interaction between these respiratory events and the mandibular position provides the data that are used in
offline analysis to predict outcome with the therapeutic custom appliance.
Once the patient initiates the study on the first night, the study progresses through a multi-night study where
different stages of data collection occur from one night to the next. The study will not progress to the next stage
if insufficient data is obtained to complete the present stage and instruction to repeat the test will be given to
the patient. During each stage of study, the device operates with a unique control function in order to collect the
comprehensive data set needed for the assessment of oral appliance outcome.
Dynamic Study Night
The dynamic test constitutes the first night test of the MATRx plus OA Study sequence. The study night begins by
holding the mandible at a rest position for up to 30 minutes to allow the patient to fall asleep. This sleep initiation
waiting period is terminated prematurely if respiratory events are detected. Following the initiation period, the
control function operates in one of two ways, namely: to eliminate respiratory events or to maximize airflow.
During the active mode, all variables (O2 saturation, airflow, mandibular position) are logged continuously and are
displayed on a data viewer after the study has been completed.
The study starts in a respiratory event elimination function (i.e. RE elimination), where the system responds to the
occurrence of respiratory events by reactively protruding the mandible. At this time, the control system detects
and internally classifies transient reductions in airflow and O2 saturation which are used as feedback respiratory
events to the control system. Each event is classified with respect to the magnitude of decrease in airflow and the
depth of desaturation, and their rate of occurrence (frequency). The result of this two-dimensional classification
(decrease in airflow and O2 saturation) determines the magnitude of a protrusive movement that is commanded
by the controller. This movement can range from commanded movements ranging from around 0.2 up to
1.4mm and is subdivided into 0.2mm steps 5 seconds apart. By step wise movement of the mandible, the system
attempts to eliminate respiratory event occurrence (i.e. achieve an occurrence rate of zero). The mandible is never
moved beyond the limits defined by the HCP during the device set up.
After 3 minutes without detection of a respiratory event, the system shifts to airflow maximization condition and
remains there until a respiratory event occurs. In this condition, the system searches for the minimal protrusive
position at which peak inspiratory airflow is maximal. Two types of searches, protrusive or retrusive, are executed
in alternating fashion. Each search entails one or more 0.6mm (2 x 0.3mm) perturbing step movement of the
mandible. The process begins with a protrusive or a retrusive search depending on whether the mandibular
position is less than or greater than 80%, respectively. Mean peak inspiratory airflow (five consecutive breaths) is
calculated before and after the perturbation and compared. In the protrusive search, protrusive steps occur, until
no difference in pre- and post-protrusive step mean values is observed. In the retrusive search, retrusive steps
occur until the post-retrusive step mean value is less than the pre-retrusion value.
Note
In the RE elimination condition, the system makes only protrusive movements of the mandible, whereas, in the airflow
maximization condition the system can make protrusive or retrusive movements.
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