Abstract
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.
Study design
Prospective, randomized, cross-over study.
Animals
Ten healthy adult Beagles.
Methods
Instrumented dogs received a DMED-loading bolus (25 μg m−2) at time 0 followed by a 24-hour CRI (25 μg 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 O2 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 α2-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.
Keywords
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Article info
Publication history
Accepted:
April 23,
2007
Received:
April 23,
2006
Identification
Copyright
© 2008 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.
