Case report: respiratory inductance plethysmography as a monitor of ventilation during laser ablation and balloon dilatation of subglottic tracheal stenosis.

We describe a 61-year-old female who underwent KTP laser ablation and CRE balloon dilatation of symptomatic idiopathic subglottic stenosis (50% obstruction). The procedure was conducted, using our standard approach for such cases, under total intravenous general anesthesia with subglottic high-frequency jet ventilation (HFJV) via Lindholm laryngoscope. The patient was enrolled in an ongoing investigational protocol in which respiratory inductance plethysmography (RIP; Ambulatory Monitoring Inc., Ardsley, N.Y., USA) bands were used to monitor ventilation in addition to pulse oximetry and visual inspection. HFJV instituted with an Acutronic Monsoon jet ventilator (Acutronic Medical, Hirzel, Switzerland) resulted in a rapid increase in RIP signal amplitude consistent with breath stacking and inadequate expiratory flow around the tight stenosis. High pressure alarms sounded and automatic cessation of jet ventilation ensued. After successful tracheal dilation under intermittent apnea, subsequent jet ventilation produced only modest RIP amplitude changes. RIP may be an important safety monitor during jet ventilation for patients with obstructive tracheal lesions to lessen the risk of both barotrauma and hypoventilation. RIP remains under active study by our group for this purpose.