Venous blood gases in the assessment of respiratory failure in patients undergoing sleep studies: a randomized study.

Study Objectives: Venous blood gases (VBGs) are not consistently considered suitable surrogates for arterial blood gases (ABGs) in assessing acute respiratory failure due to variable measurement error. The physiological stability of patients with chronic ventilatory failure may lead to improved agreement in this setting.

Methods: Adults requiring ABGs for sleep or ventilation titration studies had VBGs drawn before or after each ABG, in a randomized order.

A randomized controlled trial of a multi-dimensional intervention to improve CPAP use and self-efficacy.

Objectives: To assess the utility of a tailored intervention program to improve continuous positive airway pressure (CPAP) use and self-efficacy in individuals with obstructive sleep apnea (OSA).

Methods: 81 participants (mean age 52.1 ± 11.

A Randomized Controlled Clinical Trial of Lung Volume Recruitment in Adults with Neuromuscular Disease.

Clinical care guidelines advise that lung volume recruitment (LVR) be performed routinely by people with neuromuscular disease (NMD) to maintain lung and chest wall flexibility and slow lung function decline. However, the evidence base is limited, and no randomized controlled trials of regular LVR in adults have been published. To evaluate the effect of regular LVR on respiratory function and quality of life in adults with NMD.

Rapidly and slowly progressive neuromuscular disease: differences in pulmonary function, respiratory tract infections and response to lung volume recruitment therapy (LVR).

Introduction: Reduced lung volumes are a hallmark of respiratory muscle weakness in neuromuscular disease (NMD). Low respiratory system compliance (C) may contribute to restriction and be amenable to lung volume recruitment (LVR) therapy. This study evaluated respiratory function and the immediate impact of LVR in rapidly progressive compared to slowly progressive NMD.

External proficiency testing improves inter-scorer reliability of polysomnography scoring.

Purpose: This study evaluated whether or not polysomnography (PSG) inter-scorer reliability (ISR) across sleep centres could be improved by external proficiency testing (EPT), or by EPT combined with method alignment training.

Methods: Experienced scorers form 15 sleep centres were randomised to the following: (1) a control group, (2) a group that received a self-directed intervention of EPT reports (EPT) or (3) a group that received an active intervention of method alignment training and EPT reports (EPT). Respiratory, arousal and sleep scoring ISR from sixteen PSG fragments were compared between groups across time.

Fetal heart rate events during sleep, and the impact of sleep disordered breathing, in pregnancies complicated by preterm fetal growth restriction: An exploratory observational case-control study.

Objectives: To evaluate fetal heart rate (FHR) patterns during sleep in pregnancies complicated by preterm fetal growth restriction (FGR). To determine whether co-existing sleep-disordered breathing (SDB) impacts on acute FHR events or perinatal outcome.

Design: Observational case control study.

Genioglossus muscle responses to resistive loads in severe OSA patients and healthy control subjects.

This study aimed to determine whether there is impairment of genioglossus neuromuscular responses to small negative pressure respiratory stimuli, close to the conscious detection threshold, in obstructive sleep apnea (OSA). We compared genioglossus electromyogram (EMGgg) responses to midinspiratory resistive loads of varying intensity (≈1.2-6.

The effect of sex and body weight on lung volumes during sleep.

Study Objectives: Low lung volumes are thought to contribute to obstructive sleep apnea (OSA). OSA is worse in the supine versus lateral body position, men versus women, obese versus normal-weight (NW) individuals and REM versus NREM sleep. All of these conditions may be associated with low lung volumes.

Apnoea and hypopnoea scoring for people with spinal cord injury: new thresholds for sleep disordered breathing diagnosis and severity classification.

Study Design: Descriptive study.

Objectives: To determine the effect of respiratory event rule-set changes on the apnoea hypopnoea index, and diagnostic and severity thresholds in people with acute and chronic spinal cord injury.

Setting: Eleven acute spinal cord injury inpatient hospitals across Australia, New Zealand, Canada and England; community dwelling chronic spinal cord injury patients in their own homes.

Evidence against a subcortical gate preventing conscious detection of respiratory load stimuli.

Respiratory related evoked potentials (RREP) were used to examine respiratory stimulus gating. RREPs produced by consciously detected vs. undetected loads, near the detection threshold, were compared.

Genioglossus reflex responses to negative upper airway pressure are altered in people with tetraplegia and obstructive sleep apnoea.

Key Points: Protective reflexes in the throat area (upper airway) are crucial for breathing. Impairment of these reflexes can cause breathing problems during sleep such as obstructive sleep apnoea (OSA). OSA is very common in people with spinal cord injury for unknown reasons.

Light sensors for objective light measurement in ambulatory polysomnography.

Ambulatory polysomnography (PSG) does not commonly include an objective measure of light to determine the time of lights off (Loff), and thus cannot be used to calculate important indices such as sleep onset latency and sleep efficiency. This study examined the technical specifications and appropriateness of a prototype light sensor (LS) for use in ambulatory Compumedics Somte PSG.Two studies were conducted.

The Influence of CO2 on Genioglossus Muscle After-Discharge Following Arousal From Sleep.

