An inner cannula is a removable tube that fits inside a tracheostomy tube, acting as a protective liner for the airway. It slides into the larger outer tube (which stays fixed in the throat) and can be pulled out for cleaning or replacement without disturbing the tracheostomy itself. This simple design is one of the most important safety features of modern tracheostomy tubes, because it lets you clear mucus buildup quickly and keep the airway open.
How It Fits Into the Tracheostomy System
A tracheostomy tube with an inner cannula is called a “double cannula” system. The outer cannula sits in the stoma (the surgical opening in the neck) and stays in place between scheduled tube changes. The inner cannula slides inside it and locks into position, creating a smooth, continuous airway. Larger tracheostomy tubes made for older children and adults typically use this double cannula design, while smaller pediatric tubes often have only a single tube because there isn’t enough space for two layers.
The inner cannula reduces the internal diameter of the airway slightly, but the tradeoff is significant: you get a tube that can be maintained daily without a full tube change, which is a more involved procedure usually done by a healthcare provider.
Why the Inner Cannula Matters
The primary job of an inner cannula is to trap mucus and secretions before they can clog the main airway. Over time, the body naturally produces mucus that can dry and crust along the walls of a tracheostomy tube. Without an inner cannula, that buildup narrows the tube until breathing becomes difficult or impossible. The leading cause of tracheostomy tube obstruction is inadequate cleaning and maintenance of the inner cannula.
In an emergency, this design becomes critical. If the tube gets blocked, the inner cannula can be pulled out in seconds to immediately reopen the airway. A clean replacement is then inserted while the blocked one is cleaned or discarded. Without this option, a fully obstructed single-cannula tube would require removing and replacing the entire tracheostomy, a far more difficult and risky procedure, especially outside a hospital.
Disposable vs. Reusable Types
Inner cannulas come in two main varieties: disposable (single-use) and reusable. The difference affects daily care routines and cost over time.
- Disposable inner cannulas (DIC) are designed to be used once and thrown away. They typically lock into place with a clip mechanism. When secretions build up, you remove the old one and snap in a fresh one. This is the simplest approach and eliminates the need for a cleaning routine, though it means keeping a steady supply on hand.
- Reusable inner cannulas (RIC) are built from more durable materials and lock with a twist mechanism. Some brands mark them with a colored dot (Shiley uses a blue dot, for example) to distinguish them from disposable versions. These need to be cleaned regularly but can be used many times before replacement.
Inner cannulas are not interchangeable across brands. The locking mechanism, diameter, and length vary by manufacturer and tube size. Always use the specific inner cannula designed for your tracheostomy tube model.
Cleaning a Reusable Inner Cannula
If you or someone you care for has a reusable inner cannula, cleaning it at least once a day is the baseline recommendation. Some people need to clean more often, particularly if secretions are thick or frequent. Your care team will give you a specific schedule.
The general process starts with washing your hands and putting on clean gloves. Hold the neck plate of the tracheostomy steady with one hand while unlocking and sliding out the inner cannula with the other. Soak the removed cannula in the cleaning solution your provider has recommended. A common choice is a mixture of equal parts saline and hydrogen peroxide, though metal inner cannulas should never be soaked in hydrogen peroxide because it can damage the material. Use a small brush to clear any dried secretions from inside the tube, rinse thoroughly, and reinsert.
While the inner cannula is out for cleaning, some people use a spare inner cannula to maintain the airway and keep any ventilator connections intact. Having a spare on hand is especially important for anyone on mechanical ventilation, since even a brief disconnection can be a problem.
Fenestrated Inner Cannulas and Speech
Some tracheostomy systems include a fenestrated inner cannula, which has one or more small holes cut into its wall. These openings allow air to pass upward through the vocal cords, making speech possible. In practice, a person might use a standard (non-fenestrated) inner cannula most of the time and switch to the fenestrated version when they want to talk.
Fenestrated tubes do come with tradeoffs. They’ve been associated with granulation tissue (excess healing tissue that can grow into the holes) and weakening of the tracheal wall over time. They also add complexity to daily care, since the fenestrated and non-fenestrated cannulas need to be swapped correctly. Using the wrong one during suctioning, for instance, can cause tissue damage. Specialist speech cannulas exist that allow voice without deflating the tracheostomy cuff, but these are uncommon and can increase airflow resistance, which matters for people who are still weaning off ventilator support.
What to Do if the Airway Becomes Blocked
A blocked inner cannula is a breathing emergency. The first step is to remove the inner cannula immediately. In many cases, this alone clears the obstruction and restores airflow. Once the blocked cannula is out, replace it with a clean one using a sterile technique.
If removing the inner cannula doesn’t resolve the blockage, the obstruction may be in the outer tube or the trachea itself. In that situation, deflating the tracheostomy cuff (if the tube has one), covering the stoma, and attempting to ventilate through the mouth and nose are part of the emergency response. These steps should be part of any emergency plan established with your care team, especially for home care situations where hospital staff aren’t immediately available.