Noninvasive ventilation for acute hypercapnic respiratory failure: intubation rate in an experienced unit.

Background Failure of noninvasive ventilation (NIV) is common in patients with chronic obstructive pulmonary disease (COPD) admitted to the intensive care unit (ICU) for acute hypercapnic respiratory failure (AHRF). We aimed to assess the rate of NIV failure and to identify early predictors of intubation under NIV in patients admitted for AHRF of all origins in an experienced unit.

Methods Observational cohort study using data prospectively collected over a 3-year period after the implementation of a nurse-driven NIV protocol in a 24-bed medical ICU of a French university hospital.

Results Among 242 patients receiving NIV for AHRF (PaCO₂ > 45mmHg), 67 had cardiogenic pulmonary edema (CPE), 146 had acute-on-chronic respiratory failure (AOCRF) - including patients with COPD (n=99) or another chronic respiratory disease (n=47) - and 29 had non-AOCRF (mostly pneumonia). Overall, the rates of intubation and ICU mortality were respectively 15% and 5%. Intubation rates were 4% in CPE, 15% in AOCRF and 38% in non-AOCRF (p<0.001). After adjustment, non-AOCRF was independently associated with NIV failure, as well as acidosis (pH <7.30) and severe hypoxemia (PaO₂/FiO₂ ≤ 200) after 1 hour of NIV initiation, whereas altered consciousness on admission and ventilatory settings had no influence on outcome.

Conclusion Intubation rate could be reduced to 15% in patients receiving NIV for AHRF, with a mortality rate of only 5%. Whereas the risk of NIV failure is associated with hypoxemia and acidosis after initiation of NIV, it is also markedly influenced by the presence or absence of an underlying chronic respiratory disease.