Office of Technology Transfer – University of Michigan

Respiratory rhythm matrix (RRM), a new method for sleep apnea detection

Technology #6918

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Jimo Borjigin
Managed By
Drew Bennett
Associate Director - Software Licensing 734-615-4004

Sleep apnea can be defined as a group of disorders characterized by abnormalities of breathing while sleeping. Breathing is interrupted from a few seconds to minutes, occurring several times over the course of a routine sleep. Airway blockage occurs as the patient sleeps. The blockage occurs between the soft palate and/or the back of the tongue and the pharynx. As the patient breathes, the reduced area in the upper airway can cause snoring, and more seriously, obstructive sleep apnea (OSA). When breathing is obstructed, oxygen levels drop resulting in low supply to the heart and brain.

Obstructive sleep apnea is a common sleep disorder that affects 1 in 30 people. Diagnosis of sleep apnea relies on sleep tests conducted at home overnight (8-10hrs). Currently, apnea scoring is conducted manually by trained sleep technicians, which is time consuming, tedious, and error prone. A faster and more reliable method of detecting sleep apnea is predicted to allow faster and more accurate diagnosis of sleep apnea.

Technology Description

The invention under consideration involves a new and automated method of apnea scoring, termed Respiratory Rhythm Matrix (RRM). The RRM depends on the 3D representation of periodic breathing signals, which lines up consecutive breathing peaks in its X-axis (time) and displays two or more consecutive breaths in its Y-axis (seconds). The depth of breathing is denoted in its Z-axis shown as a heat map.


  • Home sleep apnea diagnosis test
  • Polysomnograph tests
  • Diagnosis of cardiac and neurological disorders


  • Unlike the traditional method that displays respiratory rhythms in 2D, RRM displays breathing data in 3D
  • Simultaneously provides information on the timing, duration, and amplitude of breathing deficits in a home or PSG sleep test.