People with sleep apnea or other breathing disorders may benefit from a monitor that records their breathing rate. There are now several devices on the market for this task, but it is important to check all monitors against each other to ensure accuracy. This comparison study checked four models against each other and found good agreement between them.
The first monitor was the Equivital EQ02 LifeMonitor, which records breathing rate via a belt worn around the rib cage. The second monitor was the Resmed Quotient XF-60, which uses airflow to measure respiratory effort. A third device used chest straps to detect breathing movement and was known as the 3D printed elastic pebble-shaped sensor (3D printed EPS). This monitor was developed as a proof of concept for a method of obtaining breathing measurements during sleep. The final device used chest straps and electrodes on the rib cage to detect respiratory movement and was known as the 3D printed electrocardiogram sensor with adhesive electrode patches. This is similar to an electrocardiogram but is designed to detect breathing movements instead of heartbeats.
Features of Equivital EQ02 LifeMonitor:
It fits securely around the rib cage
Part of a system with a smartphone app to analyze data from multiple sensors
Features an alarm if breathing becomes too slow or fast Features of Resmed Quotient XF-60: Tracks respiratory effort
Monitors pulse rate through airflow around the nose at the same time as respiratory effort
Has a function to check the signals are being appropriately recorded Features of 3D printed elastic pebble-shaped sensor (3D printed EPS): Uses strain gauges to measure changes in chest circumference caused by breathing movements
Features an alarm if respiratory rate exceeds recommended safe limits
Can be used multiple times Features of 3D printed electrocardiogram sensor with adhesive electrode patches: Uses electrodes on the rib cage and chest straps to detect breathing movements
Tracks respiratory rate via an ECG.
Participants wore each device overnight in a randomized order for less than one week each, during which time they also kept a sleep diary. The devices were compared against the reference standard of the gold-standard polysomnography (PSG). The PSG records brain activity, eye movement, muscle activity, airflow, and oxygen levels during sleep.
After study entry, participants were asked to continue their normal sleeping habits until the end of the study. Participants kept a sleep diary during each night so researchers could assess whether devices recorded this disrupted data. The study found:
The PE+ and EQ02 LifeMonitor devices had a good agreement for the measurement of respiratory rate.
When using PSG as a reference standard, Resmed Quotient XF-60 detects significant obstructive sleep apnea with 95 percent accuracy.
3D printed EPS detected clinically significant obstructive sleep apnea with 94 percent accuracy.
The Resmed Quotient XF-60 was shown to be more accurate than the EQ02 LifeMonitor device, but that both devices were capable of detecting obstructive sleep apnea. The study found that 3D printed EPS is also a feasible alternative to traditional methods of measuring breathing rate during sleep. However, further studies will be needed to assess the device’s accuracy in capturing clinically significant obstructive sleep apnea.
All four devices were tested on a mannequin with schematic human anatomy. The mannequin was placed in six different sleeping positions, and for three-minute periods the four monitors were evaluated while the mannequin was at rest and when it breathed rapidly through a snorkel. The breathing rate was confirmed via a button that the mannequin wore on its hand, which could be pressed to indicate that it needed more air.
The results found good agreement between all four devices for most of the testing conditions. However, one unusual condition found poor agreement between the chest strap models and both monitors placed on the mannequin. This is because it requires too much movement to detect breathing with these devices unless the person remains in very specific positions while sleeping. Overall this study found that all four monitors can be used interchangeably for measuring breathing rate during sleep.
In Conclusion, the three chest strap monitors are interchangeable for determining breathing rate during sleep. The EPS monitor is not interchangeable because it requires too much movement to be useful in the majority of sleeping positions.