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Unexpected cardiac arrest in spinal anaesthesia.

Spinal anaesthesia has been used for more than a century and is considered as a relatively simple and safe technique. Occasionally unexpected bradycardia and/or asystole may develop during the administration of spinal anaesthesia in apparently healthy and young patients. These situations are often attributed as the consequence of mismanagement of the spinal technique and not due to an intrinsic risk of the technique itself. Although cardiac arrests were sporadically reported as early as the 40s and 50s of the last century (1-3), it was not until 1988 that CAPLAN et al. (4) described 14 unexpected cardiac arrests (UCA) during spinal anaesthesia, collected from the Closed Claims Analysis of the American Society of Anaesthesiologists (ASA). Surprisingly all patients were apparently healthy individuals undergoing minor surgery. Although in some cases previous bradycardia was noticed, in the majority of the cases there were no prodromes. In addition those with UCA showed to be very resistant to apparently well conducted cardio-pulmonary resuscitation with devastating outcomes. The cases extracted from legal files, showed that six patients died in the hospital and among the eight who survived, only one had no neurological sequelae. These cases could be easily defined as Sentinel Events (5) : “An unexpected negative outcome that should not occur under normal situations of medical care ”. Since that historical review, more reports were published (6-8). KOPP et al. (9) reported 181 cases of UCA registered in the data bank of the Closed Claims Analysis of the American Society of Anaesthesiologists. In this review, we are including an update of the current knowledge concerning unexpected cardiac arrests during spinal anaesthesia, with emphasis on physiopathology, prevention and treatment. Extreme bradycardia and cardiac arrest will be considered as synonyms, due to their similarity in pathophysiology. INCIDENCE OF CARDIAC ARRESTS DURING SPINAL ANAES-