Evaluation of the airway mechanics of modified toggle laryngoplasty constructs using a vacuum chamber airflow model.
Authors: Gray Sarah M, Gutierrez-Nibeyro Santiago D, Couëtil Laurent L, Horn Gavin P, Kesler Richard M, McCoy Annette M, Stewart Matt C, Schaeffer David J
Journal: Veterinary surgery : VS
Summary
Laryngeal hemiplegia impairs airway function in horses, and laryngoplasty (LP) surgery aims to restore patency, though construct stability during swallowing remains a clinical concern. Researchers tested 51 cadaveric equine larynges fitted with either modified toggle or standard LP constructs in a vacuum chamber airflow model, measuring cross-sectional area (CSA) of the rima glottidis, translaryngeal airflow, and impedance before and after cyclic loading designed to simulate postoperative swallowing. Both techniques maintained comparable airway mechanics—modified toggle constructs averaged 15.2 cm² CSA (15.1% decrease post-cycling) versus standard constructs at 16.4 cm² (4.3% decrease)—though standard LP constructs showed statistically significant impedance increases after cycling whilst modified toggle constructs remained stable. The modified toggle approach offers the practical advantage of resistance to mechanical drift during the critical early healing phase, potentially reducing the risk of laryngeal collapse from suture loosening and recurrent clinical signs. Although this ex-vivo model provides valuable biomechanical data, clinical validation through endoscopic studies and longer-term outcome comparisons would be needed to establish whether improved construct stability translates to superior functional outcomes and durability in living horses.
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Practical Takeaways
- •Modified toggle laryngoplasty may offer superior stability to cyclic loading (simulating swallowing) compared to standard techniques, suggesting potentially better durability in clinical use
- •Both techniques maintain adequate airway cross-sectional areas, but only ex-vivo data available; clinical outcomes in living horses with RLN still need investigation
- •The modified toggle technique warrants further clinical evaluation to determine if improved construct stability translates to better long-term functional outcomes for horses with recurrent laryngeal neuropathy
Key Findings
- •Modified toggle laryngoplasty constructs achieved mean rima glottidis cross-sectional area of 15.2 cm² before and 14.7 cm² after cyclic loading, compared to 16.4 cm² and 15.7 cm² for standard constructs
- •Modified toggle constructs maintained stable peak translaryngeal impedance after cyclic loading (p=0.13), whereas standard constructs showed significant increase in impedance (p=0.02)
- •Both modified toggle and standard laryngoplasty constructs demonstrated comparable overall airway mechanics in the ex-vivo model