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Cerebral pharmacodynamics of anaesthetic and subanaesthetic doses of ketamine in the normoventilated pig

Åkeson, Jonas LU ; Björkman, S; Messeter, K; Rosen, I and Helfer, M (1993) In Acta Anaesthesiologica Scandinavica 37(2). p.211-218
Abstract
There are still divergent opinions regarding the pharmacodynamic effects of ketamine on the brain. In this study, the cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2) and electroencephalographic (EEG) activity were sequentially assessed over 80 min in 17 normoventilated pigs following rapid i.v. infusions of anaesthetic (10.0 mg.kg-1; n = 7) or subanaesthetic (2.0 mg.kg-1; n = 7) doses of ketamine or of its major metabolite norketamine (10.0 mg.kg-1; n = 3). The animals were continuously anaesthetized with fentanyl, nitrous oxide and pancuronium. CBF was determined by the intra-arterial 133Xe technique. Ketamine (10.0 mg.kg-1) induced an instant, gradually reverting decrease in CBF, amounting to -26% (P < 0.01) at 1... (More)
There are still divergent opinions regarding the pharmacodynamic effects of ketamine on the brain. In this study, the cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2) and electroencephalographic (EEG) activity were sequentially assessed over 80 min in 17 normoventilated pigs following rapid i.v. infusions of anaesthetic (10.0 mg.kg-1; n = 7) or subanaesthetic (2.0 mg.kg-1; n = 7) doses of ketamine or of its major metabolite norketamine (10.0 mg.kg-1; n = 3). The animals were continuously anaesthetized with fentanyl, nitrous oxide and pancuronium. CBF was determined by the intra-arterial 133Xe technique. Ketamine (10.0 mg.kg-1) induced an instant, gradually reverting decrease in CBF, amounting to -26% (P < 0.01) at 1 min and -13% (P < 0.05) at 10 min, a delayed increase in CMRO2 by 42% (P < 0.01) at 10 min and a sustained rise in low- and intermediate-frequency EEG voltage by 87% at 1 and 97% at 10 min (P < 0.0001). It is concluded that metabolically formed norketamine does not contribute to these effects. Considering the dissociation of CBF from CMRO2 found 10-20 min after ketamine (10.0 mg.kg-1) administration, it is suggested that ketamine should be used with caution for anaesthesia in patients with suspected cerebral ischaemia in order not to increase the vulnerability of brain tissue to hypoxic injury. Ketamine (2.0 mg.kg-1) had no significant effects on CBF, CMRO2 or EEG. It therefore seems that up to one fifth of the minimal anaesthetic i.v. dose can be used safely for analgesia, provided that normocapnaemia is preserved. (Less)
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author
organization
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type
Contribution to journal
publication status
published
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in
Acta Anaesthesiologica Scandinavica
volume
37
issue
2
pages
211 - 218
publisher
Wiley-Blackwell
external identifiers
  • pmid:8447213
  • scopus:0027388969
ISSN
0001-5172
language
English
LU publication?
yes
id
06dc6a35-8f9e-45a5-8cb1-8d2d710aaf7a (old id 1107377)
date added to LUP
2008-07-30 17:04:38
date last changed
2017-01-01 04:41:31
@article{06dc6a35-8f9e-45a5-8cb1-8d2d710aaf7a,
  abstract     = {There are still divergent opinions regarding the pharmacodynamic effects of ketamine on the brain. In this study, the cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2) and electroencephalographic (EEG) activity were sequentially assessed over 80 min in 17 normoventilated pigs following rapid i.v. infusions of anaesthetic (10.0 mg.kg-1; n = 7) or subanaesthetic (2.0 mg.kg-1; n = 7) doses of ketamine or of its major metabolite norketamine (10.0 mg.kg-1; n = 3). The animals were continuously anaesthetized with fentanyl, nitrous oxide and pancuronium. CBF was determined by the intra-arterial 133Xe technique. Ketamine (10.0 mg.kg-1) induced an instant, gradually reverting decrease in CBF, amounting to -26% (P &lt; 0.01) at 1 min and -13% (P &lt; 0.05) at 10 min, a delayed increase in CMRO2 by 42% (P &lt; 0.01) at 10 min and a sustained rise in low- and intermediate-frequency EEG voltage by 87% at 1 and 97% at 10 min (P &lt; 0.0001). It is concluded that metabolically formed norketamine does not contribute to these effects. Considering the dissociation of CBF from CMRO2 found 10-20 min after ketamine (10.0 mg.kg-1) administration, it is suggested that ketamine should be used with caution for anaesthesia in patients with suspected cerebral ischaemia in order not to increase the vulnerability of brain tissue to hypoxic injury. Ketamine (2.0 mg.kg-1) had no significant effects on CBF, CMRO2 or EEG. It therefore seems that up to one fifth of the minimal anaesthetic i.v. dose can be used safely for analgesia, provided that normocapnaemia is preserved.},
  author       = {Åkeson, Jonas and Björkman, S and Messeter, K and Rosen, I and Helfer, M},
  issn         = {0001-5172},
  language     = {eng},
  number       = {2},
  pages        = {211--218},
  publisher    = {Wiley-Blackwell},
  series       = {Acta Anaesthesiologica Scandinavica},
  title        = {Cerebral pharmacodynamics of anaesthetic and subanaesthetic doses of ketamine in the normoventilated pig},
  volume       = {37},
  year         = {1993},
}