Regional changes in brain blood flow during severe passive hyperthermia: effects of PaCO2 and extracranial blood flow
Bain AR, Smith KJ, Lewis NC, Foster GE, Wildfong KW, Willie CK, Hartley GL, Cheung SS, Ainslie PN
Journal of applied physiology (Bethesda, Md. : 1985) · 71 citations
How it was studied
- Design
- Controlled clinical trial (classified by our AI screen)
- Studied in
- People
- Main outcome
- Health markers and function
Who paid for it
- Funding
- Independent funding
- Government
- Canadian Institutes of Health Research
Based on 1 listed funder(s).
Publication
- Published
- 2013-07-04 · J Appl Physiol (1985) · vol. 115 · issue 5 · pp. 653–659
- Publisher
- American Physiological Society
- Cited
- 85 citations · more than 96% of similar papers · 5.1× the field average
- Impact
- Top 10% most cited in its field
- References
- 27 works
- Access
- Paywalled
- Research areas
- Thermoregulation and physiological responses · Thermal Regulation in Medicine · Ultrasound and Hyperthermia Applications
- Keywords
- Cerebral blood flow, Blood flow, Hyperthermia, Medicine, Hemodynamics, Cardiology, Internal medicine, Anesthesia
- MeSH
- cerebral arteries, vertebral artery, brain, humans, fever, carbon dioxide, blood flow velocity, blood pressure, heart rate, cerebrovascular circulation, adult, female, male, hemodynamics, young adult
9 authors
From CA
- Anthony Richard Bain · correspondingUniversity of British Columbia; University of British Columbia, Okanagan Campus
- Kurt J. SmithUniversity of British Columbia; University of British Columbia, Okanagan Campus
- Nia C. S. LewisUniversity of British Columbia; University of British Columbia, Okanagan Campus
- Glen E. FosterUniversity of British Columbia; University of British Columbia, Okanagan Campus
- Kevin W. WildfongUniversity of British Columbia; University of British Columbia, Okanagan Campus
- Christopher K. WillieUniversity of British Columbia; University of British Columbia, Okanagan Campus
Abstract
We investigated 1) the regional distribution of cerebral blood flow (CBF), 2) the influence of end-tidal Pco2 (PetCO2) on CBF, and 3) the potential for an extracranial blood "steal" from the anterior brain region during passive hyperthermia. Nineteen (13 male) volunteers underwent supine passive heating until a steady-state esophageal temperature of 2°C above resting was established. Measurements were obtained 1) during normothermia (Normo), 2) during poikilocapnic hyperthermia (Hyper), and 3) during hyperthermia with PetCO2 and end-tidal Po2 clamped to Normo levels (Hyper-clamp). Blood flow in the internal carotid (Qica), vertebral (QVA), and external carotid (Qeca) arteries (Duplex ultrasound), blood velocity of the middle cerebral (MCAv) and posterior cerebral (PCAv) arteries (transcranial Doppler), and cutaneous vascular conductance on the cheek (cheek CVC; Doppler velocimetry) were measured at each stage. During Hyper, PetCO2 was lowered by 7.0 ± 5.2 mmHg, resulting in a reduction in Qica (-18 ± 17%), Qva (-31 ± 21%), MCAv (-22 ± 13%), and PCAv (-18 ± 10%) compared with Normo (P < 0.05). The reduction in QVA was greater than that in QICA (P = 0.017), MCAv (P = 0.047), and PCAv (P = 0.034). Blood flow/velocity was completely restored in each intracranial vessel (ICA, VA, MCA, and PCA) during Hyper-clamp. Despite a ∼250% increase in QECA and a subsequent increase in cheek CVC during Hyper compared with Normo, reductions in QICA were unrelated to changes in QECA. These data provide three novel findings: 1) hyperthermia attenuates QVA to a greater extent than QICA, 2) reductions in CBF during hyperthermia are governed primarily by reductions in arterial Pco2, and 3) increased QECA is unlikely to compromise QICA during hyperthermia.
Abstract via Europe PMC. Copyright remains with the authors or publisher.
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