Common mechanisms and strategies for prevention and treatment of cardiac arrest during epidural anesthesia.

Cardiac arrests continue to occur during epidural anesthesia and frequently result in death or brain damage. Although unintentional "total spinal" anesthesia, respiratory depression, myocardial ischemia, and local anesthetic toxicity can also lead to cardiac arrest, often the arrests do not fit any of these four categories. Many of the unexplained arrests may be attributed to vagal predominance. The evidence for a vagal-linked circulatory mechanism for these arrests is reviewed, and the characteristics that are associated with an increased risk for cardiac arrest during epidural anesthesia are identified. Specific strategies to forestall vagal predominance are discussed. In case these strategies fail, multiple interventions are discussed that should increase the likelihood of a successful resuscitation in the setting of extensive sympathetic blockade.