Striking the Perfect Balance:  Home Sleep Test Devices

by Jeff Wyscarver, RPSGT., President DDMEOnline

The vast majority of home test devices fall into one of three broad categories:  Black Box, Low-end Traditional and High end traditional.  Each category has its place in the market based on the clinician’s requirements.  

Black box

Generally speaking, “black box” technology gathers data that is to some degree not the same type of data collected in the traditional attended sleep lab environment.   There are a number of technological and sensor strategies which have been used which are innovative and clever which have met with varying degrees of success.  Some companies opted to place emphasis on a simplified patient experience and others have taken two or three existing channels and run a variety of algorhythms to create their sleep study data and reports.  The benefit is usually the data acquisition is simple.  There are 2 tradeoffs for this type of approach:  first, is extrapolated or derived data typically found in “black box” systems is vulnerable to artifact and secondly, these systems tend to have very high disposable costs     It has been my experience the patient experience is not significantly different among these technologies. 

Low-end Traditional

Unlike the “black box” devices, this category uses a limited number of traditional channels meaning the type of channels used in the attended sleep lab environment.     The typical sensors are:

• Oximeter

• 1 channel of respiratory effort

• Airflow

• Optionally - Body Position

These devices are small and light weight making them less intrusive and simple to use for the patient.   One very good reason to use a low end, type III device is as a triage tool by a busy traditional sleep lab.   Another good application is as a follow-up tool for people already diagnosed with OSA.  O word of caution about using low-end type III devices to diagnose and treat OSA is there is only a limited number of disorders that can be ruled out and some devices do not have body position data which many believe is critical in the diagnostic process.    

High-end Traditional

There are a number of standard Type III devices which differ from the previous category in that there are a greater number of sensors consequently the clinical yield is greater, there is some redundancy or back-up channels. 

The typical sensors are:

• Oximeter

• 2 channels of respiratory effort - Respiratory Inductive Plethysmography (RIP)

• 2 channels of airflow

• Body Position Data

• Actigraphy

• Snore mic

• And some number of derived channels

The increased clinical yield is the result of being able to rule out a greater number of apnea types.  

For example, in the case of the low-led type III devices there is only 1 effort channel and the AASM guidelines indicate 2 effort channels are needed to rule out Central Sleep Apnea (CSA).  Since the high- end devices have 2 RIP belts they can rule out CSA.  This is critical when deciding whether to refer the patient to a sleep lab if significant CSA is noted.  The low-end devices might miss this.   The high-end type III devices do have a disadvantage in that the patient hook-up process is somewhat more complicated and takes more training for the patient by the clinician.   Additionally, the software is usually more complicated as there is more channels to evaluated and more features available.   This group of devices are widely used and accepted by the traditional sleep community and the emerging home sleep market as well.

DDME Online and NOX-T3

There is on the market a device and service that fall into a unique category:  The NOX-T3 introduced and supported by DDMEOnline. 

One key advantage using the NOX-T3 is the 5 step hookup and we know the patient’s experience has been very positive.  The NOX-T3 also has the advantage of several redundant channels which greatly reduces the likely hood of a repeat study due to a failed sensor.   

Moreover, the NOX-T3 software can calculate Pulse Transit Time (PTT) and Heart Rate Variability (HRV) which are data analysis features typically reserved for the attended sleep lab environment.  In additional to PTT and HRV the NOX-T3 device using DDME Online can also collect ABI™ which stands for Apnea-Bruxism Index.  This insightful data lets the clinician know if bruxism can be associated with disordered breathing events.  For dentists in particular this is critical because it separates bruxism associated with apnea from idiopathic bruxism.   Based on my 20 years as a clinician, it is NOX-T3’s combination of ease of use and complex capability that strikes the perfect balance.