Dexmedetomidine constant rate infusion for 24 hours during and after propofol or isoflurane anaesthesia in dogs.
OBJECTIVE
To evaluate cardiovascular and respiratory effects and pharmacokinetics of a 24-hour intravenous constant rate infusion (CRI) of dexmedetomidine (DMED) during and after propofol (PRO) or isoflurane (ISO) anaesthesia in dogs.


METHODS
Prospective, randomized, cross-over study.


METHODS
Ten healthy adult Beagles.


METHODS
Instrumented dogs received a DMED-loading bolus (25 microg m(-2)) at time 0 followed by a 24-hour CRI (25 microg m(-2) hour(-1)), with PRO or ISO induction/maintenance of anaesthesia during the first 2 hours (PRO and ISO treatment groups, respectively). Cardiovascular, respiratory, blood gas, airway gas, serum chemistry variables and DMED plasma concentration data were collected at -15, 5, 15, 30, 45, 60, 90 and 120 minutes. A number of cardiorespiratory and tissue oxygenation variables were calculated from the above data. After the 2-hours of anaesthesia, heart and respiratory rates and electrocardiograms were recorded and DMED plasma concentrations were determined for up to 26 hours.


RESULTS
Vasopressor effects and the decrease in heart rate (HR) and cardiac index induced by DMED were greater for PRO than ISO, but were within clinically acceptable ranges. Adequate oxygenation was maintained above the critical O(2) delivery level. The overall incidence of unfavourable arrhythmias was low and tended to vary inversely with HR. Mean DMED plasma concentration ranged from 0.23 to 0.47 ng mL(-1) for both groups during the 24-hour CRI with a mean elimination half-life of approximately 0.46 hour. CONCLUSION AND/CLINICAL RELEVANCE: DMED CRI resulted in typical alpha(2)-agonist induced haemodynamic changes with minimal respiratory effects, and appeared to be an efficacious adjunct during and after PRO or ISO anaesthesia in healthy dogs.
Lin
Guan-Yu
GY
Department of Clinical Sciences of Companion Animals, Utrecht University, Utrecht, The Netherlands.
Robben
Joris H
JH
Murrell
Joanna C
JC
Aspegrén
John
J
McKusick
Brett C
BC
Hellebrekers
Ludo J
LJ
D000768:Anesthesia, General / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D000818:Animals; D001784:Blood Gas Analysis / Q000662:veterinary; D018592:Cross-Over Studies; D020927:Dexmedetomidine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D004285:Dogs / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D007262:Infusions, Intravenous / Q000662:veterinary; D007530:Isoflurane / Q000008:administration & dosage; D008297:Male; D010100:Oxygen / Q000097:blood; D015742:Propofol / Q000008:administration & dosage; D011446:Prospective Studies; D012119:Respiration / Q000187:drug effects; D016896:Treatment Outcome
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D020927:Dexmedetomidine; D007530:Isoflurane; D010100:Oxygen; D015742:Propofol