| The Effects of Rewarming Speed
on Cerebral Circulation and Oxygen Metabolism during the Rewarming
Period of Cardiopulmonary Bypass |
(Second Department of Surgery, Faculty of Medicine,
Tottori University, Yonago, Japan and Osaka Medical Center and
Research Institute for Maternal and Child Health*, Izumi, Japan)
| Tasuku Honda |
Satoshi Kamihira |
Shingo Ishiguro |
| Hiroaki Kuroda |
Shigetsugu Ohgi |
Tohru Mori* |
|
We investigated the effects of rewarming
speed on cerebral circulation and oxygen metabolism during cardiopulmonary
bypass (CPB). Twenty-four adult patients who had undergone open
heart surgery with moderately hypothermic CPB were divided into
two groups. In the slow rewarming group (group S), the rates
of increase of blood temperature were under 0.1ºC/min.
In the rapid rewarming group (group R), they were more than 0.1ºC/min. Mean blood flow velocity in
the middle cerebral artery (mean MCAv) was measured by transcranial
Doppler ultrasonography, and the index of cerebral oxygen consumption
was evaluated by Doppler-estimated cerebral metabolic rate for
oxygen (D-CMRO2). The change of oxyhemoglobin level
in the brain (Oxy Hb) was monitored by near-infrared spectroscopy.
In group S, mean MCAv and D-CMRO2 changed in a parallel
manner following the changes of the rectal temperature throughout
the periods, and mean MCAv was always higher than D-CMRO2.
In group R, however, the rate of increase of D-CMRO2
was more rapid than that in group S from the beginning of rewarming,
and D-CMRO2 exceeded the level of mean MCAv just before
termination of CPB. In addition, Oxy Hb in group R showed more
rapid changes than that of group S. In conclusion, rapid rewarming
during CPB may cause the disruption of cerebral flow-metabolism
coupling.
Jpn. J. Cardiovasc. Surg. 30: 1-6 (2001) |
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