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Shivering threshold during spinal anesthesia is reduced in elderly patients
N Vassilieff1, N Rosencher, D I Sessler
1Department of Anesthesiology and Intensive Care, Cochin Port-Royal University Hospital, Paris, France.
Anesthesiology
|December 1, 1995
Summary
Elderly patients, especially those over 80, have a lower shivering threshold during spinal anesthesia, increasing hypothermia risk. This highlights the need for careful temperature monitoring in this population.
Area of Science:
- Anesthesiology
- Geriatric Medicine
- Thermoregulation
Background:
- Hypothermia is common in the elderly due to delayed or inefficient thermoregulation.
- The vasoconstriction threshold is lower in elderly patients under anesthesia.
- Impaired cold defenses in the very elderly (>80 years) require further investigation.
Purpose of the Study:
- To test the hypothesis that shivering threshold decreases with age during spinal anesthesia.
- To quantify age-related differences in thermoregulatory responses.
Main Methods:
- Studied 28 patients undergoing orthopedic procedures under spinal anesthesia.
- Monitored electrocardiogram and identified shivering onset via electromyography.
- Determined shivering threshold by tympanic membrane temperature.
Main Results:
- Patients aged 80+ (mean age 89) shivered at a significantly lower temperature (35.2°C) than younger patients (<80 years, mean age 58; 36.1°C).
- Seven of ten patients over 80 had shivering thresholds below 35.5°C, unlike all younger patients.
- Three patients did not shiver even at core temperatures above 36.2°C.
Conclusions:
- Age-related impairment of autonomic thermoregulation increases hypothermia risk in elderly patients under spinal anesthesia.
- Behavioral regulation may compensate for impaired autonomic control in daily life but not under anesthesia.
- Elderly patients receiving regional anesthesia are at risk due to blunted shivering responses and potentially unrecognized hypothermia.