Transition in respiratory support - Decannulation.
When to close the tracheostomy?
Transition from invasive ventilation to another ventilatory support is generally performed, not earlier than 6 years of age, in children who are ventilated only during sleep. In cases of patients being 24 hours dependent, such change should be considered later (10-12 years of age) using phrenic nerve stimulation while awake and non invasive ventilation during sleep.
How to switch from invasive to non invasive ventilation?
CHS patients who have their tracheostomy removed invariably start another kind of ventilatory support, usually mask ventilation or phrenic pacing; negative pressure ventilation is not now commonly used.
Mask ventilation has been the first choice for the majority of patients. However, some CHS patients who are used to tracheal ventilation find the use of the mask uncomfortable and difficult to start with and they can be afraid to remove their tracheostomy tube. For this purpose a period of training is provided, keeping the tracheostomy tube in place and plugged off. Eventually a smaller one can be inserted and plugged, increasing the breathing space around it. Once the patient is assessed during sleep, with both nasal mask ventilation and plugged cannula, they can safely be sent home. When the child becomes used to the mask, and is able to sleep all night with it, a second sleep study is performed. If both breathing and neurological parameters are good, the cannula can be removed. Usually the stoma closes spontaneously over a few days to weeks, otherwise surgery is needed.
How to switch from invasive ventilation to phrenic nerve pacing?
Recently, it has been suggested that patients may switch from tracheostomy ventilation to phrenic nerve pacing. Since phrenic pacing cannot be used 24 hours a day, this is suitable only for patients requiring ventilatory support during sleep. When the patient starts using diaphragmatic pacing, the following steps are essential before the tracheostomy can be removed:
1) the tracheostomy tube should be kept during the first months, as previously described for non invasive ventilation;
2) ventilation with diaphragmatic pacing is at first established using an open tracheostomy tube for some months;
3) after the tracheostomy tube is downsized, an overnight sleep study with diaphragmatic pacing and plugged tracheostomy is performed: if the result shows normal level of blood gases, the tracheostomy tube can be removed . In all such cases, patients must learn to use non-invasive ventilation in case the pacer malfunctions, allowing back up ventilatory support until the pacer is replaced.