This section will discuss the components of a tracheostomy tubes as well as different materials, manufacturers and sizes of tracheostomy tubes and discuss the differences in function. Tracheostomy tubes facilitate positive pressure ventilation, allow for access for secretion removal, and provide a patent airway for patients with obstructed upper airways. Understanding the differences is important in the care of individuals with tracheostomy and in selecting the appropriate tube.
The hub of the tracheostomy tube is the part that protrudes from the patient’s neck. It has a universal 15mm diameter so that it can connect to the ventilator circuit, resucitation bags, speaking valves, and caps.
Although all the diameters of the tracheostomy hub are universal, the inner and outer diameter of the flange have different sizes to correspond to the patient’s unique anatomy.
Some manufacturers (Portex) have a color coded hub to quickly identify the size of the patient’s tracheostomy . See tracheostomy comparisons for more information.
NOTE: Some tracheostomy tubes have lower profile inner cannulas so that there is not a 15mm hub. These patients would be off mechanical ventilation and spontaneously breathing. There is a 15mm inner cannula that comes packaged with the tracheostomy tube, which should always be at the bedside in case of emergency. The inner cannula would then quickly be changed to the inner cannula with a 15mm hub for connection to a rescucitation bag or ventilator circuit. Changing to a 15mm hub is also required for speaking valves and caps.
Outer Cannula or Tube Shaft
The outer cannula, or tube shaft, makes up the main component of the tracheostomy tube and is the part that is inserted into the trachea. It can either be fenestrated or non-fenestrated, cuffed or cuffless. The outer cannula comes in many different sizes. The size of the outer cannula be shown on the flange as the outer diameter (OD). The outer diameter is the distance between the outside walls of the outer cannula, and is measured in millimeters.
The outer diameter of the tracheostomy tube should be two-thirds to three-quarters of the tracheal diameter (NTSP, 2013).
Note: The larger the outer cannula, the more difficult it will be for a patient to breathe with a speaking valve or cap in place. This is because the patient exhales around the tracheostomy tube and through the upper airway. Go to our section on speaking valves for more information on the design of speaking valves and how speaking valves work.
Dual cannula tracheostomy tubes have an inner cannula. The inner cannula is placed inside the outer cannula. The inner cannula can be easily removed or replaced for cleaning and therefore can help to prevent obstruction such as from mucous plugs. There are different sizes of inner cannulas that must be matched to the corresponding outer cannula or it will not fit appropriately. The appropriate size comes packaged with the tracheostomy tube. Additional inner cannulas can be purchased separately as needed.
Portex DIC tracheostomy tubes have a color coded inner cannula, which corresponds to the matching hub of the Portex tracheostomy tube, allowing for quick identification of the correct tube.
There are four ways the inner cannula is secured inside the outer cannula: prong clip, luer lock, ring clip, and telephone jack style. Single lumen airways do not use an inner cannula.
Inner cannulas can be disposable or non-disposable, fenestrated or non-fenestrated. If the inner cannula is fenestrated, the outer cannula should also be fenestrated or it would not function as intended.
The inner diameter (ID) refers to the distance between the inside walls of the inner cannula, and is measured in millimeters. Using an inner cannula decreases the usable airway diameter, increases airway resistance, and may increase the work of breathing (Carter, A. et al, 2013; Cowan, T. et al, 2001). Pediatric tubes do not offer inner cannulas, because the tube itself is already very small.
Check Sizing of the Tracheostomy Tube for more information about the differences in tracheostomy tube sizes and the implications.
Flange (neck plate)
The flange is the part of the tracheostomy tube that extends from the outer part of the tracheostomy tube and has holes to attach the tracheostomy tube tie. The flange should lye flush against the skin on the neck. The flange has important information about the tracheostomy tube including the tracheostomy tube size, the size of the outer diameter (mm), the size of the inner diameter (mm), the brand and cuff type.
Here are some common tracheostomy tube abbreviations on the flange:
- DCT- Disposable Cannula Cuffed Tracheostomy
- DCFS- Disposable Cannula Cuffless
- CFN- Cuffless Fenestrated (non-disposable)
- LPC- Low Pressure Cuffed
- FEN- Fenestrated
- DIC- Disposable Inner Cannula
Tracheostomy Tube Tie
The trach tie is used to keep the tracheostomy tube in place to prevent accidental decannulation. It attaches to the flange and wraps around the patient’s neck. Tracheostomy tube ties should be used unless the patient recently underwent local or free flap reconstructive surgery or other major neck surgery (Mitchell, 2013). This is to avoid neck pressure from the ties. A patient should not be discharged from the hospital with a tracheostomy tube sutured in place. (Mitchell, 2013).
