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Midazolam minimally impairs thermoregulatory control
A Kurz1, D I Sessler, R Annadata
1Department of Anesthesia, University of California, San Francisco 94143-0648, USA.
Anesthesia and Analgesia
|August 1, 1995
Summary
Midazolam, a common sedative, impairs the body's ability to regulate temperature, lowering sweating and shivering thresholds. This effect is less pronounced than with other anesthetics but still significant for perioperative hypothermia risk.
Area of Science:
- Anesthesiology
- Thermoregulation
- Pharmacology
Background:
- Perioperative hypothermia is often caused by drugs that inhibit thermoregulation.
- The thermoregulatory effects of midazolam, a common sedative and anesthetic adjuvant, are not well understood.
Purpose of the Study:
- To test the hypothesis that midazolam administration impairs thermoregulatory control.
- To quantify the effects of midazolam on core temperature thresholds for sweating, vasoconstriction, and shivering.
Main Methods:
- Eight volunteers were studied under two conditions: without midazolam and with a target plasma concentration of 0.3 micrograms/mL.
- Core and skin temperatures were manipulated to elicit sweating, vasoconstriction, and shivering responses.
- Mathematical compensation for skin temperature changes was used to determine core temperature thresholds.
Main Results:
- Midazolam administration significantly decreased the core temperature thresholds for sweating (by ~0.3°C), vasoconstriction (by ~0.8°C), and shivering (by ~0.6°C).
- The interthreshold range (sweating to vasoconstriction) increased from 0.2°C to 0.7°C with midazolam.
- These changes, while statistically significant, were smaller than those observed with clinical doses of volatile anesthetics, propofol, or opioids.
Conclusions:
- Midazolam impairs thermoregulatory control by lowering the core temperature thresholds for key thermoregulatory responses.
- The observed increase in the interthreshold range suggests a potential contribution to perioperative hypothermia.
- Further research may be needed to compare these effects with other anesthetic agents in clinical settings.