Articles

Sleep Problems in Autism Spectrum Disorder

24/09/2010

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder composed
of a spectrum of psychological conditions, including abnormal social
interactions, communication and behaviour.

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The Diagnosis and Treatment of Circadian Rhythm Disorders

26/10/2009

Topics discussed include delayed and advanced sleep phase disorders in relation to shift work and jet lag.

Professor Leon Lack, School of Psychology, Flinders University

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Nasal Pressure Measurement in PSG

10/10/2009

How and Why Nasal Pressure Monitors Flow in a PSG (and How to Do it Better)

David M. Rapoport

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Lung Volume Pressure Changes In Obese Male Obstructive Sleep Apnoea Patients

08/10/2009

Lung Volume, Gastric And Transdiaphragmatic Pressure Changes Leading Into, During And Following Apnoea In Obese Male Obstructive Sleep Apnoea Patients

Daniel Stader, Denzil Paul, Jana Bradley, Peter Catcheside, Doug McEvoy

Adelaide Institute for Sleep Health, Repatriation General Hospital, Daws Road, Daw Park, SA, 5041

INTRODUCTION: Previous studies show an inverse relationship between end-expiratory lung volume (EELV) and upper airway (UA) collapsibility and resistance (RUA). These effects are potentially mediated via obesity dependent lung compression effects leading to cranial displacement of the diaphragm and reduced tracheal tension exerted on the UA. We recently reported an increase in UA collapsibility with abdominal compression in obstructive sleep apnoea (OSA) patients during sleep, consistent with abdominal obesity effects on UA function. In this study, we sought to further explore the potential role of EELV and transdiaphragmatic pressure changes in obese OSA patients by examining the magnitude and time-course of changes in EELV, gastric (Pga) and transdiaphragmatic (Pdi) pressure leading into, during and following apnoea events.

METHODS: Six obese (body mass index; 35.0±1.8 kg∙m-2) males aged 44.2±3.7 years with moderate-to-severe OSA (apnoea-hypopnoea index; 77.2±11.7 events∙hr-1) participated. Patients breathed via a nasal mask fitted with a pneumotachograph and slept supine throughout the night. Changes in EELV were assessed by two pairs of magnetometer coils placed anterior-posteriorly on the chest and abdomen. End-expiratory Pga, oesophageal (Poes) and transdiaphragmatic (Pdi=Pga-Poes) were measured via an intra-oesophageal catheter. A separate air-perfused catheter was used to measure epiglottic pressure for UA resistance (RUA) measurements. For each apnoea, changes in minute ventilation (VI), RUA, EELV, Pga and Pdi for the last four breaths leading into UA obstruction, the first two and last two apnoea efforts, and the first four breaths following apnoea termination were investigated.

RESULTS: Prior to UA obstruction, VI declined from ~11.3-4.7 L∙min-1 (p<0.001) and RUA increased from ~14.1-26.9 cmH2O∙L-1∙s (p<0.001). EELV fell by ~150 ml (p<0.001), while there was a small decrease in Pga and Pdi (<2 cmH2O, p<0.001). EELV decreased by a further ~130 ml during UA obstruction (p<0.001). There was a marked increase in VI immediately following apnoea termination, in association with a decrease in RUA, a ~380 ml rise in EELV, and an increase in Pga and Pdi.

CONCLUSIONS: EELV, Pga and Pdi decrease leading into UA obstruction and increase following apnoea termination. These effects are likely associated with changes in diaphragm position, and may contribute importantly to the development and resolution of UA collapse during sleep in OSA patients.

CPAP Treatment, Sleep Restriction and Alcohol

08/10/2009

CPAP Treatment Partially Improves Driving Simulator Performance In Severe OSA Patients and Reduces OSA-Dependent Vulnerability to Sleep Restriction and Alcohol

Andrew Vakulin, Peter Catcheside, Doug McEvoy

Adelaide Institute for Sleep Health, Repatriation General Hospital, Daws Road, Daw Park, SA, 5041

Introduction: Obstructive sleep apnoea (OSA) affects ~7% of the middle-aged population causing driving performance deficits with a 2-7 fold increased motor vehicle accident risk. Furthermore, OSA patients have been found to be more vulnerable to additional sleep restriction and low dose alcohol. CPAP treatment has been shown to be beneficial in improving driving performance, however some evidence suggests only partial resolution in cognitive function. Given a 46-83% treatment adherence failure and the uncertainty in the degree of treatment benefit, it is unclear if CPAP normalises driving performance and reduces patient vulnerability to sleep restriction and alcohol. We postulated that CPAP would partially improve driving performance in patients compared to controls and reduce vulnerability to sleep restriction and alcohol
Methods: 11 severe OSA patients (Mean±SD, age 54.2±13.0yrs, BMI 35.9±9.6kg/m2, AHI 69.1±20.1evnts/hr) and 9 controls (age 53.2±9.6yrs, BMI 24.3±2.66kg/m2, AHI 6.6±3.8 evnts/hr) completed 3 initial 90-minute driving simulation tests (AusEd) under normal sleep (NS-8h), restricted sleep (RS-4h), and alcohol (ALC-BAC 0.05g/dL) conditions, which were repeated 3 months later (Patients-CPAP, controls-no CPAP). Driving measures were steering deviation (cm) crashes and braking reaction time.

