Long acting single injection caudal anesthesia; 1,208 obstetrical deliveries with mepivacaine.

Long acting, single injection caudal anesthesia with mepivacaine was studied in 1,208 obstetrical cases.A 1 per cent solution was used in 671 patients and compared with a 1.5 per cent concentration in 537. No remarkable differences were found between the two groups. The 1 per cent solution provided relief of labor discomfort for from 60 to 180 minutes with an average of 110 minutes. In contrast, the 1.5 per cent solution provided an average of 115 minutes with a range of 80 to 210 minutes.A total volume of 30 ml of anesthetic agent yielded anesthesia to a level of the tenth thoracic vertebra or higher in 91 per cent of patients. Significant alterations in blood pressure were uncommon. About 1 per cent of patients required a vasopressor because of a drop in systolic blood pressure below 80 mm of mercury. Another 8 per cent had a drop of over 20 points in systolic pressure but from high enough levels that they did not require a vasopressor. Toxic effects similar to those of lidocaine were found in slightly more than 1 per cent of cases. This anesthesia requires a higher incidence of operative intervention for delivery.