Factors associated with mortality in acute respiratory failure patients without acute respiratory distress syndrome

Background: Excess tidal volume and driving pressure were associated with increased mortality in patients with acute respiratory distress syndrome (ARDS). Still, the appropriate mechanical ventilation strategy for patients who do not have ARDS needs to be understood. This study aimed to identify risk factors for mortality in acute respiratory failure patients without ARDS. Methods: We included all mechanically ventilated patients who did not meet the criteria for ARDS and were admitted to the medical intensive care unit (ICU) from October 2017 to September 2018. Patients who had tracheostomy before admission, were intubated for more than 24 hours before transfer to ICU, or underwent extracorporeal membrane oxygenation within 24 hours of ICU admission were excluded. Clinical and physiologic data were recorded and compared between survived and non-survived patients. Results: Of 289 patients with acute respiratory failure, 134 patients without ARDS were included; 69 (51%) died within 28 days. Demographics, principal diagnosis, and lung injury score on the first day of admission were not significantly different between survived and non-survived patients. In multivariate analysis, higher peak inspiratory pressure (PIP) during the first 3 days of admission [odds ratio (OR) 1.11, 95% confidence interval (CI): 1.01-1.22, P=0.04], higher sequential organ failure assessment score (OR 1.15, 95% CI: 1.04-1.28, P=0.008) and underlying cerebrovascular diseases (OR 7.09, 95% CI: 1.78-28.28, P=0.006) were independently associated with mortality in these patients, whereas dynamic lung compliance (Cdyn) and respiratory rate were not associated with mortality in the multivariate model. Conclusions: Mortality was high in mechanically ventilated patients without ARDS. Higher PIP is a potentially modifiable risk factor for mortality in these patients, independent of the baseline Cdyn. Underlying cerebrovascular diseases and increased disease severity are also independent factors associated with 28-day mortality.