Anatomical position of a tracheostomy
Indications for insertion
There are a number of indications for a tracheostomy. However perhaps the main one in critical care is to enable long-term mechanical ventilation of patients. Some patients are more difficult to wean from the ventilator. It may be because they have copious secretions, or initially become very agitated when awake meaning that they might pull on their endotracheal tube before it is appropriate to take it out. It might be that they have already been extubated once or twice and have had to be re-intubated because of respiratory failure.
Under these circumstances it is often appropriate to create a tracheostomy. This is more comfortable for the patient in the long term, means that the nurse can provide oral care, and later on with the aid of other equipment the patient will be able to speak whilst still having the tracheostomy. The dead space is also reduced which improves ventilation to the lungs as the upper airway is no longer involved.
Other reasons for a tracheostomy may include protection of the airway for patients who are at risk of aspiration, to secure and maintain a safe airway in patients with injuries to the face, head or neck and following some types of surgery.
Types of tracheostomies
There are many different types of tubes which will go into a tracheostomy. This can be a little confusing but essentially one needs to ask if the tube is cuffed or uncuffed, with or without an inner tube and fenestrated or un fenestrated. A fenestrated tube is simply one with a hole in it.
Cuffed tracheostomy tubes, like endotracheal tubes in the adult, have a soft balloon at the end which will inflate thereby sealing the airway. This is essential in the patient who is receiving positive pressure ventilation or where there are increased oral or gastric secretions making the risk of aspiration a possibility.
Obviously uncuffed tubes do not have the same cuff at the end. It is important that the patient has a good gag and cough reflex in order to clear their secretions and protect them from aspiration. These tubes tend to be used in the longer term patients and positive pressure ventilation will not be tolerated with this tube in situ.
The fenestrated tube has an opening on the outer cannula. This allows the movement of air through the patient’s mouth and nose and enables speech. It is possible to block off the whole with a non-fenestrated inner cannula.
Any patient transferred out of critical care to the wards should have a double lumen uncuffed tube. This ensures that any secretions can be cleaned out of the tube should they occur and also that cuff will not be inadvertently inflated when the tube is blocked.
The percutaneous tracheostomy is the most frequently performed type of tracheostomy in the intensive care unit. This is because it is simple quick and can be performed at the bedside with the use of some local anaesthetic. It utilises a seldinger technique which involves inserting a needle into the trachea, pushing wire through the needle and then using a series of dilator is over the wire making a hole big enough for the insertion of the tracheostomy tube. All this is aided by the use of a fibreoptic scope down the endotracheal tube to ensure that the needle is entering the trachea. In skilled hands this is a procedure that can be done in under 30 minutes.
Surgical tracheostomy is one carried out in an operating theatre using a general anaesthetic. It can be carried out using local anaesthesia. A surgical tracheostomy is usually carried out on the intensive care patient who may have some difficult neck anatomy, possibly a short fat neck where the anatomy may be unclear or some vessels which with a percutaneous technique might be difficult to avoid.
It might be that the surgery is required as part of an ENT or maxillofacial surgical procedure. The larynx might have been removed in which case a tracheostomy is the only option for ventilating this patient.
A mini tracheostomy is a small four millimetre non-cuffed tracheostomy tube which is inserted through the cricothyroid membrane. It is inserted essentially for the removal of secretions and can only be used for ventilation in an emergency situation. Even in an emergency situation it would not be terribly appropriate and would need to be replaced as soon as possible.
Changing/cleaning inner tube
The inner cannula is prone to collect secretions which increase the risk of obstruction and also infection. These secretions if allowed to collect will also reduce the diameter of the inner lumen which can make the work of breathing harder for the patient.
It is important therefore that the inner tube is removed and inspected regularly or if the patient shows any signs of distress. The inner tube should be removed and if not disposable should be cleaned with sterile normal saline. It should be replaced with another inner tube whilst this process is taking place.
Checking cuff pressures
The cuff to the tracheostomy tube is there to provide an effective seal so that positive pressure ventilation can take place. It also provides some limited protection against aspiration.
However if it is over inflated it potentially can cause some ischaemia to the surrounding tissues and therefore the pressure within the cuff should be checked regularly with a handheld pressure manometer and should be maintained below 20 to 25 cm of water.
Wound care management
It is important that the tracheostomy stoma should be kept clean and dry to prevent infection and possible wound breakdown. Secretions from the tracheostomy may collect around the stoma which could cause problems. Increased moisture from these secretions can act as a medium for bacterial growth or prevent the site from healing properly.
The stoma dressing should be checked regularly and changed at least every 24 hours. It may need to be changed more often than this if there are excessive secretions and it should be monitored regularly to ensure that this will happen.
Tracheostomy dressings which are specifically designed for this purpose are of the keyhole type which wrap around the tracheostomy tube. They are designed to absorb moisture away from the skin.
When a tracheostomy is removed the wound is not sutured but is allowed to heal naturally. This can take from 5 to 7 days and during the healing time the stoma should be dressed with an absorbent dressing.