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Assessing Changes in Volatile General Anesthetic Sensitivity of Mice after Local or Systemic Pharmacological Intervention
Published on: October 16, 2013
Theoretical context-sensitive elimination times for inhalation anaesthetics
1Centre for Perioperative Medicine and Critical Care Research, Hammersmith Hospital, Ducane Road, London W12 0HS, UK. g.lockwood@imperial.ac.uk
British Journal of Anaesthesia
|March 18, 2010
Summary
Volatile anesthetics are significantly absorbed during surgery, with substantial amounts remaining in the body for days post-anesthesia. Complete recovery is delayed due to residual anesthetic effects, impacting patient outcomes.
Area of Science:
- Pharmacokinetics and Anesthesiology
- Physiological Modeling
- Drug Metabolism and Elimination
Background:
- Previous calculations of anesthetic brain elimination times did not account for metabolism or residual effects.
- Complete recovery from anesthesia is not solely defined by brain elimination percentages.
Purpose of the Study:
- To develop and validate a physiologically based model of anesthetic uptake, distribution, and metabolism.
- To determine the kinetics of various volatile anesthetics and noble gases.
- To assess the impact of metabolism on anesthetic elimination rates.
Main Methods:
- A physiologically based pharmacokinetic model was created, incorporating anesthetic metabolism and fluoride kinetics.
- Model predictions were validated against existing experimental data.
- Simulations calculated anesthetic partial pressures in the brain after administration of common anesthetics.
Main Results:
- The model accurately predicted anesthetic kinetics and fluoride production.
- Metabolism had a minimal impact on the elimination rates of the studied anesthetics.
- 99.9% brain elimination times varied significantly, from 9 hours (nitrous oxide) to 71 hours (sevoflurane).
- Substantial amounts of anesthetics (4-13% of the absorbed dose) remained in the body days after administration.
Conclusions:
- Significant quantities of anesthetics are absorbed and retained in the body long after apparent recovery.
- Anesthetic metabolism is not a major factor influencing elimination kinetics.
- Extended elimination times, particularly for sevoflurane and desflurane, highlight prolonged physiological effects.
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