Phytohemagglutinin skin testing in critically ill surgical patients

Phytohemagglutinin (PHA) skin tests were performed in 225 critically ill surgical patients with respiratory failure. The study population was composed of 68 trauma patients who had suffered severe multiple injuries and 157 nontrauma patients who had a variety of surgical complications. The initial skin test response, obtained at the beginning of mechanical ventilation, was negative in 31% of the trauma patients and in 49% of the nontrauma patients. In the group of trauma patients, a higher mortality rate was noted in negative initial skin test responders compared with positive initial responders (38 and 15%, respectively; p less than 0.05). In the group of nontrauma patients, no association could be demonstrated between skin test unresponsiveness and mortality. With sequential testing, most (70%) of the patients were found to show at least one negative skin test reaction while in the intensive care unit. There was no difference in mortality between patients who remained reactive to PHA and patients with one or more negative skin test responses. These findings show that surgical intensive care patients frequently have an impaired cellular immunocompetence as indicated by a failed skin test response to PHA. However, PHA skin testing has little or no value in predicting outcome in these patients.