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

Two recent retrospective reports on the incidence of failed spinal anesthetics that indicated extremely variable results prompted the present prospective study of 200 consecutive spinal anesthetics to determine the incidence and causes of failed spinal anesthetics. Tetracaine was the spinal anesthetic agent utilized in all cases--crystalline tetracaine (Niphanoid) in 71% and a 1% solution in 19% of the cases. The failure rate overall was 4%, with all failures being due to anesthetic factors, both technical and pharmacologic. However, only 25% of the failures were due to errors in technique, and 75% were due to errors in judgment with respect to pharmacologic factors (dosage, use of epinephrine, and/or positioning of the patient). Our data, therefore, differ from those of Levy et al. (Anesth Analg 1985;64:705-10), both in terms of failure rate, which is 25% of theirs, and in terms of causation, with our data indicating errors in judgment to be the causative factor three times as often as errors in technique. Presumably, this difference is due to the greater experience in spinal anesthesia that a resident receives at our institution.