Pulmonary interstitial gas: first sign of barotrauma due to PEEP therapy.

Radiographic identification of pulmonary interstitial gas is a prime indicator of possible further complications in patients treated with PEEP therapy for severe respiratory failure. Records and chest radiographs of 89 adult patients treated with PEEP in a 40-month period were reviewed. Data of 7 were incomplete, 82 cases were analyzed. Of 17 patients who developed interstitial gas, 9 progressed to further barotrauma complications of pneumomediastinum, pneumothorax, and extrathoracic dissection. Interstitial gas is manifested radiographically by vesicular rarefactions (cystic changes), linear streaks along the bronchi and vessels, halos of gas around vessels, and subpleural gas.