Hemodynamics and oxygen consumption during warm heart surgery

Area of Science:

• Cardiovascular Surgery
• Physiology
• Anesthesiology

Background:

• Cardiopulmonary bypass (CPB) is a critical component of coronary artery bypass grafting (CABG).
• The choice between normothermic and hypothermic CPB strategies impacts patient hemodynamics and oxygen balance.
• Understanding these differences is crucial for optimizing surgical outcomes.

Purpose of the Study:

• To compare the effects of normothermic versus hypothermic CPB on hemodynamics and oxygen balance in CABG patients.
• To evaluate the impact of temperature management during CPB on cardiac function recovery and metabolic parameters.
• To determine if normothermia offers advantages over hypothermia in specific perioperative aspects.

Main Methods:

• A comparative study involving two groups of CABG patients: systemic normothermia with warm blood cardioplegia (Group W, n=36) and systemic hypothermia with cold crystalloid cardioplegia (Group C, n=26).
• Hemodynamic parameters (cardiac index, arterial pressure), metabolic markers (serum glucose, base excess), and oxygen balance indicators (oxygen consumption, oxygen extraction ratio, mixed venous oxygen saturation) were monitored.
• Incidence of defibrillation and duration of CPB and reperfusion were recorded.

Main Results:

• Group W showed less frequent defibrillation, shorter CPB and reperfusion times, higher post-CPB cardiac index and arterial pressure, and lower dopamine requirements.
• Normothermic CPB (Group W) was associated with lower serum glucose levels and higher base excess during CPB compared to hypothermic CPB (Group C).
• Oxygen consumption remained stable in Group W, while it decreased and then increased in Group C. Oxygen extraction ratio increased in Group W during CPB, unlike in Group C. Mixed venous oxygen saturation was maintained above 65% in both groups.

Conclusions:

• Normothermic CPB may be superior to hypothermic CPB for enhancing cardiac function recovery and preventing hyperglycemia after CABG.
• Both normothermic and hypothermic CPB strategies appear capable of preserving the overall balance between oxygen supply and demand.
• The findings suggest that temperature management during CPB significantly influences perioperative physiological responses.