Prone Position and Pattern of Oxygenation in Acute Lung Injury Patients

Body position of critically ill patients can have a profound effect on arterial oxygenation. Specifically, the prone position can improve arterial oxygenation in severely hypoxemic acute lung injury (ALI) and Acute Respiratory Distress Syndrome (ARDS) patients without deleterious effects on hemodynamics (Jolliet, 1998). Although hypothesized for many years, evidence was provided only recently that this relatively simple maneuver might play a valuable role in the treatment of acute lung injury (Pappert, 1994). Prone positioning represents a safe, non-invasive therapeutic modality that deserves early consideration in the treatment course of ALI/ARDS. Mortality in this patient population remains greater than 50% and there is no widespread acceptable approach or agent available for the prevention or treatment of severe acute lung injury.

However, current research does not provide consistent data on the pattern of oxygenation, which is required to determine the optimal time to keep patients in the prone position. Therefore, the specific aims of this multi-site, descriptive study will be to examine the pattern of oxygenation in 60 ALI/ARDS patients (PaO2/FiO2 ratio 20 mmHg above baseline. Hemodynamic parameters of heart rate, blood pressure, respiratory rate and compliance, and oxygen saturation will also be monitored.

Descriptive statistics will be performed on all data and graphic display of data will be used to assist in the pattern identification. Trend analysis will be conducted to determine the pattern of oxygenation. A two (ALI without ARDS versus ALI with ARDS) by 7 (times) way repeated measures ANOVA will be used to compare the change in oxygenation for the 2 groups across the time series of measurements.

It is anticipated that the results of this study, along with available data, will facilitate the development of evidence-based guidelines for the frequency of turning patients to and from the prone position and support early, routine use of prone positioning in an appropriately selected population of acute lung injury patients