ACTIVATION OF THE BEZOLD-JARISCH REFLEX IN THE SITTING POSITION FOR SHOULDER ARTHROSCOPY USING INTERSCALENE BLOCK

A retrospective analysis of 116 patients who underwent shoulder arthro scopy in the sitting position with interscalene block (ISB) revealed 2 0 patients who experienced potentially dangerous vasovagal events char acterized by sudden severe hypotension and bradycardia (Group 1). The event occurred 61 +/- 18 min after the block placement. Ninety-six pat ients (Group 2) did not experience a vasovagal event. Of the patients in Group 2, 18 received beta-adrenergic blockers for increasing heart rate and/or arterial blood pressure (Group 2B) while 78 did not (Group 2A). The number receiving beta-adrenergic blockers was significantly greater than in Group 1 (18/96 vs 0/20, P < 0.05). There were no signi ficant demographic or baseline hemodynamic differences between groups, but the beta-adrenergic blocker and vagal groups showed significantly greater intraoperative peak heart rates (P < 0.05). All patients rece ived epinephrine in their local anesthetic for ISB, incision sites, an d articular irrigating solution. Total and weight-corrected epinephrin e doses differed significantly between groups (lowest in Group 2A, P < 0.01). Activation of the Bezold-Jarisch reflex, induced by increased circulating epinephrine levels and the sitting position, is the postul ated mechanism.