CLINICAL RISK-FACTORS FOR PULMONARY BAROTRAUMA - A MULTIVARIATE-ANALYSIS

Previous investigations have suggested that elevated airway pressures increase the risk of ventilator-induced pneumothorax. However, risk fa ctor analysis using multivariate techniques has not been done. We inve stigated the hypothesis that airway pressures would not independently correlate with pneumothorax when underlying disease was considered. Al l ventilated patients over a 1 yr period in the Hohenburg Critical Car e Unit at the University of Alabama were followed until death or disch arge from the ICU. Ventilator data were collected daily and the presen ce of pneumomediastinum and pneumothorax determined by review of chest radiographs. Maximal values of airway pressures, minute ventilation, tidal volume, and respiratory rate, as well as age, sex, and underlyin g disease, were entered into logistic regression analysis. A total of 168 patients was studied, and 20 experienced pneumothorax. Multivariat e analysis of the entire ventilated population revealed that only the presence of ARDS independently correlated with pneumothorax. A similar analysis performed on the ARDS population revealed independent correl ation only with male sex. Trends toward elevation in airway pressures were seen that did not reach statistical significance. We conclude tha t development of pneumothorax is most closely correlated with underlyi ng disease, specifically ARDS, and that the associations previously no ted between airway pressures and barotrauma largely relate to the occu rrence of high airway pressures in ARDS.