Jen Walsh

Sir Charles Gairdner Hospital | SCGH · Centre for Sleep Science

The legalization of cannabis for medicinal, and in some countries, recreational, purposes in addition to growth in the cannabis industry has meant that cannabis use and interest in the area has increased rapidly over the past 20 years. Treatment of poor sleep and sleep disorders are two of the most common reasons for the current use of medicinal ca...

Study Objectives Randomized controlled trials (RCTs) have shown no reduction in adverse cardiovascular (CV) events in patients randomized to continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA). This study examined whether randomized study populations were representative of OSA patients attending a sleep clinic. Met...

Introduction Recent work has shown that head flexion has a modest worsening effect and head rotation has a modest protective effect on OSA severity. However, there is substantial variability both within and between individuals. In this analysis we aimed to identify if this variability is explained by sleep-state, BMI, age or sex. Methods 28 partic...

Introduction There are limited data on the association of chronotype and hypertension and on their interaction on hypertension. This study aimed to investigate the independent and combined effects of chronotype and OSA on risk for prevalent hypertension in a middle-aged community population. Methods Baseline data on adult participants (n=1098, fem...

Background Perioperative respiratory adverse events (PRAE) pose significant risk in paediatric anaesthesia, and identifying risk is vital. Perioperative measurement of pharyngeal closing pressure (PCLOSE) is a quick, objective method of assessing upper airway collapsibility that may identify PRAE risk. Aim To investigate if PCLOSE measurement is f...

The relationship between obstructive sleep apnoea (OSA) and the development of long-term cardiovascular disease (CVD) is incompletely understood. We therefore investigated the impact of OSA severity, assessed by polysomnographic (PSG) metrics, on the development of long-term CVD in a sleep clinic cohort. Participants in the Western Australian Sleep...

Introduction Randomized controlled trials (RCTs) have shown no reduction in adverse cardiovascular (CV) events in patients randomized to continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA). This study examined whether randomized study populations were representative of OSA patients attending a sleep clinic. Methods...

We recently read with great interest the recent paper by Gratwicke, M et al. (2021) [...]

There is a scarcity of research examining the effects of long-distance transmeridian travel (LDTT) on the sleep and match performance of team sport players. To address this, 37 elite male rugby union players from a Super Rugby team undertaking LDTT were recruited. The participants completed validated sleep questionnaires and wore a wrist-worn activ...

Study Objectives This randomized, double-blind, placebo-controlled, cross-over study was conducted to evaluate the safety and efficacy of two-weeks of nightly sublingual cannabinoid extract (ZTL-101) in treating chronic insomnia (symptoms ≥three months). Methods Co-primary study endpoints were safety of the medication based on adverse event report...

Head posture influences the collapsibility of the passive upper airway during anaesthesia. However, little is known about the impact of head posture during sleep. The objective of this study was to develop and validate an instrument to measure head posture during supine sleep and to apply this instrument to investigate the influence of head posture...

This study examined the nature and characteristics of sleep‐disordered breathing, including obstructive sleep apnea and central sleep apnea, in patients with post‐stroke dysphagia, to determine the demographic, anthropometric and clinical variables that were associated with sleep‐disordered breathing. Thirty‐nine patients diagnosed with acute strok...

Background: The propensities for the upper airway to collapse during anesthesia and sleep are related, although much of our understanding of this relationship has been inferred from clinical observation and indirect measures such as the apnea-hypopnea index. The aim of this study was to use an identical, rigorous, direct measure of upper airway co...

Study objectives: Body posture has a significant impact on the presence and severity of obstructive sleep apnea (OSA). The majority of polysomnography (PSG) systems have the capacity to categorize body (torso) posture as supine, left-lateral, right-lateral or prone, each within a 90-degree range. However, such broad categorization may limit the id...

Study Objectives In pregnancy, the prevalence of both obstructive sleep apnea (OSA) and depression increases. Research reveals an association in the general population with up to 45% of patients diagnosed with OSA having depressive symptoms. Therefore, this study aimed to investigate the relationship between OSA and depression in pregnant women. M...

Background and Aim Hypoglossal Nerve Stimulation (HNS) decreases Obstructive Sleep Apnea (OSA) severity via genioglossus muscle activation and decreased upper airway collapsibility. This study assessed the safety and effectiveness at 6 months post-implantation of a novel device delivering bilateral HNS via a small implanted electrode activated by a...

What we already know about this topic: Dexmedetomidine is a relatively new sedative promoted as having minimal effect on ventilatory drive or the propensity to upper airway obstruction WHAT THIS ARTICLE TELLS US THAT IS NEW: At comparable levels of light to moderate sedation, dexmedetomidine and propofol exhibit similar degrees of pharyngeal colla...

