Incidence and causes of failed spinal anesthetics in a university hospital: a prospective study.

The failure rates associated with spinal anesthesia using bupivacaine and lidocaine were studied prospectively in 1891 patients. The failure rate was 3.1%, with the most common reason for failure an inadequate level of anesthesia for the surgical procedure. Demographic variables showed no significant correlation with the failures. The primary technical reason for failure was use of a low interspace for the administration of the anesthetic agent. All the anesthetic agents used were found reliable in producing spinal anesthesia.