Empyema associated with pneumonia was present in 9 patients, and in 3 patients a subdiaphragmatic septic process was thought to have contributed to empyema. To estimate the incidence of empyema, we used data from the first year that our computer database tracked days of mechanical ventilation. Forty of these patients had blunt trauma, and 4 developed empyema. From these numbers, we estimate that between 5 and 10 per cent of patients with respiratory failure and ventilator dependence after blunt trauma developed empyema. With blunt trauma, making the diagnosis of empyema is more problematic.
Patients often have pulmonary contusions, pleural effusions, atelectasis, or infiltrates.
The possibility of pleural space infection is often not considered. In our experience, fever was not always present, but leukocytosis was frequent. Although frequently abnormal, standard chest radiography was not specific enough to be diagnostic. Most patients only had a pleural effusion, which can have numerous causes in the multiple trauma patient. The CT scan has become a very valuable tool in aiding our diagnosis of empyema in complex, critically ill patients.