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Early cerebral functional outcome after coronary artery bypass surgery using different acid-base management during
W Engelhardt1, T Dierks, M Pause
1Institute of Anesthesiology, University of Würzburg, Germany.
Insights
This study found no significant difference in early brain function outcomes between pH-stat and alpha-stat carbon dioxide management during hypothermic cardiopulmonary bypass. Both methods proved equally safe for cerebral function in patients undergoing bypass surgery.
Area of Science:
- Cardiovascular Surgery
- Neuroscience
- Anesthesiology
Background:
- Cerebral injury can compromise cardiac surgery outcomes.
- Carbon dioxide management during cardiopulmonary bypass impacts cerebral blood flow and postoperative brain function.
- Understanding optimal CO2 management is crucial for patient recovery.
Purpose of the Study:
- To compare the effects of pH-stat and alpha-stat CO2 management on brain function during hypothermic cardiopulmonary bypass.
- To assess postoperative cerebral function using non-invasive methods.
Main Methods:
- Prospective, controlled, double-blind study involving 45 patients undergoing aortocoronary bypass grafting.
- Randomization into pH-stat (n=23) and alpha-stat (n=22) groups.
- Non-invasive assessment of cerebral function including neurological exams, neuropsychological testing, EEG, and P300 evoked potentials.
Main Results:
- No significant differences in cerebral function parameters were observed between the pH-stat and alpha-stat groups.
- Minor, clinically irrelevant differences were noted in specific parameters, favoring either group by chance.
- One patient in each group experienced new paresis, indicating similar neurological complication rates.
Conclusions:
- pH-stat and alpha-stat CO2 management strategies yield comparable early cerebral functional outcomes during hypothermic cardiopulmonary bypass.
- The choice between pH-stat and alpha-stat does not appear to influence immediate postoperative brain function under the study's conditions.
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).
Conclusion:
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.