The cardiopulmonary effects of dobutamine and norepinephrine in isoflurane-anesthetized foals.
OBJECTIVE
To evaluate the cardiovascular effects of norepinephrine (NE) and dobutamine (DB) in isoflurane-anesthetized foals.


METHODS
Prospective laboratory study.


METHODS
Norepinephrine (0.05, 0.10, 0.20, and 0.40 microg kg(-1) minute(-1)) and dobutamine (2.5, 5.0, and 10 microg kg(-1) minute(-1)) were alternately administered to seven healthy, 1- to 2-week-old isoflurane-anesthetized foals. Arterial and pulmonary arterial blood pressure, right atrial pressure, pulmonary artery occlusion pressure, heart rate, body temperature, cardiac output, arterial and mixed venous blood pH, partial pressure of carbon dioxide, partial pressure of oxygen [arterial partial pressure of oxygen (PaO(2)) and mixed venous partial pressure of oxygen (PvO(2))], and packed cell volume were measured. Standard base excess, bicarbonate concentration, systemic and pulmonary vascular resistance, cardiac index (CI), stroke volume, left and right stroke work indices, oxygen delivery (DO(2)), consumption, and extraction were calculated. Results Norepinephrine infusion resulted in significant increases in arterial and pulmonary arterial pressure, systemic and pulmonary vascular resistance indices, and PaO(2); heart rate was decreased. Dobutamine infusion resulted in significant increases in heart rate, stroke volume index, CI, and arterial and pulmonary arterial blood pressure. Systemic and pulmonary vascular resistance indices were decreased while the ventricular stroke work indices increased. The PaO(2) decreased while DO(2) and oxygen consumption increased. Oxygen extraction decreased and PvO(2) increased.


CONCLUSIONS
Norepinephrine primarily augments arterial blood pressure while decreasing CI. Dobutamine primarily augments CI with only modest increases in arterial blood pressure. Both NE and DB could be useful in the hemodynamic management of anesthetized foals.
Craig
Cary A
CA
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
Haskins
Steve C
SC
Hildebrand
Susan V
SV
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000758:Anesthesia / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000187:drug effects*; D004280:Dobutamine / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006736:Horses / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007262:Infusions, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D011669:Pulmonary Wedge Pressure / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D018685:Anesthetics, Inhalation; D002245:Carbon Dioxide; D004280:Dobutamine; D007530:Isoflurane; D010100:Oxygen; D009638:Norepinephrine