What are the best management strategies for shivering in a patient with central fever who is being cooled?

Shivering Management in Central Fever During Active Cooling

Use a stepwise multimodal approach starting with non-pharmacologic surface counterwarming and acetaminophen/magnesium, escalating to meperidine (25-50 mg IV) as the most effective single agent, and reserving neuromuscular blockade for refractory cases only after adequate sedation is established. 1

Initial Non-Pharmacologic Interventions

• Initiate surface counterwarming immediately by warming extremities (particularly ears, palms, and soles) to reduce the shivering threshold by approximately 4°C per degree of mean skin temperature increase. 1
• Ensure adequate ambient room temperature and use warmed intravenous fluids if the patient is receiving fluid resuscitation. 2, 3
• These measures should be implemented before or concurrent with pharmacologic therapy, as they have minimal adverse effects and can reduce medication requirements. 4

Pharmacologic Management Algorithm

First-Line Adjunctive Agents

• Administer acetaminophen as a non-sedating adjunct, though recognize it is typically insufficient alone for clinically significant shivering. 1
• Consider magnesium sulfate (2-4 g bolus, then 1 g/h infusion) maintaining serum levels below 4 mg/dL for safety, though its effect on shivering threshold is modest. 1
• These agents are safe and should be used routinely but never as monotherapy for significant shivering. 1, 3

Second-Line: Meperidine (Drug of Choice)

• Meperidine 12.5-50 mg IV is the single most effective pharmacologic agent, stopping shivering in nearly 100% of patients within 5 minutes. 1, 2
• Meperidine is approximately 2,800 times more effective at inhibiting shivering than predicted by its analgesic potency alone, uniquely lowering the shivering threshold while directly suppressing shivering. 1, 2
• Critical caveat: The active metabolite is associated with neurotoxicity and decreases seizure threshold, so use with caution in patients at risk for seizures or those not continuously monitored. 1

Enhanced Combination Therapy

• For aggressive temperature management, combine meperidine with high-dose buspirone (30 mg every 8 hours) to reduce the shivering threshold to as low as 33°C through synergistic effects. 1, 5
• Buspirone can be used preventatively without primary sedation concerns, though it does lower seizure threshold and requires continuous monitoring when combined with meperidine. 1, 5

Alternative Sedative/Analgesic Approach

If meperidine is contraindicated or additional sedation is needed:

• Use an analgesic-first approach with moderate-dose continuous opioid infusion (fentanyl or hydromorphone). 1
• Add short-acting sedative (dexmedetomidine or propofol infusion) titrated to minimum dose that suppresses shivering. 1
• All opioids and sedatives blunt shivering but at the expense of sedation and potential hemodynamic compromise—balance carefully in hemodynamically unstable patients. 1

Last Resort: Neuromuscular Blockade

• Neuromuscular blockade (NMB) is the most effective abortive measure for refractory shivering when less aggressive measures fail. 1, 3
• Cisatracurium (0.1-0.2 mg/kg bolus, then 0.5-10 μg/kg/min infusion) is preferred due to non-enzymatic plasma degradation, making it safe in renal and hepatic impairment. 1
• Critical safety requirement: Never administer NMB without adequate sedation, as this risks patient awareness and does not address central thermoregulatory drive. 3
• Titrate to minimum dose that suppresses shivering and maintains goal temperature, not necessarily to train-of-four targets. 1
• Monitor with continuous EEG during NMB as it masks clinical seizure manifestations, risking delayed recognition and treatment. 1

Special Considerations for Central Fever

• Shivering in central fever patients doubles metabolic rate and nearly triples oxygen consumption, creating significant energy supply-demand mismatch that can worsen secondary brain injury. 1, 3
• In patients with labile intracranial pressure (ICP) where shivering is detected, have a lower threshold to initiate NMB after ensuring appropriate sedation depth. 3
• Rule out infection as a concurrent cause of fever and shivering—obtain blood cultures if temperature ≥38.0°C and consider empiric antibiotics if sepsis is suspected. 2, 3

Common Pitfalls to Avoid

• Do not rely on acetaminophen or magnesium alone for clinically significant shivering—these are adjuncts only and insufficient as monotherapy. 1, 3
• Do not use propofol or dexmedetomidine as first-line agents in hemodynamically unstable patients due to higher risk of hypotension; minimize sedative doses and have lower threshold for NMB in shock states. 1
• Avoid long-acting benzodiazepines (midazolam, lorazepam) as they are highly deliriogenic, cause delayed awakening, and accumulate during temperature management. 1
• Do not ignore shivering in neurologically injured patients—it reduces brain tissue oxygenation and causes cerebral metabolic stress, potentially negating neuroprotective benefits of cooling. 3