Jane's 5 point Anesthesia Articles

Question 1

Warne LN, Beths T, Holm M, Carter JE, Bauquier SH.

Evaluation of the perioperative analgesic efficacy of buprenorphine, compared with butorphanol, in cats.

Journal of the American Veterinary Medical Association. 2014;245(2):195.

Answer 1

• Butorphanol is a kappa agonist and mu antagonist, buprenorphine is a partial mu agonist and kappa antagonist
• 2 phase prospective study looking at butorphanol and buprenorphine for surgical pain from an OHE
• Premed with either butorphanol 0.4mg/kg or buprenorphine 0.02 mg/kg and then evaluated post-op.
• 9/10 cats required rescue analgesia, in phase 1 (design had drug in their pre-med only)
• For phase 2 they added a redose of initial med during closure of the wound.

•In phase 2 all cats in butorphanol group needed rescue analgesia at 20 minutes, while no cats in the buprenorphine group did. Data could not be analyzed futher than 20 minute score for this reason

•Concluded buprenorphine more effective for pain relief in this setting

Question 2

Snyder LBC, Snyder CJ, Hetzel S.

Effects of Buprenorphine Added to Bupivacaine Infraorbital Nerve Blocks on Isoflurane Minimum Alveolar Concentration Using a Model for Acute Dental/Oral Surgical Pain in Dogs.

Journal of Veterinary Dentistry. 2016;33(2):90-96.

Answer 2

• Used a dental dolorimetry electrical stimulator. Determined baseline MAC in each dog by stimulating and walking down ISO to lowest level that prevented purposeful movement
• Blocked bilateral infraorbital with either Bupivicaine only or Bupivicaine/buprenorphine, and determined MAC reduction q 24h for each dog with same method. After dog returned to baseline, washout period of 2d and switched to other group
• At 48h 50% of dogs in the BupBup group and 25% in the Bup group had MAC reduction (NOT SIGNIFICANTLY DIFFERENT). Increasing sample size to 40 would have made it significant.
• No major cardiorespiratory changes, but minor decrease in HR in the Bupbup group
• Bup may have analgesic effects of 24-72 hours, MAC reduction 22% BupBup may have analagesic for up to 96 hours, MAC reduction 19%

Question 3

Krug W, Losey J.

Area of Desensitization Following Mental Nerve Block in Dogs.

Journal of Veterinary Dentistry. 2011;28(3):146-150.

Answer 3

• Administered bupivacaine nerve blocks to mental nerve, tested with cold on teeth, curette on MGJ and hemostat on MCJ
• Teeth tested were canine, P3, P4 and mesial/distal M1 – teeth blocked better that ST, but still poor

•Most reliably desensitized:

• tooth was P3 (100%) P4 (83%);

•soft tissue desensitization was at I3 (57%) then P1, P3, P4 (43%);

•MCJ almost never blocked

• Proposed Reasons for failure to desensitize:
• redundant collateral innervation;

•blocked canal dt anatomy;

• additional branches of CNV coming from buccal branch of mandibular n.;
• cross over of fibres from CNV on the other side;
• anastomoses between CNV and CNVII mean CNVII may have some sensory properties here;
• need to block 3 nodes for it to work (humans 1.8mm apart, so need to cover 6 mm of nerve)
• Mylohyoid nerve provides innervation to vetral lip and cheek and is not blocked
• No controls, lower dose of bupivacaine than can be used

Question 4

Ambros B, Alcorn J, Duke-Novakovski T, Livingston A, Dowling PM.

Pharmacokinetics and pharmacodynamics of a constant rate infusion of fentanyl (5 μg/kg/h) in awake cats.

American journal of veterinary research. 2014;75(8):716.

Answer 4

• Prospective on 8 cats fentanyl 5 ug/kg loading dose followed by 5 ug/kg/hr or placebo given and monitored for antinociception with mechanical and thermal testing
• Found that fentanyl was effective in causing anti-nociception with concentrations >1.33 ng/mL
• Found that fentanyl did not accumulate in cats and plasma concentration decreased during the infusion at the rate of 5 ug/kg/hr
• Profuse salivation in 1 cat receiving fentanyl and mild sedation in the others.