Hypocapnia attenuates, and nitrous oxide disturbs the cerebral oximetric response to the rapid introduction of desflurane.
The aim of this study was to develop a nonlinear mixed-effects model for the increase in cerebral oximetry (rSO(2)) during the rapid introduction of desflurane, and to determine the effect of hypocapnia and N(2)O on the model. Twelve American Society of Anesthesiologist physical status class 1 and 2 subjects were allocated randomly into an Air and N(2)O group. After inducing anesthesia, desflurane was then increased abruptly from 4.0 to 12.0%. The PET(CO2), PET(DESF) and rSO(2) were recorded at 12 predetermined periods for the following 10 min. The maximum increase in rSO(2) reached +24-25% during normocapnia. The increase in rSO(2) could be fitted to a four parameter logistic equation as a function of the logarithm of PET(DESF). Hypocapnia reduced the maximum response of rSO(2), shifted the EC(50) to the right, and increased the slope in the Air group. N(2)O shifted the EC(50) to the right, and reduced the slope leaving the maximum rSO(2) unchanged. The N(2)O-effects disappeared during hypocapnia. The cerebrovascular reactivity of rSO(2) to CO(2) is still preserved during the rapid introduction of desflurane. N(2)O slows the response of rSO(2). Hypocapnia overwhelms all the effects of N(2)O.
Lee
Younsuk
Y
Department of Anesthesiology and Pain Medicine, and Medical Research Institute, Dongguk University College of Medicine, Goyang, Korea. ylee@dongguk.ac.kr
Lee
Jeoung Hyuk
JH
Yoon
Dong-Il
DI
Lee
Youngmin
Y
Kim
Kyoung Ok
KO
Chung
Seunghyun
S
In
Junyong
J
Choi
Jun Gwon
JG
Cho
Hun
H
D000328:Adult; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000098:blood supply / Q000187:drug effects / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology; D000077335:Desflurane; D005260:Female; D006439:Hemodynamics; D006801:Humans; D016857:Hypocapnia / Q000378:metabolism*; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009609:Nitrous Oxide / Q000378:metabolism*; D010092:Oximetry; D011897:Random Allocation; D012039:Regional Blood Flow / Q000187:drug effects
D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane; D009609:Nitrous Oxide