Transcranial Doppler Study in Carbon Dioxide Reacitivity of Middle Cerebral Blood Flow Velocity During Hypothermic Nonpulsatile Cardiopulmonary Bypass.

Lee,  Hye Won; Kim,  Myung Hyun; Chae,  Byung Kook; Chang,  Seong Ho

doi:1994.27.10.1378

Running title
Authors Initials	HW Lee, MH Kim, BK Chae

Clinical Research Article

Korean Journal of Anesthesiology 1994;27(10):1378-1385.
DOI: https://doi.org/10.4097/kjae.1994.27.10.1378

Transcranial Doppler Study in Carbon Dioxide Reacitivity of Middle Cerebral Blood Flow Velocity During Hypothermic Nonpulsatile Cardiopulmonary Bypass.

Hye Won Lee, Myung Hyun Kim, Byung Kook Chae, Seong Ho Chang

¹Department of Anesthesiology, College of Medicine, Korea University, Seoul, Korea.
²Department of Neurosurgery, College of Medicine, Ewha Womans University, Seoul, Korea.

Abstract

The recording of middle cerebral artery (MCA) flow veloeity by transcrsnisl Doppler technique offers s new, noninvasive, and continuous technique for studies of cerebral circu lation. The influence of changes in PaCO2 on MCA flow velocity were observed during hypothermic cardiopulmonary bypass(CPB) surgery by means of transcranial Doppler tech- niques. In ten patients who were undergoing hypothermic CPB surgery, the right MCA flow velocity was measured before initiation of CPB(prebypass period) and after the termination of CPB (postbypass period). During steady state CPB(constant hematocrit, constant temperature, and constant total pump flow), baseline MCA flow velocity(CPB I period) was measured and then repeated after specific alteration of PaCO2 achieved by changing of fresh gas flow to oxygenetors(CPB II period). And carbon dioxide reactivity defined as percent change of MCA flow velocity per mmHg changes in PaCO2 was observed during stable hypothermic CPB. MCA flow veocity showed no statistical difference between the prebypass value(56.9+/-13.5 cm/sec) and the postbypass value(64.7+/-29.7 cm/sec). PaCO2 of 20.5+/-2.5 mmHg was associated with MCA flow velocity of 25.2+/-10.1 cm/sec in the CPB I period while PaCO2 of 27.1+/-3.5 mmHg was associated with MCA flow velocity of 35.3+/-12.9 cm/sec. MCA flow velocity carbon dioxide reactivity during steady state hypothermie CPB was 6.68+/-2.26 %/ mmHg. These results have demonstrated that the response of MCA flow velocity to changes in PaO2 was well maintained during hypothermic CPB and the use of transcrsnial Doppler would give valuable results in the study of cerebral circulation during hypothermic CPB.

Key Words: Transcranial Doppler; Middle cerebral artery flow velocity; Carbon dioxide reactivity; Hypothermic cardiopulmonary bypass