Abstract ID: A17
Abstract Title: Verapamil Does Not Prevent Hypotensive/Bradycardic Events During Shoulder Arthroscopy in the Sitting Position Under Interscalene Block
Poster Type: Poster
ABSTRACT BODY
Introduction: Shoulder surgery in the sitting position under interscalene block is associated with a 17 – 28 % (1,2) incidence of acute hypotension and/or bradycardia. Metoprolol has been shown to significantly decrease the incidence of these events (2). The proposed mechanism for this effect is inhibition of the Bezold-Jarisch reflex by the negative inotropic effects of metoprolol. The authors hypothesized that the negative inotropic effects of verapamil would have a similar preventative effect during this procedure.
Methods: We prospectively randomized and followed 71 patients undergoing shoulder arthroscopy in the sitting position under interscalene block to receive either verapamil 7.5 mg IV or placebo, immediately upon completion of the block. All blocks were performed with 50-60 ml of mepivacaine 1.5% with 1:200,000 epinephrine and 0.1 meq/ml sodium bicarbonate, using the paresthesia technique. A hypotensive bradycardic event (HBE) was defined as a decrease in HR of greater than 30 bpm in less than 5 min, or any decrease in HR to 50 bpm or less, and/or a decrease in SBP of greater than 30 mmHg in less than 5 min, or any decrease in SBP to 90 mmHg or less. If this event was associated (within 30 minutes) with the administration of an anti-hypertensive medication (enaloprilat) or a bolus of propofol, the HBE was discounted. Signs and symptoms such as nausea, lightheadedness, pallor, diaphoresis, or feelings of impending doom were recorded.
Results: There were no demographic differences between the two groups. HBE occurred in 23.9% of patients (17/71). However, the hemodynamic criteria set above occurred in 6 patients who received enaloprilat or propofol within 30 minutes and did not exhibit any signs or symptoms noted above. Therefore, the corrected incidence of HBE was 15.5% (11/71). The corrected incidence of HBE in the control group was 13.9% (5/36) and 17.1% (6/35) in the verapamil group (p = 0.8). All patients were rapidly and successfully treated with atropine, ephedrine, and/or epinephrine. The incidence of intra-operative hypertension requiring treatment with enaloprilat was 17.1% in the verapamil group and 27.8% in the placebo group (p=0.4).
Discussion: Verapamil did not decrease the incidence of HBE during shoulder surgery in the sitting position under interscalene block. Similarly, verapamil has been shown to be less efficacious than metoprolol in preventing tilt table inducible hypotension or bradycardia in patients prone to unexplained syncope (3). Our results suggest that the hemodynamic processes involved in both settings is similar. However, the exact mechanism of HBE in patients undergoing shoulder surgery in the sitting position remains controversial.
References
1. D’Alessio JG, Weller RS, Rosenblum M. Anesth Analg 1995:80:1158-62.
2. Liguori GA, Kahn RL, Gordon J, et al. Anesth Analg 1998;87:1320-5.
3. Jhamb DK, Singh B, Sharda B, et al. American Heart J 1996;132(3):608-11.
ATTACHED FILES
Reg Anesth Pain Med 2004; 29(2):A17