Integrity of the cerebral blood-flow response to hyperoxia after cardiopulmonary bypass.
OBJECTIVE
In this study, the hypothesis that cardiopulmonary bypass (CPB) alters the cerebral blood flow (CBF) vasoconstrictive response to hyperoxia was tested.


METHODS
A prospective, observational study was conducted.


METHODS
The study was conducted at a single university hospital.


METHODS
Subjects were patients who presented for cardiac surgery with CPB.


METHODS
CBF was measured before and after CPB in 12 subjects while breathing 21% O(2) and 100% O(2). CBF was measured by using continuous arterial spin labeling (CASL) perfusion magnetic resonance imaging. Arterial pO(2) (mmHg), pCO(2) (mmHg), hemoglobin (Hgb), and oxygen content (CaO(2)) were also measured.


RESULTS
Mean age of the 12 subjects was 63 +/- 16 years. Hgb decreased from 12.0 (+/-2.4) g/dL to 9.2 (+/-2.9) g/dL postoperatively (p = 0.008). CBF increased by 39%, from 37.2 (+/-10.8) mL/100 g/min to 49.2 (+/-14.3)mL/100 g/min postoperatively (p = 0.01). In response to the hyperoxic challenge CBF decreased by 8.0 (+/-7.1) mL/100 g/min (21%) preoperatively and by 9.4 (+/-6.4) mL/100 g/min (19%) postoperatively (p = 0.58). By using multiple regression, the contribution of CPB to the hyperoxic CBF response (DeltaCBF) was evaluated, while controlling for other potentially important covariates known to influence CBF, including age, baseline CBF on 21% O(2), and changes in arterial pO(2), pCO(2), and CaO(2). CPB state was not found to be a significant covariate in controlling the CBF response to hyperoxia.


CONCLUSIONS
CPB does not impair the CBF response to hyperoxia.
Floyd
Thomas F
TF
Department of Anesthesiology, Penn-Presbyterian Hospital, University of Pennsylvania, Philadelphia, PA 19104-4283, USA. floydt@uphs.upenn.edu
Ratcliffe
Sarah J
SJ
Detre
John A
JA
Woo
Y Joseph
YJ
Acker
Michael A
MA
Bavaria
Joseph E
JE
Resh
Brooke F
BF
Pochettino
Alberto A
AA
Eckenhoff
Roderic A
RA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D001921:Brain / Q000098:blood supply; D002245:Carbon Dioxide / Q000097:blood; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation; D005260:Female; D006331:Heart Diseases / Q000601:surgery; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D018496:Hyperoxia / Q000175:diagnosis / Q000503:physiopathology*; D016014:Linear Models; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011184:Postoperative Period; D011446:Prospective Studies; D016896:Treatment Outcome; D014661:Vasoconstriction
D015415:Biomarkers; D006454:Hemoglobins; D002245:Carbon Dioxide; D010100:Oxygen