This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Verhaegen, M. J. Articles by Warner, D. S. Search for Related Content PubMed PubMed Citation Articles by Verhaegen, M. J. Articles by Warner, D. S. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB CARBON DIOXIDE Medline Plus Health Information Hypothermia

Stroke, Vol 24, 407-414, Copyright © 1993 by American Heart Association

ARTICLES

Cerebral autoregulation during moderate hypothermia in rats

MJ Verhaegen, MM Todd, BJ Hindman and DS Warner
Department of Anesthesia, University of Iowa College of Medicine, Iowa City.

BACKGROUND AND PURPOSE: Little is known about the effects of hypothermia on cerebral autoregulation. The present study was designed to examine cerebral blood flow responses to controlled hemorrhagic hypotension in normothermic and hypothermic rats. METHODS: Cortical blood flow was measured with a laser-Doppler flowmeter in halothane- anesthetized rats assigned to one of three groups: normothermic group 1 (n = 8) with a pericranial temperature of approximately 36.5 degrees C or hypothermic group 2 (n = 8) or group 3 (n = 8) with a pericranial temperature of approximately 30.5 degrees C. In group 2, a PaCO2 of approximately 40 mm Hg was maintained without correction for body temperature. To evaluate the role of PaCO2, in group 3 animals PaCO2 was kept at approximately 40 mm Hg as corrected for body temperature. In all animals, the mean arterial blood pressure was reduced by hemorrhage in increments of 10 mm Hg every 2 minutes. RESULTS: In group 1 animals, a typical autoregulatory curve was observed with cerebral blood flow first falling at or below 75% of baseline at a mean arterial pressure of 57 +/- 15 mm Hg (mean +/- SD). Absolute normotensive cerebral blood flow in group 2 fell to < or = 75% of baseline at a mean arterial pressure of 73 +/- 21 mm Hg. In group 3, no evidence of autoregulation was seen. Cerebral blood flow reached values < or = 75% of baseline at a mean arterial pressure of 82 +/- 14 mm Hg, whereas calculated cerebrovascular resistance failed to show any compensatory vasodilation as the mean arterial pressure decreased. CONCLUSIONS: Different PaCO2 management schemes used during hypothermia may have profound effects on cerebral blood flow and on autoregulation. If PaCO2 is maintained at 40 mm Hg after correction for temperature, autoregulation is abolished. If uncorrected PaCO2 is maintained at approximately 40 mm Hg, some degree of autoregulation is preserved, albeit with a right-shifted "knee."

This article has been cited by other articles:

				A. Sarajuuri, E. Jokinen, R. Puosi, M. Eronen, L. Mildh, I. Mattila, L. Valanne, and T. Lonnqvist Neurodevelopmental and neuroradiologic outcomes in patients with univentricular heart aged 5 to 7 years: Related risk factor analysis J. Thorac. Cardiovasc. Surg., June 1, 2007; 133(6): 1524 - 1532. [Abstract] [Full Text] [PDF]

				D. Georgiadis, S. Schwarz, D.H. Evans, S. Schwab, and R.W. Baumgartner Cerebral Autoregulation Under Moderate Hypothermia in Patients With Acute Stroke Stroke, December 1, 2002; 33(12): 3026 - 3029. [Abstract] [Full Text] [PDF]

				R. R. Leker, H. Ovadia, S. Schwab, D. Georgiadis, P. D. Schellinger, J. Berrouschot, C. Graffagnino, and S. A. Mayer Re: Feasibility and Safety of Moderate Hypothermia After Massive Hemispheric Infarction Stroke, March 1, 2002; 33(3): 877 - 878. [Full Text] [PDF]

				J. Takada, S. Ibayashi, T. Nagao, H. Ooboshi, T. Kitazono, and M. Fujishima Bradykinin Mediates the Acute Effect of an Angiotensin-Converting Enzyme Inhibitor on Cerebral Autoregulation in Rats Stroke, May 1, 2001; 32(5): 1216 - 1219. [Abstract] [Full Text] [PDF]

				K. Kishi, M. Kawaguchi, K. Kurehara, S. Inoue, T. Sakamoto, T. Einaga, K. Kitaguchi, and H. Furuya Hypothermia Attenuates the Vasodilatory Response of Pial Arterioles to Hemorrhagic Hypotension in the Cat Anesth. Analg., July 1, 2000; 91(1): 140 - 144. [Abstract] [Full Text] [PDF]

				G. Zaharchuk, J. B. Mandeville, A. A. Bogdanov Jr, R. Weissleder, B. R. Rosen, J. J. A. Marota, C. Iadecola, and S.-G. Kim Cerebrovascular Dynamics of Autoregulation and Hypoperfusion : An MRI Study of CBF and Changes in Total and Microvascular Cerebral Blood Volume During Hemorrhagic Hypotension • Editorial Comment: An MRI Study of CBF and Changes in Total and Microvascular Cerebral Blood Volume During Hemorrhagic Hypotension Stroke, October 1, 1999; 30(10): 2197 - 2205. [Abstract] [Full Text] [PDF]

				S. C. Jones, C. R. Radinsky, A. J. Furlan, D. Chyatte, and A. D. Perez-Trepichio Cortical NOS inhibition raises the lower limit of cerebral blood flow-arterial pressure autoregulation Am J Physiol Heart Circ Physiol, April 1, 1999; 276(4): H1253 - H1262. [Abstract] [Full Text] [PDF]

				S. Schwab, S. Schwarz, M. Spranger, E. Keller, M. Bertram, and W. Hacke Moderate Hypothermia in the Treatment of Patients With Severe Middle Cerebral Artery Infarction Stroke, December 1, 1998; 29(12): 2461 - 2466. [Abstract] [Full Text] [PDF]

				L. V. Kuznetsova, N. Tomasek, G. H. Sigurdsson, A. Banic, D. Erni, and A. M. Wheatley Dissociation between volume blood flow and laser-Doppler signal from rat muscle during changes in vascular tone Am J Physiol Heart Circ Physiol, April 1, 1998; 274(4): H1248 - H1254. [Abstract] [Full Text] [PDF]