Use of a perfusion index to confirm the presence of sciatic nerve blockade in dogs.
OBJECTIVE
To evaluate perfusion index (PI) as a determinant of regional nerve block success following sciatic nerve blockade with bupivacaine in dogs undergoing stifle surgery.


METHODS
Prospective clinical trial.


METHODS
Ten adult dogs, aged 5.6 ± 2.6 years and weighing 36.9 ± 16.8 kg, undergoing a tibial plateau leveling osteotomy.


METHODS
Dogs were premedicated with acepromazine (0.03 mg kg-1) and hydromorphone (0.1 mg kg-1) intramuscularly, and anesthetized with propofol (up to 4 mg kg-1) intravenously and isoflurane in oxygen. An ultrasound-guided femoral and sciatic (F+S) nerve block was performed on the surgical limb with bupivacaine (0.75%), 0.2 mL kg-1at the femoral site and 0.3 mL kg-1at the sciatic site, with a maximum volume of 10 mL per site. Physiological variables were recorded every 5 minutes throughout anesthesia. A pulse co-oximeter probe was placed between the third and fourth digits of both pelvic limbs, and the PI was recorded 5 minutes before infiltration with bupivacaine, immediately afterwards, and every 5 minutes for 30 minutes. Motor nerve conduction velocity (MNCV) of the sciatic nerve was performed on the surgical limb 5 minutes before and 20 minutes after bupivacaine administration to confirm nerve block.


RESULTS
The PI of the surgical limb was significantly greater than the contralateral pelvic limb at 10 minutes (p = 0.03) and 15 minutes (p < 0.01) after F+S nerve blockade. The MNCV performed after sciatic nerve blockade revealed a functional motor blockade for all dogs. There were no significant changes in physiological variables.


CONCLUSIONS
The PI provided a reliable indication of successful sciatic nerve blockade in the clinical patients in this study. No increase in the PI by 15 minutes after bupivacaine administration around the sciatic nerve could indicate partial or total failure of anesthetic blockade.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Bonnie J
BJ
Gatson
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA. garciaf@ufl.edu.
Fernando L
FL
Garcia-Pereira
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Michelle
M
James
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Shelia
S
Carrera-Justiz
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
Daniel D
DD
Lewis
D000779:Anesthetics, Local / Q000008:administration & dosage*; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage*; D004285:Dogs / Q000601:surgery*; D005260:Female; D008297:Male; D009407:Nerve Block / Q000662:veterinary*; D010027:Osteotomy / Q000662:veterinary; D010092:Oximetry / Q000662:veterinary; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000187:drug effects; D012584:Sciatic Nerve
D000779:Anesthetics, Local; D002045:Bupivacaine
bupivacaine; dog; perfusion index; regional anesthesia; sciatic nerve block