Results: Prior to CPAP treatment, OSA patients had greater steering deviation under all conditions compared to controls (all p<0.03) and were more affected by sleep restriction and alcohol (all P<0.001). CPAP (~6hrs/night) significantly improved steering deviation of OSA patients under all conditions (all P<0.01), however patient steering impairment persisted under NS and SR conditions compared with controls (all P<0.03). More OSA patients crashed than controls under all conditions before treatment (OSA under NS=2, SR=5, ALC=4 and controls had no crashes) and after treatment (OSA under NS=3, SR=3, ALC=5 and for controls 1 crash under SR condition), with no significant treatment affects No significant differences were observed for braking reaction time.

Conclusions: Three months CPAP treatment only partially improved driving performance in OSA patients. This suggests irreversible hypoxic cortical damage and/or inadequate treatment period. Despite these residual driving deficits it appears that OSA patients are no longer more vulnerable to additional sleep loss and alcohol. Thus, encouraging CPAP use by severe OSA drivers seems warranted to obtain at least some treatment benefit. Future studies should test the efficacy of longer term CPAP treatment in a larger population.

Portable Sleep Device Survey 2005 - Australia and NZ

01/10/2005

The aim of this study was to assess the prevalence and reason for the use of portable devices in Australia and New Zealand

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Autoset CS vs Oxygen in CHF and CSA-CSR

16/10/2004

OXYGEN VERSUS ADAPTIVE PRESSURE SUPPORT SERVO-VENTILATION (AUTOSET CS) IN PATIENTS WITH CENTRAL SLEEP APNOEA- CHEYNE STOKES RESPIRATION (CSA-CSR) AND CONGESTIVE HEART FAILURE (CHF)

Angela Campbell, Katherine Ferrier, Alister Neill
WellSleep, Department of Medicine, Wellington School of Medicine and Health Sciences, Wellington New Zealand

There is a debate regarding the need for and optimum treatment of CSA-CSR in patients with CHF. Aim: To compare Autoset-CS and overnight oxygen therapy utilising a crossover study design. Methods: Ten stable outpatients with CSA-CSR and CHF (LVEF < 45%) were randomised to either 8 weeks oxygen 2l/min via nasal prongs or 8 weeks Autoset-CS, separated by a 3 week washout. At baseline and at completion of each arm, we compared polysomnography, shuttle walk distance, symptoms, urine catecholamines, plasma NT-BNP and bi-planar echocardiography. Results: Ten subjects were recruited (mean age 64±10 years, LVEF 28±10.5%, AHI 63±30/hr). Seven completed the protocol (one died, one refused Autoset-CS and one was withdrawn after CCU admission). Mean AHI on oxygen therapy, 19.4±14.6/hr, Autoset-CS, 5.0 ±5.9/hr (p=0.03). CSA-CSR was prevented (AHI of < 10/hr) in 4/9 using oxygen (44%), 6/8 using Autoset-CS (75%) and 6/7 with either therapy (86%). Autoset-CS compliance averaged 4.7±2.3 hrs/night (range 1.2 - 7.1 hr/night). LVEF did not change with either therapy (Oxygen arm 28.7% vs baseline 28.7% p = 0.97, Autoset-CS arm 31.4% vs baseline 33.5% p = 0.23). NTBNP, urinary catecholamines, shuttle walk distance and symptoms were unchanged.

Conclusion: Over eight weeks Autoset-CS reduced polysomnographic indices of CSA-CSR more than oxygen therapy. Neither intervention improved prognostic indices of heart failure, symptoms or exercise capacity. A larger study would better address any potential long-term benefits.

Supported by funding: ResMed Ltd

Key words: Congestive heart failure, Central sleep apnoea-Cheyne Stokes respiration, oxygen therapy, adaptive servo-ventilation

Cardioventilatory Coupling during sleep

16/10/2004

CARDIOVENTILATORY COUPLING DURING SLEEP

Karyn O'Keeffe 1, 2, Peter Larsen 1, Angela Campbell 2, Duncan Galletly 1
Departments of (1) Surgery and Anaesthesia and (2) Medicine, Wellington School of Medicine and Health Sciences

We investigated the temporal synchronisation of heart beats and the onset of inspiration (cardioventilatory coupling) in 10 adult subjects aged 18-49 years during normal sleep. We observed cardioventilatory synchronisation in all 10 subjects, although the strength, pattern and duration of synchronisation varied considerably between subjects and over time. Using the proportional Shannon entropy (SHa) as a measure of synchronisation strength, we observed that coupling was significantly different between the awake state and sleep (p=0.01). SHa in the awake state was significantly higher (less synchronised) than in sleep, but that there was no significant differences in SHa between sleep stages. We have previously described cardioventilatory synchronisation in spontaneously breathing anaesthetised subjects. Each of the patterns of synchronisation that we have previously described in anaesthesia was observed in the current study. In addition, we observed previously described patterns of respiratory variability and distinct patterning in the heart rate time series. The clinical significance of cardioventilatory synchronisation during sleep is worthy of further research.

