What is the best approach to manage shivering in a patient with fever, considering their medical history and current health status, including potential renal impairment or gastrointestinal issues?

Management of Shivering in Fever Patients

For fever patients with shivering, initiate treatment with NSAIDs (such as ibuprofen) as first-line therapy, combined with surface counterwarming of extremities; if shivering persists despite these measures, escalate to meperidine 25-50 mg IV, which stops shivering in nearly 100% of patients within 5 minutes. 1

Initial Assessment and Immediate Interventions

Before treating shivering, determine the underlying cause of fever:

• Measure core temperature to confirm fever (≥38.0°C suggests possible infection requiring evaluation) 1
• Assess for infection sources: check wound sites, respiratory status, IV cannula sites for phlebitis, and obtain blood cultures if fever is present 1
• Rule out sepsis if temperature ≥38.0°C with associated shivering, as this requires prompt antibiotics 1, 2

Stepwise Treatment Algorithm

Step 1: Non-Pharmacologic Measures (Initiate Immediately)

• Surface counterwarming of extremities should be started immediately, as this reduces shivering threshold without sedation 1, 3
• Ensure adequate ambient temperature and use warmed IV fluids if the patient is receiving fluid resuscitation 1
• Avoid aggressive external cooling (cold blankets), as this paradoxically increases shivering and oxygen consumption 4

Step 2: First-Line Pharmacologic Therapy

• NSAIDs (ibuprofen or similar) are the preferred initial agents for pain-related or fever-related shivering 5, 1
• Acetaminophen can be added as an adjunct, though insufficient as monotherapy for significant shivering 1, 3
• Magnesium sulfate (2-4 g bolus, then 1 g/h every 2-4 hours) provides additional benefit with favorable safety profile 1, 3

Important caveat: NSAIDs should be avoided in patients with renal impairment, GI bleeding risk, or recent hematemesis 6

Step 3: Escalation for Persistent Shivering

If shivering continues despite Step 1-2 interventions:

• Meperidine 25-50 mg IV is the most effective single agent, stopping shivering in nearly 100% of patients within 5 minutes 1
• Meperidine is approximately 2,800 times more effective at inhibiting shivering than predicted by its analgesic potency alone 1
• Dose reduction required in elderly patients, those with renal/hepatic impairment, or debilitated patients 7

Critical safety considerations for meperidine:

• Exercise caution in patients at risk for seizures, as meperidine lowers seizure threshold 1
• Avoid in patients with significant renal impairment due to accumulation of the active metabolite normeperidine 7
• Use with caution in elderly patients who have slower elimination rates 7

Step 4: Adjunctive Agents for Combination Therapy

• Buspirone 30 mg combined with meperidine can lower shivering threshold to as low as 33°C, providing synergistic benefit 1
• Ondansetron 4-8 mg every 4-8 hours can be used preventatively, though effects are limited 8

Step 5: Refractory Shivering

• Neuromuscular blockade (NMB) is the most effective measure when pharmacologic approaches fail 1
• Before administering NMB, ensure adequate depth of sedation to prevent awareness 5
• NMB is particularly appropriate when shivering control is expected to be transient 1

Special Clinical Contexts

Traumatic Brain Injury or Neurologic Injury

• Shivering reduces brain tissue oxygenation and causes cerebral metabolic stress, potentially negating neuroprotective benefits 5
• When ICP is labile and shivering is detected, neuromuscular blockers should be considered after ensuring appropriate depth of sedation 5
• In self-ventilating patients in subacute phase, permissive hyperthermia may be considered if risk of secondary brain injury from fever is low and shivering cannot be controlled with first-line treatments 5

Patients with Cardiovascular or Respiratory Compromise

• Shivering doubles metabolic rate and nearly triples oxygen consumption, creating significant energy supply-demand mismatch 2, 8
• This can trigger bioenergetic failure with demand ischemia in vulnerable patients 2
• Aggressive shivering control is particularly important in these populations to prevent cardiovascular decompensation 2

Patients with Renal or Hepatic Impairment

• Avoid or reduce doses of meperidine due to accumulation of drug and active metabolites 7
• NSAIDs should be used with extreme caution or avoided in renal impairment, as they can reduce natriuretic effect and worsen renal function 6
• Consider magnesium sulfate and surface counterwarming as safer alternatives 1

Patients with GI Bleeding or Ulcer History

• Absolutely avoid NSAIDs in patients with active hematemesis, history of GI ulcers, or bleeding risk 6
• Proceed directly to meperidine if pharmacologic intervention is needed 1
• Ensure all transfused fluids are warmed to prevent hypothermia-induced coagulopathy 8

Common Pitfalls to Avoid

• Do not use aggressive external cooling (ice packs, cold blankets) as first-line therapy, as this worsens shivering and increases oxygen consumption 4
• Do not rely on acetaminophen or magnesium alone for clinically significant shivering—these are adjuncts only 1
• Do not administer neuromuscular blockers without adequate sedation, as this risks patient awareness and does not address the central thermoregulatory drive 5
• Do not ignore shivering in neurologically injured patients, as it can worsen secondary brain injury 5
• Do not use meperidine as first-line in elderly or renally impaired patients without dose adjustment 7