One finger should be used to ensure that the tracheostomy tie is tight enough to prevent dislodgement. The edges of the tracheostomy flange may cause small ulcerations if the collar/ties that hold the tracheostomy tube in place are too tight.
There are a few different materials used for tracheostomy ties: twill, Velcro ties, and stainless steel metal chain. There is currently no consensus as to the superiority of one material over another. The most commonly utilized trach ties in institutional settings is Velcro material.
The purpose of the obturator, which is sometimes called a pilot, is to assist with the insertion of the tracheostomy tube. The inner cannula is removed and the obturator inserted which extends slightly beyond the tracheostomy tube. The obturator has a blunt tip and cushions the placement of the tube in the trachea to avoid tissue damage. Immediately following placement, the obturator is removed and replaced with the inner cannula.
Cuffed and Cuffless Tracheostomy Tubes
A tracheostomy tube can be either cuffed or cuffless. The cuff of a tracheostomy is a balloon-like feature located around the outer cannula, near the bottom of the tracheostomy tube. This is termed a cuffed tracheostomy tube. The cuffed tracheostomy tube has a pilot line and pilot balloon as an indicator for cuff status.
If the tracheostomy tube does not have the balloon-like feature, then the tracheostomy tube is termed “cuffless.” Most pediatric tubes are cuffless, even if the individual requires mechanical ventilation.
Purpose of the Tracheostomy Cuff
The purpose of the cuff is to maintain the air delivered from the mechanical ventilator to the lungs. The cuff fills the tracheal space around the tracheostomy tube to prevent airflow from escaping around the tube and through the upper airway. Therefore, positive pressure ventilation can be applied more effectively when the cuff is inflated.
There is a common misconception in the medical field that the cuff prevents aspiration.
Overinflation of the cuff can result in tracheal damage or esophageal impingement. Therefore, it is important to monitor the pressure/volume of air/water in the cuff. Monitoring cuff pressure can be achieved through manometry, minimal leak technique, or minimal occlusion.
The pilot line, or inflation line, leads from the cuff to the pilot balloon. It is a pathway for air to flow into and out of the cuff.
The pilot balloon is a balloon-like feature located at the end of the pilot line. The bottom of the pilot balloon contains a spring loaded valve, called a luer valve, which prevents air from leaking out of the pilot balloon. A syringe attaches to the luer valve to either inflate or deflate the cuff of the tracheostomy tube.
When the pilot balloon is inflated, this indicates that the cuff is inflated. When the pilot balloon is deflated, this indicates that the cuff is deflated.
Fenestrated Tracheostomy Tubes
A fenestration is a hole in the curvature of the posterior wall of the tracheostomy tube. Fenestrated tubes have various shaped openings along the shaft of the inner and outer cannulas that were designed to allow airflow through the fenestration for better voicing. They also provide less work of breathing when the cuff is deflated (Hussey, MJ & Bishop, JD, 1996) . Some tubes offer both fenestrated and non fenestrated inner cannulas. The use of the fenestrated inner cannula is indicated in order to achieve the benefits of the fenestration. Use of the standard inner cannula will block the fenestration and therefore block airflow through the fenestration.
NOTE: It is not a requirement for the patient to have a fenestrated tracheostomy tube during speaking valve use.
Due to the location of the fenestrations, they are often poorly positioned near the posterior tracheal wall and may rub and irritate against the wall. This can result in the proliferation of granulation tissue (scar tissue) to grow into, and occlude the fenestrations. This scar tissue diminishes the effectiveness of the fenestrations, makes it difficult to pass a suction catheter, and complicates removal of the inner cannula or changing of the tracheostomy tube. For these reasons, unless you have a tube custom made with fenestrations in the optimal position along the shaft, standard fenestrated tracheostomy tubes are rarely used during prolonged tracheostomy.
Shrivastava et al. (2003) demonstrated that patients with fenestrated tubes had a longer average weaning duration (12 days vs. 7 days) and a higher rate of complications (56% vs. 16%) than patients with non-fenestrated tubes. In this study, granuloma formation, stuck tube, and tracheostomy obstruction were approximately seven times more likely with a fenestrated tube.
Click to enlarge images
Remove fenestrated inner cannula and provide non-fenestrated inner cannula prior to suctioning to avoid tracheal injury.
