1992 Fiscal Year Final Research Report Summary
CEREBRAL PERFUSION DURING CARDIOPULMONARY BYPASS: ANALYSIS BY TRANSCRANIAL DOPPLER TECHNIQUE.
| Project/Area Number |
02454333
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Thoracic surgery
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| Research Institution | St. Marianna University School of Medicine |
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Principal Investigator |
KAWADA Tadanori ST.MARIANNA UNIVERSITY SCHOOL OF MEDICINE ASSOCIATE PROFESSOR, 医学部, 助教授 (80081735)
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| Co-Investigator(Kenkyū-buntansha) |
YAMATE Noboru ST.MARIANNA UNIVERSITY SCHOOL OF MEDICINE PROFESSOR, 医学部, 教授 (10089716)
OKADA Tadahiko ST.MARIANNA UNIVERSITY SCHOOL OF MEDICINE Assistant Professor, 医学部, 講師 (60097342)
KAMATA Satoshi ST.MARIANNA UNIVERSITY SCHOOL OF MEDICINE Research Associate, 医学部, 助手 (70224649)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Transcranial Doppler technique / Cardiopulmonary bypass / Hypothermia / alpha-stat management / pH-stat management |
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| Research Abstract |
The middle cerebral artery flow velocity (MCA-V) was continuously measured by the transcranial Doppler (TCD) technique in consecutive 50 patients who underwent open heart surgery with the aid of hypothermic cardiopulmonary bypass(CPB). This study was intended to evaluate the effects of changes in blood gas management, perfusion pressure and flow rate on MCA-V. MCA-V measurement was performed by the use of TCD sonography (EME, TC2-64).
The first 10 patients were managed by alpha-stat management and in the other 30 cases, CPB was started by alpha-stat management followed by pH-stat conversion for 15 minutes by adding CO_2 gas into the oxygenator gas line. In additional 10 cases, perfusion flow rate was manipulated from 2.4 L/m^2/min to 1.5 L/m^2/min at the body temperature below 30ﾟC.
In the case of alpha-stat management during CPB, MCA-V reduced to 47.8 * 19.8% of pre-CPB value and increased to 112.0 * 56.2% after weaning from CPB. Reduced MCA-V during alpha-stat management significantly
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increased immediately after pH-stat conversion. The change in MCA-V (DELTAMCA-V) did not correlate with the change in mean arterial pressure (DELTAMAP) in alpha-stat management, however, correlated in pH-stat management. DELTAMCA-V/DELTAPaCO_2 (PaCO_2-R) correlated with the change in body temperature at least of 20ﾟC or more. MCA-V showed no significant reduction in response to the reduction of the flow rate from 2.4 to 1.5 L/m^2/min in alpha-stat management. On the other hand, MCA-V reduced correlating with the flow rate reduction in pH-stat management. But, MCA-V levels in pH-stat management were always kept higher during hypothermia at least above 20ﾟC than those in alpha-stat management.
In conclusions;
1) Cerebral autoregulation is maintained in the case of alpha-stat management during moderate hypothermic CPB, however, it is abolished by pH-stat management.
2) Sensitivity of cerebral resistance vessels to PaCO_2 changes decreased with a drop of body temperature.
3) Higher cerebral blood flow is maintained in pH-stat management in hypothermin, however, further study is necessary to confirm it being beneficial or not for the protection of the brain during CPB. Less
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