[Effect of S-(+)-ketamine on autoregulation of cerebral blood flow].
OBJECTIVE
The present study investigates the effects of S-(+)-ketamine on cerebral blood flow (CBF) autoregulation in rats.


METHODS
Following IRB approval, 24 nonfasted male Sprague-Dawley rats were anesthetised with isoflurane, intubated and mechanically ventilated. Catheters were inserted into the right femoral artery, both femoral veins, and into the right jugular vein for drug administration, measurement of mean arterial blood pressure (MAP), and blood sampling. Cortical cerebral blood flow was measured using laser-Doppler-flowmetry (PF 403, Perimed). At the end of surgery isoflurane was discontinued and all animals were randomly assigned to one of the following anaesthetic treatments. In group 1 (n = 8, control), anaesthesia was maintained using fentanyl (10 micrograms/kg i.v. bolus, followed by 25 micrograms/kg/h i.v.) and N2O/O2 (FiO2: 0.3). In group 2 (n = 8) and group 3 (n = 8) animals received 0.5 mg/kg/min S-(+)-ketamine i.v. or 1.0 mg/kg/min S-(+)-ketamine i.v. and O2/air (FiO2: 0.3), respectively. CBF was tested by graded haemorrhage. Arterial blood gases, arterial pH, and pericranial temperature were controlled over time.


RESULTS
CBF autoregulation was maintained under low and high doses of S-(+)-ketamine compared to fentanyl/N2O-anaesthetised controls. However, low-dose S-(+)-ketamine shifted the autoregulatory curve towards higher MAP values.


CONCLUSIONS
The present study indicates that autoregulatory cerebrovascular dilation is preserved with low and high doses of S-(+)-ketamine. Differences in the lower limit of CBF autoregulation may be consistent with an increased sympathetic tone induced by low doses of S-(+)-ketamine.
Engelhard
K
K
Institut für Anaesthesiologie, Technischen Universität München.
Werner
C
C
Lu
H
H
Möllenberg
O
O
Kochs
E
E
D000778:Anesthetics, Dissociative / Q000494:pharmacology*; D018685:Anesthetics, Inhalation; D000818:Animals; D001921:Brain / Q000098:blood supply*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D016001:Confidence Intervals; D005283:Fentanyl / Q000494:pharmacology; D006706:Homeostasis; D007530:Isoflurane; D007649:Ketamine / Q000494:pharmacology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D009609:Nitrous Oxide / Q000494:pharmacology; D010100:Oxygen / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D012121:Respiration, Artificial; D013237:Stereoisomerism; D014664:Vasodilation
D000778:Anesthetics, Dissociative; D018685:Anesthetics, Inhalation; D002245:Carbon Dioxide; D007649:Ketamine; D007530:Isoflurane; D009609:Nitrous Oxide; D010100:Oxygen; D005283:Fentanyl
Einfluss von S-(+)-Ketamin auf die Autoregulation der Hirndurchblutung.