Purpose: To determine the effect of temazepam on assessment of the severity of obstructive sleep apnea (OSA) by polysomnography (PSG). Methods: Analysis of diagnostic laboratory-PSG studies was performed in OSA patients who were administered temazepam (10 mg) to facilitate sleep ("temazepam group", n = 73) and in OSA patients (matched for age, g...

The aim of this study was to determine the prevalence of sleep disorders in an elite rugby union team using in-laboratory polysomnography (PSG) and sleep questionnaires. Twenty-five elite rugby union players underwent a night of PSG during the “off season” of the Super Rugby competition. Of interest were measurements that detected the presence of o...

Introduction: Very little is known about the effects of jet-lag on sleep and game performance in team sports. The Perth based professional rugby union team, the ‘Western Force’, were the most travelled professional sporting team in the world in 2017, travelling over 68,000km and across 44-time zones in the 2017 season. This provided an opportunity...

Australian Rules football (AFL) is a multi-factored sport that requires both physical fitness and high cognitive performance effectiveness. As AFL is a national competition air travel is necessary and the literature has shown that travel across time zones can have significant detrimental effects on both physical and cognitive performance. Air trave...

Background: The capacity to rapidly identify the presence and severity of obstructive sleep apnoea (OSA) is desirable. As an alternative to polysomnography (PSG) two- dimensional facial photography is quick and has shown promising results. However, the ability of more sophisticated three-dimensional (3D) capture systems, which have the capacity to...

Wrist actigraphy is commonly used to measure sleep, and hip actigraphy is commonly used to measure activity. It is unclear whether hip-based actigraphy can be used to measure sleep. This study assessed the validity of wrist actigraphy and hip actigraphy compared to polysomnography (PSG) for the measurement of sleep. 108 healthy young adults (22.7 ±...

Catheters that traverse the pharynx are often in place during clinical or research evaluations of upper airway function. The purpose of this study was to determine whether the presence of such catheters affects measures of upper airway collapsibility itself. To do so, pharyngeal critical closing pressure (Pcrit) and resistance upstream of the site...

Reduced upper airway muscle activity during sleep is a key contributor to obstructive sleep apnoea pathogenesis. Hypoglossal nerve stimulation activates upper airway dilator muscles, including the genioglossus, and has the potential to reduce obstructive sleep apnoea severity. The objective of this study was to examine the safety, feasibility and e...

The most collapsible part of the upper airway in the majority of individuals is the velopharynx which is the segment positioned behind the soft palate. As such it is an important morphological region for consideration in elucidating the pathogenesis of obstructive sleep apnea (OSA). This study compared steady flow properties during inspiration in t...

Rationale: Increasing lung volume increases upper airway patency and decreases airway resistance and collapsibility. The role of diaphragm contraction in producing these changes remains unclear. Objectives: To determine the effect of selective diaphragm contraction, induced by phrenic nerve stimulation, on upper airway collapsibility and the extent...

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. To examine safety and efficacy of a novel HGNS system (HGNS, Apnex Medical, Inc.) in treating OSA. Twenty-one patients, 67% male, age (m...

The critical pressure at which the pharynx collapses (Pcrit) is an objective measurement of upper airway collapsibility, an important pathogenetic factor in obstructive sleep apnoea. This study examined the inherent variability of passive Pcrit measurement during sleep and evaluated the effects of sleep stage and body posture on Pcrit. Repeated mea...

Repetitive closure of the upper airway characterizes obstructive sleep apnea. It disrupts sleep causing excessive daytime drowsiness and is linked to hypertension and cardiovascular disease. Previous studies simulating the underlying fluid mechanics are based upon geometries, time-averaged over the respiratory cycle, obtained usually via MRI or CT...

Upper airway collapsibility is known to increase under anesthesia. This study assessed how this increase in collapsibility evolves during slow Propofol induction and how it relates to anesthesia-induced changes in upper airway muscle activity and conscious state. Nine healthy volunteers were studied. Anesthesia was induced with Propofol in a step-w...

Anatomical optical coherence tomography (aOCT) is a long-range endoscopic imaging modality capable of quantifying size and shape of the human airway. A challenge to its in vivo application is motion artifact due to respiratory-related movement of the airway walls. This paper represents the first demonstration of respiratory gating of aOCT airway da...

Flexible bronchoscopy is a common procedure that is used in both diagnostic and therapeutic settings but does not readily permit measurement of central airway dimensions. Anatomic optical coherence tomography (a OCT), a modification of conventional optical coherence tomography (OCT), is a novel light-based imaging tool with the capacity to measure...

In patients with obstructive sleep apnea (OSA), the severity and frequency of respiratory events is increased in the supine body posture compared with the lateral recumbent posture. The mechanism responsible is not clear but may relate to the effect of posture on upper airway shape and size. This study compared the effect of body posture on upper a...

