Cardiopulmonary effects of dobutamine and norepinephrine infusion in healthy anesthetized alpacas.
OBJECTIVE
To characterize the cardiopulmonary effects of dobutamine and norepinephrine infusion in isoflurane-anesthetized healthy alpacas.


METHODS
8 adult alpacas.


METHODS
Initial baseline cardiovascular, respiratory, and metabolic variables were obtained 30 minutes after induction of isoflurane anesthesia in 8 alpacas (3 females and 5 sexually intact males). Four treatments (dobutamine at 4 and 8 microg/kg/min and norepinephrine at 0.3 and 1 microg/kg/min) were administered in random order via constant rate infusion over 15 minutes, followed by repeat measurements of cardiopulmonary values and a 20-minute washout period. Subsequent baseline and posttreatment measurements were similarly repeated until both drugs and dosages were administered to each animal. Baseline data in awake alpacas were obtained 18 to 24 hours following recovery from anesthesia.


RESULTS
Both dobutamine and norepinephrine significantly increased cardiac index and arterial blood pressure from baseline values. Similar increases in hemoglobin concentration, oxygen content, and oxygen delivery were observed following administration of each drug at either dosage. Only dobutamine, however, reduced relative oxygen consumption while improving overall tissue oxygenation. Furthermore, heart rate was selectively enhanced by dobutamine and systemic vascular resistance by norepinephrine. Norepinephrine infusion resulted in dose-dependent changes in cardiopulmonary variables.


CONCLUSIONS
Results indicated that both dobutamine and norepinephrine were appropriate choices to improve cardiac index, mean arterial pressure, and overall oxygen delivery in alpacas with isoflurane-induced hypotension. Careful titration by use of low infusion rates of dobutamine and norepinephrine is recommended to avoid potential arrhythmogenic effects and excessive vasoconstriction, respectively.
Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA.
Caitlin J
CJ
Vincent
Alexander T
AT
Hawley
Elizabeth A
EA
Rozanski
Kara M
KM
Lascola
Daniela
D
Bedenice
D000768:Anesthesia, General / Q000662:veterinary*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002161:Camelids, New World; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*
D002316:Cardiotonic Agents; D004280:Dobutamine; D009638:Norepinephrine