Oxygen toxicity in normal and anoxic ventilated perfused canine lungs

Oxygen toxicity was studied in 26 canine isolated, perfused lung lobes which included nine control lobes, 13 lungs ventilated with FIO2 1.0 for 4 hours, and four lobes ventilated with FIN2 1.0 for 1 hour prior to 4 hours of FIO2 1.0 to evaluate the postulated protective effect of anoxia. A significant increase in wet weight was seen in the O2 ventilated lungs which did not alter pulmonary capillary isogravimetric pressure (PCI), alveolar-arterial oxygen gradient, or pulmonary vascular resistance. In contrast, preliminary N2 ventilation resulted in a significant increase in PCI and greater weight gain while pulmonary vascular resistance was reduced. Pulmonary compliance was reduced minimally in all groups. Anoxic ventilation not only failed to protect the isolated canine lung from presumed increased capillary permeability of oxygen toxicity, but seemed to contribute to the formation of interstitial pulmonary edema.