The cap, plug, or cork, is a small plastic piece that is placed on the 15mm hub of the tracheostomy tube. The cap blocks all airflow through the tracheostomy tube and the patient must therefore inhale and exhale around the tracheostomy tube and through the upper airway. Capping is frequently used as a tool during decannulation trials. Some individuals with sleep apnea use caps or speaking valves throughout the day, and remove them at night. Others may need to uncap for an occasional suction procedure.
The cap is typically placed on the end of the 15mm hub of a deflated cuff or cuffless tracheostomy tube. Some inner cannulas may be removed to place a cap. Shiley™ dual inner cannulas are an example.
Caps are often used with smaller diameter tubes, cuffless tubes, or fenestrated tubes and are therefore not packaged with every tracheostomy tube. However, most manufacturers have some variation available for their product, even if it is sold separately.
Beard and Monaco (1993) found that the presence of a cuff, either inflated or deflated, increased resistance. They recommended that uncuffed tubes be used to decrease patient work of breathing when the tube is capped and to improve patient comfort during the process of decannulation.
Tracheostomy tubes are available in a variety of sizes and styles from several manufacturers. Some examples of manufacturers of tracheostomy tubes include Shiley™, Portex™, Bivona™, Traco®, and Blom®. It is imperative that clinicians are able to identify the patient has a tracheotomy tube, the brand, type, size (ID and OD), composition, material of the tube and cuff, whether or not the tube is fenestrated, or if it is a custom tube. The tracheostomy tube should be selected based on the individual patient’s anatomy and clinical needs. Therefore an adequate range of tracheostomy tubes should be stocked. Tube selection/preference is also influenced by physicians and purchasing contract.
Tracheostomy tubes are made of a variety of medical grade materials: plastic, silicone, sterling silver, and stainless steel. Two types of plastics commonly used are (PVC) polyvinyl chloride (Shiley™ and Portex™) and polyurethane (Tracoe®).
Plastic tubes are single patient use, and considered disposable. They are the most common tubes for institutional settings.
Silicone tubes are softer and less rigid than plastic or metal, and are commonly used in pediatric airways. Due to the flexibility of silicone, they are able to accommodate a wide range of anatomies. Because of the secretion resistance properties of silicone, they are manufactured without inner cannulas. Silicone tubes are single patient use, but may be sterilized and reused for the same patient.
Metal tubes, commonly referred to as Jackson tubes, are constructed of silver or stainless steel. They are heavier and more rigid than plastic, and typically cuffless. Many metal tracheostomy tubes do not have the 15mm hub as a standard part. For these reasons, they are rarely used in acute care facilities, but are sometimes utilized in the skilled nursing facility or the home care environment. Metal tubes are considered non-disposable and can be sterilized for multiple patient use.
If a metal tube is in use and it does not have a 15mm hub, this tube would not connect to the ventilator circuit or resuscitation equipment in case of emergency. Therefore, this tube should be replaced in critical care environment to a tube that has a standard 15mm hub.
Metal tubes without a 15mm hub are also unable to connect to speaking valves or caps. The metal Jackson with improved inner cannula in size 4, 5, and 6 can be used with the PMV 2020 with the PMV 2020-S adapter which essentially provides a 15mm connection. Once the adapter is attached to the inner cannula, a speaking valve can be attached to the “0”ring. For patient comfort, attach the “0” ring and valve in sterile fashion, then insert the inner cannula.
Tracheostomy Tube Dimensions
The dimensions of tracheostomy tubes are given by their ID, OD, length, and curvature. These variables should be considered when selecting the appropriate tracheostomy tube. The tracheostomy tube size, shape and diameter should be chosen based on the tube fit with the airway without pressure on the tracheal wall, and also taking speech and airway clearance into consideration (Mitchell, 2013). The type of tracheostomy tube should be clearly documented in the patient’s notes and it is important for the care provider to know this information.
Sizing of the Tracheostomy Tube
Choosing the appropriate inner and outer diameter sizes of the tracheostomy tube are important when recommending a the initial tracheostomy tube and any tracheostomy tube changes. When determining the appropriate diameter of the tracheostomy tube, there are a few aspects to consider: lung mechanics, upper airway resistance and airway clearance, ventilation and communication/speech needs, and indications for the procedure (Mitchell, 2013 ). These requirements may change over time.
It is also important to understand that different manufacturers follow different sizing guidelines. Some tracheostomy tubes utilize the Jackson sizing system, while other tubes use the International Organization for Standardization (ISO) method. Most Shiley dual cannula tracheostomy tubes still use the Chevalier Jackson sizing system. The appropriate dimensions are listed on the flange of the tracheostomy tube. The ISO requires that tracheostomy tubes are sized according to the most narrow part of the inner diameter which includes the inner cannula if it is required to connect to the ventilator circuit. The inner diameter of the outer cannula is used for tubes with a single cannula. The inner diameter of the inner cannula is used if that tube requires the inner cannula to connect to mechanical ventilation. The outer cannula is measured as the largest diameter of the outer cannula.
