Monitoring at Home
Optimal monitoring strategies for
the home environment continue to be debated.
In-build ventilator alarms are
often inadequate and insensitive to the small tidal volumes seen in
paediatric patients, necessitating additional external monitoring
devices to minimise risk. Commonly, centres will opt to provide pulse
oximeters at home for children on invasive mechanical ventilation.
Others have used cardiorespiratory monitors, end-tidal
CO2 monitors or rely on direct observation by a nurse
24hr a day. Both The American Thoracic Society and Canadian Thoracic
Society clinical practice guideline provide an excellent summary of the
rationale for pulse oximetry as the preferred monitoring method for this
population of children over other options.(14, 16) However, it is also
important to remember that continuous oximetry monitoring may be
difficult to undertake in some children and has the potential to falsely
alarm or even falsely reassure parents and carers. Therefore, the data
needs to be interpreted in the context of the clinical situation and by
those with the experience to determine its reliability.
In recent times, the role of home carbon-dioxide monitoring in children
on invasive ventilation has been raised, recognising that this is an
important measure to gauge effectiveness of ventilation. Non-invasive
capnographs and capnometers that can measure either end-tidal carbon
dioxide (EtCO2) or transcutaneous CO2(TCM) have become increasingly available and are attractive for use in
children, who often cannot tolerate regular invasive blood gas
monitoring.(24) Foster et al. recently evaluated the potential of
a portable endotracheal capnograph (EMMATM Capnograph)
for measurements of EtCO2 at home in children on home
invasive ventilation. Overall, this device was demonstrated to show
promise for spot-checking carbon dioxide levels in this population of
children, but it has not been evaluated for continuous home monitoring
purposes.(24) Similarly, there is little evidence for the use of
ambulatory transcutaneous carbon dioxide monitoring (TCM) in children on
home invasive ventilation. One study has been undertaken in children
with neuromuscular disease to determine if ambulatory TCM monitoring
could be used for early screening and diagnosis or nocturnal
hypoventilation.(25) However, this study did not demonstrate sufficient
accuracy for this tool to be used for this purpose, despite patient
preference for this option over in-lab polysomnography. Therefore, at
present further research is required before non-invasive
CO2 monitoring of any type can be recommended as part of
routine home continuous routine monitoring.(24)
The exception is in congenital central hypoventilation syndrome, a
genetic condition where there is absent or abnormally reduced
ventilatory responses to hypercapnia and hypoxia, in the context of
systemic autonomic dysfunction. These patients fail to display the
typical responses to hypoxia and/or hypercapnia such as increases in
respiratory rate or effort. Here, home CO2 monitoring
can identify early hypoventilation in times of illness or stress. Which
in turn enables parents to institute a predetermined escalation plan
such as a ventilation ladder or a second program on the ventilator to
better reflect the increasing need for respiratory support. This can
avert attendance or admission to hospital. Furthermore, many emergency
departments do not have ready routine access to non-invasive
CO2 monitoring relying on CO2assessments taken by capillary or arterial blood gases. The pain/
arousal generated by these procedures often alter sleep state and
breathing, rendering results potentially less reliable. There has thus
been a movement towards providing these patients with home
CO2 monitoring, albeit funding can be an issue.
Follow up
It is important for children receiving home ventilation to receive
regular follow up at specialist respiratory centres with experience in
looking after these children. This may be in the form of an overnight
hospital stay, an out-patient visit, a home visit, via telemonitoring or
telemedicine, or a combination thereof. Clinical evaluation, nocturnal
oximetry and capnography monitoring and/or poly(somno)graphy and
analysis of ventilator download data are recommended as part of routine
monitoring. Gas exchange, delivered pressure, tidal volumes,
inspiratory: expiratory ratio, leak, residual respiratory events, and
patient ventilator synchrony ideally should be assessed. Follow up
should be provided by a multidisciplinary team, members of which include
a pulmonologist, long term ventilation/ tracheostomy nurses, respiratory
therapists, physiotherapists and ENT surgeon.