SHORT-TERM EFFECTS OF PRONE POSITION IN CRITICALLY ILL PATIENTS WITH ACUTE RESPIRATORY-DISTRESS SYNDROME

Objective: Changing the position from supine to prone is an emerging s trategy to improve gas exchange in patients with the acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the a cute effects on gas exchange, hemodynamics, and respiratory system mec hanics of turning critically ill patients with ARDS from supine to pro ne. Design: Open, prospective study Setting: General intensive care un its. Patients: 23 patients [mean age 56 +/- 17 (SD) years] who met ARD S criteria and had a Lung Injury Score > 2.5 (mean 3.25 +/- 0.3). Inte rventions: The decision to turn a patient was made using a protocol ba sed on impaired oxygenation despite the use of positive end-expiratory tory pressure and a fractional inspired oxygen (FIO2) of 1. Measureme nts and results: We measured gas exchange and hemodynamic variables in all patients and in 16 patients calculated respiratory system complia nce when they were supine and 60 to 90 min after turning them to a pro ne position. This latter position was remarkably well tolerated, and n o clinically relevant complications or events were detected either dur ing turning or while prone. The partial pressure of oxygen in arterial blood (PaO2)/FIO2 ratio improved from 78 +/- 37 mm Hg supine to 115 /- 31 mm Hg prone (p < 0.001), and intrapulmonary shunt decreased from 43 +/- 11 to 34 +/- 8 % (p < 0.001). Cardiac output and other hemodyn amic parameters were not affected. Respiratory system compliance sligh tly improved from 24.7 +/- 10.2 ml/cmH(2)O supine to 27.8 +/- 13.2 ml/ cmH(2)O prone (p < 0.05). An improvement in PaO2/FIO2 of more than 15 % from changing from supine to prone was found in 16 patients (respond ers). Responders had more hypoxemia (PaO2/FIO2 70 +/- 23 vs 99 +/- 53 mm Hg in non-responders, p < 0.01), more hypercapnia (partial pressure of carbon dioxide in arterial blood (70 +/- 27 vs 64 +/- 9 mm Hg, p < 0.01), and a shorter elapsed time to the onset of ARDS and turning to the prone position (11.8 +/- 16 vs 32.8 +/- 42 days, p < 0.01). Concl usions: Turning critically ill, severely hypoxemic patients from the s upine to the prone position is a safe and useful therapeutic intervent ion. Our data suggest that prone positioning should be carried out ear ly in the course of ARDS.