Related Experiment Videos
Reduction of the MAC of desflurane with fentanyl
P S Sebel1, P S Glass, J E Fletcher
1Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia.
Abstract:
Opioids are known to affect the MAC of inhalational anesthetics. We have determined the interaction between fentanyl and desflurane, following a bolus injection of fentanyl at induction in 134 adult patients. Five groups of patients were studied. Four groups received desflurane or isoflurane in oxygen with either fentanyl 3 or 6 micrograms/kg and thiopental 2-5 mg/kg given as a bolus injection at the time of induction. An additional group received desflurane in oxygen alone. Groups were stratified by age. MAC determination, in response to the stimulus of skin incision, was made using the "up-down" method and logistic regression. The MAC desflurane in oxygen was 6.3% (5.3-7.6%, 95% confidence interval [CI]). Fentanyl 3 micrograms/kg produced a fentanyl plasma concentration of 0.78 +/- 0.53 ng/ml at skin incision and resulted in a MAC for desflurane of 2.6% (2.0-3.2%, 95% CI) %. Fentanyl 6 micrograms/kg produced a fentanyl plasma concentration of 1.72 +/- 0.76 ng/ml at skin incision and resulted in a MAC for desflurane of 2.1% (1.5-2.6%, 95% CI). To compare recovery times to eye-opening and response to commands, patients were grouped according to the plasma fentanyl concentrations at the time of awaking. Recovery was faster in patients who received desflurane than in those who received isoflurane. The authors conclude that the MAC of desflurane is significantly reduced 25 min following a single dose of 3 micrograms/kg of fentanyl and that increasing the fentanyl dose to 6 micrograms/kg produces little further decrease in MAC. Desflurane is also associated with faster recovery from anesthesia than is isoflurane.
Insights
Fentanyl significantly reduces the minimum alveolar concentration (MAC) of desflurane anesthesia. Higher fentanyl doses offer minimal additional MAC reduction, and desflurane allows for faster patient recovery compared to isoflurane.
Area of Science:
- Anesthesiology
- Pharmacology
Background:
- Opioids are known to modulate the minimum alveolar concentration (MAC) of volatile anesthetics.
- Understanding the interaction between fentanyl and desflurane is crucial for optimizing anesthetic management.
Purpose of the Study:
- To determine the interaction between fentanyl and desflurane, specifically its effect on the MAC of desflurane.
- To compare recovery times between desflurane and isoflurane when combined with fentanyl.
Main Methods:
- A study involving 134 adult patients undergoing anesthesia induction.
- Patients were divided into groups receiving varying doses of fentanyl (3 or 6 µg/kg) with either desflurane or isoflurane, or desflurane alone.
- The MAC of desflurane was determined using the up-down method and logistic regression in response to skin incision.
Main Results:
- The MAC of desflurane in oxygen alone was 6.3%.
- Fentanyl at 3 µg/kg reduced desflurane MAC to 2.6%; a dose of 6 µg/kg resulted in a MAC of 2.1%.
- Recovery was faster with desflurane compared to isoflurane.
Conclusions:
- A single dose of 3 µg/kg of fentanyl significantly reduces the MAC of desflurane.
- Increasing fentanyl dose beyond 3 µg/kg provides minimal additional reduction in desflurane MAC.
- Desflurane is associated with quicker recovery from anesthesia than isoflurane.