Noninvasive Ventilation in Acute Hypercapnic Respiratory Failure Caused by Obesity Hypoventilation Syndrome and Chronic Obstructive Pulmonary Disease

Rationale: Noninvasive ventilation (NIV) is widely used in episodes of acute hypercapnic respiratory failure (AHRF) in patients with chronic obstructive pulmonary disease (COPD). However, there is no evidence on the efficacy of NIV during similar episodes in obesity hypoventilation syndrome (OHS). Objectives: To compare the efficacy of NIV in episodes of AHRF caused by OHS and COPD. Methods: We prospectively assessed 716 consecutive patients (173 with OHS and 543 with COPD) with AHRF (arterial pH < 7.35 and PaCO2 > 45 mm Hg) treated with a similar protocol of NIV. We defined successful NIV as avoidance of intubation and intensive care unit survival at least 24 hours in the ward. Hospital survivors were followed for 1 year to assess hospital readmission and survival. Measurements and Main Results: Both groups had similar (mean +/- SD) baseline respiratory acidosis (arterial pH, 7.22 +/- 0.08; Pa-CO2, 86 +/- 21 mm Hg). Patients with OHS were older (74 +/- 11 vs. 71 +/- 10 yr; P < 0.001); were more frequently female (134, 77% vs. 66, 12%; P < 0.001); had less late NIV failure (12, 7% vs. 67, 13%; P = 0.037); had lower hospital mortality (10, 6% vs. 96, 18%; P < 0.001); and had higher 1-year survival (odds ratio, 1.83; 95% confidence interval, 1.24-2.69; P = 0.002). However, survival adjusted for confounders (adjusted odds ratio, 1.41; 95% confidence interval, 0.70-2.83; P = 0.34), NIV failure (11,6% vs. 59, 11%; P = 0.11), length of stay, and hospital readmission were similar in both groups. Among patients with COPD, obesity was associated with less late NIV failure and hospital readmission. Conclusions: Patients with OHS can be treated with NIV during an episode of AHRF with similar efficacy and better outcomes than patients with COPD.