Related Experiment Videos
Hemodynamic and hormonal responses to hypothermic and normothermic cardiopulmonary bypass
Insights
This study compared hypothermic versus normothermic cardiopulmonary bypass (CPB) in adults undergoing cardiac surgery. Normothermic CPB resulted in higher hormone levels and lower oxygen saturation, while hypothermic CPB increased systemic vascular resistance.
Area of Science:
- Cardiovascular Surgery
- Physiology
- Anesthesiology
Background:
- Normothermic cardiopulmonary bypass (CPB) is an alternative to hypothermic CPB in cardiac surgery.
- Understanding the hemodynamic and hormonal differences is crucial for patient management.
Purpose of the Study:
- To compare hemodynamic and hormonal responses between hypothermic (29°C) and normothermic nonpulsatile CPB.
- To investigate the impact of CPB temperature on physiological parameters and hormone levels.
Main Methods:
- 20 adult patients undergoing coronary artery bypass graft and/or aortic valve replacement were studied.
- Hemodynamic measurements and plasma hormone concentrations were collected from preinduction to the third postoperative hour.
- Comparison between hypothermic and normothermic CPB groups.
Main Results:
- Systemic vascular resistance increased only during hypothermic CPB; heart rate was higher at the end of hypothermic CPB.
- Oxygen consumption decreased significantly during hypothermic CPB, while mixed venous oxygen saturation (SvO2) was lower during normothermic CPB.
- Plasma epinephrine, norepinephrine, and dopamine concentrations were significantly higher during normothermic CPB compared to hypothermic CPB.
Conclusions:
- Higher systemic vascular resistance during hypothermic CPB may be due to factors like blood viscosity, not hormonal changes.
- Normothermic CPB may lead to higher SvO2 due to a higher perfusion index.
- Significant hormonal differences, particularly catecholamines, were observed between the two CPB temperatures.
Abstract:
Normothermic cardiopulmonary bypass (CPB) is used in cardiac surgery at some institutions. To compare hemodynamic and hormonal responses to hypothermic (29 degrees C) and normothermic nonpulsatile CPB, 20 adults undergoing coronary artery bypass graft and/or aortic valve replacement were studied. Hemodynamic measurements and plasma hormone concentrations were obtained from preinduction to the third postoperative hour. The two groups were given similar amounts of anesthetics and vasodilators. Systemic vascular resistance increased only during hypothermic CPB, and heart rate was higher at the end of hypothermic CPB. Postoperative central venous pressure and pulmonary capillary wedge pressure were lower after hypothermic CPB. Oxygen consumption decreased by 45% during hypothermic CPB, did not change during normothermic CPB, but increased similarly in the two groups after surgery; mixed venous oxygen saturation (SvO2) was significantly lower during normothermic CPB. Urine output and composition were similar in the two groups. In both groups, plasma epinephrine, norepinephrine, renin activity, and arginine vasopressin concentrations increased during and after CPB. However, epinephrine, norepinephrine, and dopamine were 200%, 202%, and 165% higher during normothermic CPB than during hypothermic CPB, respectively. Dopamine and prolactin increased significantly during normothermic but not hypothermic CPB. Atrial natriuretic peptide increased at the end of CPB and total thyroxine decreased during and after CPB, with no difference between groups. This study suggests that higher systemic vascular resistance during hypothermic CPB is not caused by hormonal changes, but might be caused by other factors such as greater blood viscosity. A higher perfusion index during normothermic CPB might have allowed higher SvO2.