High values of the pulmonary artery wedge pressure in patients with acute lung injury and acute respiratory distress syndrome

Objective. To determine the incidence and severity of pulmonary artery wedge pressure (PAWP) elevation in patients with ALI/ARDS. In addition, to examine the effects of clinical variables on the presence of a high PAWP (>18 mmHg) and the effect of an elevated PAWP on mortality.Design and patients. Post hoc analysis of 120 patients with or at high risk of ARDS, enrolled in a randomized controlled trial of pressure- and volume-limited ventilation. Patients with or at high risk of congestive heart failure were excluded from the original study.Setting. Eight tertiary intensive care units.Measurements and results. Pulmonary artery catheters were inserted at the discretion of the attending physician, and PAWP was collected every 8 h when present. Of 120 subjects 71 (59%) had a pulmonary artery catheter (44 at randomization, 27 later). The mean maximum PAWP reading among patients was 22.5 mmHg (95% CI 21.2–23.8) and mean median was 16.6 mmHg (95% CI 15.6–17.5). Patients who met standard criteria for ARDS were more likely to develop a high PAWP. In a multivariate stepwise logistic regression model a persistently elevated PAWP (median >18 mmHg) was a strong predictor of mortality after correction for baseline differences (OR estimate 6.82; 95% CI 1.66–37.81).Conclusions. We conclude that in this group of patients a PAWP higher than 18 mmHg is common. Mandating a PAWP of 18 mmHg or less may negatively impact clinical trials in which ARDS is an inclusion/exclusion criteria or an endpoint.