The stability of cerebrovascular CO2 reactivity following attainment of physiological steady-state
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The stability of cerebrovascular CO2 reactivity following attainment of physiological steady-state. / Carr, Jay M J R; Caldwell, Hannah Grace; Carter, Howard; Smith, Kurt; Tymko, Michael M; Green, Daniel J; Ainslie, Philip N; Hoiland, Ryan L.
I: Experimental Physiology, Bind 106, Nr. 12, 2021, s. 2542-2555.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - The stability of cerebrovascular CO2 reactivity following attainment of physiological steady-state
AU - Carr, Jay M J R
AU - Caldwell, Hannah Grace
AU - Carter, Howard
AU - Smith, Kurt
AU - Tymko, Michael M
AU - Green, Daniel J
AU - Ainslie, Philip N
AU - Hoiland, Ryan L
N1 - Publisher Copyright: © 2021 The Authors. Experimental Physiology © 2021 The Physiological Society
PY - 2021
Y1 - 2021
N2 - This study assessed cerebrovascular CO2 reactivity (CVR) and examined data extraction time points and durations with the hypotheses that: (1) there would be no difference in CVR values when calculated with cerebral blood flow (CBF) measures at different time points following the attainment of physiological steady-state, (2) once steady-state was achieved there would be no difference in CVR values derived from 60 to 30 s extracted means, and (3) that changes in (Formula presented.) would not be associated with any changes in CVR. We conducted a single step iso-oxic hypercapnic CVR test using dynamic end-tidal forcing (end-tidal (Formula presented.), +9.4 ± 0.7 mmHg), and transcranial Doppler and Duplex ultrasound of middle cerebral artery (MCA) and internal carotid artery (ICA), respectively. From the second minute of hypercapnia onwards, physiological steady-state was apparent, with no subsequent changes in end-tidal (Formula presented.), (Formula presented.) or mean arterial pressure. Therefore, CVR measured in the ICA and MCA was stable following the second minute of hypercapnia onwards. Data extraction durations of 30 or 60 s did not give statistically different CVR values. No differences in CVR were detected following the second minute of hypercapnia after accounting for mean arterial pressure via calculated conductance or covariation of mean arterial pressure. These findings demonstrate that, provided the (Formula presented.) stimulus remains in a steady-state, data extracted from any minute of a CVR test during physiological steady-state conditions produce equivalent CVR values; any change in the CVR value would represent a failure of CVR mechanisms, a change in the magnitude of the stimulus, or measurement error.
AB - This study assessed cerebrovascular CO2 reactivity (CVR) and examined data extraction time points and durations with the hypotheses that: (1) there would be no difference in CVR values when calculated with cerebral blood flow (CBF) measures at different time points following the attainment of physiological steady-state, (2) once steady-state was achieved there would be no difference in CVR values derived from 60 to 30 s extracted means, and (3) that changes in (Formula presented.) would not be associated with any changes in CVR. We conducted a single step iso-oxic hypercapnic CVR test using dynamic end-tidal forcing (end-tidal (Formula presented.), +9.4 ± 0.7 mmHg), and transcranial Doppler and Duplex ultrasound of middle cerebral artery (MCA) and internal carotid artery (ICA), respectively. From the second minute of hypercapnia onwards, physiological steady-state was apparent, with no subsequent changes in end-tidal (Formula presented.), (Formula presented.) or mean arterial pressure. Therefore, CVR measured in the ICA and MCA was stable following the second minute of hypercapnia onwards. Data extraction durations of 30 or 60 s did not give statistically different CVR values. No differences in CVR were detected following the second minute of hypercapnia after accounting for mean arterial pressure via calculated conductance or covariation of mean arterial pressure. These findings demonstrate that, provided the (Formula presented.) stimulus remains in a steady-state, data extracted from any minute of a CVR test during physiological steady-state conditions produce equivalent CVR values; any change in the CVR value would represent a failure of CVR mechanisms, a change in the magnitude of the stimulus, or measurement error.
KW - cerebrovascular reactivity
KW - internal carotid artery
KW - middle cerebral artery
U2 - 10.1113/EP089982
DO - 10.1113/EP089982
M3 - Journal article
C2 - 34730862
AN - SCOPUS:85119066133
VL - 106
SP - 2542
EP - 2555
JO - Experimental Physiology
JF - Experimental Physiology
SN - 0958-0670
IS - 12
ER -
ID: 306292365