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Hepatic blood flow during cardiopulmonary bypass
1Department of Surgery, Royal Postgraduate Medical School, London, UK.
Critical Care Medicine
|February 1, 1993
Summary
Higher pump flow rates during cardiopulmonary bypass better maintain hepatic blood flow. Hypothermic bypass may benefit liver circulation, but pulsatile flow advantages diminish with high flow and hypothermia.
Area of Science:
- Cardiovascular Surgery
- Hepatology
- Physiology
Background:
- Hepatic blood flow is crucial for liver function, supplied by both hepatic artery and portal vein.
- Understanding hemodynamic factors during cardiopulmonary bypass (CPB) is key to preventing post-operative hepatic dysfunction.
- Hepatic circulation has unique characteristics influenced by hemodynamic stimuli common during CPB.
Purpose of the Study:
- To determine how different cardiopulmonary bypass methods affect hepatic blood flow.
- To elucidate the hemodynamic factors contributing to liver dysfunction after CPB.
- To review the liver's unique circulation and the impact of CPB-related stimuli.
Main Methods:
- Comprehensive literature search of clinical and experimental studies on CPB and hepatic blood flow up to 1991.
- Inclusion of studies with sound CPB or blood flow measurement techniques.
- Analysis of experimental data on pump flow rate, temperature, and pulsatile vs. non-pulsatile perfusion.
Main Results:
- Higher CPB flow rates (2.4 vs. 1.2 L/min/m2) better preserve total liver blood flow.
- Hypothermia (28°C) increases portal flow but slightly decreases hepatic arterial flow.
- Pulsatile flow at 1.2 L/min/m2 better preserves hepatic blood flow than non-pulsatile, but this difference is lost at 2.4 L/min/m2, especially with hypothermia.
Conclusions:
- Optimizing pump flow rate is essential for maintaining hepatic blood flow during CPB.
- Hypothermic CPB can be beneficial for hepatic circulation.
- The benefits of pulsatile perfusion may be reduced when combined with high flow rates and hypothermia.