PMID: 39475Oct 1, 1979

Fentanyl concentrations in brain and serum during respiratory acid--base changes in the dog

Anesthesiology
S G AinslieG Corkill

Abstract

It is a clinical impression that less fentanyl is needed for anesthesia during hyperventilation and hypocarbia. If true, it might be due to both increased penetration of fentanyl, a highly lipid-soluble agent, into the brain and increased brain tissue binding. Serum and brain concentrations of fentanyl were determined in dogs anesthetized with halothane during normocarbia, hypocarbia by hyperventilation, and hypercarbia by addition of CO2 to the inspired mixture. Fentanyl, 12.5 micrograms/kg, was injected iv, and serum and brain samples were taken for fentanyl analysis by radioimmunoassay. Brain fentanyl values peaked latest (15--20 min) and were highest during hypocarbia; brain fentanyl values peaked earliest (0--5 min) and were lowest during hypercarbia; values during normocarbia were intermediate in time to peak (10--15 min) and concentration. Thereafter, brain levels declined, but during hypocarbia were significantly higher and during hypercarbia were significantly lower than during normocarbia. Interestingly, serum fentanyl levels were also significantly higher during hypocarbia. The brain--blood fentanyl ratios for each of the three CO2 levels increased for 30 min and thereafter stayed relatively constant. The brain--bloo...Continue Reading

References

Jun 1, 1993·Der Schmerz·H W StriebelA Rieger
Jan 1, 1983·Canadian Anaesthetists' Society Journal·L L Priano
Aug 21, 2012·Journal of Pharmacokinetics and Pharmacodynamics·Richard N UptonLars Popper
May 1, 1996·Journal of Clinical Anesthesia·D A MacGregor, L A Bauman
Jul 1, 1992·Anaesthesia·G VarrassiD Niv
Feb 1, 1990·Acta Anaesthesiologica Scandinavica·H SchmittM Brandl
Sep 1, 1996·Anesthesiology·A SchubertZ Y Ebrahim
Oct 1, 1982·Acta Anaesthesiologica Scandinavica·J Hovorka
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Related Concepts

Blood - Brain Barrier Anatomy
Halothane
Intravenous Injections
Brain
Absence of Pain Sensation
Hypercapnia
Soluble
Decreased Vascular Flow
Hyperventilation
Absence of Sensation

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