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.

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.

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.

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.

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.

Pilot study of remote telemonitoring in COPD.

Background: Remote in-home monitoring (RM) of symptoms and physiological variables may allow early detection and treatment of exacerbations of chronic obstructive pulmonary disease (COPD). It is unclear whether RM improves patient outcomes or healthcare resource utilization. This study determined whether RM is feasible in patients with COPD and if RM reduces hospital admissions or length of stay (LOS) or improves health-related quality of life (HRQOL).

Inspiratory-resistive loading increases the ventilatory response to arousal but does not reduce genioglossus muscle activity on the return to sleep.

Arousals from sleep are thought to predispose to obstructive sleep apnea by causing hyperventilation and hypocapnia, which reduce airway dilator muscle activity on the return to sleep. However, prior studies of auditory arousals have not resulted in reduced genioglossus muscle activity [GG-electromyogram (EMG)], potentially because airway resistance prior to arousal was low, leading to a small ventilatory response to arousal and minimal hypocapnia. Thus we aimed to increase the ventilatory response to arousal by resistive loading prior to auditory arousal and determine whether reduced GG-EMG occurred on the return to sleep.

AASM criteria for scoring respiratory events: interaction between apnea sensor and hypopnea definition.

Study Objectives: To examine the impact of using a nasal pressure sensor only vs the American Academy of Sleep Medicine (AASM) recommended combination of thermal and nasal pressure sensors on (1) the apnea index (AI), (2) the apnea-hypopnea index (AHI), where the AHI is calculated using both AASM definitions of hypopnea, and (3) the accuracy of a diagnosis of obstructive sleep apnea (OSA).

Design: Retrospective review of previously scored in-laboratory polysomnography.

Setting: A tertiary-hospital clinical sleep laboratory.

Magnetic resonance spectroscopy and neurocognitive dysfunction in obstructive sleep apnea before and after CPAP treatment.

Study Objectives: To determine whether cerebral metabolite changes may underlie abnormalities of neurocognitive function and respiratory control in OSA.

Design: Observational, before and after CPAP treatment.

Setting: Two tertiary hospital research institutes.

Treating obstructive sleep apnea with hypoglossal nerve stimulation.

Background: Reduced upper airway muscle activity during sleep is fundamental to obstructive sleep apnea (OSA) pathogenesis. Hypoglossal nerve stimulation (HGNS) counteracts this problem, with potential to reduce OSA severity.

Study Objectives: To examine safety and efficacy of a novel HGNS system (HGNS, Apnex Medical, Inc.

Transcutaneous measurement of carbon dioxide tension during extended monitoring: evaluation of accuracy and stability, and an algorithm for correcting calibration drift.

Background: When polysomnography is indicated in a patient with a presumed sleep disorder, continuous monitoring of arterial carbon dioxide tension (P(aCO(2))) is desirable, especially if nocturnal hypoventilation is suspected. Transcutaneous CO(2) monitors (P(tcCO(2))) provide a noninvasive correlate of P(aCO(2)), but their accuracy and stability over extended monitoring have been considered inadequate for the diagnosis of hypoventilation. We examined the stability and accuracy of P(tcCO(2)) measurements and the performance of a previously described linear interpolation technique designed to correct for calibration drift.

The 2007 AASM recommendations for EEG electrode placement in polysomnography: impact on sleep and cortical arousal scoring.

Study Objective: To examine the impact of using American Academy of Sleep Medicine (AASM) recommended EEG derivations (F4/M1, C4/M1, O2/M1) vs. a single derivation (C4/M1) in polysomnography (PSG) on the measurement of sleep and cortical arousals, including inter- and intra-observer variability.

Design: Prospective, non-blinded, randomized comparison.