PURPOSE: Protective mechanical ventilation has become the mainstay treatment for hypoxemic respiratory failure secondary to acute lung injury. While patients with interstitial lung disease (ILD) may be more susceptible to ventilator induced lung injury, appropriate ventilator strategies have not been studied in this group of patients.
METHODS: Retrospective review of patients with ILD admitted to five ICUs between February 2002 and March 2005. We extracted information on demographics, pulmonary function tests, cause of ICU admission, and initial 24 hours of continuous ventilator parameters. Protective mechanical ventilation was defined as tidal volume (Vt) <8mL/kg and peak airway pressure <30 cm H2O. Primary outcome was survival to hospital discharge.
RESULTS: Of 75 patients with ILD, 24 (32%) patients had idiopathic pulmonary fibrosis. Mean age was 71±14 years. Causes of ICU admission were respiratory failure 58(77%), sepsis 8(11%), cardiopulmonary arrest 3(4%), cerebrovascular accident 3(4%), myocardial ischemia 2(3%) and pneumothorax 1(1%). While 17 patients initially received noninvasive ventilation, all patients eventually required invasive ventilatory support. 38 patients (51%) survived to hospital discharge. At the time of ICU admission, the PaO2/FIO2 ratio was higher in survivors (381±291) than nonsurvivors (156±92, p=0.001). There were no differences in FEV1, FVC, TLC and DLCO between those who did and did not survive. Subjects with IPF tended to have higher mortality than non-IPF forms of ILD (65% vs 42%, p=0.073). Protective ventilation was applied in 27% of patients but did not improve survival (29% vs 54%, p=0.072). Compared to those who did survive, nonsurvivors received lower Vt (7 vs 9 mL/Kg, p=0.002), had higher peak airway pressures (30 vs 25 cmH2O, p=0.002), higher PEEP (9 vs 6 cmH2O, p=0.001) and higher FIO2 (75% vs 40%, p<0.001).
CONCLUSION: The mortality of mechanically ventilated patients with ILD is high. Conventional lung protective mechanical ventilation was not associated with improved outcome.
CLINICAL IMPLICATIONS: Poor outcome seen in ILD patients with respiratory failure might represent a terminal event after a progressive disease course. Optimal ventilatory strategies for patients with ILD remain uncertain.
DISCLOSURE: Evans Fernandez-Perez, None.