Prone ventilation in trauma or surgical patients with acute lung injury and adult respiratory distress syndrome: is it beneficial?

BACKGROUND: To compare the effectiveness of supine versus prone kinetic therapy in mechanically ventilated trauma and surgical patients with acute lung injury (ALI) and adult respiratory distress syndrome (ARDS).
METHODS: A retrospective review of all patients with ALI/ARDS who were placed on either a supine (roto-rest) or prone (roto-prone) oscillating bed was performed. Data obtained included age, revised trauma score (RTS), base deficit, Injury Severity Score (ISS), head Abbreviated Injury Scale score (AIS), chest (AIS), PaO2/FiO2 ratio, FiO2 requirement, central venous pressure (CVP), days on the bed, ventilator days, use of pressors, complications, mortality, and pulmonary-associated mortality. Data are expressed as mean+/-SE with significance attributed to p<0.05.
RESULTS: From March 1, 2004 through May 31, 2006, 4,507 trauma patients were admitted and 221 were identified in the trauma registry as having ALI or ARDS. Of these, 53 met inclusion criteria. Additionally, 8 general surgery patients met inclusion criteria. Of these 61 patients, 44 patients were positioned supine, 13 were placed prone, and 4 patients that were initially placed supine were changed to prone positioning. There was no difference between the groups in age, CVP, ISS, RTS, base deficit, head AIS score, chest AIS score, abdominal AIS score, or probability of survival. The PaO2/FiO2 ratios were not different at study entry (149 vs. 153, p=NS), and both groups showed improvement in PaO2/FiO2 ratios. However, the prone group had better PaO2/FiO2 ratios than the supine group by day 5 (243 vs. 200, p=0.066). The prone group had fewer days on the ventilator (13.6 vs. 24.2, p=0.12), and shorter hospital lengths of stay (22 days vs. 40 days, p=0.08). There were four patients who failed to improve with supine kinetic therapy that were changed to prone kinetic therapy. These patients had significant improvements in PaO2/FiO2 ratio, and significantly lower FiO2 requirements. There were 18 deaths (7 pulmonary related) in the supine group and 1 death in the prone group (p < 0.01 by chi test).
CONCLUSIONS: ALI/ARDS patients who received prone kinetic therapy had greater improvement in PaO2/FiO2 ratio, lower mortality, and less pulmonary-related mortality than did supine positioned patients. The use of a prone-oscillating bed appears advantageous for trauma and surgical patients with ALI/ARDS and a prospective, randomized trial is warranted.