Comparison of incomplete (135°) and complete prone position (180°) in patients with acute respiratory distress syndrome.: Results of a prospective, randomised trial

Background. Ventilation in the prone position is carried out for improvement of pulmonary gas exchange in patients with acute respiratory distress syndrome (ARDS). We compared the effects of an incomplete prone position (IPP 135) with a complete prone position (CPP 180) in patients with ARDS. Patients and methods. For this trial 59 patients with ARDS were randomly assigned and were positioned in a cross-over design: patients of group A were placed in IPP for 6 h and then immediately positioned in CPP for another 6 h. Patients in group B were positioned in reverse order. Blood gases, hemodynamic measurements, quasistatic respiratory compliance and assessments of side effects were performed before begin, 30 min and 6 h after first positioning, then 30 min and 6 In after second positioning and 2 after repositioning. Results. Turning patients in IPP and CPP resulted in a significant increase in the arterial oxygenation index (p(a)O(2)/F1O2), but this effect was more pronounced in the CPP (before: 142 46 mm Hg, 6 h: 253 107 mm Hg) than in the IPP (before: 139 54 mm Hg, 6 h: 206 75 mm Hg), and compliance was improved only in CPP. The improvement in arterial oxygenation persisted 2 h after repositioning in the supine position in both groups. The oxygenation responder rate was lower during the IPP (70.3%) in comparison with the UP (84.0%, p < 0.05). The incidence of side effects tended to be increased during the CPP. Conclusion. Incomplete prone position improves oxygenation in ARDS patients, but less effectively than a classic CPP. In these patients the use of a UP should be preferred.