A retrospective study of the incidence and causes of failed spinal anesthetics in a university hospital.

One hundred sequential spinal anesthetic procedures were reviewed retrospectively to study specifically the incidence and causes of spinal anesthesia. Variables examined included the patient population, the technical aspects of performing subarachnoid tap and subsequent blockade, and the level of training of the anesthetists. We found a 17% incidence of spinal failure, defined as the need to use general anesthesia during the surgical procedure. Failure was found to be significantly associated with a lack of free flow of cerebral spinal fluid, the use of tetracaine without epinephrine, and an increased administration of intravenous supplementation. Forty-one% of the failures represented errors in judgement, either in not properly anticipating the duration of surgery or injecting local anesthetic solution in the absence of a free flow of cerebral spinal fluid. An incidental finding was the lack of documentation in many of the variables examined. We attribute the high incidence of failed spinal anesthesia mainly to technical reasons, most of them avoidable. The use of local and regional anesthesia requires considerable technical skills and demands a precise and total understanding of regional anatomic relationships. With the decreasing use of regional anesthesia in our operating rooms, only those regional anesthesia techniques that require minimum dexterity, such as spinal and epidural anesthesia, continue to be utilized widely; and even these techniques, safe as they are, are being poorly taught.