Severe oxygen toxicity in patients with bleomycin lung

Nineteen patients who had been treated with high doses of bleomycin were submitted to surgical procedures of considerable magnitude and duration. Some of these patients received anesthesis with N₂0/O₂ in the usual proportions of 6 to 4 liters/minute; in others the proportion was 7.5 to 2.5 liters/minute or less. Fluids infusion rate and balance/duration of surgery, variations of alveolar arterial oxygen gradient were monitored. Of the 19 patients treated, 14 survived and 5 died in the immediate postoperative period. The cause of death was diffuse interstitial pneumonia. In no cases could viral or bacterial causative agents be found. Histopathological findings were consistent with the general picture of adult respiratory distress syndrome. Statistical evaluation of all parameters considered suggests that oxygen was the major causative agent. Patients who survived were exposed to an average oxygen concentration of 0.26 as opposed in 0.39 in those who died, with a statistical significance .001. This data was confirmed by several more statistical tests. The variations in alveolar arterial oxygen gradient before and after surgery was significantly higher in those who died as opposed to those who survived and correlated with the FiO₂ used during surgery. Bleomycin is usually responsible for an interstitial fibrosis. It seems that although clinically insignificant, the lung lesion can be severely enhanced by levels of oxygen that would be otherwise safe even for long periods of time in normal patients. Some of the possible causes are explored and suggestions for therapy are offered.