Incidence and risk factors of pneumonia acquired in intensive care units. Results from a multicenter prospective study on 996 patients

OBJECTIVE: To estimate the incidence of pneumonia acquired in the intensive care unit (ICU), and to define risk factors for developing such an event. DESIGN: European prospective survey, in which all patients admitted to the participating ICU from January, 17 to 23, 1990, were followed until ICU discharge. SETTING: 107 general ICUs from 18 countries. PATIENTS: Of 1078 admitted to the ICUs, 996 patients without pneumonia at admission were studied. MEASUREMENTS: Pneumonia was diagnosed by the staff physician on the basis of clinical, radiological and microbiological criteria, secondly validated by an expert committee who reviewed all the forms and even recontacted ICU physicians. Crude incidence and time to occurrence of pneumonia were estimated, then both used as end-points for prognosis analysis. RESULTS: 89 pneumoniae were observed: crude incidence was estimated at 8.9% 7-day and 14-day pneumonia rates at 15.8% and 23.4%, respectively. The risk of developing pneumonia increased when either coma, trauma, respiratory support, Apache II > 16 and/or imparied air-way reflexes were present at ICU admission. To predict time to occurrence of pneumonia, only two variables remained significant: the presence of impaired airway reflexes at admission and the use of mechanical ventilation during ICU course. CONCLUSIONS: The role of the injury to the respiratory system-with the subsequent need for respiratory support--appears central in determining the risk to acquire pneumonia in ICU. In the future, the predictive value of severity scores during ICU course should be otherwise assessed.