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Is calcium or ephedrine superior to placebo for emergence from cardiopulmonary bypass?
W E Johnston1, P G Robertie, J F Butterworth
1Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, NC 27157-1009.
Insights
Ephedrine improved right ventricular performance and blood pressure in cardiac surgery patients during cardiopulmonary bypass. Calcium chloride (CaCl2) did not significantly enhance hemodynamics in these patients.
Area of Science:
- Cardiology
- Anesthesiology
- Pharmacology
Background:
- Cardiac surgery patients emerging from cardiopulmonary bypass often experience hemodynamic instability.
- Optimizing right ventricular (RV) function and arterial pressure is crucial during this phase.
Purpose of the Study:
- To compare the efficacy of ephedrine and calcium chloride (CaCl2) in improving hemodynamics in patients undergoing cardiac surgery.
- To evaluate their effects on RV performance and arterial blood pressure during separation from cardiopulmonary bypass.
Main Methods:
- A prospective, randomized, double-blind study involving three sequential doses of CaCl2 (200 mg/dose), ephedrine (5 mg/dose), or placebo.
- Thermodilution catheters were used to measure RV volumes and ejection fraction.
- Hemodynamic parameters including mean arterial pressure and serum ionized calcium were monitored.
Main Results:
- Ephedrine significantly improved RV stroke volume and ejection fraction after the first dose, with sustained effects.
- Ephedrine also significantly increased mean arterial pressure after the third dose.
- CaCl2 and placebo showed minimal effects on RV performance and arterial pressure; CaCl2 did not improve RV function in hypocalcemic patients.
Conclusions:
- Ephedrine is an effective short-acting drug for improving RV performance and arterial blood pressure in cardiac surgery patients separating from cardiopulmonary bypass.
- CaCl2 failed to demonstrate significant hemodynamic benefits in this patient population.
- Ephedrine offers a superior alternative to CaCl2 for hemodynamic support in this clinical setting.
Abstract:
To determine whether ephedrine or CaCl2 improves hemodynamics in cardiac surgery patients emerging from cardiopulmonary bypass, three sequential doses of either CaCl2 (200 mg/dose; n = 12), ephedrine (5 mg/dose; n = 12), or placebo (n = 12) were administered in a prospective, randomized, double-blind fashion. Thermodilution volumetric catheters were used to calculate right ventricular (RV) volumes and ejection fraction. The first dose of ephedrine improved RV stroke volume from 57 +/- 3 to 63 +/- 4 mL/beat (P < 0.05) and ejection fraction from 44 +/- 2% to 49 +/- 2% (P < 0.05). Subsequent doses maintained this improvement but without further change. In contrast, placebo and CaCl2 had minimal effects on RV end-systolic volume, stroke volume, and ejection fraction. After the third injection of ephedrine, mean arterial pressure had significantly increased from 78 +/- 2 to 93 +/- 4 mmHg (P < 0.05) in contrast to insignificant increments with placebo and CaCl2. Serum ionized calcium increased by 6% to 8% after each CaCl2 bolus but remained stable in the ephedrine and placebo groups. CaCl2 failed to improve RV performance in mildly hypocalcemic patients during separation from cardiopulmonary bypass. In patients with normal preoperative ventricular function, ephedrine more effectively improved RV performance and arterial blood pressure than placebo or CaCl2, and is a suitable short-acting drug to assist separation from cardiopulmonary bypass.