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Should blood flow during cardiopulmonary bypass be individualized more than to body surface area?
S A Thomassen1, A Larsson, J J Andreasen
1Department of Anaesthesia, Center for Cardiovascular Research, Aalborg Hospital, Aarhus University Hospital, Denmark. siat@rn.dk
Insights
Cardiopulmonary bypass (CPB) blood flow based on individual cardiac index (CI) did not improve patient oxygenation compared to standard body surface area (BSA) calculations. This study suggests current BSA methods are adequate for CPB blood flow management.
Area of Science:
- Cardiovascular Surgery
- Physiology
- Anesthesiology
Background:
- Current cardiopulmonary bypass (CPB) blood flow calculations rely on body surface area (BSA).
- Increasing patient comorbidity, age, and weight challenge the adequacy of BSA-based calculations for individual metabolic needs.
- The study investigated whether a patient-specific cardiac index (CI) offers a superior method for determining CPB blood flow.
Purpose of the Study:
- To compare the efficacy of CPB blood flow determined by individual CI versus BSA calculation.
- To evaluate the impact of different blood flow strategies on patient outcomes during cardiac surgery.
Main Methods:
- A crossover study design was employed with 22 elective cardiac surgery patients.
- Patients were randomly assigned to receive CPB blood flow based on BSA calculation (2.4 L/min/m(2)) for 20 minutes, followed by CPB based on individual CI for another 20 minutes, or vice versa.
- Effect parameters monitored included cerebral oxygenation, mixed venous saturation, and arterial lactate levels.
Main Results:
- Individual CI values ranged from 1.9 to 3.1 L/min/m(2), with a median of 2.4 L/min/m(2).
- No significant differences were observed in cerebral oxygenation, mixed venous saturation, or arterial lactate levels between the two blood flow strategies.
- The study found no improvement in measured effect parameters when using CI-based CPB blood flow compared to BSA-based flow.
Conclusions:
- CPB blood flow management based on individual CI did not demonstrate superiority over BSA calculations in improving cerebral and systemic oxygenation.
- The findings suggest that BSA-based blood flow calculations remain a viable approach for CPB in patients with normal ventricular function.
- Further research may be warranted to explore optimal CPB flow strategies in more complex patient populations.
Abstract:
Blood flow during cardiopulmonary bypass (CPB) is calculated on body surface area (BSA). Increasing comorbidity, age and weight of today's cardiac patients question this calculation as it may not reflect individual metabolic requirement. The hypothesis was that a measured cardiac index (CI) prior to normothermic CPB is a better estimate. A cross-over study, with random allocation to CPB blood flow for 20 minutes based on either a calculation (2.4 L/min/m(2)) or on CI, with a switch to the opposite flow for another 20 minutes, was performed. Twenty-two elective cardiac surgery patients with normal ventricular function were included. Effect parameters were cerebral oxygenation, mixed venous saturation and arterial lactate. CI varied from 1.9 to 3.1 L/min/m(2) (median 2.4 L/min/m(2)). No differences in effect parameters were seen. In conclusion, a CPB blood flow based on an individual estimate did not improve cerebral and systemic oxygenation compared to a blood flow based on BSA.
