Effect of Inhaled XXXX on Laryngeal Abduction.

@entity235 @entity544 @entity2944
UNASSIGNED: Hypercapnia produces a profound effect on respiratory drive and upper airway function to maintain airway patency. Previous work has evaluated the effects of @entity2944 on the sole arytenoid abductor, the posterior cricoarytenoid (PCA), using indirect measures of function such as electromyography and direct nerve recording. Here we describe a novel method to evaluate laryngeal function in anesthetized animals and use this method to determine the effects of @entity2944 on PCA function. Eight @entity235 were anesthetized and a laryngeal mask airway used in combination with high speed video endoscopy to evaluate laryngeal function. A stepwise increase in inspired partial pressure of @entity544 produced marked arytenoid abduction above 70mmHg ETCO2 (p<0.001). Glottic length increased above 80mmHg ETCO2 (p<0.02) and this lead to under representation of changes in glottic area if standard measures of glottic area (Normalized Glottic Gap Area, NGGA) were used. Use of a known scale to determine absolute glottic area demonstrated no plateau with increasing ETCO2 up to 120mmHg. Ventilatory parameters also continued to increase with no evidence of a maximal response. In a second anesthetic episode, repeated bursts of transient @entity2944 for 60 seconds with an end tidal CO2 of 90mmHg produced a 43-55% increase in glottic area (p<0.001) at or shortly after the end of the hypercapnic burst. A laryngeal mask airway can be used in combination with video endoscopy to precisely determine changes in laryngeal function with high temporal resolution. Absolute glottic area more precisely represents PCA function than NGGA at moderate levels of @entity2944 .
