Comparative study on the cardio-respiratory change during prostaglandin E1-induced hypotension in the patients in the supine and prone position.

Prostaglandin E(1)-induced hypotension (25% reduction from the preadministration level in mean arterial pressure) was applied to thirteen patients. Eight patients among them were operated in the supine position (group I) and other five in the prone position (group II). The maintenance dose of PGE(1) was considerably lower in group II than in group I (0.067 micro g.kg(-1).min(-1) vs. 0.119 micro g.kg(-1).min(-1)). In group I, there was a significant increase in CI, with a significant decrease in SVRI and PVRI during PGE(1)-induced hypotension. Such a high dose of PGE(1) (0.119 micro g.kg(-1).min(-1)) was considered to have a direct dilating action on the systemic resistance bed as well as on the pulmonary vasculature. It was considered that the suppression of hypoxic pulmonary vasoconstriction could be a mechanism to increase venous admixture during PGE(1)-induced hypotension. In group II, there was no significant increase in CI, and no significant decrease in SVRI and PVRI. PGE(1)-induced hypotension can be safely applied to the anesthetized patients, but we should be careful to apply it to the patients in the prone position, because lower dose of PGE(1) can induce severe hypotension, which is not accompanied by the increase in CI as occurres in the patients in the supine position.