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

Short 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 (T, shortest period achieving 95% inspiratory volume), expiratory (T, shortest period achieving 95% expiratory volume), and inter-breath transition period (T, period between T and subsequent T). Compared with reference segments, sustained-PAO segments had a mean relative reduction in T (−24.7\ua0±\ua017.6%, P\ua

Introduction to Special Issue - In-depth study of air pollution sources and processes within Beijing and its surrounding region (APHH-2 Beijing)

Abstract. The Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing) programme is an international collaborative project focusing on understanding the sources, processes and health effects of air pollution in the Beijing megacity. APHH-Beijing brings together leading China and UK research groups, state-of-the-art infrastructure and air quality models to work on four research themes: (1) sources and emissions of air pollutants; (2) atmospheric processes affecting urban air pollution; (3) air pollution exposure and health impacts; and (4) interventions and solutions. Themes 1 and 2 are closely integrated and support Theme 3, while Themes 1-3 provide scientific data for Theme 4 to develop cost-effective air pollution mitigation solutions. This paper provides an introduction to (i) the rationale of the APHH-Beijing programme, and (ii) the measurement and modelling activities performed as part of it. In addition, this paper introduces the meteorology and air quality conditions during two joint intensive field campaigns - a core integration activity in APHH-Beijing. The coordinated campaigns provided observations of the atmospheric chemistry and physics at two sites: (i) the Institute of Atmospheric Physics in central Beijing, and (ii) Pinggu in rural Beijing during 10 November – 10 December 2016 (winter) and 21 May- 22 June 2017 (summer). The campaigns were complemented by numerical modelling and automatic air quality and low-cost sensor observations in the Beijing megacity. In summary, the paper provides background information on the APHH-Beijing programme, and sets the scene for more focussed papers addressing specific aspects, processes and effects of air pollution in Beijing

Measurement of the inclusive isolated-photon cross section in pp collisions at √s = 13 TeV using 36 fb−1 of ATLAS data

The differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb. The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. [Figure not available: see fulltext.

Reducing crash risk for young drivers: Protocol for a pragmatic randomised controlled trial to improve young driver sleep

Background: Road trauma is a leading cause of death and disability for young Australians (15–24 years). Young adults are overrepresented in crashes due to sleepiness, with two-thirds of their fatal crashes attributed to sleepy driving. This trial aims to examine the effectiveness of a sleep extension and education program for improved road safety in young adults. Methods: Young adults aged 18–24 years (n = 210) will be recruited for a pragmatic randomised controlled trial employing a placebo-controlled, parallel-groups design. The intervention group will undergo sleep extension and receive education on sleep, whereas the placebo control group will be provided with information about diet and nutrition. The primary outcomes of habitual sleep and on-road driving performance will be assessed via actigraphy and in-vehicle accelerometery. A range of secondary outcomes including driving behaviours (driving simulator), sleep (diaries and questionnaire) and socio-emotional measures will be assessed. Discussion: Sleep is a modifiable factor that may reduce the risk of sleepiness-related crashes. Modifying sleep behaviour could potentially help to reduce the risk of young driver sleepiness-related crashes. This randomised control trial will objectively assess the efficacy of implementing sleep behaviour manipulation and education on reducing crash risk in young adult drivers

The impact of daytime transoral neuromuscular stimulation on upper airway physiology - A mechanistic clinical investigation.

There is a need for alternatives to positive airway pressure for the treatment of obstructive sleep apnea and snoring. Improving upper airway dilator function might alleviate upper airway obstruction. We hypothesized that transoral neuromuscular stimulation would reduce upper airway collapse in concert with improvement in genioglossal muscle function. Subjects with simple snoring and mild OSA (AHI < 15/h on screening) underwent in-laboratory polysomnography with concurrent genioglossal electromyography (EMGgg) before and after 4-6 weeks of twice-daily transoral neuromuscular stimulation. Twenty patients completed the study: Sixteen males, mean ± SD age 40 ± 13 years, and BMI 26.3 ± 3.8 kg/m2 . Although there was no change in non-rapid eye movement EMGgg phasic (p = 0.66) or tonic activity (p = 0.83), and no decrease in snoring or flow limitation, treatment was associated with improvements in tongue endurance, sleep quality, and sleep efficiency. In this protocol, transoral neurostimulation did not result in changes in genioglossal activity or upper airway collapse, but other beneficial effects were noted suggesting a need for additional mechanistic investigation

