Response of Cerebral Blood Flow and Metabolism to Changes in Arterial Carbon Dioxide Tension during Moderate Hypothermic Cardiopulmonary Bypass in Patients with Cerebrovascular Disease.
10.4326/jjcvs.24.11
- VernacularTitle:脳血管障害患者における体外循環中のＣＯ２ ｒｅａｃｔｉｖｉｔｙに関する検討
- Author:
Satoshi Kamihira
;
Tasuku Honda
;
Yasushi Kanaoka
;
Youichi Hara
;
Shingo Ishiguro
;
Hiroaki Kuroda
;
Shigetsugu Ohgi
;
Tohru Mori
- Publication Type:Journal Article
- Keywords:
CO2 reactivity
- From:Japanese Journal of Cardiovascular Surgery
1995;24(1):11-17
- CountryJapan
- Language:Japanese
-
Abstract:
The purpose of this study was to examine the responses of cerebral blood flow and metabolism to changes in arterial carbon dioxide tension during moderate hypothermic cardiopulmonary bypass in patients with cerebrovascular disease undergoing open heart surgery. Computed tomography scan (CT) and single photon emission computed tomography (SPECT) were performed preoperatively for 17 patients. The patients were categorized according to their CT and SPECT findings. Ten patients were included in the normal group, 7 patients were included in the CVD group. Blood flow velocity in the middle cerebral artery (MCAv) was measured by means of transcranial Doppler ultrasonography at two different arterial carbon dioxide tensions (at a high PaCO2 of 45-50mmHg, at a low PaCO2 of 30-35mmHg, uncorrected for body temperature) during moderate steady-state hypothermic cardiopulmonary bypass. Simultaneously cerebral oxygen consumption was estimated by relating the arteriovenous oxygen content difference to flow velocity (D-CMRO2). MCAv and D-CMRO2 were expressed as percentages of the values determined at 30 minutes before cardiopulmonary bypass. In the normal group, a PaCO2 of 47.4±2.5mmHg (mean±SD) was associated with an MCAv of 99.4±17.8% and a D-CMRO2 of 53.4±25.5%, while a PaCO2 of 33.7±1.3mmHg was associated with an MCAv of 64.3±18.1% and a D-CMRO2 of 53.5±26.2%. In the CVD group, a PaCO2 of 49.1±4.2mmHg was associated with an MCAv of 81.4±22.3% and a D-CMRO2 of 34.0±19.4%, while a PaCO2 of 33.6±1.3mmHg was associated with an MCAv of 54.7±23.8% and a D-CMRO2 of 49.0±19.4%. We conclude that in patients with cerebrovascular disease cerebral blood flow is changed in response to changes in arterial dioxide tension during moderate hypothermic cardiopulmonary bypass, however a high PaCO2 depresses cerebral oxygen consumption because hypercarbia may cause potentially harmful redistribution of regional cerebral blood flow away from marginally-perfused to otherwise well-perfused areas.
