Cardiovascular tolerance of intravenous bupivacaine in broiler chickens (Gallus gallus domesticus) anesthetized with isoflurane.
OBJECTIVE
To determine the median effective dose (ED50) of intravenous (IV) bupivacaine associated with a 50% probability of causing clinically relevant cardiovascular effects [defined as 30% change in heart rate (HR) or mean arterial pressure (MAP)] in chickens anesthetized with isoflurane.


METHODS
Randomized up-and-down study.


METHODS
A total of 14 Ross-708 broiler chickens (Gallus gallus domesticus) weighing 1.70-2.75 kg.


METHODS
Anesthesia was induced and maintained with isoflurane. Monitoring included the electrocardiogram and invasive arterial pressures. Chickens were administered bupivacaine IV over 2 minutes using a dose based on the response of the previous animal. Dose was decreased when HR and/or MAP in the previous animal increased or decreased ≥30% after bupivacaine administration, or increased when HR or MAP changed <30%. The ED50was defined as the dose resulting in ≥30% variation in HR or MAP in 50% of the population studied.


RESULTS
The IV ED50of bupivacaine was 1.94 mg kg-1using Dixon's up-and-down method and 1.96 mg kg-1by logistic regression.


CONCLUSIONS
These results suggest that 1.33 and 1.96 mg kg-1of IV bupivacaine are associated with a respective 1 or 50% probability of a clinically significant change in MAP in isoflurane-anesthetized chickens. Identification of the cardiovascular changes associated with different doses of bupivacaine can be used as the basis for studies of therapeutic applications in the domestic chicken. Further studies are required to determine interspecies variation.
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA.
Peter M
PM
DiGeronimo
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA. Electronic address: adacun1@lsu.edu.
Anderson F
AF
da Cunha
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
Bruno
B
Pypendop
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA.
João
J
Brandão
Division of Laboratory Animal Medicine, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA.
Rhett
R
Stout
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA.
Max
M
Rinaldi
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA.
Thomas N
TN
Tully
D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local / Q000008:administration & dosage*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002045:Bupivacaine / Q000008:administration & dosage*; D002645:Chickens; D006339:Heart Rate / Q000187:drug effects*; D007530:Isoflurane
D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D007530:Isoflurane; D002045:Bupivacaine
analgesia; avian; bird; local anesthesia