Contradictory effects of dopamine at 32 degrees C in pigs anesthetized with ketamine.
BACKGROUND
In critically ill patients who were surface cooled to 33 +/- 2 degrees C, we have observed that dopamine sometimes causes a substantial decrease in blood pressure. The present study was designed to compare the effects of dopamine in normothermia to those seen after surface cooling to 32 degrees C.


METHODS
Seven pigs with a mean body weight of 21 kg were anesthetized with ketamine and muscle relaxation was induced with pancuronium. They were mechanically ventilated and given dopamine infusions (5 and 12 micrograms.kg-1.min-1)in normothermia and after surface cooling by cold water immersion to a central blood temperature of 32.0 degrees C (range 31.6-32.6 degrees C).


RESULTS
In normothermia, dopamine at a dose of 5 micrograms.kg-1.min-1 increased mean arterial blood pressure (MAP) by 16% (P < 0.01) and cardiac output (CO) by 9% (P = 0.051); at 12 micrograms.kg-1.min-1 dopamine increased MAP by 26% (P < 0.01) and CO by 18% (P < 0.01). In hypothermia, MAP and CO did not change at an administration rate of 5 micrograms.kg-1.min-1; at 12 micrograms.kg-1.min-1 CO was unchanged but MAP was significantly reduced by 15% (P < 0.01).


CONCLUSIONS
Dopamine increased CO and MAP in normothermia but not at 32 degrees C, where there was even a significant reduction of MAP in this porcine model.
Roscher
R
R
Department of Anesthesiology and Intensive Care, University Hospital, Lund, Sweden.
Ingemansson
R
R
Wetterberg
T
T
Algotsson
L
L
Sjöberg
T
T
Steen
S
S
D000771:Anesthesia, Intravenous; D000778:Anesthetics, Dissociative; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004298:Dopamine / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007036:Hypothermia, Induced; D007649:Ketamine; D013552:Swine; D013696:Temperature; D014655:Vascular Resistance / Q000187:drug effects
D000778:Anesthetics, Dissociative; D007649:Ketamine; D004298:Dopamine