Contemporary Ventilator Management in Patients With and at Risk of ALI/ARDS

Abstract

BACKGROUND:

Ventilator practices in patients at risk for acute lung injury (ALI) and ARDS are unclear. We examined factors associated with choice of set tidal volumes (V_T), and whether V_T < 8 mL/kg predicted body weight (PBW) relates to the development of ALI/ARDS.

METHODS:

We performed a secondary analysis of a multicenter cohort of adult subjects at risk of lung injury with and without ALI/ARDS at onset of invasive ventilation. Descriptive statistics were used to describe ventilator practices in specific settings and ALI/ARDS risk groups. Logistic regression analysis was used to determine the factors associated with the use of V_T < 8 mL/kg PBW and the relationship of V_T to ALI/ARDS development and outcome.

RESULTS:

Of 829 mechanically ventilated patients, 107 met the criteria for ALI/ARDS at time of intubation, and 161 developed ALI/ARDS after intubation (post-intubation ALI/ARDS). There was significant intercenter variability in initial ventilator settings, and in the incidence of ALI/ARDS and post-intubation ALI/ARDS. The median V_T was 7.96 (IQR 7.14–8.94) mL/kg PBW in ALI/ARDS subjects, and 8.45 (IQR 7.50–9.55) mL/kg PBW in subjects without ALI/ARDS (P = .004). V_T decreased from 8.40 (IQR 7.38–9.37) mL/kg PBW to 7.97 (IQR 6.90–9.23) mL/kg PBW (P < .001) in those developing post-intubation ALI/ARDS. Among subjects without ALI/ARDS, V_T ≥ 8 mL/kg PBW was associated with shorter height and higher body mass index, while subjects with pneumonia were less likely to get ≥ 8 mL/kg PBW. Initial V_T ≥ 8 mL/kg PBW was not associated with the post-intubation ALI/ARDS (adjusted odds ratio 1.30, 95% CI 0.74–2.29) or worse outcomes. Post-intubation ALI/ARDS subjects had mortality similar to subjects intubated with ALI/ARDS.

CONCLUSIONS:

Clinicians seem to respond to ALI/ARDS with lower initial V_T. Initial V_T, however, was not associated with the development of post-intubation ALI/ARDS or other outcomes. (ClinicalTrials.gov registration NCT00889772)