To determine the effect of head posture on upper airway collapsibility and site of collapse of the passive human upper airway. Pharyngeal critical closing pressure (Pcrit) and site of airway collapse were assessed during head flexion, extension and rotation in individuals undergoing propofol anesthesia. Operating theatre of major teaching hospital....

Anatomical optical coherence tomography (aOCT) is an endoscopic imaging modality that can be used to quantify size and shape of the upper airway. We report the application of respiratory gating to aOCT images. Our results show that respiratory gating can reduce motion artefact in upper airway images. Using an error metric based on distance to the d...

This study compared shape, size and length of the pharyngeal airway in individuals with and without obstructive sleep apnoea (OSA) using a novel endoscopic imaging technique, anatomical optical coherence tomography (aOCT). The study population comprised a preliminary study group of 20 OSA patients and a subsequent controlled study group of 10 OSA p...

In this paper, we report on anatomical optical coherence tomography, a catheter-based optical modality designed to provide quantitative sectional images of internal hollow organ anatomy over extended observational periods. We consider the design and performance of an instrument and its initial intended application in the human upper airway for the...

Anatomical optical coherence tomography (aOCT) is an endoscopic optical technique that enables continuous, quantitative assessment of hollow organ size and shape in three dimensions. It is a powerful alternative to X-ray computed tomography, magnetic resonance imaging, and video endoscopy for the assessment of gross hollow-organ anatomy. This paper...

Endoscopic visualization of the internal surface of hollow organ systems is widely used in medical practice. Examples include endoscopy of the urinary tract, gastrointestinal tract, and upper and lower respiratory tracts. Although valuable for visualizing the internal anatomy, a limitation of endoscopy has been the inability, to date, to easily qua...

The advances reported herein form part of a larger project that has as its objective the development of a full flow-structure-interaction model of the human upper airway. Here we first briefly report on a two-dimensional (saggital section) model built using published CT-scan geometric data. For the development of our three-dimensional capability, w...

We have developed an anatomical optical coherence tomography system for imaging the human upper airway in vivo. We describe an example of clinical research currently underway with this system; the ability to measure the change in airway dimensions due to anatomical position. Although the system imaging range is well-matched to a typical airway, we...

Imaging of the human upper airway is widely used in medicine, in both clinical practice and research. Common imaging modalities include video endoscopy, X-ray CT, and MRI. However, no current modality is both quantitative and safe to use for extended periods of time. Such a capability would be particularly valuable for sleep research, which is inhe...

Measurements of upper airway size and shape are important in investigating the pathophysiology of obstructive sleep apnea (OSA) and in devising, applying, and determining the effectiveness of treatment modalities. We describe an endoscopic optical technique (anatomic optical coherence tomography, aOCT) that provides quantitative real-time imaging o...

The contribution of endothelium-derived nitric oxide (NO) to exercise hyperaemia remains controversial. Disparate findings may, in part, be explained by different shear stress stimuli as a result of different types of exercise. We have directly compared forearm blood flow (FBF) responses to incremental handgrip and cycle ergometer exercise in 14 su...

Type 2 diabetes is associated with vascular dysfunction, accelerated atherosclerotic morbidity, and mortality. Abnormal vasomotor responses to chemoreflex activation may contribute to the acceleration of atherosclerotic diabetes complications, but these responses have not previously been investigated. We measured forearm mean blood flow (MBF) and m...

Exercise training improves vascular function in subjects with cardiovascular disease and risk factors, but there is mounting evidence these vascular adaptations may be vessel bed specific. We have therefore examined the hypothesis that exercise-induced improvements in conduit vessel function are related to changes in resistance vessel function. End...

We have pooled data from a series of our exercise training studies undertaken in groups with a broad range of vascular (dys) function to the examine the hypothesis that exercise-induced improvements in the conduit and/or resistance vessel function are related to improvements in risk factors for cardiovascular (CV) disease. Endothelium-dependent and...

Despite the importance of both lipid metabolism and physical activity to cardiovascular health, few studies have examined the effect of exercise training on vascular function in hypercholesterolaemic humans. A randomized, cross-over design investigated the effect of 8 weeks of combined aerobic and resistance exercise training on conduit and resista...

It is well established that endothelial dysfunction is present in coronary artery disease (CAD), although few studies have determined the effect of training on peripheral conduit vessel function in patients with CAD. A randomized, crossover design determined the effect of 8 wk of predominantly lower limb, combined aerobic and resistance training, i...

The purpose of this study was to determine and compare the thermoregulatory and hemodynamic responses to moderate intensity exercise (60% of peak oxygen consumption [.VO(2peak)]) in warm (35 degrees C, 45% relative humidity) and cool (18 degrees C, 65% relative humidity) environments in men who had previously undergone coronary artery bypass graft...