Physiology of a Tracheostomy
Physiological changes with a tracheostomy
In tracheostomy patients, there are several physiological changes that occur. These include:
Reduction of anatomical dead space
Loss of air humidification
Loss of voice
Changes to swallow
The upper airway anatomical dead space can be reduced by up to 50% post tracheostomy. This can be advantageous when weaning patients from mechanical ventilation. The dead space takes no part in gas exchange and adds to the work of breathing. Reducing this can help patients with critical respiratory reserves wean from a ventilator.
The natural warming, humidification and filtering of air that usually takes place in the upper airway are lost. This is one of the biggest dangers with a tracheostomy or laryngectomy. Secretions will become thick and dried and can easily obstruct a stoma or tube. This situation is made worse if there are copious secretions – often the case with these patients.
The patient's ability to speak is removed. This is a big problem for the patient and can lead to distress and anxiety. Sometimes, we can use aids like speaking valves to help patients vocalise.
The ability to swallow is adversely affected. Most people with a new tracheostomy will have a nasogastric or similar feeding regimen established. The cuff of the tracheostomy or the tube itself interferes with the swallowing mechanics of the larynx. These muscles can waste if not used (during prolonged ventilation) and require careful rehabilitation and assessment.