Expiratory airflow obstruction due to tracheostomy tube: a spirometric studyin 50 patients.

OBJECTIVES: Tracheostomy is commonly used in intensive care units and in head and neck departments. Airway obstruction due to occluded cuffless tracheostomy tubes themselves remains unknown, although capping trials are commonly used before decannulation. The aim of this study was to evaluate the extent to which airway obstruction can be caused by occluded cuffless tubes in patients who underwent head and neck surgery. DESIGN: Prospective Research Outcome. SETTINGS: University teaching hospital. PARTICIPANTS: Fifty patients requiring transient tracheostomy after head and neck surgery. MAIN OUTCOME MEASURES: A flow-volume loop (FVL) through the mouth using a portable spirometer, with the occluded fenestrated cuffless tube, was measured before and immediately after decannulation, by obstructing the orifice of tracheostomy tube. The measurement of FVL recorded the forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1 ), peak expiratory flow (PEF), forced expiratory flow at 50% of FVC, peak inspiratory flow (PIF) and forced inspiratory flow at 50% of FVC. RESULTS: A statistically significant difference between all spirometric parameters was found. Mean PEF and PIF, respectively, increased from 2.8 to 4.5 L/s (P < .0001) and 2.3 to 2.7 L/s (P < .01) before and after decannulation, with a strong positive correlation (r = 0.7; P < .05). A mean expiratory (34%) and inspiratory (9%) airflow reduction was observed due to cannula. CONCLUSIONS: Occluded cuffless tracheostomy tubes cause a dramatic airflow obstruction, mainly in the expiratory phase of FVL. This should be taken into account during capping trials.