Changes in the respiratory gas tensions of a pneumonectomy space and their application to the diagnosis of bronchopleural fistula.

The oxygen (pO2) and carbon dioxide (pCO2) gas tensions of a pneumonectomy space were studied in an animal model. The 2 gases were measured in a standard blood gas analyser. The space gas pO2 and pCO2 equilibrated to a steady state within 48 hours of thoracotomy (pO2 mean 53.9 +/- 9.3 SD torr; pCO2 mean 44.8 +/- 9.9 SD torr). In the presence of a bronchopleural fistula (BPF), the pO2 rose significantly (mean pO2 118.4 +/- 13.2 SD torr; p less than 0.001). The space pCO2 usually fell, but the response was inconsistent (mean pCO2 33.6 +/- 16.4 SD; p = NS). A further rise in space pO2 could sometimes be induced by allowing the animals to breathe 100% oxygen by face mask. Data from 4 clinical cases of BPF support the concept that measurement f the space gas pO2 could be used as a bedside test for BPF.