The relationship between partial upper-airway obstruction and inter-breath transition period during sleep

Abstract

I., The relationship between partial upper-airway obstruction and inter-breath transition period during sleep.Respiratory Physiology and Neurobiology http://dx.doi.org/10. 1016/j.resp.2017.06.006 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights• Short pauses (transition periods) between breaths are often observed during sleep.• We hypothesized that the transition period reduces as inspiratory period increases.• Unobstructed breathing and events with partial airway obstruction were identified.• We observed an increase in the inspiratory period during upper airway obstruction.• A reduction in the transition period rather than the expiratory period was observed.3 AbstractShort pauses or "transition-periods" at the end of expiration and prior to subsequent inspiration are commonly observed during sleep in humans. However, the role of transition periods in regulating ventilation during physiological challenges such as partial airway obstruction (PAO) has not been investigated. Twenty-nine obstructive sleep apnea patients and eight controls underwent overnight polysomnography with an epiglottic catheter. Sustained-PAO segments (increased epiglottic pressure over ≥5 breaths without increased peak inspiratory flow) and unobstructed reference segments were manually scored during apnea-free non-REM sleep. Nasal pressure data was computationally segmented into inspiratory (TI, shortest period achieving 95% inspiratory volume), expiratory (TE, shortest period achieving 95% expiratory volume), and inter-breath transition period (TTrans, period between TE and subsequent TI). Compared with reference segments, sustained-PAO segments had a mean relative reduction in TTrans (−24.7±17.6%, P<0.001), elevated TI (11.8±10.5%, P<0.001), and a small reduction in TE (−3.9±8.0, P≤0.05). Compensatory increases in inspiratory period during PAO are primarily explained by reduced transition period and not by reduced expiratory period.

Neural crest-specific loss ofBmp7leads to midfacial hypoplasia, nasal airway obstruction and disordered breathing, modeling obstructive sleep apnea

“…Here, we showed evidence that morphological changes in the upper airways disrupt regular breathing pattern, possibly due to airway obstruction. Increased inspiratory airway resistance may lead to two mechanisms to maintain ventilation: (1) an increase in inspiratory muscle drive; and (2) an increase in the T i , to achieve a comparable V T over an expanded T i ( Hernandez et al, 2012 ; Mann et al, 2017 ). In the present study, Bmp7 ncko (a) mice showed an increased T TOT , mainly due to an increase in the T i and a tendency for a prolonged T e compared to control mice, resulting in no changes in V T and V̇ E .…”

Developing methods to quantify the severity of airflow obstruction in the clinical sleep environment

“…We recognised that detection of the appropriate inspiratory and expiratory start and end times could play a major role in determining values from each feature. As such, two approaches were employed: 1) our "original" in-house algorithm for detecting start and end times of breaths based primarily on volume maxima and minima, and 2) a modified timing algorithm that separately identifies the start and end times of inspiration and expiration based on the periods where 95% of the volume inspired/expired is observed, referred to as "transition" timing (Mann, Edwards et al 2017).…”