Misconception: What if the Tracheostomy Tube is Too Large?
Many clinicians are unaware that larger tracheostomy tubes cause resistance to airflow through the upper airway and reduced airway patency.
When the patient inhales, the Passy Muir® Valve opens, allowing air to enter the tracheostomy tube and the lungs. At the end of inspiration, the Valve closes automatically and remains closed throughout exhalation, without leakage. During exhalation, air is redirected around the tracheostomy tube and up through the mouth and nose to enable speech.
Therefore, if the tracheostomy tube is too large in outer diameter or length in proportion to the trachea, a patient will be unable to adequately exhale air around the tube.
Clinical Research that Supports Downsizing of the Tracheostomy Tube:
According to the American Thoracic Society and the Intensive Care Society Standards and Guidelines, initial tracheostomy tube selection should be considered to avoid damage to the tracheal wall, to minimize work of breathing, and to promote trans-laryngeal airflow.1-2 Criteria for speaking valve use should include a tracheostomy tube size that does not exceed two-thirds of the tracheal lumen.
Downsizing the tracheostomy tube improves speaking valve tolerance. Patients with larger outer diameter tubes or tubes with larger deflated cuffs have higher expiratory pressures. Downsizing the tube leads to a significant reduction of expiratory pressures, resulting in more recommendations for speaking valves and capping. With appropriately sized tracheostomy tubes, patients have improved comfort levels and tolerance when the Passy Muir Valve is used.3
Downsizing within seven days of the tracheotomy procedure is associated with earlier use of a speaking valve, earlier oral intake, and reduced length of stay.4
Downsizing and cuff deflation improve weaning for patients on spontaneous breathing trials. In a randomized controlled study of critically ill patients, increasing effective airway diameter by deflating the tracheal cuff and downsizing the tracheal cannula shortened weaning time, reduced respiratory infections, and improved swallowing.5
- American Thoracic Society Official Statement, Care of the Child with a Chronic Tracheostomy, American Journal of Respiratory Critical Care Medicine, Vol 161. pp 297-308, 2000.
- Standards for the care of adult patients with a temporary tracheostomy, Intensive Care Society (2008)
- Johnson DC, Campbell SL and Rabkin JD. Tracheostomy tube manometry: evaluation of speaking valves, capping and need for downsizing. The Clinical Respiratory Journal 2009; 3: 8–14.
- Fisher, D. et al. (2013). Tracheostomy Tube Change Before Day 7 is Associated With Earlier Use of Speaking Valve and Earlier Oral Intake. Respiratory Care. 2013 Feb;58(2):257-63.
- Hernandez, G. et al. (2013). The effects of increasing effective airway diameter on weaning from mechanical ventilation tracheostomized patients: a randomized controlled trial. Intensive Care Medicine. Jun;39(6):1063-70