Indomethacin and Ketanserin Block Ethchlorvynol-lnduced Hypoxemia in Dogs

Intravenous injection of ethchlorvynol (ECV) leads to hypoxemia and a permeability pulmonary edema. Whether the hypoxemia is directly attributable to the pulmonary edema or caused by release of mediators has not been explored. Three groups of dogs were studied: (1) ECV, (2) indomethacin—ECV, and (3) ketanserin—ECV. In group 1, 25 to 30 mg/kg of ECV caused a significant fall in PaO2 at 4 min (92 ± 12.6 to 77 ± 21 mm Hg, p < 0.05), which persisted throughout the experiment. The P(A-a)O2 gradient widened significantly at 3 min (22 ± 11 to 31 ± 16.8 mm Hg, p < 0.05) and remained abnormal for the remainder of the experiment. There was no significant fall in PaO2 in groups 2 and 3. Lung tissue water to dry weight ratio increased significantly in all groups at 60 min. Lung tissue water to dry weight ratios were normal at 10 min after ECV injection in additional groups. It was concluded that ECV causes hypoxemia, which is mediated by cyclooxygenase products and 5 hydroxytryptamine. This hypoxemia can be prevented by the administration of drugs that block these products.