Normal and obstructive breathing physiology during sleep
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SLEEP BREATHING PHYSIOLOGY AND DISORDERS • ORIGINAL ARTICLE
Normal and obstructive breathing physiology during sleep Jens Kerl 1
&
Pia Noeke 1 & Detlev Heyse 1 & Dominic Dellweg 1
Received: 17 July 2020 / Revised: 30 September 2020 / Accepted: 6 October 2020 # Springer Nature Switzerland AG 2020
Abstract Purpose To estimate the severity of flow limitation in patients with OSA, the number of breaths with flattened inspiratory flow curves should be identified. Attempts to do a quantitative analysis of the flattening degree for all breaths in a nighttime recording have failed up to now. Methods SOMNOmedics (Randersacker, Germany) developed an automated flattening analysis parameter called the obstructive coefficient (OC). Polysomnographic measurement including esophageal manometry was done in 25 subjects (10 healthy, 9 patients with mild OSA, and 6 with severe OSA). For each breath, the data couple of OC and esophageal pressure (EP) was used for analysis. Results Data couples of OC and EP were recorded for 104,608 breaths. Airway patency histogram profiles for each study group showed no remarkable differences between each other. Increase in EP with increasing RDI was identified as the only marker of OSA severity. A strong shift was observed in N3 breaths from maximum OC/lowest EP values in healthy subjects to low OC values in association with maximum EP values in OSA. Conclusion The OC enables quantification of all breaths of a nighttime recording according to their degree of flattening. The relation of strong limited to less strong limited breaths is the same across the three study groups. The analysis of the corresponding EP to a given OC value for each study group identified the EP that is necessary to cause a given flow as the only parameter that discriminates degrees of severity of OSA. The trial registration number is DRKS00018095 from 2019 to 10-09. Keywords Breathing physiology . Sleep apnea . Esophageal manometry . Flow limitation . Nasal cannula . Pressure transducer
Introduction Obstructive sleep apnea (OSA) is a disorder that is characterized by obstructive apneas, hypopneas, and/or respiratory effort-related arousals (RERA) caused by repetitive narrowing or collapse of the upper airway during sleep. The sleep apnea syndrome has been linked to a variety of comorbidities such as hypertension, coronary artery disease, cardiac arrhythmias, and heart failure [1]. In OSA and transitional states between normal breathing during sleep and OSA, the contour of inspiratory flow curve is characteristically transformed. Flattening of the inspiratory flow curve, a sign of flow limitation, was shown to be associated with
* Jens Kerl [email protected] 1
Fachkrankenhaus Kloster Grafschaft GmbH, Annostr. 1, 57392 Schmallenberg, Germany
increased negative esophageal pressure values (EP) [2–4]. Arousals during obstructive episodes are generally thought to restore upper airway patency by means of increased of upper airway dilator muscle tone. As a consequence EP and inspiratory flow curve contour normalize [2–4]. Schwart
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