Background: There is paucity of data from India on the use of noninvasive ventilation (NIV) in acute respiratory failure (ARF). In this observational study, we report the indications and outcomes of patients requiring NIV in the respiratory ICU of a tertiary care hospital.
Methods: All patients with ARF requiring NIV were included in the study. NIV was delivered through critical care ventilators, using oronasal mask. The disease severity and new-onset organ dysfunction/failure were calculated using the Acute Physiology and Chronic Health Evaluation (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores, respectively. A multivariate logistic regression model was used to analyze the factors predicting NIV failure.
Results: There were 92 subjects (48 men, 44 women, mean ± SD age 48 ± 17.5 y) who received 101 NIV applications (42 and 59 applications for episodes of hypoxemic and hypercapnic ARF, respectively) during the study period. The most common causes of hypoxemic and hypercapnic respiratory failure were acute lung injury/ARDS (29%) and COPD (29%), respectively. There was significant improvement in heart rate and respiratory rate after 1, 2, and 4 hours, compared to the baseline, in both the groups. Of the NIV applications, 53.5% required endotracheal intubation, with the number being significantly higher in hypoxemic (67%), compared to hypercapnic (44%), ARF (P = .03). The P(aO(2))/F(IO(2)) measured after 1 hour of NIV application had significant impact on outcome in patients with hypoxemic but not hypercapnic ARF. A P(aO(2))/F(IO(2)) of ≤ 146 mm Hg at one hour had a better specificity (85.7% vs 71.4%), versus a P(aO(2))/F(IO(2)) of ≤ 175 mm Hg in predicting NIV failure in patients with hypoxemic ARF. On multivariate logistic regression analysis, baseline APACHE II score, ΔSOFA score, hypoxemic respiratory failure, and change in P(aO(2))/F(IO(2)) at 1 hour from baseline were associated with NIV failure.
Conclusions: NIV was found to be a useful modality in management of patients with hypercapnic versus hypoxemic respiratory failure. The severity of illness at admission, new-onset organ dysfunction, hypoxemic ARF, and delay in improvement in P(aO(2))/F(IO(2)) at 1 hour from baseline are independent predictors of NIV failure.