Early cerebral functional outcome after coronary artery bypass surgery using different acid-base management during hypothermic cardiopulmonary bypass.
BACKGROUND
Cerebral injury can render meaningless an otherwise successful cardiac operation. As carbon dioxide management during hypothermic cardiopulmonary bypass has a major impact on cerebral blood flow during bypass, it may also influence postoperative cerebral function. The objective of this prospective, controlled, double-blind study was to compare the effect of pH-stat (temperature correction of blood gas analyses) or alpha-stat (no temperature correction) on brain function.


METHODS
Cerebral function was assessed non-invasively using neurological examination, a neuropsychological test battery, quantitative electroencephalogram and the cognitive evoked potential P300 preoperatively and on postoperative day 7 or 8. Forty-five patients undergoing elective aortocoronary bypass grafting in barbiturate/opiate anesthesia were randomised into a pH-stat-(n = 23) and an alpha-stat-group (n = 22). Membrane oxygenators with arterial line filtration and non-pulsatile flow at a perfussion pressure of 50-60 mmHg were used throughout.


RESULTS
One patient in each group developed a new paresis. Among 49 comparisons of cerebral function parameters, only 3 showed significant differences at the 5%-level, i.e. exactly what is expected purely by chance. These differences were too small to be clinically relevant and favored either pH-stat (theta-amplitude) or alpha-stat (subtest 3 of syndrome-short-test, number of mistakes in aiming).


CONCLUSIONS
Under the bypass conditions of this study there was no difference in early cerebral functional outcome between pH-or alpha-stat carbon dioxide management during hypothermic cardiopulmonary bypass.
Engelhardt
W
W
Institute of Anesthesiology, University of Würzburg, Germany.
Dierks
T
T
Pause
M
M
Hartung
E
E
D000136:Acid-Base Equilibrium; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000097:blood; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D004311:Double-Blind Method; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance
D002245:Carbon Dioxide