Effects of different catecholamines on the dynamics of volume expansion of crystalloid infusion.
BACKGROUND
The authors studied the influence of alpha, beta, and dopaminergic catecholamines on blood volume expansion in conscious normovolemic sheep before, during, and after a bolus infusion of a crystalloid.


METHODS
A 0.9% NaCl bolus (24 ml/kg in 20 min) was infused in four paired experiments each: no drug, dopamine infusion (50 microg . kg . min), isoproterenol infusion (0.1 microg . kg . min), and phenylephrine infusion (3 microg . kg . min). Blood volume expansion was calculated by the dilution of blood hemoglobin concentration.


RESULTS
Dopamine had little effect on peak blood volume expansion (12.7 +/- 0.9 ml/kg) compared with 0.9% NaCl (13.0 +/- 2.7 ml/kg); in contrast, isoproterenol augmented blood volume expansion (18.5 +/- 1.8 ml/kg), and phenylephrine reduced blood volume expansion (8.9 +/- 1.4 ml/kg). Two hours after the 0.9% NaCl bolus, sustained blood volume expansion was greatest in the isoproterenol protocol (12.2 ml/kg), whereas the dopamine protocol (6.8 ml/kg) remained similar to the control protocol (4.1 ml/kg), and the phenylephrine protocol had a net volume loss (-1.9 ml/kg). Some blood volume expansion differences were attributed to changes in renal function as phenylephrine infusion increased urinary output, whereas isoproterenol was associated with antidiuresis. However, dopamine caused diuresis and sustained augmentation of blood volume.


CONCLUSIONS
Catecholamines can alter the intravascular volume expansion of fluid therapy. beta-Receptor (isoproterenol) stimulation augmented blood volume expansion, whereas alpha (phenylephrine) stimulation reduced blood volume expansion. Combined dopaminergic, beta, and possibly alpha stimulation with dopamine augmented blood volume expansion and cardiac output while inducing diuresis.
Vane
Luiz A
LA
Department of Anesthesiology, University of Texas Medical Branch Galveston, USA.
Prough
Donald S
DS
Kinsky
Michael A
MA
Williams
Chad A
CA
Grady
James J
JJ
Kramer
George C
GC
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001810:Blood Volume / Q000187:drug effects*; D002302:Cardiac Output / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology; D002395:Catecholamines / Q000494:pharmacology*; D000077324:Crystalloid Solutions; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D007552:Isotonic Solutions; D010656:Phenylephrine / Q000494:pharmacology; D010952:Plasma Substitutes / Q000494:pharmacology*; D012756:Sheep; D014655:Vascular Resistance / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D002316:Cardiotonic Agents; D002395:Catecholamines; D000077324:Crystalloid Solutions; D006454:Hemoglobins; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D010656:Phenylephrine; D007545:Isoproterenol; D004298:Dopamine