Changes in cerebral blood flow velocity elicited by surgical stimulation are dependent on the PaCO(2) level.
OBJECTIVE
To investigate the influence of PaCO(2) manipulation on the cerebral hemodynamic response to surgical stimulation.


METHODS
Twenty-one female patients undergoing elective gynecological surgery performed through a lower median abdominal incision were enrolled. After obtaining steady general anesthesia with 1.7% sevoflurane and 60% nitrous oxide, the patients were randomly assigned to three groups, hypocapnia (PaCO(2)=30 mmHg), normocapnia (PaCO(2)=38 mmHg), and hypercapnia (PaCO(2)=44 mmHg) groups. The changes in mean blood flow velocity in the middle cerebral artery (Vmca) were evaluated using transcranial Doppler ultrasonography during nine minutes after surgical incision.


RESULTS
The change in Vmca (Delta Vmca) with surgical incision during hypercapnia (30-36 cm*sec(-1)) was significantly greater than during normocapnia (20-22 cm*sec(-1)) and hypocapnia (13-15 cm*sec(-1)). The Delta Vmca in the hypocapnia group was significantly smaller than in the normocapnia group. Arterial blood pressure increased with incision but there was no significant difference among the three groups.


CONCLUSIONS
Cerebral hemodynamic changes evoked by surgical stimulation are attenuated by hypocapnia and are augmented by hypercapnia, even within a clinically relevant range of PaCO(2).
Kawata
R
R
Department of Anesthesiology-Resuscitology, Yamaguchi University School of Medicine, Yamaguchi, Japan. sakabe@po.cc.yamaguchi-u.ac.jp
Matsumoto
M
M
Haranishi
Y
Y
Ishida
K
K
Nakakimura
K
K
Sakabe
T
T
D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood*; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D013514:Surgical Procedures, Operative
D002245:Carbon Dioxide; D010100:Oxygen