What is the cause and management of shivering in elderly adults?

Shivering in Elderly Adults: Causes and Management

Primary Causes to Evaluate

In elderly adults, shivering most commonly results from infection/sepsis, hypothermia (including iatrogenic causes), or medication effects, and requires immediate assessment of core temperature and infection markers. 1

Physiological Mechanisms

• Thermoregulatory shivering occurs when core temperature drops below 35.5–36°C, triggered by the hypothalamic preoptic region 2
• Shivering doubles metabolic rate and nearly triples oxygen consumption, creating significant cardiorespiratory stress particularly dangerous in elderly patients 2, 3
• The metabolic cost can trigger bioenergetic failure and demand cerebral ischemia in vulnerable older adults 2

Critical Causes Requiring Immediate Action

Infection/Sepsis:

• Shivering with temperature ≥38.0°C suggests infection requiring prompt evaluation 1
• Respiratory and wound infections are common culprits in elderly populations 1

Hypothermia:

• Measure core temperature using esophageal, nasopharyngeal, or pulmonary artery catheter (most accurate methods) 2
• Rectal and bladder temperatures lag behind true core temperature and should not be relied upon 2
• Elderly patients are particularly vulnerable due to age-related autonomic changes and decreased fluid conservation 2

Medication-Related:

• Review all medications for tremor-inducing or shivering-provoking agents 4
• Recent reduction in sedatives can unmask shivering response 1
• Polypharmacy assessment is essential given altered pharmacokinetics in elderly patients 4

Management Approach

Step 1: Initial Assessment and Stabilization

• Measure core temperature using esophageal or nasopharyngeal probe (not rectal/axillary) 2
• Check vital signs including orthostatic measurements, as elderly patients with syncope often have multifactorial causes 2
• Obtain infection markers: Complete blood count, lactate, procalcitonin if sepsis suspected 1
• ECG to rule out cardiac causes, particularly in patients >60 years with known heart disease 2

Step 2: Non-Pharmacologic Interventions (First-Line)

Implement these immediately before escalating to medications: 5, 6

• Skin counterwarming using air-circulating blankets to reduce afferent temperature signals 2, 6
• Environmental warming to minimize heat loss 5
• These methods have minimal adverse effects and should be used in all patients 5

Step 3: Pharmacologic Management (Stepwise Escalation)

For elderly patients, start with least sedating agents and escalate only as needed: 7, 5

Tier 1 - Preventive/Minimal Sedation:

• Acetaminophen 650-1000 mg (initiate before shivering onset) 5
• Buspirone 30 mg every 8 hours (preventive, synergistic with other agents but lowers seizure threshold) 2, 5
• Magnesium sulfate 2-4 g bolus, then 1 g/h infusion (safe at levels <4 mg/dL) 2, 5

Tier 2 - Moderate Sedation:

• Meperidine is the drug of choice, providing greatest reduction in shivering threshold 6
• Dexmedetomidine 0.2-0.7 mcg/kg/h (lower delirium risk but causes hypotension; use cautiously in elderly with cardiovascular disease) 2, 7
• Fentanyl as alternative opioid 6

Tier 3 - Deeper Sedation (Use with Extreme Caution in Elderly):

• Propofol (avoid in hemodynamically unstable patients; common in elderly with cardiac disease) 2
• Midazolam (increases delirium risk, avoid if possible in elderly) 2

Tier 4 - Refractory Cases Only:

• Neuromuscular blocking agents as last resort when patient already deeply sedated/comatose 2, 5, 6
• Dantrolene 1-2.5 mg/kg for truly refractory shivering (emerging evidence in severe cases) 8

Critical Considerations for Elderly Patients

Cardiovascular Risks:

• Any sedative can worsen hemodynamic compromise in elderly patients with cardiogenic shock or heart failure 2
• Minimize sedative doses in patients with shock; have lower threshold for neuromuscular blockade if already unresponsive 2
• Elderly patients >75 years with syncope have poor outcomes; comprehensive cardiovascular assessment is essential 2

Neurological Concerns:

• Long-acting benzodiazepines accumulate during hypothermia and interfere with neurological assessment 2
• All sedatives predispose to delirium (highest risk: benzodiazepines and ketamine; lowest: dexmedetomidine) 2
• Cannot diagnose brain death until patient rewarmed to 34°C 2

Multidisciplinary Approach:

• Collaboration with geriatric specialists is beneficial for elderly patients with multifactorial causes, frailty, or multiple comorbidities 2, 4
• Assess functional status, cognitive function, and medication burden comprehensively 2
• Consider patient preferences and goals of care in treatment decisions 2, 4

Common Pitfalls to Avoid

• Do not rely on rectal or axillary temperatures - they lag significantly behind core temperature 2
• Do not use benzodiazepines as first-line in elderly due to delirium risk and delayed awakening 2
• Do not overlook infection - fever with shivering requires immediate sepsis evaluation 1
• Do not apply single-disease guidelines rigidly to elderly patients with multimorbidity 4
• Do not use high-dose sedatives without considering hemodynamic effects in patients with cardiac disease 2

Monitoring Requirements

• Continuous core temperature monitoring using validated method 2
• Serial assessment of shivering intensity using validated shivering scale 5
• Frequent hemodynamic monitoring given cardiovascular vulnerability in elderly 2
• Daily reassessment of medication appropriateness and sedation depth 4