Pneumonia: incidence, risk factors, and outcome in injured patients.

One hundred thirty (44.2%) of 294 patients hospitalized for trauma and admitted to the Surgical Intensive Care Unit for mechanical ventilation developed hospital-acquired bacterial pneumonia. The predominant pathogens isolated were gram-negative enteric bacilli (72%), but there was not an increase in mortality associated with gram-negative pneumonia compared with similar patients without pneumonia. Of the seven admission risk factors univariately associated with the development of acquired bacterial pneumonia, only emergent intubation (p less than 0.001), head injury (p less than 0.001), hypotension on admission (p less than 0.001), blunt trauma as the mechanism of injury (p less than 0.001), and Injury Severity Score (p less than 0.001) remained significant after stepwise logistic regression. Not surprisingly, as mechanical ventilation is continued, the probability of pneumonia emerging increases. The consequences of hospital-acquired bacterial pneumonia are a significant seven-, five-, and two-fold increase in mechanically ventilated days, intensive care, and hospital stay, respectively. We conclude that the incidence of hospital-acquired pneumonia in injured patients admitted to the ICU for mechanical ventilation occurs in nearly half the patients, is associated with specific risk factors, and significantly increases morbidity but does not increase mortality.