Supported by: Wellington Medical Research Foundationoea-Cheyne Stokes respiration, oxygen therapy, adaptive servo-ventilation

Single channel flow study for diagnosis of OSA

16/10/2004

DIAGNOSIS OF OBSTRUCTIVE SLEEP APNOEA/HYPOPNOEA SYNDROME USING A SINGLE CHANNEL FLOW STUDY AT HOME

Melissa Thomas, Kim Ward, David Hillman
West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Perth WA 6009

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) affects 2-4% of the middle aged population. The diagnostic gold standard is laboratory polysomnography (PSG) but insufficient resources delay OSAHS diagnosis and treatment. Single channel flow study (SCFS) devices utilising nasal pressure measurement could provide a simple, low cost, readily available alternative. Methods: Patients attending for laboratory diagnostic PSG used a microMESAM® SCFS device at home the following night. Apnoea/hypopnoea index (AHI) from automated microMESAM® analysis was compared to that derived from technologist-analysed PSG. Results: To date 10 adult subjects have been recruited (2F: 8M). While positively correlated (r = 0.94, p< 0.001) microMESAM® AHI was significantly less than PSG AHI (28.1±36.7 (mean±SD) vs 38.1±37.9, p< 0.04). Where OSA was defined as PSG AHI ³10, 8 patients had the condition and microMESAM® demonstrated a high positive predictive value (1) but a modest negative predictive value (0.5). Conclusion: microMESAM® appears to be a useful tool to rule in OSA but less useful in ruling it out. Where clinical pretest probability is high, a positive test would allow treatment to proceed while a negative test indicates further investigation by PSG. Given its low relative cost, microMESAM® screening appears a cost-effective option for such patients.

Grant Support: Resmed Travel expenses.

Key words: Screening device, Obstructive Sleep Apnoea, nasal pressure, diagnosis.ne Stokes respiration, oxygen therapy, adaptive servo-ventilation

Inter and Intra-rater Reliability of Manual and Automatic Sleep, Respiratory and Arousal Scoring in a Paediatric Population

15/10/2004

INTER & INTRA-RATER RELIABILITY OF MANUAL AND AUTOMATIC SLEEP, RESPIRATORY AND AROUSAL SCORING IN A PAEDIATRIC POPULATION.

Rebecca Smith1, Rosemary Horne2, Nicole Verginis1, Margot Davey1
1 Melbourne Children's Sleep Unit, Dept of Respiratory and Sleep Medicine, Monash Medical Centre, and 2 Ritchie Centre for Baby Health Research, Monash University, Victoria, 3168

Introduction: In paediatric polysomnography (PSG) there is currently no automatic analysis software available, hence studies are routinely manually scored. It is therefore necessary to ensure good inter and intra-rater reliability. Previous investigations in adult laboratories have observed sleep staging agreement between 65-90%. There is less inter-rater agreement for respiratory disturbance (RDI) and arousal indices (ArI).

Aim: To evaluate the inter- and intra-rater reliability in sleep staging, respiratory disturbance and arousal indices of scorers within the same paediatric sleep laboratory.

Methods: Five overnight PSG's (age range; 4-8 years), recorded using Compumedics, were scored manually by 5 sleep technologists (experience 9 months - 6 years) and automatically using Compumedics software. To determine intra-rater agreement the same technologist re-scored one of the PSG recordings with an average of one month between scorings. Agreement values for sleep staging were calculated on an epoch-by-epoch basis. RDI and ArI were also compared.

Results: The average inter-rater agreement was 87% (range 80-92%; kappa 0.64 - 0.90) and the average intra-rater agreement was 89% (range 87-91%; kappa 0.78 -0.88). There was no statistically significant difference between or within raters for RDI or ArI. Average agreement between manually and computer scored sleep staging was 23% (range 26-31%; kappa 0.004 - 0.16). There was a statistically significant difference between manually and automatically scored ArI (p < 0.01), but not for RDI, however automatic analysis often scored inappropriate respiratory events.

Conclusions: This study has provided quality assurance for our sleep laboratory, which should routinely be conducted in all paediatric sleep laboratories. Future studies should investigate agreement between paediatric sleep laboratories.

Key words: reliability, sleep staging, paediatric laboratory, agreement

Nasal Pressure Airflow Measurement, An Introduction

08/06/2002

This article discusses recording of nasal pressure in both diagnostic and CPAP studies, technical factors, troubleshooting of poor nasal pressure signals as well as detection of snoring and respiratory events.

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