Comparing Maxillary Nerve Block Methods
Lynelle Graham, DVM, MS, DACVAA, CVA (IVAS), CAVCA, North Carolina State University
In the Literature
Chohan AS, Pascoe PJ. Comparison of the efficacy and duration of desensitization of oral structures following injection of a lidocaine-bupivacaine mixture via lateral percutaneous and modified infraorbital approaches in dogs. Am J Vet Res. 2021;82(1):22-27.
The Research ...
Supplemental perioral analgesia via local blockade is standard in veterinary dentistry. Various methods of maxillary nerve desensitization, including lateral percutaneous, infraorbital, transorbital, and intraoral approaches have been used.
This crossover study compared 2 anatomic approaches (ie, modified infraorbital using a catheter and lateral percutaneous using nerve stimulation) to desensitize the maxillary nerve. For both approaches, 2 mL of a 50:50 mixture (based on volume) of lidocaine 2% and bupivacaine 0.5% was administered. Electrical stimulus was applied to 4 maxillary sites (ie, canine tooth, fourth premolar, second molar, hard palate) to simulate surgical stimulation.
The modified infraorbital approach used a 4.5-cm 22-gauge IV catheter gently threaded up the infraorbital canal to place local anesthetic closer to more branches of the maxillary nerve. Six mesocephalic dogs weighing ≈44 lb (≈20 kg) received 1 mL of local anesthetic when the catheter was fully advanced into the infraorbital foramen and 1 mL when the catheter was retracted approximately halfway.
Both approaches to maxillary nerve blockade were equally effective. Time to blockade onset did not differ, but the duration of blockade was longer with the modified infraorbital approach.
... The Takeaways
Key pearls to put into practice:
Modified infraorbital approaches to maxillary nerve blockade are effective and longer lasting than lateral percutaneous approaches. In patients with anatomic variables (eg, infection, tumor, fracture) that prevent an infraorbital approach, a lateral percutaneous approach can be effective.
The authors posited that success of the modified infraorbital approach was related to the volume of local anesthetic. In medium-sized dogs, 2 mL of local anesthetic were deposited along the infraorbital canal. Although it is important to be mindful of the total local anesthetic dose, adequate local anesthetic volume should be administered when performing oral blocks.
Mixing local anesthetics is controversial. Critical evaluation of dental blocks has not been published, but comparisons have been made when lidocaine, bupivacaine, or a combination thereof were used in veterinary species for epidural and peripheral limb administration. Mixing local anesthetics is discouraged because the speed of onset is not improved despite the inclusion of lidocaine, and the duration of action is shortened compared with bupivacaine alone.
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