Carbon dioxide excretion via bronchopleural fistulas in adult respiratory distress syndrome.

Expired gas and gas leaked via thoracostomy tubes was collected in nine patients with the adult respiratory distress syndrome (ARDS) and bronchopleural fistulas. Mean minute ventilation in the group was 23.9 +/- 7.5 L/min with 31 +/- 23 percent of the gas escaping via the leak. Carbon dioxide was present in the leaked gas in every patient, with the fraction of CO2 excreted via the leak highly correlated with the fraction of minute ventilation exiting via the leak (r = 0.86, p less than 0.005). Mean concentration of CO2 in leaked gas was 1.3 +/- 0.5 percent. We conclude that some of the gas leaked via a bronchopleural fistula in such patients participated in gas exchange.