV was 56% in avoiding intubation. The success rate in the ACPE, sepsis-related ARDS and miscellaneous subgroups were 71.79%, 29.26% and 80%, respectively. Logistic regression analysis exhibited duration of NIPPV (OR 4.137, P = 0.02), number of organ failures besides the respiratory system (negative coefficient -1.4193) and post-NIPPV PO₂/FiO₂ ratio (P = 0.0342) as significant predictors of outcome of NIPPV. In subgroup analysis of ACPE, left ventricular ejection fraction >30% was a predictor of successful outcome. In subgroup analysis of sepsis-related ARDS, a lower PO₂/FiO₂ ratio and a higher number of organ failures were associated with unfavourable outcome (P = 0.02 and P = 0.0184).

Conclusion

In HARF, ACPE as a cause of ARF, shorter duration of NIPPV, higher post-NIPPV PO₂/FiO₂ ratio and fewer organ failures were associated with a favourable outcome of NIPPV. In subgroup analysis of ACPE, left ventricular ejection fraction >30% was a predictor of successful outcome of NIPPV. In subgroup analysis of sepsis-related ARDS, a lower PO₂/FiO₂ ratio and higher number of organ failures were associated with poorer outcome.