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Dobutamine pharmacokinetics and pharmacodynamics in pediatric intensive care patients
D M Habib1, J F Padbury, N G Anas
1Harbor-UCLA Medical Center, UCLA School of Medicine, Torrance.
Insights
Dobutamine effectively increases cardiac output in critically ill children with minimal heart rate changes. Pharmacokinetics followed a first-order model, showing predictable drug levels with increasing infusion rates.
Area of Science:
- Pediatric Critical Care
- Pharmacology
- Cardiovascular Medicine
Background:
- Critically ill children often require inotropic support.
- Dobutamine is a commonly used inotropic agent, but its pharmacokinetic and pharmacodynamic profile in pediatric populations requires further elucidation.
Purpose of the Study:
- To evaluate the pharmacokinetics and pharmacodynamics of dobutamine in critically ill children.
- To determine the dose-response relationship and identify threshold concentrations for hemodynamic effects.
Main Methods:
- Prospective study in a pediatric critical care unit.
- Continuous dobutamine infusions (2.5–10.0 µg/kg/min) in 12 pediatric patients.
- Measurement of plasma dobutamine concentrations and hemodynamic parameters at steady state.
Main Results:
- Dobutamine plasma clearance ranged from 40 to 130 mL/kg/min, with linear increases in plasma concentration (r² = .97).
- Maximal doses increased cardiac output by 30%, blood pressure by 17%, and heart rate by 7%.
- Threshold concentrations for hemodynamic effects were identified for cardiac output, blood pressure, and heart rate.
Conclusions:
- Dobutamine pharmacokinetics in critically ill children follow a first-order kinetic model.
- Dobutamine effectively improves cardiac output with minimal chronotropic effects in this population.
- Cardiac output increases typically precede heart rate changes with dobutamine administration.
Objective:
To evaluate the pharmacokinetics and pharmacodynamics of dobutamine in critically ill children.
Design:
A prospective study of pediatric patients receiving continuous infusions of dobutamine in a stepwise format from 2.5 to 10.0 micrograms/kg/min.
Setting:
A pediatric critical care unit.
Patients:
Twelve children ranging in age from 1 month to 17 yrs with primary medical conditions.
Measurements:
Plasma dobutamine concentrations and hemodynamic responses were measured at each infusion rate at steady state. Dose response data were analyzed to determine the threshold or minimum plasma dobutamine concentration necessary for discernible hemodynamic effects.
Main Results:
Dobutamine plasma clearance rates ranged from 40 to 130 mL/kg/min. Each patient presented a linear increase in the plasma dobutamine concentration at each infusion rate (r2 = .97, p less than .001). Plasma clearance rate vs. actual dobutamine concentration did not vary. Cardiac output, BP, and heart rate increased 30%, 17%, and 7%, respectively, at maximal dose. The dobutamine concentration thresholds for changes in cardiac output, BP, and heart rate were 13 +/- 6, 23 +/- 14, and 65 +/- 30 ng/mL, respectively.
Conclusions:
There was no effect of plasma dobutamine concentration or infusion rate on plasma clearance rate. For this group of patients, over the range of the intravenous doses studied, dobutamine pharmacokinetics followed a first-order kinetic model. Threshold values for dobutamine usually show increases in cardiac output before changes in heart rate. These data demonstrate that dobutamine is an effective inotropic agent in critically ill pediatric patients and has minimal chronotropic action.