Incidence of Hypothension and Bradicards during the Spinal Aneshesion in Patients on Beta-Blockers Therapy

Abstract

Introduction: Spinal anesthesia (synonyms: subarachnoidal nerve block, subdural nerve block, subdural anesthesia, lumbar anesthesia, subarachnoid anesthesia) occurs by injection of local anesthetics within the subarachnoid space in the lumbal interspace. 1 It is also called a neuroaxial blockade that represents the primary anesthetic technique in one-third of surgical procedures. 2 A local anesthetic, given in this way, transits blocking the transmission of sensory, motor and autonomic nerve impulses transiently, resulting in the desired effects, sensory and motor blockade, as well as the side effects due to blocking autonomic nerve fibers, when unwanted effects of spinal anesthesia, hyopotension, bradycaria, nausea, vomiting and retention of urine occur. In this paper we examined the effect of spinal anesthesia on cardiovascular functions in patients whose sympathetic tonus is partly suppressed due to the chronic use of β-blockers due to essential hypertension. We wanted to know whether spinal anesthesia is a safe anesthetics technique in this group of patients or their effects are summed up, which would lead to cardiovascular instability that would result in greater use of pharmacological agents for the treatment of hypotension and bradycardia. Aim of the Study: To examine cardiovascular stability during spinal anesthesia in patients on β-blocker therapy and determine the safety of its use in this group of patients. Patients and Methods: After approval by the Ethics Committee of UCC Banja Luka, a prospective, observation study was conducted on 70 patients divided into two groups, aged 35-65 years, and it lasted from June 1st, 2013. until May 31st, 2016. Group N1, a working group, consisted of 35 patients who used beta-blocker, Metoprolol, in chronic therapy due to essential hypertension. The second group was a control group, N2, and it consisted of 35 healthy patients of the same age limit. Patients underwent spinal anesthesia for "bloodless" surgery on the inguines, perineum, urinary bladder, prostate, urethrae and lower extremities. No pregnant women, diabetic patients, kidney, liver and heart disease were involved in the work. Results: The results showed that there were a significantly higher number of patients with a critical drop in blood pressure, in the group of patients undergoing therapy with beta-blockers, ≥30%, and alone with this more frequent use of vasopressor. Likewise, in the group of patients on beta-blocker therapy, significantly more patients developed bradycardia, i.e. a pulse of 50/min, which required the use of Atropine. Conclusion: Spinal anesthesia is not a safe anesthetic technique in patients on beta-blocking therapy