Quantifying the magnitude of pharyngeal obstruction during sleep using airflow shape

Non-invasive quantification of the severity of pharyngeal airflow obstruction would enable recognition of obstructive central manifestation of sleep apnoea, and identification of symptomatic individuals with severe airflow obstruction despite a low apnoea-hypopnoea index (AHI).Here we provide a novel method that uses simple airflow--time ("shape") features from individual breaths on an overnight sleep study to automatically and non-invasively quantify the of airflow obstruction without oesophageal catheterisation.41 individuals with suspected/diagnosed obstructive sleep apnoea (AHI range=0-91 events·hr) underwent overnight polysomnography with gold-standard measures of airflow (oronasal pneumotach, ) and ventilatory drive (calibrated intraoesophageal diaphragm EMG, ). Obstruction severity was defined as a continuous variable ( ratio). Multivariable regression used airflow shape features (inspiratory/expiratory timing, flatness, scooping, fluttering) to estimate in 136 264 breaths (performance based on leave-one-patient-out cross-validation). Analysis was repeated using simultaneous nasal pressure recordings in a subset (N=17).Gold-standard obstruction severity () varied widely across individuals independent of AHI. A multivariable model (25 features) estimated obstruction severity breath-by-breath (R=0.58 gold-standard,

Assessing the physiological endotypes responsible for REM and NREM based obstructive sleep apnea

BackgroundPatients with obstructive sleep apnea (OSA) can have the majority of their respiratory events in REM (rapid eye movement) sleep or in NREM (non-rapid eye movement) sleep. No previous studies have linked the different physiology in REM and NREM sleep to the common polysomnographic patterns seen in everyday clinical practice, namely REM predominant OSA (REMOSA) and NREM predominant OSA (NREMOSA).Research Question1) How does OSA physiology change with sleep stage in NREMOSA\ua0and REMOSA\ua0patients? 2) Do patients with NREMOSA\ua0and REMOSA\ua0have different underlying OSA pathophysiology?Study Design and MethodsWe recruited patients with three polysomnographic patterns. 1) REMOSA\ua0– twice as many respiratory events in REM sleep; 2) NREMOSA\ua0- twice as many events in NREM sleep 3) Uniform OSA – equal number of events in NREM/REM sleep. We deployed a non-invasive phenotyping method to determine OSA endotype traits (Vpasssive, Vactive, loop gain, arousal threshold) in NREM sleep, REM sleep and total night sleep in each group of patients (NREMOSA, REMOSA, Uniform OSA).ResultsNREMOSA\ua0patients have significantly worse ventilatory control stability in NREM sleep compared with REM sleep (Loop Gain 0.546 [0.456,0.717] in NREM vs 0.365 [0.238,0.459] in REM sleep, p = 0.0026) while REMOSA\ua0patients displayed a significantly more collapsible airway (i.e. lower Vpassive) in REM compared to NREM sleep (98.4 [97.3,99.2] %Veupnea in NREM vs 95.9 [86.4,98.9] %Veupnea in REM sleep,

Loop gain predicts the response to upper airway surgery in patients with obstructive sleep apnea

Upper airway surgery is often recommended to treat patients with obstructive sleep apnea (OSA) who cannot tolerate continuous positive airways pressure. However, the response to surgery is variable, potentially because it does not improve the nonanatomical factors (ie, loop gain [LG] and arousal threshold) causing OSA. Measuring these traits clinically might predict responses to surgery. Our primary objective was to test the value of LG and arousal threshold to predict surgical success defined as 50% reduction in apnea-hypopnea index (AHI) and AH