Nox Receives US and EU Patents for Innovative Physiological Sleep Testing Solutions


Nox Medical, a leading innovator in sleep testing technologies and the medical device business unit of Nox Health, announced its receipt of a patent each from the United States Patent and Trademark Office (USPTO) and the European Patent Office (EPO) related to the Nox RIP [respiratory inductance plethysmography] belts that are incorporated into all of Nox Medical’s diagnostic sleep tests.

Nox Medical‘s systems include two RIP belts, which record changes in the volume of the abdomen and chest, to help the sleep professional measure breathing effort during sleep. While the American Academy of Sleep Medicine’s guidelines specify that the preferred measurement of respiratory effort for diagnostic home sleep tests is RIP with two belts, not all diagnostic sleep tests include this important technology.¹

These new patents recognize the groundbreaking methods, apparatus, and systems developed by Nox engineers to advance the field of sleep medicine and physiological monitoring and analysis with RIP flow. 

“Nox is thrilled to receive these patents, which reflect our ongoing dedication to advancing the field of physiological sleep study monitoring and analysis. These innovations not only underscore our commitment to excellence but also highlight the potential to revolutionize the way sleep apnea and other physiological conditions are diagnosed and managed,” says Nox VP of Artificial Intelligence and Data Research Jón Skírnir Ágústsson.

Unlike others, the Nox RIP belts are unique in the sense that they are consistently calibrated to address position changes during the study. This ongoing calibration helps to correctly determine how the movements of the abdomen and thorax contribute to breathing. 

“Nox RIP technology is the foundation of Nox’s entire product suite and our current and ongoing innovations,” said Sveinbjörn Höskuldsson, Nox chief technology officer, and co-founder. 

US Patent: Coherence-based Method, Apparatus, and System for Identifying Corresponding Signals of a Physiological Study

Nox has been granted U.S. Patent No. US11896386B2 for its coherence-based method, apparatus, and system designed to identify corresponding signals of a physiological study. This patent represents a significant milestone in the company’s efforts to enhance the accuracy and reliability of sleep apnea studies conducted in home settings.

The patented method utilizes a sophisticated software algorithm developed by Nox, leveraging the statistical property of coherence between RIP and pulse oximetry signals recorded during home sleep apnea studies (HSAT). By analyzing the coherence between RIP signals and pulse waveforms, the system can effectively detect any potential compromise in the chain of custody of sleep study data, ensuring the integrity of the results obtained.

Coherence is a method of detecting if certain parts of two signals are synchronized, even if the two signals have very different appearances. 

“In this method we use the fact that the RIP signals from the Nox recorders are sensitive to the movements of the heart beating in the chest. We employ a coherence analysis between the RIP signals and the plethysmograph signal (pulse waveform) from the pulse oximeter to determine if there’s synchrony between the RIP signals and the pulse waveform. Using coherence, we do not need to isolate a heartbeat signal or heart rate, but we can use the signals that are in part influenced by the heart beating to see if they have a component originating from the same source,” says Ágústsson.

EU Patent: Method, Apparatus, and System for Measuring Respiratory Effort of a Subject

Additionally, Nox has been granted European Patent No. EP3500155A1 for its method, apparatus, and system designed to measure respiratory effort of a subject. The patented method involves utilizing RIP signals recorded by Nox devices and applying a simplified physiological model to derive internal components of physiology that traditionally require invasive measurements. These components include changes in diaphragm and intercostal rib muscle forces, upper airway resistance, and more, offering valuable insights without the need for invasive procedures.

“This patent not only demonstrates Nox’s long-standing commitment to developing innovative solutions for patient sleep physiology, but also our passion for finding techniques that make it easy to address sleep issues, including the development of non-invasive measurements,” says Höskuldsson. 


Troester MM, Quan SF,  Berry RB, et al; for the American Academy of Sleep Medicine. The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications. Version 3. Darien, IL: American Academy of Sleep Medicine; 2023.

Topic: Industry News

Nox Medical
Nox Medical is a global leader in the sleep diagnostic technology space. The company provides sleep specialists with patient-friendly diagnostic devices and robust, reliable data collection. With easy-to-use medical device technology, Nox Medical eliminates common diagnostic pain points by prioritizing patient comfort and reliability of results, allowing providers to better assess, diagnose and treat the entire range of sleep health issues, including sleep apnea, circadian disorders and insomnia.