DefinePK

Abstract

Background: Post-spinal anesthesia shivering is a frequent and distressing complication that may impair postoperative recovery, increase oxygen consumption, and induce cardiovascular instability. It affects up to 70% of patients receiving regional anesthesia, particularly during abdominal or lower limb surgeries. Effective pharmacologic management is essential to reduce its physiological burden and enhance patient comfort. Ketamine and tramadol have both demonstrated anti-shivering properties through distinct mechanisms, yet their comparative effectiveness remains under-explored.
Objective: To compare the prophylactic efficacy and safety of intravenous ketamine and tramadol in preventing shivering during spinal anesthesia.
Methods: This randomized comparative study included 110 adult patients (aged 18–60 years) undergoing elective lower abdominal or lower limb surgery under spinal anesthesia. Patients were randomly assigned to receive either intravenous ketamine 0.25 mg/kg (n=55) or tramadol 0.5 mg/kg (n=55) immediately after spinal block with 3 mL of 0.5% hyperbaric bupivacaine. Shivering intensity was recorded using a validated 5-point scale at baseline, and at 5, 10, 15, and 20 minutes post-administration. Core temperature was monitored tympanically. Adverse effects such as hypotension, hallucinations, and gastrointestinal disturbances were documented.
Results: At 20 minutes, 81.8% of ketamine patients and 89.1% of tramadol patients exhibited no shivering (score 0). However, moderate to severe shivering (scores 5–8) was more common in the tramadol group (25.5%) than in the ketamine group (1.8%). At 10 minutes, 65.5% of ketamine patients had no shivering compared to 78.2% in the tramadol group. Ketamine showed superior control during early intraoperative periods with fewer adverse events.
Conclusion: Both ketamine and tramadol effectively reduced intraoperative shivering during spinal anesthesia. Ketamine offered more consistent control with fewer moderate to severe cases, suggesting it as the preferable agent, especially in high-risk patients.