The Passy-Muir Valve
This is very simply a one-way valve which is fitted on to the end of a cuff-down tracheostomy tube, in order to allow speech. It was asked about in Question 27.3 from the second paper of 2011. A more detailed exploration is carried out in a comprehensive tribute website which is owned by the manufacturer of the valve. In brief, it is a one-way valve which allows a uni-directional movement of air across a tracheostomy with an inflated cuff. Exhaled air comes out through the upper airway, allowing speech, expectoration of secretions, and a more effective cough.
In summary:
Indications for use:
- Enabling speech in a tracheostomy patient
- Enabling forceful expectoration of upper airway secretions in a tracheostomy patient
- Decreasing the risk of aspiration in a patient with a cuff-down tracheostomy
Complications of use
- The valve may block
- If the upper airway fails, you wont be able to exhale
- A good cough can dislodge the valve, sending it across the room
- Work of breathing may increase
- A small amount of apparatus dead space is added
Contraindications to use
- Inflated (or foam filled) tracheostomy cuff (you wont be able to exhale)
- Absence of a cuff leak with tracheostomy cuff deflated (you wont be able to exhale)
- Thick uncontrolled tracheal secretions (you will clog the valve)
- Thick uncontrolled oral secretions (you need to swallow those, or they will get inhaled)
- Severe respiratory weakness (you will not be able to overcome the valve resistance to inspiration)
- Unconsciousness (You cant deflate the cuff in these people)
- Gas trapping with autoPEEP (the valve will increase PEEP)
Anatomy of the item
This thing is a simple one-way valve.
One end plugs into the patient's tracheostomy via a standard connector; the other end can plug into a ventilator, or remain open. The standard connectors make it impossible to reverse the valve (which would have ridiculous consequences)
Details of function
Having one of these on a tracheostomy enables the wearer to speak. Instead of exhaling through the tracheostomy, the closed valve causes air to travel around the tracheal tube and into the vocal cords. This device prevents the need to finger-block one's tracheostomy each time one is inclined to speak or spit.
The fact that the valve remains closed until inspiration begins is helpful, because it keeps a column of air in the trachea, which is under positive pressure while the lungs recoil in expiration. This prevents the aspiration of upper airway secretions and swallowed food or liquids.
References
Dettelbach, Mark A., et al. "Effect of the Passy‐Muir valve on aspiration in patients with tracheostomy." Head & neck 17.4 (1995): 297-302.