The impact of positive pressure ventilation on the diagnosis of traumatic diaphragmatic injury.

Initial chest radiography (CXR) has been noted to have limited diagnostic sensitivity to detect acute diaphragmatic injury (ADI). A further confounding variable may be intubation and positive pressure ventilation which may prevent herniation of abdominal organs until weaning is achieved. We sought to determine the impact of positive pressure ventilation on the sensitivity of the initial CXR to identify ADI as well as to document the incidence of late herniation occurring as positive pressure ventilation is weaned. A retrospective chart review of 166 patients over an 8-year period in whom diagnosis of ADI was made on the same admission was performed. Etiology was penetrating trauma in 91 (55%). Eighty-five (51%) patients were intubated and ventilated with positive pressure before the initial chest radiograph. Diagnosis was made within 24 hours in 144 (87%) cases. The ability to correctly identify ADI by CXR was affected by whether or not the patient was intubated (intubated 12% vs nonintubated 27%; P = 0.001), side (right 10% vs left 27%; p = 0.04), and injury size (> 5 cm 81% vs < or = 5 cm 3%, P = 0.02). Late diagnosis was made in 22 cases: eight during surgery, six because of persistent radiographic abnormalities, and six when high levels of ventilator support were decreased with subsequent herniation of stomach above the diaphragm. Two cases were described at autopsy. Diaphragmatic injuries cannot be excluded if patients are intubated. Late diagnosis can be facilitated if chest radiographs are reviewed in sequence as ventilator support is decreased.