Written and maintained by CASRAI Editorial Board
Last updated
General product information for clinic, lab and supply staff. It is not medical advice and does not describe how to carry out a capping trial; clinical decisions belong to the patient’s care team and the manufacturer’s instructions for use.
Short answer
A tracheostomy cap is an accessory that closes the outer opening of a tracheostomy tube, so air no longer passes through the tube and the person breathes through the upper airway instead. “Capping” and “capped tracheostomy” describe that state, and clinicians use it as a test of whether the tube can be removed. A “tracheostomy plug” is the same idea in a different form, matched to a specific inner cannula.
Definition and scope
Medtronic describes its Shiley decannulation products as closing “the proximal end” of a tracheostomy tube or its inner cannula. The company’s white 15 mm cap attaches to the fenestrated inner cannula, while its decannulation plugs close the proximal end of reusable or disposable inner cannulas (Medtronic, checked 2026-11-01).
In the research literature, tube capping is described as “a commonly used test to determine if the tracheostomy tube can be removed”: it checks whether a person can breathe with the tube occluded (Nowak et al., 2022). This page covers the devices and the physical reasoning behind them. It does not cover when or how a care team starts or stops a trial.
For the broader device family, see our guides to the tracheostomy collar, the HME filter for tracheostomy and the difference between tracheostomy and tracheotomy.
How a cap or plug is used in practice
The manufacturer page describes the cap and the plugs by what they close, not by clinical steps. The cap “attaches to the fenestrated inner cannula” and fits any size of CFN or FEN tube. The decannulation plug (DCP) closes the reusable inner cannula, and the disposable decannulation plug (DDCP) closes the disposable inner cannula (Medtronic, checked 2026-11-01).
Why tube design matters is physical, and a 2022 bench study put numbers on it (see below).
Cap, plug and speaking valve: how the terms differ
People searching for a tracheostomy cap, a capped tracheostomy and a tracheostomy plug are usually looking at the same small family of occluding accessories. The table lists only what the manufacturer page states for the Shiley range; it is an example of how one maker splits the products, not a rule for every brand.
| Product (Shiley range) | What it closes | Per Medtronic page |
|---|---|---|
| Tracheostomy tube cap (CAP) | Attaches to the fenestrated inner cannula | White, 15 mm; for any size CFN or FEN tube; 10 per box |
| Decannulation plug (DCP) | Proximal end of the reusable inner cannula products | Sizes 4, 6, 8, 10, matched to 4, 6, 8, 10 FEN and CFN tubes |
| Disposable decannulation plug (DDCP) | Proximal end of the disposable inner cannula products | For any size DCFN and DFEN tube |
A speaking valve is a different device from a cap or plug. Our guide to the Passy-Muir valve covers it, and the comparison of fenestrated and non-fenestrated tubes explains the tube feature that the cap and plugs depend on.
Why tube type and cuff state matter
This is the part most product pages leave out. Nowak and colleagues measured airway pressure on a test lung at flows of 15 to 60 L/min (BMC Pulmonary Medicine 22:484, 21 December 2022). Key results from that bench study:
- Capping a cuffed tube produced a pressure drop “equivalent to severe airway obstruction” for breathing through the larynx.
- With a cuff at atmospheric pressure, the maximum was 4.2 kPa at 60 L/min. With the cuff fully deflated it was 3.4 kPa.
- An uncuffed tube with a 9 mm inner diameter measured about 0.04 kPa at 60 L/min, and stoma buttons a maximum of 0.014 kPa.
- Material, manufacturer and cuff diameter did not reliably predict the result.
The authors note the limits of the work: a dry test lung at room temperature, so measurements in a patient may be higher, and secretions, granulation tissue or upper-airway obstruction can also make capping fail.
Where it matters for clinics and supply decisions
Three points follow from the sources, and each is a checklist item for whoever stocks or reviews these accessories:
- Match the accessory to the tube family. Medtronic ties each product to a specific inner cannula type (fenestrated, reusable or disposable), so a cap or plug is selected by the tube in use, not by its name.
- Note whether the tube is cuffed or uncuffed. In the bench study, a capped cuffed tube gave a far larger pressure drop than a capped uncuffed tube, so the tube type matters when reading any capping information.
- Read the instructions for use. Warnings, single-use status and reprocessing are set out in the instructions for use supplied with the device.
Medtronic states the products are not made with natural rubber latex.
Common misunderstandings
“A cap fits every tracheostomy tube”
No. Even within one maker’s range, products are split by cannula type and size, as the table shows.
“Capping a tube is the same as putting a plug in a stoma”
They are different things. A cap or plug closes the tube or inner cannula; the bench study measured stoma buttons as a separate device category.
“Any tube can be capped safely”
The bench study suggests otherwise for cuffed tubes: a capped cuffed tube produced a pressure drop equivalent to severe obstruction. Whether and when to cap a given person’s tube is a clinical decision.
FAQ
What is a tracheostomy cap?
A tracheostomy cap is an accessory that closes the proximal end of a tracheostomy tube or inner cannula. Medtronic’s Shiley cap is a white 15 mm cap that attaches to the fenestrated inner cannula (Medtronic, checked 2026-11-01).
What is capping or a capped tracheostomy?
Capping is a commonly used test of whether the tracheostomy tube can be removed, in which breathing is checked with the tube occluded (Nowak et al., 2022). A capped tracheostomy is a tube in that state.
What is a tracheostomy plug?
The term covers closures matched to an inner cannula. Medtronic sells a decannulation plug for reusable inner cannulas and a disposable version for disposable inner cannulas.
Does a cap fit every tube?
No. Compatibility depends on the tube and inner cannula family; check the manufacturer’s product listing and instructions for use.
Sources
- Medtronic, Shiley decannulation plug and cap, product page, checked 2026-11-01.
- Nowak et al., Tracheal airway pressure in tracheostomy tube capping trials: an experimental study, BMC Pulmonary Medicine 22:484, 21 December 2022, checked 2026-11-01.
