Adverse effects of beta adrenergic blockers during spinal anesthesia with 0.5% bupivacaine

Introduction

Protocol for perioperative usage of beta blockers was used in only 9% of major clinics in the USA. It is a very common practice to discontinue beta blockers during the perioperative period or to maximally reduce their doses. The main purpose of this paper is to investigate the incidence of adverse effects of beta blockers during large-scale trauma and orthopedic surgeries in spinal anesthesia.

Methods

In this open prospective study we evaluated the adverse effects of beta blockers in ASA II and III research subjects who received beta blockers 1 to 12 hours preoperatively, n = 37, mean age 67 ± 12, with adjacent metabolic syndrome. Results were compared with the same number of patients and ASA group, mean age 57 ± 18, who have not received beta blockers. Patients from both groups received midazolam premedication 30 minutes before arriving in the operating room and spinal anesthesia with 0.5% bupivacaine. Patient surveillance was conducted by continued EKG, blood pressure, pulse (all non-invasive) and SpO₂ monitoring. Systolic and diastolic pressure and pulse were recorded every 10 minutes. Results were statistically tested (M ± SD, t test).

Results

The results are shown in Figure 1. The group receiving beta blockers shows a higher percentage of patients with hypertension on arrival in the operating room for 11% and hypotension after the start of spinal anesthesia. Occurrence of bradycardia (HR <60/minute) was increased with statistical significance for 24% (P < 0.05), with use of atropine for 27% (P < 0.05). The occurrence of arrhythmias shows a statistical increase in the same group, for 27% (P < 0.05), as well as nausea for 29% (P < 0.05).

Figure 1

Adverse beta blocker effects. 1. Preoperative hypertension. 2. Intraoperative hypotension. 3. Intraoperative bradycardia. 4. Arrhythmia. 5. Nausea. 6. Atropine applied. 7. Ephedrine applied.

Conclusions

Due to their adverse effects, beta blockers should be discontinued before spinal anesthesia and surgical procedures with significant circulating volume loss.