Background: The effect of body position on oxygenation in acute respiratory distress syndrome (ARDS) patients has long been known. Prone position improves the PaO2 in 60-70% of ARDS patients. However, the effect of the lateral positions, which are used in routine critical care, has never been reported.
Objective: To determine whether placing the patient in a lateral position has any effect on oxygenation in ARDS.
Material and Method: Prospective observational study, comparing oxygenation in ARDS patients between supine, right and left lateral positions (>60 degree).
Results: We included 18 ARDS patients, their mean aged was 52.2+19.6 years, 14 were men and the ICU mortality rate was 61.1%. There was no significant change in the mean PaO2, arterial blood gas parameters, respiratory mechanics and hemodynamic parameters between the supine and decubitus positions in the overall group. However, there was a trend toward increasing the mean PaO2 during right lateral position compared with the supine position (90.3+29.0 vs 84.6+20.4, p=0.23). Nine patients who responded to the right lateral position had significantly higher mean PaO2 during the right lateral position than in the supine position (107.8+29.0 vs 85.6+21.8, p<0.0001). In this group, four patients had predominant left pulmonary infiltration and five patients had equally bilateral pulmonary infiltration on chest X-ray. Unfortunately, the PaO2 in three patients decreased more than 10 mmHg during right lateral decubitus.
Conclusion: The PaO2 increased while in the right lateral position in patients with predominant left pulmonary infiltration or bilateral infiltration. This effect may be due to the small sample size. A further large-sized randomized controlled study is needed.

Keywords: Acute respiratory distress syndrome, ARDS, Lateral position, Decubitus posture