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Integrity of the cerebral blood-flow response to hyperoxia after cardiopulmonary bypass
Thomas F Floyd1, Sarah J Ratcliffe, John A Detre
1Department of Anesthesiology, Penn-Presbyterian Hospital, University of Pennsylvania, Philadelphia, PA 19104-4283, USA. floydt@uphs.upenn.edu
Insights
Cardiopulmonary bypass (CPB) does not alter the cerebral blood flow (CBF) vasoconstrictive response to hyperoxia. This study found no significant impairment in CBF regulation during hyperoxic challenges after CPB in cardiac surgery patients.
Area of Science:
- Cardiovascular Physiology
- Neurology
- Surgical Research
Background:
- Cardiopulmonary bypass (CPB) is a critical procedure in cardiac surgery.
- Understanding its effects on cerebral blood flow (CBF) is vital for patient outcomes.
- The vasoconstrictive response of CBF to hyperoxia may be altered by CPB.
Purpose of the Study:
- To test the hypothesis that CPB alters the cerebral blood flow (CBF) vasoconstrictive response to hyperoxia.
- To investigate the impact of CPB on the cerebrovascular regulation during oxygen challenges.
Main Methods:
- A prospective, observational study was conducted involving 12 cardiac surgery patients undergoing CPB.
- Cerebral blood flow (CBF) was measured using continuous arterial spin labeling (CASL) perfusion MRI before and after CPB.
- Subjects breathed 21% O(2) and 100% O(2) to assess the vasoconstrictive response, with simultaneous measurement of arterial blood gases and hemoglobin.
Main Results:
- Postoperatively, hemoglobin levels decreased, and CBF significantly increased.
- The vasoconstrictive response of CBF to hyperoxia was observed both preoperatively and postoperatively.
- Multiple regression analysis, controlling for covariates like age and blood gases, indicated that CPB state did not significantly affect the hyperoxic CBF response.
Conclusions:
- Cardiopulmonary bypass (CPB) does not impair the cerebral blood flow (CBF) vasoconstrictive response to hyperoxia.
- Cerebrovascular regulation during hyperoxia remains intact following CPB in patients undergoing cardiac surgery.
Objective:
In this study, the hypothesis that cardiopulmonary bypass (CPB) alters the cerebral blood flow (CBF) vasoconstrictive response to hyperoxia was tested.
Design:
A prospective, observational study was conducted.
Setting:
The study was conducted at a single university hospital.
Participants:
Subjects were patients who presented for cardiac surgery with CPB.
Interventions:
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.
Measurements And Main 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.
