Underuse of lung protective ventilation: analysis of potential factors to explain physician behavior

Abstract

Objective: To determine the frequency of use of low-tidal-volume ventilation in appropriate patients with acute lung injury (ALI) and the factors associated with the choice of tidal volume.

Design: Prospective observational cohort study of patients identified with ALI or acute respiratory distress syndrome from September 2000 to November 2002.

Setting: Medical and surgical intensive care unit (ICU) at an academic tertiary-care hospital.

Measurements and main results: Measurements included the proportion for whom the ventilation tidal volume (TV) was <or=7.5 mL/kg predicted body weight (PBW) on days 2, 4, and 7 of ALI and the proportion for whom the ventilation TV was <or=6.5 and <or=8.5 mL/kg/PBW (sensitivity analysis). Demographic and clinical characteristics of patients undergoing ventilation with low and high TV were compared. Of 88 total patients studied, 39% had ventilation with TV <or=7.5 mL/kg/PBW on day 2 of ALI, 49% on day 4, and 56% on day 7. In contrast, 49% of patients had ventilation with TV >8.5 mL/kg/PBW on day 2 of ALI, 30% on day 4, and 24% on day 7. The use of low TV was significantly associated with clinical parameters indicative of worse disease severity, including low values for Pao2 (p = .01), Pao2/Fio2 (p = .08), and static compliance of the respiratory system (p = .006).

Conclusions: Ventilation with a low TV was used in a minority of patients with ALI, despite results published in 1998 and 2000 supporting this approach. This may be related to clinicians' underrecognition of less severe cases of ALI, their reserving of low-TV ventilation for more severe cases, or both.