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Propofol clearance and distribution volume increase in patients with hyperthyroidism
T Tsubokawa1, K Yamamoto, T Kobayashi
1Department of Anesthesiology and Intensive Care Medicine, School of Medicine, Faculty of Medicine, Kanazawa University, Japan. tsune@med.kanazawa-u.ac.jp
Anesthesia and Analgesia
|July 14, 1998
Summary
Hyperthyroid patients require higher propofol infusion rates due to increased clearance and distribution volume. This necessitates adjusted anesthetic management for effective propofol levels in hyperthyroidism.
Area of Science:
- Anesthesiology
- Pharmacology
- Endocrinology
Background:
- Hyperthyroidism alters drug pharmacokinetics, potentially affecting anesthetic requirements.
- Understanding propofol behavior in hyperthyroid patients is crucial for safe anesthesia.
Purpose of the Study:
- To investigate and compare propofol pharmacokinetics in hyperthyroid versus euthyroid patients undergoing surgery.
- To determine the impact of hyperthyroidism on propofol infusion rates and blood concentrations.
Main Methods:
- Studied seven hyperthyroid and eight euthyroid patients undergoing subtotal thyroidectomy.
- Administered propofol intravenously for induction and maintenance of anesthesia.
- Monitored physiological signs and measured arterial propofol concentrations.
Main Results:
- Hyperthyroid patients required significantly higher propofol infusion rates (median 10.0 mg.kg-1.h-1 vs. 6.5 mg.kg-1.h-1).
- Average propofol concentrations were lower in hyperthyroid patients (1.8 µg/mL vs. 3.3 µg/mL).
- Propofol clearance and steady-state distribution volume were significantly increased in hyperthyroid patients.
Conclusions:
- Increased propofol clearance and distribution volume in hyperthyroidism necessitate higher infusion rates to achieve anesthetic blood concentrations.
- Propofol's hypotensive and bradycardic effects are beneficial for hyperthyroid patients, but require careful titration.