Cerebral blood flow affects dose requirements of intracarotid propofol for electrocerebral silence.
BACKGROUND
The authors hypothesized that cerebral blood flow (CBF) changes will affect the dose of intracarotid propofol required to produce electrocerebral silence.


METHODS
The authors tested their hypothesis on New Zealand White rabbits. The first group of 9 animals received intracarotid propofol during (1) normoventilation, (2) hyperventilation, and (3) hypoventilation. The second group of 14 animals received intracarotid propofol with or without concurrent intraarterial verapamil, a potent cerebral vasodilator. The third group of 8 animals received bolus injection of propofol during normotension, during severe cerebral hypoperfusion, and after hemodynamic recovery.


RESULTS
In the first group, there was a linear correlation between the dose of intracarotid propofol and percent change (%Delta) in CBF from the baseline due to changes in the minute ventilation, Total Dose (y) = 0.17 + 0.012 * %Delta CBF (x), n = 27, r = 0.76. In the second group, the dose of propofol was also a function of CBF change after verapamil, Total Dose (y) = 0.98 + 0.1 * %Delta CBF (x), n = 14, r = 0.75. In the third group, the duration of electrocerebral silence after intracarotid propofol (3 mg) was significantly increased with concurrent cerebral hypoperfusion compared with prehypoperfusion and posthypoperfusion values (141 +/- 38 vs. 19 +/- 24 and 16 +/- 12 s, respectively, P < 0.0001).


CONCLUSIONS
The authors conclude that CBF affects the dose requirements of intracarotid propofol required to produce electrocerebral silence. Furthermore, the manipulation of CBF might be a useful tool to enhance the efficacy of intracarotid drugs.
Joshi
Shailendra
S
Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, 630 West 168th Street, New York, NY 10032, USA. sj121@columbia.edu
Wang
Mei
M
Etu
Joshua J
JJ
Nishanian
Ervant V
EV
Pile-Spellman
John
J
D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000494:pharmacology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D017536:Carotid Artery, Common; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D007269:Injections, Intra-Arterial; D015742:Propofol / Q000008:administration & dosage* / Q000494:pharmacology*; D011817:Rabbits; D015656:Respiratory Mechanics / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology
D018686:Anesthetics, Intravenous; D002121:Calcium Channel Blockers; D014700:Verapamil; D015742:Propofol