Independent effects of denervating the cricothyroid muscle and stenting on the anterior cricoid split: canine model.

The anterior cricoid split (ACS) has gained in popularity since its introduction in 1980, for the treatment of the difficult to extubate child. The procedure allows a successful extubation and avoids a tracheotomy about 75% of the time. How the ACS allows extubation remains poorly understood. Animal research has shown that in the canine model the ACS results in a gap in the cricoid cartilage with a subjective increase in the subglottic space (Senders and Eisele, 1978). This gap in the cricoid cartilage develops whether or not an endotracheal tube stent is used. This experiment was designed to quantitatively evaluate the effect of the ACS on the subglottic space with or without the use of the stent, and to evaluate the effect of the cricothyroid muscle on the ACS procedure. The results show that the ACS does result in an increase in the subcricoid space, and that the use of an endotracheal tube stent does result in a larger increase. The cricothyroid muscle has a strong immediate effect on the gap in the cricoid cartilage, which is eliminated by sectioning the external laryngeal nerve. The long-term effects of sectioning the external laryngeal nerve on the gap in the cricoid cartilage were not conclusive.