Ventilator settings and outcome of respiratory failure in chronic interstitial lung disease

Background: While patients with interstitial lung disease (ILD) may be particularly susceptible to ventilator-induced lung injury, ventilator strategies have not been studied in this group of patients. Purpose: To describe the clinical course and outcome of patients with ILD and acute respiratory failure in relation to ventilatory parameters. Methods: We retrospectively identified a cohort of ventilated patients with ILD who had been admitted to five ICUs at a single institution. We analyzed demographic data, pulmonary function test results, severity of illness, and the parameters of continuous ventilation for the initial 24 h after admission to the ICU. Primary outcomes were survival to hospital discharge and 1-year survival. Main results: Of 94 patients with ILD, 44 (47%) survived to hospital discharge and 39 (41%) were alive at 1 year. Nonsurvivors were less likely to be postoperative, had higher severity of illness, and were ventilated at higher airway pressures and lower tidal volumes. Step changes in positive end-expiratory pressure (PEEP) of > 10 cm H₂O were attempted in 20 patients and resulted in an increase in plateau pressure (median difference, + 16 cm H₂O; interquartile range [IQR], 9 to 24 cm H₂O) and a decrease in respiratory system compliance (median difference, -0.28 mL/kg/cm H₂O; IQR, - 0.43 to - 0.13 mL/kg/cm H₂O). The Cox proportional hazards model revealed that high PEEP (hazard ratio, 4.72; 95% confidence interval [CI], 2.06 to 11.15), acute physiology and chronic health evaluation (APACHE) III score predicted mortality (hazard ratio 1.33; 95% CI, 1.18 to 1.50), age (hazard ratio, 1.03; 95% CI, 1 to 1.05), and low PaO₂/fraction of inspired oxygen ratio (hazard ratio, 0.96; 95% CI, 0.92 to 0.99) to be independent determinants of survival. Conclusion: Both severity of illness and high PEEP settings are associated with the decreased survival of patients with ILD who are receiving mechanical ventilation.