Evaluation of partial arytenoidectomy as a treatment for equine laryngeal hemiplegia

Abstract

Summary The efficacy of partial arytenoidectomy was assessed in 6 Standardbred horses, with surgically induced laryngeal hemiplegia, at rest (Period A) and during exercise at speeds corresponding to maximum heart rate (Period C) and 75% of maximum heart rate (Period B). Peak expiratory and inspiratory airflow rate (PEF and PIF), and expiratory and inspiratory transupper airway pressure (PUE and PUI) were measured and expiratory and inspiratory impedance (ZE and ZI) were calculated. Simultaneously, tidal breathing flow‐volume loops (TBFVL) were acquired using a respiratory function computer. Indices derived from TBFVL included airflow rates at 50 and 25% of tidal volume (EF50, IF50, EF25. and IF25) and the ratios of expiratory to inspiratory flows. Measurements were made before left recurrent laryngeal neurectomy (baseline), 2 weeks after left recurrent laryngeal neurectomy (LRLN) and 16 weeks after left partial arytenoidectomy coupled with bilateral ventriculectomy (ARYT). After LRLN, during exercise Periods B and C, Z1 and the ratio of EF50/IF50 significantly increased and PIF, IF50 and IF25 significantly decreased from baseline values. At 16 weeks after ARYT, Z1 returned to baseline values during Periods B and C. Although PIF, IF50, IF25, PEF/PIF, and EF50/IF50 returned to baseline values during Period B, these indices remained significantly different from baseline measurements during Period C. After ARYT, TBFVL shapes from horses during Period C approached that seen at the baseline evaluation. Partial arytenoidectomy improved upper airway function in exercising horses with surgically induced left laryngeal hemiplegia, although qualitative and quantitative evaluation of TBFVLs suggested that some flow limitation remains at near maximal airflow rates. These results indicate that, although the procedure does not completely restore the upper airway to normal, partial arytenoidectomy is a viable treatment option for failed laryngoplasty and arytenoid chondropathy in the horse.

The impact of technology on the study of equine upper airway surgery

“…Partial arytenoidectomy combined with bilateral ventriculocordectomy improves upper airway flow mechanics in exercising horses with experimentally induced laryngeal hemiplegia (Lumsden et al 1994). However, flow volume loop analysis demonstrates that some airway obstruction remains, and postoperative racing performance is not as good as following prosthetic laryngoplasty combined with ipsilateral ventriculocordectomy (Witte et al 2009).…”

“…Note that inspiratory pressures increase and airflow is limited by the obstruction (center) compared to return toward normal (left) after laryngoplasty (right). strated that the technique is more sensitive than the measurement of flow mechanics in the detection of airway obstruction (Fig 8) (Lumsden et al 1993, Lumsden et al 1994). …”

RACING PERFORMANCE RECOVERY OF A HORSE SUBMITTED TO ARYTENOIDECTOMY AND VENTRICULECTOMY FOR THE TREATMENT OF RIGHT LARYNGEAL HEMIPLEGIA NOT RESPONSIVE TO LARYNGOPLASTY – CASE REPORT / Retorno à função esportiva de um cavalo submetido à aritenoidectomia...

“…Of the various surgical maneuvers described in the literature to treat these diseases, arytenoidectomy procedure is indicated in cases of HL, especially when laryngoplasty fails (LUMSDEN et al 1994). In general, the laryngoplasty has been effective in the treatment of HL since it reduces wheezing and improves athletic performance (FULTON et al, 1991;LAGUNA, 2006).…”

“…Inversely to Beech (1991), the chondrite diagnosed in the equine was observed in both arytenoids and their presence would be enough to consequently obstruct airflow. Thus, the only therapy indication is arytenoidectomy (BEECH, 1991;LUMSDEN et al, 1994;D'UTRA VAZ et al, 2000).…”

Evaluation of the upper respiratory tract in the horse during treadmill exercise - A review – Part l: Endoscopy

“…The individual horses maximal heart rate is determined by an incremental exercise test. Then the horses are tested at the treadmill speed corresponding to their 75o/o of maximal heaft rate (HR75 max) and at maximal heart rate (HR,u") for 2 minutes (Lumsden et al, 1994). Often several trials are necessary to fatigue the horse and induce certain dvsfunctions.…”