[The effect of epidural anesthesia on prostaglandin synthesis during alveolar hypoxia].

The effect of epidural anesthesia on prostaglandin synthesis during alveolar hypoxia was investigated in 20 patients. Group I received intravenous anesthesia and group II received epidural and intravenous anesthesia. Patients in both groups were intubated with a double-lumen end tracheal tube, allowing separate ventilation of the right lung with 5% CO2, 6% O2 and 89% N2 as a hypoxic challenge and the left lung with 100% O2. In both groups, adequate systemic oxygenation was maintained. Pulmonary artery pressure and pulmonary vascular resistance increased significantly in both groups. Cardiac index decreased significantly in group II. Both 6-keto PGF1 alpha and thromboxane B2 increased in group I, but only 6-keto PGF1 alpha increased in group II. Hypoxic pulmonary vasoconstriction (HPV) stimulated prostaglandin synthesis. 6-keto PGF1 alpha is the major arachidonic acid metabolite released during HPV. The results suggest that epidural anesthesia does not inhibit HPV, but exerts some effects on thromboxane B2 synthesis during alveolar hypoxia.