Sizing is important when recommending tracheostomy tube changes. Tracheostomy tubes with the same internal diameter (‘size’) may have different external diameters and length. A clinician recommending downsizing needs to be aware that one size 6 tracheostomy tube is not necessarily the same outer diameter or length as a different brand of size 6 tracheostomy tube. The clinician should assess the inner and outer diameter measurements and length to compare the tracheostomy tubes and ensure the appropriate selection.
It is important when selecting an appropriate tube to understand the differences in sizing. There is an unavoidable compromise to be made between a desire to maximize the functional internal diameter (and thereby reduce airway resistance and the work of breathing during weaning) and a need to limit the OD to approximately three-quarters of the internal diameter of the trachea (in order to facilitate airflow through the upper airway when the cuff is deflated). When the cuff is inflated, a smaller inner diameter will increase the resistance through the tube and airway clearance may be more difficult. Furthermore, if the tube selected is too small, the cuff may need to be overinflated to maintain positive pressure ventilation. Overinflating the cuff can result in tracheal damage such as necrosis and stenosis. However with a deflated cuff, the individual will also be breathing around the tracheostomy tube and therefore the size of the inner diameter is less important. With a speaking valve or cap in place, a smaller outer diameter will allow for easier exhalation around the tracheostomy tube and through the upper airway.
Tracheostomy Tube Length
The length of the tracheostomy tube may also vary between tubes of the same inner diameter for different manufacturers. These variations are not commonly appreciated, but may have important clinical implications. If the tracheostomy tube is too short, the end of the tube can hit against the posterior tracheal wall.
Tracheostomy tubes are available in standard lengths or extra lengths. Extra length tracheostomy tubes can be constructed with extra proximal length or distal length.
Extra proximal length tubes are for patients with thicker necks (obese patients). Standard tracheostomy tubes are too short and too curved for proper positioning due to the distance between the skin and the trachea. Therefore, standard tracheostomy tubes are more likely to be dislodged in patients with thick necks.
Extra distal length tubes are used to bypass tracheal anomalies such as stenosis or malacia. A study by Rumbek (1999) of 37 patients with substantial tracheal obstruction caused failure to wean. Insertion of a longer tracheotomy tube relieved the obstruction and allowed 35 out of 37 patients to be weaned from the ventilator within 1 week.
There are also adjustable tracheostomy tubes which have a movable flange so that the length of the tracheostomy tube from skin surface to trachea can be adjusted at the bedside. A locking mechanism on the flange maintains the chosen tube length. These tubes are used for patients with atypical anatomy. The locking mechanism often fails after a period of time and therefore these tubes are for short term use. Custom tubes are available with fixed flanges that can be made with specific sizes on an individual basis.
Tracheostomy Tube Curvature
Tracheostomy tubes can be curved or angled. These features can help to improve the fit of the tracheostomy tube into the airway. Patients with a fenestrated tracheostomy tube may need a particular angled tracheostomy tube so that the fenestration fits in an appropriate place in the trachea, and not against the anterior or posterior tracheal wall.
Single Lumen Tracheostomy Tubes
Single lumen tubes consist of the outer cannula only (there is not an inner cannula). Some brands are made of secretion resistant silicone. Most pediatric tracheostomy tubes are single lumen tubes, because their diameters are too small to accommodate an inner cannula. Since there is no inner cannula, resistance may be reduced. However, the entire tracheostomy tube would require to be changed if an obstruction occurred inside the single lumen tube. An example of this would be a mucous plug.
It is important to check the patency of single lumen tubes regularly.
Double Lumen Tracheostomy Tubes
Tracheostomy tubes with an inner cannula are called dual-cannula or double lumen tubes. Double lumen tubes are the most commonly used tracheostomy tube. Use of an inner cannula increases airway resistance (Cowan et al, 2001), but lends a safety factor in that it can be quickly changed in the event of a mucus plug, leaving the outer cannula in tact. Sometimes the inner cannula contains the 15mm hub, and a ventilator, resuscitation equipment, speaking valve or cap cannot be placed unless the inner cannula is in place to provide the hub for connection.
