Airway pressure release ventilation increases cardiac performance in patients with acute lung injury/adult respiratory distress syndrome

Abstract

Background. The purpose of the present study is to determine whether airway pressure release ventilation (APRV) can safely enhance hemodynamics in patients with acute lung injury (ALI) and/or adult respiratory distress syndrome (ARDS), relative to pressure control ventilation (PCV). Methods. Patients with severe acute lung injury or ARDS who were managed with inverse-ratio pressure control ventilation, neuromuscular blockade and a pulmonary artery catheter were switched to APRV. Hemodynamic performance, as well as pressor and sedative needs, was assessed after discontinuing neuromuscular blockade. Results. Mean age was 58 ± 9 years (n = 12) and mean Lung Injury Score was 7.6 ± 2.1. Temperature and arterial oxygen tension/fractional inspired oxygen (FiO2) were similar among the patients. Peak airway pressures fell from 38 ± 3 for PCV to 25 ± 3 cmH2O for APRV, and mean pressures fell from 18 ± 3 for PCV to 12 ± 2 cmH2O for APRV. Paralytic use and sedative use were significantly lower with APRV than with PCV. Pressor use decreased substantially with ARPV. Lactate levels remained normal, but decreased on APRV. Cardiac index rose from 3.2 ± 0.4 for PCV to 4.6 ± 0.3 l/min per m2 body surface area (BSA) for APRV, whereas oxygen delivery increased from 997 ± 108 for PCV to 1409 ± 146 ml/min for APRV, and central venous pressure declined from 18 ± 4 for PCV to 12 ± 4 cmH2O for APRV. Urine output increased from 0.83 ± 0.1 for PCV to 0.96 ± 0.12 ml/kg per hour for APRV. Conclusion. APRV may be used safely in patients with ALI/ARDS, and decreases the need for paralysis and sedation as compared with PCV-inverse ratio ventilation (IRV). APRV increases cardiac performance, with decreased pressor use and decreased airway pressure, in patients with ALI/ARDS.