Evaluation of a modified infraorbital approach for a maxillary nerve block for rhinoscopy with nasal biopsy of dogs

Abstract

OBJECTIVE To determine whether a maxillary nerve block via a modified infraorbital approach, applied before rhinoscopy and nasal biopsy of dogs, would decrease procedural nociception, minimize cardiorespiratory anesthetic effects, and improve recovery quality. ANIMALS 8 healthy adult hound-type dogs PROCEDURES In a crossover study, dogs received 0.5% bupivacaine (0.1 mL/kg) or an equivalent volume of saline (0.9% NaCl) solution as a maxillary nerve block via a modified infraorbital approach. A 5-cm, 20-gauge over-the-needle catheter was placed retrograde within each infraorbital canal, and bupivacaine or saline solution was administered into each pterygopalatine region. Rhinoscopy and nasal biopsy were performed. Variables monitored included heart rate, systolic arterial blood pressure (SAP), mean arterial blood pressure (MAP), diastolic arterial blood pressure (DAP), plasma cortisol and norepinephrine concentrations, purposeful movement, and pain scores. After a 14-day washout period, the other treatment was administered on the contralateral side, and rhinoscopy and nasal biopsy were repeated. RESULTS SAP, MAP, and DAP were significantly higher for the saline solution treatment than for the bupivacaine treatment, irrespective of the time point. Plasma cortisol concentrations after saline solution treatment were significantly higher 5 minutes after nasal biopsy than at biopsy. Heart rate, norepinephrine concentration, purposeful movement, and pain score were not significantly different between treatments. CONCLUSIONS AND CLINICAL RELEVANCE Maxillary nerve block via a modified infraorbital approach prior to rhinoscopy and nasal biopsy reduced procedural nociception as determined on the basis of blood pressures and plasma cortisol concentrations during anesthesia. These findings warrant further evaluation in dogs with nasal disease.

Accidental arterial catheterisation during a maxillary nerve block using a modified infraorbital approach in a dog

“…However, Fizzano et al performed the MNB using the modified approach on live animals and did not report on the occurrence of intravascular injection. Another possible factor is catheter size, as previous studies describing the technique have used catheter sizes ranging from 20 to 22‐G 9 16 17. The use of a 24‐G catheter with a length of 19 mm (BD Insyte) in the present case may have increased the risk of intravascular catheterisation.…”

Iatrogenic ocular trauma associated with infraorbital block performed for rhinoscopy in a cat: case report and preliminary imaging findings

“…Rhinoscopy can present an anesthetic challenge, as head movement, sneezing and gagging frequently accompany the procedure, limiting visualization and sample collection, and potentially compromising patient safety. 7,8,16 Interest has thus arisen in regional anesthetic techniques to facilitate rhinoscopy and improve patient comfort and safety. 7,8,17 Sensory innervation to nasal structures is provided by the ophthalmic and maxillary divisions of the trigeminal nerve.…”

“…7,8,16 Interest has thus arisen in regional anesthetic techniques to facilitate rhinoscopy and improve patient comfort and safety. 7,8,17 Sensory innervation to nasal structures is provided by the ophthalmic and maxillary divisions of the trigeminal nerve. The ophthalmic division of the nerve cannot be accessed readily in companion animals, but the maxillary nerve may be approached as it courses along the orbital floor.…”

“…[1][2][3][4][5][6] More recently, caudal maxillary and infraorbital blocks have also been suggested for use in conjunction with rhinoscopy, a procedure sometimes associated with unanticipated patient movements despite an adequate plane of anesthesia. 7,8 Caudal maxillary blocks used in conjunction with dental procedures have been associated with globe penetration and endophthalmitis in both cats and dogs. [9][10][11] Infraorbital blocks have been proposed as a simpler and potentially safer alternative.…”

“…11,12 However, infraorbital blocks performed to desensitize the nasal mucosa for rhinoscopy (hereafter denoted as 'caudal infraorbital block') require delivery of local anesthetic to the region of the pterygopalatine fossa, which necessitates introduction of the anesthetic delivery device into the infraorbital canal and potentially the orbit. 7,8 This modification of the technique increases the risk of iatrogenic ocular trauma.…”