A protocolized approach to pulmonary failure and the role of intermittent prone positioning

We present a series of adult patients treated under a protocol for severe lung failure (acute respiratory distress syndrome [ARDS]) that uses positive end-expiratory pressure (PEEP) optimization and intermittent prone positioning (IPP) to reduce shunt, improve oxygen (O(2)) delivery, and reduce FiO(2).

Trauma, emergency vascular, and general surgical patients with PaO(2)/FiO)(2) (PF) ratio < 200 were entered into a protocol designed to maintain mixed venous saturation (SVO(2)) > 70% with FiO(2) < 0.50. Therapy involved a sequential algorithmic approach that included pulmonary artery oximetry, "best-PEEP" determination, optimization of cardiac function, limitation of VO(2), transfusion to hematocrit of 35%, frequent bronchoscopy, rational diuresis and, if the FiO(2) was > 0.50, a trial of IPP with every-6-hour rotations. Unstable spine fractures and pelvic external fixators were the only contraindications to IPP. We collected data prospectively and from the charts and trauma registry.

Forty adults were treated by protocol, 29 were injured and 11 had vascular or general surgical primary problems. The patients were 46.3 +/- 3.1 years old (the trauma patients were 42.9 +/- 3.2, and the vascular/general patients were 62 +/- 7.5 years old). Average Injury Severity Score was 25.9 +/- 3.7 and the Murray lung injury score was 2.65 +/- 0.9. IPP was used in all patients including those with recent tracheostomy, open abdomens, laparotomy, thoracotomy, leg external fixators, central nervous system injury, continuous venovenous hemofiltration and extracorporeal membrane oxygenation cannulae, vasopressor therapy, recent chest wall open reduction and internal fixation, and facial fractures. With the initiation of IPP therapy, the PF ratio increased from 132.1 +/- 8.5 to 231.6 +/- 14.2 (p < 0.001), the FiO(2) was decreased from 65.9 +/- 4.0% to 47.0 +/- 1.1% (p < 0.001), and the SVO(2) increased from 75.3 +/- 1.8% to 78.6 +/- 1.6% (p = 0.023). PEEP and static compliance were unchanged. The duration of IPP was 85.6 +/- 14.9 hours (median, 55 hours; range, 12 to 490 hours). Within 48 hours, all patients were on FiO(2) < or = 50. Mortality was 20% (14% for trauma) and none died of ARDS. The only complications of IPP were one case of partial-thickness skin loss from a malpositioned nasogastric tube and a case of transient lingual edema.

IPP was independently responsible for an increase in PF ratio and SVO(2). We effectively and safely used IPP in our patients with ARDS, including many with issues generally considered to be contraindications. IPP and best-PEEP therapy enabled us to wean all of our patients' Fio2 to < or = 0.50 within 48 hours of ARDS onset.