Amrinone loading during cardiopulmonary bypass in neonates, infants, and children.
OBJECTIVE
To determine whether amrinone is bound to cardiopulmonary bypass circuits. When amrinone is administered to children during cardiopulmonary bypass, determine whether measured amrinone concentrations differ from those predicted based on a reported volume of distribution of 1.6 L/kg.


METHODS
In vitro study: Uptake of amrinone by cardiopulmonary bypass circuits was determined. Clinical study: Prospective, open label investigation.


METHODS
University-affiliated tertiary children's hospital.


METHODS
Clinical study: 27 children participated, including 5 neonates and 9 infants.


METHODS
In vitro study: Waste blood was circulated within seven pediatric cardiopulmonary circuits. Amrinone was administered, and blood was serially assayed for amrinone levels. Clinical study: Amrinone (mean dose 4.9 mg/kg) was loaded during cardiopulmonary bypass and amrinone concentrations in pump blood were determined at termination of bypass. Amrinone measured by high-performance liquid chromatography.


RESULTS
Cardiopulmonary bypass circuit uptake reduced amrinone concentrations to 79% of predicted. After correcting for circuit uptake, serum amrinone levels in patients were significantly higher than predicted. The levels, expressed in the ratio of measured: predicted amrinone concentration, did not differ among neonates, infants, and children older than 1 year of age.


CONCLUSIONS
When amrinone is administered to children during cardiopulmonary bypass, about 20% of the dose becomes bound to the circuit. Available drug is distributed within a smaller volume than predicted. This may be the consequence of the physiologic perturbations of hypothermic cardiopulmonary bypass.
Williams
G D
GD
Department of Anesthesiology, University of Washington School of Medicine, Seattle, USA.
Sorensen
G K
GK
Oakes
R
R
Boggs
D P
DP
Mulroy
J J
JJ
Lynn
A M
AM
D000676:Amrinone / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D002315:Cardiopulmonary Bypass / Q000295:instrumentation; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D005544:Forecasting; D006330:Heart Defects, Congenital / Q000601:surgery; D006801:Humans; D007036:Hypothermia, Induced; D007223:Infant; D007231:Infant, Newborn; D011446:Prospective Studies; D013499:Surface Properties
D000676:Amrinone