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Calcium does not augment phenylephrine's hypertensive effects.
J F Butterworth1, R A Strickland, L J Mark
1Department of Anesthesia, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27103.
Critical Care Medicine
|June 1, 1990
Summary
Calcium (Ca) and phenylephrine are used together in critical care. This study found that calcium did not enhance phenylephrine's ability to raise blood pressure in post-surgery patients.
Area of Science:
- Cardiovascular pharmacology
- Critical care medicine
- Clinical research
Background:
- Calcium and phenylephrine are commonly co-administered to increase mean arterial pressure (MAP) in critically ill patients.
- Understanding potential drug interactions is crucial for optimizing resuscitation strategies.
Purpose of the Study:
- To investigate whether calcium administration potentiates the pressor response to phenylephrine.
- To evaluate the combined effects of calcium and phenylephrine on hemodynamic parameters.
Main Methods:
- Eight adult patients undergoing aortocoronary bypass surgery received escalating doses of phenylephrine (150, 300, 450 ng/kg/min).
- Phenylephrine was administered alone and concurrently with calcium chloride (CaCl2) (5 mg/kg bolus followed by 2 mg/kg/h infusion).
- Hemodynamic parameters including MAP and cardiac index were monitored.
Main Results:
- Phenylephrine alone increased MAP by 2% to 17% depending on the dose.
- Calcium alone increased serum ionized calcium levels and MAP but did not affect cardiac index.
- Concomitant calcium administration resulted in similar MAP increases (6% to 13%) compared to phenylephrine alone, showing no significant potentiation.
Conclusions:
- Concomitant calcium administration does not augment the hypertensive response to phenylephrine in normotensive patients recovering from open heart surgery.
- The findings suggest that the pressor effects of phenylephrine are not significantly enhanced by concurrent calcium administration in this patient population.