2023 Fiscal Year Final Research Report
Dose-dependent effects of head-ward fluid shift with hypercapnia on cerebral blood flow autoregulation
| Project/Area Number |
20K06844
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 45060:Applied anthropology-related
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| Research Institution | Nihon University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
小川 洋二郎 日本大学, 医学部, 准教授 (60434073)
加藤 智一 日本大学, 医学部, 助教 (10786346)
田子 智晴 日本大学, 医学部, 助手 (70780229)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 体液シフト / 高二酸化炭素血症 / 脳血流調節 / 頭低位 |
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| Outline of Final Research Achievements |
We evaluated cerebral autoregulation during 10-min combined exposure to three angles of head-down tilt (HDT) and 3% CO2 inhalation (5°HDT+CO2, 15°HDT+CO2, and 30°HDT+CO2), on twenty healthy participants. Arterial pressure and cerebral blood flow (CBF) waveforms were obtained. Cerebral autoregulation was evaluated by transfer function analysis between waveforms. One of the cerebral autoregulation indexes (Gain) increased significantly with 15°HDT+CO2 and 30°HDT+CO2, but not with 5°HDT+CO2. These results suggest weakened dynamic cerebral autoregulation with the combination of moderate cephalad fluid shift and mild hypercapnia.
We also reported following findings from related our experiments. CBF would maintain with 30°HDT alone. Contrary to our expectation, regional cerebral oxygen saturation increased by HDT. There are no major differences in CBF between head positions with neck flexion and extension despite the difference in the cerebral perfusion pressure
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| Free Research Field |
環境医学、宇宙医学
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| Academic Significance and Societal Importance of the Research Achievements |
宇宙飛行や頭低位状態で行う腹腔鏡手術の広まりにより人類は体液上方変位の状態に曝される機会が多くなってきた。また、国際宇宙ステーションでは環境中の二酸化炭素濃度が高く重力による空気の自然対流もなく呼気の高濃度二酸化炭素が停滞しやすく、腹腔鏡手術では二酸化炭素ガスを注入し腹腔を膨らませ軽度の高二酸化炭素血症になる。これらの状態に関連した視機能変化や頭部臓器の合併症リスクが捉えられている。今回の研究で得られた知見は、宇宙飛行士の健康管理や頭低位腹腔鏡手術患者の合併症リスク軽減のために応用可能であり、体液シフト予防対策や頭低位角度を浅くすること、二酸化炭素濃度の上昇を抑えることなどが重要と示唆できる。
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