Investigating the effect of surface cryotherapy on equine patient compliance to infraorbital nerve block placement.

Overview

• This study examined whether applying ice to the skin before placing an infraorbital nerve block would improve how well sedated horses tolerate the procedure.
• The researchers found that icing the skin did not significantly affect the horses’ compliance during the nerve block placement.

Objective and Background

• The primary goal was to determine if surface cryotherapy (applying ice) to the skin over the infraorbital canal would enhance compliance in horses undergoing infraorbital nerve block placement.
• The infraorbital nerve block is commonly used in equine veterinary medicine for analgesia during procedures involving the face.
• Compliance during block placement can be challenging because of discomfort or sensitivity; improving compliance could help in smoother and safer procedures.
• Cryotherapy (icing) is known to reduce pain and discomfort in other contexts by numbing the skin and underlying tissues.

Study Design

• Type: Blinded, randomized crossover trial.
• Subjects: 30 healthy adult horses with an average age of 16 years and mean weight around 594 kg.
• Each horse served as its own control by undergoing both treatments (icing and no icing), separated by at least 7 days to avoid carryover effects.
• Horses were sedated with detomidine hydrochloride to standardize sedation level prior to the nerve block.
• Compliance to sedation was scored using a pre-existing simple descriptive scale to ensure adequate sedation.

Intervention and Procedures

• Two treatments were compared:
  • ICE: 5 minutes of applying ice to the skin over the infraorbital canal.
  • N-ICE: No ice applied.
• An infraorbital nerve block was performed using 5 mL of 2% mepivacaine in both groups.
• Effectiveness of the block was verified by pricking the area with a 25-gauge needle to test sensation loss.
• The procedures were video-recorded for unbiased analysis.

Outcome Measures

• Compliance was measured by two blinded investigators using a Visual Analogue Scale (VAS) ranging from 0 to 10, indicating how well each horse tolerated the block.
• The two scores per horse (one from each investigator) were summed for a total maximum score of 20.
• Block success was noted—whether the nerve block effectively anesthetized the area.
• Any adverse effects linked to icing were recorded.

Results

• No statistically significant difference in compliance was observed between ICE and N-ICE groups (P = 0.179).
• Mean combined VAS scores were slightly higher in the ICE group (13.74 ± 6.2) compared to the N-ICE group (11.81 ± 6.9), but this difference was not significant.
• Block success was higher in the ICE group with 24/30 successful blocks versus 18/30 in the N-ICE group; however, statistical significance was not mentioned.
• No adverse effects were reported from the application of ice.

Conclusions and Implications

• Applying ice to the skin over the infraorbital canal before nerve block placement in sedated horses did not significantly improve their compliance during the procedure.
• While there was a numerical increase in compliance and block success for the ICE group, the differences did not reach statistical significance.
• No safety concerns were identified with the use of cryotherapy, suggesting it is a safe adjunct but may not provide clear benefit in improving patient tolerance for this procedure.
• The findings suggest that other methods may be needed to enhance horse compliance during infraorbital nerve blocks.