Hyperventilation delays clinical induction of desflurane

Lee, Younsuk; In, Junyong; Kim, Kyoung Ok; Yun, Dong Il; Lee, Jeoung Hyuk; Cho, Hun; Choi, Jun Gwon; Chung, Seunghyun; Jang, Eun Jung

Clinical Research

Anesthetic Pharmacology

Anesthesia and Pain Medicine 2010;5(3):216-221.
Published online July 31, 2010.

Hyperventilation delays clinical induction of desflurane

Younsuk Lee, Junyong In, Kyoung Ok Kim, Dong Il Yun, Jeoung Hyuk Lee, Hun Cho, Jun Gwon Choi, Seunghyun Chung, Eun Jung Jang

¹Department of Anesthesiology and Pain Medicine, Dongguk University Ilsan Hospital, Ilsan, Korea. ylee@dongguk.ac.kr
²Department of Anesthesiology and Pain Medicine, St. Maria's Hospital, Uijeongbu, Catholic University, Uijeongbu, Korea.

Abstract

BACKGROUND
Ventilation is a major determinant of the alveolar concentration of inhaled anesthetics. Hyperventilation accelerates the equilibration of anesthetic in the lungs, but decelerates it in the brain. We evaluated this phenomenon for desflurane.
METHODS
Twenty healthy subjects were enrolled after IRB approval. End-tidal concentrations of desflurane (P.DESF) were recorded during 10 minutes of mask induction with 8% desflurane. P.DESF was modeled with time and end-tidal concentrations of CO2 (P.ETCO2) using a two-exponential pharmacokinetic equation. Bispectral index (BIS) values were also measured to find out the component reflecting the cerebral concentration of desflurane.
RESULTS
During induction, the rise of P.DESF could be separated into two components: early and late rises. Individual BIS values showed a higher correlation with the late component of P.DESF (P = 0.000). P.ETCO2 had two different effects on the rise of P.DESF.
CONCLUSIONS
Hyperventilation hastened the early rise and delayed the late rise of P.DESF (P = 0.00, P = 0.00). Hyperventilation should be avoided to obtain rapid anesthesia induction with desflurane.

Key Words: Desflurane, Inhalation anesthesia, Nonlinear model, Pharmacokinetics, Ventilation