ARTERIAL OXYGENATION DOES NOT PREDICT THE OUTCOME OF PATIENTS WITH ACUTE RESPIRATORY-FAILURE NEEDING MECHANICAL VENTILATION

One hundred and eighteen patients consecutively submitted to mechanica l ventilation during a one year period, and admitted to the Respirator y Intensive Care Unit of the Hospital Clinic of Barcelona, were prospe ctively studied in order to define the importance of hypoxaemia as a p redictor of mortality. Using a discriminant multivariate analysis, the following variables were selected as the best predictors of outcome: 1) the number of associated complications (NAC) on admission; 2) the s implified acute physiologic score (SAPS); 3) oxygenation index (PAO(2) - AaPO(2))/PAO(2) + 0.014 positive end-expiratory pressure (PEEP); an d 4) the age of the patients. Using these predictors, 84% of the patie nts were accurately classified as survivors or as nonsurvivors. The pa rtial contribution of each predictor to the model was also assessed us ing a logistic regression, by eliminating each single predictor and ea ch possible pair of predictors. Using this means of analysis, the NAC and SAPS were the only predictors of mortality. The inclusion of short -term mechanically-ventilated patients did not bias the accuracy of pr ediction.