Objectives: Ventilatory after-discharge (sustained elevation of ventilation following stimulus removal) occurs during sleep but not when hypocapnia is present. Genioglossus after-discharge also occurs during sleep, but CO2 effects have not been assessed. The relevance is that postarousal after-discharge may protect against upper airway collapse.

Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea.

Study Objectives: To determine whether arousals that terminate obstructive events in obstructive sleep apnea (OSA) (1) induce hypocapnia and (2) subsequently reduce genioglossus muscle activity following the return to sleep.

Methods: Thirty-one untreated patients with OSA slept instrumented with sleep staging electrodes, nasal mask and pneumotachograph, end-tidal CO2 monitoring, and intramuscular genioglossus electrodes. End-tidal CO2 was monitored, and respiratory arousals were assigned an end-arousal CO2 change value (PETCO2 on the last arousal breath minus each individual's wakefulness PETCO2).

Sensory detection of threshold intensity resistive loads in severe obstructive sleep apnoea.

Respiratory related evoked potentials (RREPs) were used to investigate whether sensory detection of small mid-inspiratory resistive loads (≈1.2-6.2 cmHOLs), delivered during wakefulness, was impaired in obstructive sleep apnoea (OSA).

The effect of body mass and sex on the accuracy of respiratory magnetometers for measurement of end-expiratory lung volumes.

Respiratory magnetometers are increasingly being used in sleep studies to measure changes in end-expiratory lung volume (EELV), including in obese obstructive sleep apnea patients. Despite this, the accuracy of magnetometers has not been confirmed in obese patients nor compared between sexes. Thus we compared spirometer-measured and magnetometer-estimated lung volume and tidal volume changes during voluntary end-expiratory lung volume changes of 1.

Nasal Resistance Is Elevated in People with Tetraplegia and Is Reduced by Topical Sympathomimetic Administration.

Study Objectives: Obstructive sleep apnea (OSA) is common in individuals with tetraplegia and associated with adverse health outcomes. The causes of the high prevalence of OSA in this population are unknown, but it is important to understand as standard treatments are poorly tolerated in tetraplegia. Nasal congestion is common in tetraplegia, possibly because of unopposed parasympathetic activity.

A prospective cohort study of pulmonary function during pregnancy in women with and without asthma.

Background And Objective: Pregnancy alters the severity of asthma unpredictably. Uncertainty still exists about longitudinal changes in pulmonary function during pregnancy in both healthy and asthmatic women. This study aimed to compare pulmonary function changes during pregnancy in healthy and asthmatic women and to determine the relationship between pulmonary function and asthma-related quality of life during pregnancy.

Patients' estimates of their sleep times: reliability and impact on diagnosis of obstructive sleep apnoea.

Background: Home polysomnography (PSG) is an alternative method for diagnosis of obstructive sleep apnoea (OSA). Some types 3 and 4 PSG do not monitor sleep and so rely on patients' estimation of total sleep time (TST).

Aim: To compare patients' subjective sleep duration estimation with objective measures in patients who underwent type 2 PSG for probable OSA.

Predicting the risk of exacerbation in patients with chronic obstructive pulmonary disease using home telehealth measurement data.

Background: The use of telehealth technologies to remotely monitor patients suffering chronic diseases may enable preemptive treatment of worsening health conditions before a significant deterioration in the subject's health status occurs, requiring hospital admission.

Objective: The objective of this study was to develop and validate a classification algorithm for the early identification of patients, with a background of chronic obstructive pulmonary disease (COPD), who appear to be at high risk of an imminent exacerbation event. The algorithm attempts to predict the patient's condition one day in advance, based on a comparison of their current physiological measurements against the distribution of their measurements over the previous month.

Polysomnography using abbreviated signal montages: impact on sleep and cortical arousal scoring.

Objective: This study examined the impact of using two abbreviated signal montages on the accuracy, precision and inter-scorer reliability of polysomnography (PSG) sleep and arousal scoring, compared to a standard reference montage, in a cohort of patients investigated for obstructive sleep apnoea (OSA). One abbreviated montage incorporated two signals dedicated to sleep and arousal scoring, and the other incorporated a single signal.

Methods: Four scorers from two laboratories each scored 15 PSGS four times in random order: once using each abbreviated montage and twice using the reference montage.

Night-to-night repeatability of supine-related obstructive sleep apnea.

Rationale: Patients with obstructive sleep apnea (OSA) experience respiratory events with greater frequency and severity while in the supine sleeping position. Postural modification devices (PMDs) prevent supine sleep, although there is a paucity of guidance to help clinicians decide when to use PMDs for their patients. In order for PMDs to treat OSA effectively, patients must experience respiratory events in the supine sleeping position consistently from night to night and must have a low nonsupine apnea and hypopnea index (AHINS).

Auto-titrating continuous positive airway pressure treatment for obstructive sleep apnoea after acute quadriplegia (COSAQ): study protocol for a randomized controlled trial.

Background: Quadriplegia is a severe, catastrophic injury that predominantly affects people early in life, resulting in lifelong physical disability. Obstructive sleep apnoea is a direct consequence of quadriplegia and is associated with neurocognitive deficits, sleepiness and reduced quality of life. The usual treatment for sleep apnoea is nasal continuous positive airway pressure (CPAP); however, this is poorly tolerated in quadriplegia.