Dysphagia and aspiration are pervasive health problems affecting children from infancy to adolescence. Approximately 50,000 die annually from aspiration pneumonia (Dray at al., 1998). The occurrence of diffuse aspiration bronchiolitis in children with dysphagia is widespread (Matsuse et al., 1998). Silent aspiration is especially prominent in children with dysphagia, occurring in and estimated 94% of that population (Arvedson et al., 1994). The incidence of dysphagia is particularly significant in acute care (25-45%), long-term care (50%) (Finiels et al., 2001), and among stroke survivors (75%) (Perry & Love, 2001).
Aspiration typically occurs during feeding, but may also occur shortly after feeding as a result of esophageal reflux (Morton et al., 1999) or outside of meal times altogether, due simply to the unsafe passage of saliva (Finder et al., 2001). Further, approximately 25% of individuals at risk of aspiration do so in a “silent” manner (Smith et al., 1999), with no overt physiological indications (e.g. coughing, face turning red, uncoordinated breathing) and care-givers may have no warning that an aspiration has occurred.
The initial application of the Aspirometer has been as an aspiration sensor / indicator / warning system to assist caregivers and clinicians in their interventions and therapies.
It is anticipated that the aspirometer will also lead to the development of a better referral strategy for videofluoroscopy. Currently, in many urban and rural centres, there are extended waiting lists for radiological examination of swallowing, often translating into unacceptable delays of more than 2 years. Based on the typical length of the radiological exam and the professionals who need to be present, it is estimated that a single exam costs at least 1000 health care dollars per patient in Ontario. The aspirometer could help to prioritize which patients actually require videofluoroscopic examination, thereby making better use of those valuable health care dollars.
The goal of this project is to develop a commercial version of a wearable, portable, battery operated, easy-to-use aspiration detector and warning system – the Aspirometer – for professional and consumer (home-based) use. The first target markets are the large and commercially significant paediatric and stroke populations. Holland Bloorview’s Aspirometer consists of a wearable accelerometer-based based detector (worn around the neck below the thyroid cartilage) with associated signal processing, communications and power supply systems. The system uses innovative patented signal processing methodologies and algorithms which for the first time enables the accurate and reliable detection of aspirations and gives warning signals to care-givers. The aspirometer’s accuracy is already greater than 80% compared to the best trained clinician’s detection rate of ~50%.
The front-end filters were constructed and an evaluation system was constructed in a metal box for use near the X-Ray equipment used in the sensor trials at Mt. Sinai hospital. An evaluation board was also completed that contains all the circuitry expected to be used on the final aspirometer design. However, this unit will not be fully functional until January as we want to ensure the filter design and cut-off frequency choices were correctly matched to the sensors. This information will be available at the conclusion of the sensor trial study.
Catriona Steele (TRI)
Dave Kenny (Sick Kids)
Mike Casas (Sick Kids)
Glenn Berall (Bloorview/NYGH)