[Four cases of cardiac arrest during spinal anesthesia].

Incident rates of cardiac arrest are reported as being from 0.54 to 17.5 per 10,000 (0.54-17.5/10,000) spinal anesthesia patients. In our hospital, four cases of cardiac arrest occurred in 903 spinal and combined spinal and epidural anesthesia patients over 15 months (44.3/ 10,000). Common denominators were ages below 60 years, ASA-PS 1, rapid onset of T10 blockade within 2 minutes and leg raising from 3 to 6 minutes after administration of hyperbaric bupivacaine and T4 blockade. All patients recovered without any side effects. The conditions suspected of causing strong bradycardia leading to cardiac arrest are thought to be maintained parasympathetic activity, lack of blood volume before anesthesia, rapid progress of spinal blockade, decreased blood return to the heart by high spinal blockade (T4) and protective cardiac parasympathetic reflex (Bezold-Jarisch reflex).