TY - JOUR
T1 - Dynamic cerebral autoregulation during the combination of mild hypercapnia and cephalad fluid shift
AU - Kurazumi, Takuya
AU - Ogawa, Yojiro
AU - Yanagida, Ryo
AU - Morisaki, Hiroshi
AU - Iwasaki, Ken Ichi
N1 - Funding Information:
The authors would like to acknowledge Dr. Ken Aoki for supporting the experimental operation of the present study. This study was supported by JSPS Kakenhi Grant Number 25514008 for conducting the experiments, and by JSPS Kakenhi Grant Number 15H05939 for editing of the manuscript. The authors have no conflicts of interest to declare. T. Kurazumi performed study design, experiment operation, data collection, data analysis, interpretation and manuscript preparation. Y. Ogawa performed study design, experiment operation, data collection, interpretation, and manuscript editing. R. Yanagida performed study design, experiment operation, interpretation, and manuscript editing. H. Morisaki performed study design, interpretation, and manuscript editing. K. Iwasaki performed study design, experiment operation, data analysis, interpretation, and manuscript editing
Publisher Copyright:
© by the Aerospace Medical Association, Alexandria, VA.
PY - 2017/9/1
Y1 - 2017/9/1
N2 - BACKGROUND: Mild hypercapnia combined with a cephalad fluid shift [e.g., that occurring during spaceflight or laparoscopic surgery with head-down tilt (HDT)] might affect cerebral autoregulation. However, no reports have described the effects of the combination on dynamic cerebral autoregulation. Therefore, we tested the hypothesis that the combination of mild hypercapnia and a cephalad fluid shift would attenuate dynamic cerebral autoregulation. METHODS: There were 15 healthy male volunteers who were exposed to 4 10-min protocols in which they received air in the supine position (Placebo/Supine), 3% carbon dioxide (CO2) in the supine position (CO2/Supine), air with 210° HDT (Placebo/ HDT) and 3% CO2 with 210° HDT (CO2/HDT). Dynamic cerebral autoregulation was evaluated using a transfer function analysis of the beat-to-beat variability in mean arterial blood pressure (ABP) and mean cerebral blood flow (CBF) velocity. RESULTS: The phase in the low-frequency range was significantly lower during CO2/HDT than all other protocols, where CO2/HDT was 225% lower than Placebo/Supine (CO2/HDT, 0.49 ± 0.21; Placebo/Supine, 0.65 ± 0.16 radians). The transfer function gain in the low-frequency range was significantly higher during CO2/HDT than all other protocols, where CO2/ HDT was 26% higher than Placebo/Supine (CO2/HDT, 1.08 ± 0.34; Placebo/Supine, 0.86 ± 0.28 cm · s-1 · mmHg-1). However, neither the CO2/Supine nor Placebo/HDT showed significant differences compared with the Placebo/Supine. DISCUSSION: Even short-term exposure to 3% CO2 plus HDT increased synchrony and the magnitude of transmission between ABP and CBF in the low-frequency range. Thus, the combination of mild hypercapnia and a cephalad fluid shift attenuated dynamic cerebral autoregulation.
AB - BACKGROUND: Mild hypercapnia combined with a cephalad fluid shift [e.g., that occurring during spaceflight or laparoscopic surgery with head-down tilt (HDT)] might affect cerebral autoregulation. However, no reports have described the effects of the combination on dynamic cerebral autoregulation. Therefore, we tested the hypothesis that the combination of mild hypercapnia and a cephalad fluid shift would attenuate dynamic cerebral autoregulation. METHODS: There were 15 healthy male volunteers who were exposed to 4 10-min protocols in which they received air in the supine position (Placebo/Supine), 3% carbon dioxide (CO2) in the supine position (CO2/Supine), air with 210° HDT (Placebo/ HDT) and 3% CO2 with 210° HDT (CO2/HDT). Dynamic cerebral autoregulation was evaluated using a transfer function analysis of the beat-to-beat variability in mean arterial blood pressure (ABP) and mean cerebral blood flow (CBF) velocity. RESULTS: The phase in the low-frequency range was significantly lower during CO2/HDT than all other protocols, where CO2/HDT was 225% lower than Placebo/Supine (CO2/HDT, 0.49 ± 0.21; Placebo/Supine, 0.65 ± 0.16 radians). The transfer function gain in the low-frequency range was significantly higher during CO2/HDT than all other protocols, where CO2/ HDT was 26% higher than Placebo/Supine (CO2/HDT, 1.08 ± 0.34; Placebo/Supine, 0.86 ± 0.28 cm · s-1 · mmHg-1). However, neither the CO2/Supine nor Placebo/HDT showed significant differences compared with the Placebo/Supine. DISCUSSION: Even short-term exposure to 3% CO2 plus HDT increased synchrony and the magnitude of transmission between ABP and CBF in the low-frequency range. Thus, the combination of mild hypercapnia and a cephalad fluid shift attenuated dynamic cerebral autoregulation.
KW - Carbon dioxide
KW - Cerebral circulation
KW - Head-down tilt
KW - Transcranial Doppler
KW - Transfer function analysis
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U2 - 10.3357/AMHP.4870.2017
DO - 10.3357/AMHP.4870.2017
M3 - Article
C2 - 28818140
AN - SCOPUS:85027526354
SN - 2375-6314
VL - 88
SP - 819
EP - 826
JO - Aerospace Medicine and Human Performance
JF - Aerospace Medicine and Human Performance
IS - 9
ER -
