What is the comparison between adrenaline (epinephrine) and dobutamine in weaning from extracorporeal bypass after coronary artery bypass grafting and mitral valve replacement with elevated pulmonary artery pressures?

From the Guidelines

For patients weaning from extracorporeal bypass after coronary artery bypass grafting and mitral valve replacement with elevated pulmonary artery pressures, dobutamine is generally preferred over adrenaline (epinephrine). Dobutamine, typically started at 2-5 mcg/kg/min and titrated up to 20 mcg/kg/min as needed, provides positive inotropic support with less pulmonary vasoconstriction compared to epinephrine, as noted in studies such as 1. This is particularly important in patients with elevated pulmonary pressures, as epinephrine can worsen pulmonary hypertension through its alpha-adrenergic effects, potentially increasing right ventricular afterload and compromising right ventricular function.

Key Considerations

• Dobutamine primarily works through beta-1 adrenergic stimulation, improving cardiac contractility while causing mild peripheral vasodilation, which can help reduce pulmonary vascular resistance.
• In some cases, combining dobutamine with a pulmonary vasodilator like milrinone (0.375-0.75 mcg/kg/min) or inhaled nitric oxide (10-40 ppm) may be beneficial, as suggested by 1 and 1.
• Continuous hemodynamic monitoring is essential during weaning, including cardiac output, pulmonary artery pressures, and mixed venous oxygen saturation.
• If dobutamine alone is insufficient, low-dose epinephrine (0.01-0.05 mcg/kg/min) might be added, but with careful monitoring of pulmonary pressures, as discussed in 1 and 1.

Additional Recommendations

• The selection of inotropes and vasopressors should be guided by the principle of maintaining systemic vascular resistance (SVR) greater than pulmonary vascular resistance (PVR) to avoid right ventricular ischemia, as emphasized in 1.
• Inhaled nitric oxide (iNO) has been shown to acutely decrease PVR and improve CO in PH, especially in patients who are post-coronary bypass surgery or valve replacement, and its use should be considered, as noted in 1.

From the Research

Adrenaline vs Dobutamine in Weaning from Extracorporeal Bypass

• The comparison between adrenaline (epinephrine) and dobutamine in weaning from extracorporeal bypass after coronary artery bypass grafting and mitral valve replacement with elevated pulmonary artery pressures is not directly addressed in the provided studies.
• However, the studies provide information on the effects of dobutamine on hemodynamics and left ventricular performance after cardiopulmonary bypass in cardiac surgical patients 2, 3, 4.
• Dobutamine has been shown to increase cardiac index and decrease pulmonary vascular resistance in patients with increased pulmonary arterial pressure following mitral valve replacement 2.
• In patients undergoing coronary artery bypass graft surgery, dobutamine has been found to improve left ventricular performance by increasing heart rate, with minimal effects on blood pressure 3.
• A study comparing dobutamine and amrinone in cardiac surgical patients with severe pulmonary hypertension after cardiopulmonary bypass found that amrinone produced a greater increase in cardiac index and right ventricular ejection fraction, and a larger decrease in pulmonary artery wedge pressure 5.
• Another study compared dopamine and dobutamine following coronary artery bypass grafting, and found that dobutamine was preferable due to its consistent, dose-related increases in cardiac index without increases in heart rate, mean arterial pressure, pulmonary capillary wedge pressure, or pulmonary vascular resistance 6.
• There is no direct comparison between adrenaline and dobutamine in the provided studies, but the available evidence suggests that dobutamine is a useful agent for improving cardiac performance in patients with elevated pulmonary artery pressures after cardiopulmonary bypass 2, 3, 4, 5, 6.