Role of Prophylactic Intramuscular Glycopyrrolate in Preventing Hypotension and Bradycardia in Patients Undergoing Elective Lower Limb Surgeries under Spinal Anaesthesia: A Randomised Placebo-controlled Study

Introduction: Spinal anaesthesia is an extensively used anaesthetic technique for infraumbilical surgeries. Despite its many advantages, hypotension and bradycardia are two common complications. The incidence of bradycardia following spinal anaesthesia is higher in young adults. Although a few previous studies have observed that intramuscular glycopyrrolate is effective in preventing spinal-induced bradycardia and hypotension in elderly and parturient patients, there is a lack of reported studies in the young population. Aim: To evaluate the role of intramuscular glycopyrrolate in the prevention of bradycardia and hypotension in adult patients undergoing lower limb surgeries. Materials and Methods: A randomised, parallel-group, doubleblind, placebo-controlled study was conducted in the Department of Anaesthesiology at Calcutta National Medical College, Kolkata, West Bengal, India. The duration of the study was 15 months, from July 2021 to September 2022. A total of 60 patients aged 18-45 years, of either sex, with American Society of Anaesthesiologists (ASA) physical status I and II, undergoing elective lower limb surgeries under spinal anaesthesia. The patients were randomised into two groups: group G received intramuscular glycopyrrolate 1 mL (0.2 mg) and group N received intramuscular normal saline 1 mL 15 minutes prior to spinal anaesthesia. Hyperbaric bupivacaine (0.5%) 3 mL and fentanyl (25 mcg) 0.5 mL were injected intrathecally. Haemodynamic parameters were monitored. All data were analysed using appropriate statistical tests. A p-value of <0.05 was considered statistically significant. Changes in Heart Rate (HR) were considered the primary outcome variable. The secondary outcome variables were changes in Mean Arterial Pressure (MAP), incidence of bradycardia and hypotension, phenylephrine requirement, and incidence of dry mouth. Results: The mean age of the study participants of group G and group N was 34.17 years and 33.63 years. The two groups were comparable in terms of demographic profile. In comparison to group N, patients in group G showed a significantly higher HR throughout the intraoperative period (p<0.001) and at 60 minutes in the postoperative period. The incidence of hypotension was significantly higher in group N (53.33%) compared to group G (3.33%, p<0.001), and the MAP was lower in group N compared to group G in the intraoperative period. The number of patients requiring phenylephrine was also higher in group N (53.33%) compared to those in group G (3.33%). Conclusion: Prophylactic use of intramuscular glycopyrrolate can maintain stable haemodynamics in patients undergoing lower limb surgeries under spinal anaesthesia. It can maintain a higher HR and reduces the incidence of hypotension following spinal anaesthesia.