The effect of romifidine on endoscopic grading of laryngeal function in horses.

Overview

• This study investigated how sedation with romifidine, a sedative drug, affects the assessment of laryngeal (voice box) function in horses using endoscopy.
• The researchers aimed to determine if romifidine influences the grading of laryngeal function or the physical measurement of the rima glottis (the opening of the vocal cords) during breathing.

Background

• Laryngeal function in horses is important for breathing and performance, and it is commonly assessed via endoscopy.
• Romifidine is a sedative used in veterinary medicine, but its effect on the evaluation of laryngeal function had not been studied prior to this research.
• Understanding whether sedation interferes with diagnostic accuracy is critical for proper clinical evaluation.

Objectives

• To examine how sedation with differing doses of romifidine affects endoscopic grading of laryngeal function in horses.
• To analyze whether the cross-sectional area of the rima glottis (CSARG), a key measurement indicating airway patency, changes under sedation.

Methods

• Ten horses were selected and underwent three separate laryngeal endoscopic examinations:
• Group R1: While unsedated (control baseline).
• Group R2: After intravenous administration of 0.04 mg/kg of romifidine.
• Group R3: After a repeat dose totaling 0.08 mg/kg intravenous romifidine, still sedated.
• The order of recorded examinations was randomized to reduce bias.
• Three independent reviewers, blinded to treatment groups, graded the laryngeal function based on the endoscopic videos.
• Measurements of the cross-sectional area of the rima glottis (CSARG) were taken from still frames at peak inspiration (the moment when the airway is most open).

Results

• There was no significant change in the endoscopic grading of laryngeal function between unsedated horses (R1) and those sedated with the initial romifidine dose (R2).
• The CSARG showed no statistical difference between groups R1 (no sedation) and R2 (0.04 mg/kg romifidine), indicating the low dose did not alter the size of the airway opening significantly.
• However, a significant reduction in CSARG was noted when comparing:
• Group R1 (no sedation) and Group R3 (higher dose 0.08 mg/kg romifidine).
• Group R2 (lower dose 0.04 mg/kg) and Group R3 (higher dose 0.08 mg/kg).
• This means that the higher dose of romifidine slightly decreased the effective airway opening.

Conclusions

• The study suggests that a low dose of romifidine (0.04 mg/kg intravenously) does not significantly influence the clinical grading of laryngeal function or airway size in horses.
• Higher sedation levels (0.08 mg/kg total dose) may reduce the cross-sectional area of the airway, potentially impacting assessments.
• The small sample size (only ten horses) may have limited the statistical power, so findings should be interpreted with caution.
• These results imply that low-dose romifidine can be used without major concern for altering laryngeal function assessment, but higher doses may affect measurement outcomes.

Implications for Veterinary Practice

• Veterinarians can consider using low-dose romifidine sedation when conducting laryngeal endoscopy without fearing interference with grading accuracy.
• Caution is warranted when higher doses of romifidine are used, as sedation may influence airway measurements.
• Further research with larger sample sizes is needed to confirm these findings and better understand sedation impacts on laryngeal function evaluation.