Subglottic Suction Port
Some tracheostomy tubes have the ability to suction above the cuff of the tracheostomy tube The Portex® Blue Line ultra® Suctionaid (BLuSA) Tracheostomy Tube has an extra lumen that can be used for suctioning or speech. The Blom Tracheostomy Tube has a subglottic suctioning cannula that replaces the inner cannula and is connected to an intermittent or continuous suction to remove secretions above the level of the cuff. Subglottic suctioning is a strategy to reduce ventilator-associated pneumonia by suctioning secretions above the cuff to reduce secretions from passing around the cuff and into the lower airways and lungs.
Tracheostomy Tube Cuffs
The tracheostomy tube cuff varies greatly in terms of the material, medium to fill the cuff and the size/dimensions. Tracheostomy tubes can be cuffed or uncuffed. Recall that the purpose of the cuff is to maintain the air delivered from the mechanical ventilator to the lungs. When an individual is removed from mechanical ventilation, deflating the cuff can speed up weaning. In a randomized study of critically ill patients with tracheostomy during spontaneous breathing trials, those with a deflated cuff had shorter weaning times, reduced respiratory infections and improved swallowing when compared to individuals who had the cuff of the tracheostomy tube inflated (Hernandez et al, 2012).
Types of tracheostomy cuffs include:
- High-volume, low-pressure
- Low volume, high pressure (tight to shaft)
high-volume, low-pressure cuffed tracheostomy tubes
High-volume, low-pressure, air filled cuffs are typically made of soft plastic (with the exception of the Silicone tube) that conform to the tracheal wall. They are the most commonly used cuffs. These cuffs should be filled with air only (MItchell, 2013).
When most plastic cuffs are deflated, they do not fold flush against the shaft of the tube, creating higher airway resistance and potential secretion retention around that deflated cuff. Patients with larger deflated cuffs had higher expiratory pressures when a speaking valve was placed (Johnson, 2009). This remaining bulk could delay successful speaking valve or capping trials, thereby increasing the length of stay.
Monitoring and managing cuff pressure is important in preventing complications. A common cause of high cuff pressure is when the tracheostomy tube is too small and the cuff is overinflated to produce a seal against the tracheal wall. Other causes are cuff overinflation, dilation of the cuff and use of low volume, high-pressure cuff (Hess, 2014). High cuff pressure may impair blood supply to the tracheal mucosal and result in tracheal injury such as necrosis or cause tracheal malacia or stenosis.
High-pressure, low-volume cuffed tracheostomy tubes
High-pressure, low volume cuffed tracheostomy tubes are available with the Bivona (Smiths Medical) line of silicone tubes, and are referred to as TTS, or Tight To The Shaft™. This tube should be filled with sterile water only. The use of air instead of sterile water may led to the spontaneous slow air leakage from the cuff balloon (Khoo & Smith, 2015).
Note: Do NOT use normal saline, as over time the salt solution will deteriorate the pilot balloon mechanism (Mitchell, 2013).
The TTS tubes are single lumen. A unique feature of this cuff is when you deflate it, the material hugs the shaft of the tube, eliminating the bulk of plastic remaining in the airway. This feature streamlines airflow around the shaft of the tube whenever the cuff is deflated, and may facilitate earlier trials of speaking valves without the need to downsize to a smaller diameter tube.
Foam cuffs are covered with a thin sheath and filled with a sponge like material composed of polyurethane foam covered by a silicone sheath. When correctly placed, the cuff is connected to the breathing circuit by means of a pilot tube and the foam cuff expands to seal the airway. When used properly, the pressure does not exceed 20 mm Hg (27 cm H2O). This pressure limiting factor helps reduce further damage to the tracheal wall. The foam cuff is especially useful in cases of tracheomalacia, as it conforms to the tracheal wall preventing airway collapse.
The self-expanding foam filled cuff of the Bivona Fome-Cuf tracheostomy must be deflated by manual aspiration of air via the deflation line and this is not possible if the deflation line is cut. Most tracheal tube cuffs are air or water-filled and deflate if the inflation line is cut. Knowledge of this is important in an emergency as the Bivona Fome-Cuf and staff training recommended.
Foam cuffs are not commonly used. These types of cuffs are typically reserved for individuals with injury to the tracheal wall due to the cuff.
Pediatrics tracheostomy tubes
Pediatric tubes are single lumen tubes due to the small inner diameter. Most pediatric tubes are cuffless.
Tracheostomy tubes come in different materials, shapes and sizes and should be chosen based on individual characteristics. There are many different manufacturers to choose from. Standardizing equipment across the facility and facility locations is recommended.
Images provided by ©2019 Medtronic. All rights reserved. Used with the permission of Medtronic
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