IDENTIFICATION OF THE EPIDURAL SPACE - IS LOSS OF RESISTANCE TO AIR ASAFE TECHNIQUE - A REVIEW OF THE COMPLICATIONS RELATED TO THE USE OF AIR

Background and Objectives. The major determinant of successful epidura l anesthesia is the localization of the epidural space. The manual los s of resistance technique is widely used by anesthesiologists in ident ifying the epidural space. Should air or saline be used in detecting t he point of loss of resistance? No consensus exists as to which techni que is superior, and individual providers currently use the technique with which they are most comfortable. The incidence of adverse effects associated with the use of epidural air is unknown and may be underre ported as the effects may be unrecognized or considered trivial. The a uthors comprehensively review the complications of epidural air from p ublished reports. Methods. Using the appropriate key words, the author s searched the Medline (National Library of Congress) scientific data bank from 1966 to 1995, for case reports of epidural complications. Re sults. There are few prospective, controlled, double-blinded studies c omparing the relative merits of using air versus saline for the loss o f resistance technique of epidural placement. There are, however, nume rous case reports. Complications associated with the use of air for th e loss of resistance technique included pneumocephalus, spinal cord an d nerve root compression, retroperitoneal air, subcutaneous emphysema, and venous air embolism. Additionally, inadequate analgesia and pares thesia have been associated with the loss of resistance technique usin g air. Transient and permanent neurologic sequelae have been attribute d to some of the complications. The simultaneous administration of nit rous oxide and positive. Pressure ventilation has also been reported t o expand localized collections of air, resulting in heightened symptom s. Conclusions. The potential complications associated with the use of air for identifying the epidural space with the loss of resistance te chnique may outweigh the benefits. The use of saline to identify the e pidural space may help to reduce the incidence of these complications.