Cardiopulmonary effects of fentanyl in conscious dogs and dogs sedated with a continuous rate infusion of medetomidine.
OBJECTIVE
To determine the hemodynamic consequences of the coadministration of a continuous rate infusion (CRI) of medetomidine with a fentanyl bolus in dogs.


METHODS
12 healthy sexually intact male dogs weighing 30.3 -/+ 4.2 kg (mean +/- SD).


METHODS
Dogs received either fentanyl alone (15.0 microg/kg, i.v. bolus) or the same dose of fentanyl during an 11-hour CRI of medetomidine (1.5 microg/kg/h, i.v.). Prior to drug administration, dogs were instrumented for measurement of cardiac output, left atrial pressure, and systemic arterial blood pressures. Additionally, blood samples were collected from the pulmonary artery and left atrium for blood gas analysis.


RESULTS
Medetomidine infusion reduced the cardiac index, heart rate, and O2, delivery while increasing left atrial pressure. Subsequent fentanyl administration further decreased the cardiac index. The Pao2 was not significantly different between the 2 treatment groups; however, fentanyl transiently decreased Pao2 from baseline values in dogs receiving a CRI of medetomidine.


CONCLUSIONS
Because of the prolonged hemodynamic changes associated with the CRI of medetomidine, its safety should be further evaluated before being clinically implemented in dogs.
Grimm
Kurt A
KA
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801, USA.
Tranquilli
William J
WJ
Gross
David R
DR
Sisson
David D
DD
Bulmer
Barret J
BJ
Benson
G John
GJ
Greene
Stephen A
SA
Martin-Jimenez
Tomas
T
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs / Q000502:physiology*; D004347:Drug Interactions; D005283:Fentanyl / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
D000700:Analgesics; D020926:Medetomidine; D005283:Fentanyl