| Size of tracheostomy tubes: The diameter of the tracheostomy tube should be determined in a way that allows minimization of the work of breathing (by increasing the diameter) and that minimizes pressure on the trachea. The four classification systems used include French, Jackson, inner diameter and outer diameter. A French unit is equal to 0.33 mm, which means that an 18 FR tube has a diameter of approximately 6 mm. Measurements differ among manufacturers.
If you consider use of a smaller size of tracheostomy tube, you should realize that the patient’s work of breathing will increase with airway resistance, and this may impact weaning (allowing the patient to be removed from a ventilator and acclimate to spontaneous breathing). The diameter also impacts cuff pressure. If the tube is too small, the cuff will require a large volume of air for inflation and to create a tracheal seal. The increase in volume is followed by an increase in pressure that may lead to tracheal damage. | | | | |
