The effect of ketamine versus tramadol on prophylactic post-spinal shivering in those patients undergoing orthopedic surgery: a prospective cohort study design, 2020

BACKGROUND: Post-spinal shivering is a common complication after spinal anesthesia with a high incidence among orthopedic patients. Untreated shivering may predispose to exacerbation of wound pain, increased metabolic demand, oxygen consumption, and hemostatic dysfunction. Various studies have been done on the effectiveness of preventing post-spinal shivering using ketamine and other drugs. However, little information on better prophylactic agents in terms of effectiveness and availability. Therefore, this study was intended to compare 0.25 mg/kg of Ketamine (K) versus 0.5 mg/kg of Tramadol (T) for the prevention of post-spinal shivering. METHOD: A prospective cohort study design was employed on 516 patients undergoing orthopedic surgery under spinal anesthesia, and they were selected by a consecutive sampling technique. Patients were divided into two groups based on the anesthetist in charge. Patients who received an intravenous prophylactic dose of Ketamine before spinal anesthesia are called Ketamine groups and patients who received Tramadol are called Tramadol groups (control). The severity and incidence of shivering, blood pressure, heart rate, and axillary body temperature were measured and recorded for one hour at 10-min intervals during the intraoperative period. Descriptive statistics, chi-square, independent t-test, and multivariable logistic regression were used. Significance was declared at a p-value lower than 0.05. RESULTS: The overall incidence of post-spinal shivering was 187 (36.2%), of which it was 74 (28.7%) on ketamine and 113 (43.8%) on tramadol with a p-value of 0.001. The incidence of nausea and vomiting was 157 (60.9%) on tramadol and 8 (3.1%) on ketamine, with a p-value of 0.001. Patients aged 18-35 years (AOR 0.08 (0.02, 0.27), 36-55 years (AOR 0.24, 0.07, 0.81), and those patients with a prolonged duration of surgery (AOR 1.47 (1.37-1.58)) were more likely to experience post-spinal shivering. And Low-dose ketamine has a protective effect against developing post-spinal shivering with an AOR of 0.427 (0.28-0.63). CONCLUSION: Low-dose ketamine is more effective in reducing the incidence and severity of shivering after spinal anesthesia. Therefore, we recommend using low-dose ketamine to be effective as a prophylactic for post-spinal shivering in those patients undergoing orthopedic surgery under spinal anesthesia.