Cerbral blood flow dynamics during anesthesia assessed by systems theory.

Research Project

Project/Area Number	09671540
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Anesthesiology/Resuscitation studies
Research Institution	Chiba University
Principal Investigator	SATO Jiro Chiba University, School of Medicine, Lecturer, 医学部, 講師 (90187203)
Co-Investigator(Kenkyū-buntansha)	AONO Mitsuo Chiba University, School of Medicine, Assistant, 医学部, 助手 (40292693) NISHINO Takashi Chiba University, School of Medicine, Professor, 医学部, 教授 (80009703) 杉森邦夫千葉大学, 医学部, 助手 (20241961)
Project Period (FY)	1997 – 1998
Project Status	Completed (Fiscal Year 1998)
Budget Amount *help	¥2,800,000 (Direct Cost: ¥2,800,000) Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000) Fiscal Year 1997: ¥2,100,000 (Direct Cost: ¥2,100,000)
Keywords	nitrous oxide / carbon dioxide / dynamic cerebrovascular respons / mathematical model / transcranial Doppler ultrasonography / propofol / 数理モデル / 脳血流 / 炭酸ガス負荷
Research Abstract	We studied the effect of N_2O on the dynamic cerebrovascular response to changes in end-tidal CO_2 tension (PETCO_2) in healthy humans. By use of a transcranial Doppler ultrasonography, blood flow velocity in the middle cerebral artery (_VMCA) was measured during a step increase followed by a step decrease in PETCO_2 between normo- and hypercapnia while subjects inspired gas mixtures containing 70% O_2 + 30% N_2 (control) and 70% 0_2+30% N_2O (N_2O) separately. In control gas breathing, both step increase and decrease in PETCO_2 produced rapid exponential changes in ^VMCA.An increase in _VMCA produced by the step increase in PETCO_2 was smaller (P < 0.001) and slower (P < 0.001) than a decrease in _VMCA induced by the step decrease in PETCO_2. These general features of the dynamic cerebrovascular response were not affected by N_2O gas breathing although N_2O increased baseline ^VMCA by 15% (P (0.001) compared with control gas breathing. We conclude that N_2O in itself does not affect the dynamic cerebrovascular response to arterial CO_2 changes although N_2O produces static mild cerebral vasodilation. We also examine the effect of propofol on the cerebrovascular dynamic response to PETCO2. When added to N_2O, propofol produced the baseline cerebral vaso constriction. Propofol blunted the dynamic cerebrovascular response to changes in PETCO2.