A New Monitoring Tool—The Ratio of the Tracheostomy Tube Cuff Diameter to the Tracheal Air Column Diameter (C/T Ratio)

Abstract

We review the pathophysiology of tracheal stenosis and discuss the use of a recently reported measurement, the C/T ratio (cuff diameter/tracheal diameter) for early prediction of risk of tracheal stenosis. We present a case of tracheal stenosis that developed in a 39-year-old man with prolonged paralysis who had required approximately 2 months of assisted ventilation via, first, a nasal endotracheal tube and, later, a tracheostomy tube. To help prevent tracheal stenosis, we recommend the following protocol for tracheostomy tube cuff management: (1) Use the 'minimal leak' technique of cuff inflation. (2) Measure the maximal leak you obtain to determine whether it is 'reasonable' (50-100 ml). (3) Determine whether only 5 ml or less of air is required to obtain the minimal leak. (4) If >5 ml of air is required, maintain the patient's C/T ratio below 1.5:1 and his cuff pressure below 25 mm Hg. Identify those patients whose tracheostomy tube cuff variables cannot be maintained within the above range as being at high risk for developing tracheal stenosis, and consider changing to a tracheostomy tube that is one or two sizes larger and of a different style, with a different cuff location. Classify those patients whose tracheostomy tube cuff volume and pressure cannot be maintained within the above ranges as being at high risk for developing tracheal stenosis. (5) Follow up such high-risk patients every 1 to 3 months for 1 year.