What is the recommended treatment for shivering in spinal anesthesia?

Treatment of Shivering in Spinal Anesthesia

Meperidine is the most effective pharmacologic agent for treating shivering during spinal anesthesia, and should be administered at 0.4 mg/kg IV (typically 25-50 mg) when shivering occurs. 1

Stepwise Treatment Algorithm

First-Line: Active Warming

• Initiate forced-air warming devices immediately as the primary intervention, which normalizes patient temperature and reduces shivering while improving patient comfort 1
• Apply warmed blankets and administer warmed IV fluids to prevent further heat loss 2, 3
• Focus warming on extremities (ears, palms, soles) as skin counterwarming reduces the shivering threshold by approximately 4°C for each degree of skin temperature increase 1

Second-Line: Pharmacologic Treatment with Meperidine

• Administer meperidine 0.4 mg/kg IV (typically 25-50 mg) when active warming alone is insufficient 1, 4
• Meperidine is superior to other opioid agonists and agonist-antagonists because it both lowers the shivering threshold and directly suppresses shivering through unique anti-shivering properties 1
• Onset of effect occurs within minutes, with duration lasting 30-60 minutes 5, 6

Alternative Pharmacologic Options

If meperidine is contraindicated or unavailable:

• Nefopam 0.15 mg/kg IV provides equivalent anti-shivering efficacy with more stable hemodynamics, though injection pain occurs in 15.6% of patients 4
• Tramadol can be used as an alternative in resource-limited settings 3
• Low-dose ketamine or dexmedetomidine are additional options, though evidence is less robust for spinal anesthesia specifically 3

Adjunctive Non-Sedating Agents

These should be combined with primary treatments for synergistic effect:

• Magnesium sulfate 2-4 g bolus has minimal side effects but only modest clinical effect when used alone 1, 3
• Acetaminophen as an adjunct, though insufficient as monotherapy 1

Preventive Strategies

• Pre-warm patients for 15 minutes before spinal anesthesia using cotton blankets, gowns, or forced-air warming to reduce shivering incidence 2, 3
• Intrathecal meperidine 0.2 mg/kg added to the spinal anesthetic reduces shivering incidence from 56.7% to 16.7%, though this requires careful consideration of side effects 6
• Prophylactic IV meperidine 25 mg IM given 15 minutes before spinal anesthesia reduces shivering incidence from 56.7% to 10% 5

Critical Pitfalls to Avoid

Treating shivering without addressing hypothermia: The ASA Task Force emphasizes that hypothermia is a common cause of shivering and must be treated by rewarming, not just pharmacologic suppression 1

Using other opioids instead of meperidine: Standard opioids like fentanyl or morphine are significantly less effective than meperidine for shivering suppression 1

Ignoring metabolic consequences: Shivering doubles metabolic rate and nearly triples oxygen consumption, which can trigger demand ischemia in patients with cardiovascular disease or anemia 1, 6

Delaying treatment: Early intervention with active warming prevents progression to severe shivering that requires higher doses of pharmacologic agents 2, 3

Monitoring Requirements

• Continuously monitor core temperature (tympanic or axillary) throughout the procedure 2
• Assess shivering intensity using a standardized scale at regular intervals 1
• Monitor for meperidine side effects including nausea, sedation, and respiratory depression 5, 6
• Maintain normothermia as the goal (>36°C) to prevent shivering recurrence 1, 2