Pamela Johnson

Acute mountain sickness is associated with sleep desaturation at high altitude

Objective:  This study was intended to demonstrate a biologically important association between acute mountain sickness (AMS) and sleep disordered breathing.

Central and obstructive sleep apnoea during ascent to high altitude

Objective:  The aim of the study was to investigate the relationship between central sleep apnoea (CSA) at high altitude and arterial blood gas tensions, and by inference, ventilatory responsiveness.

Sleep architecture changes during a trek from 1400 to 5000 m in the Nepal Himalaya.

The aim of this study was to examine sleep architecture at high altitude and its relationship to periodic breathing during incremental increases in altitude. Nineteen normal, sea level‐dwelling volunteers were studied at sea level and five altitudes in the Nepal Himalaya. Morning arterial blood gases and overnight polysomnography were performed in 14 subjects at altitudes: 0, 1400, 3500, 3900, 4200 and 5000 m above sea level. Subjects became progressively more hypoxic, hypocapnic and alkalinic with increasing altitude. As expected, sleep architecture was affected by increasing altitude. While time spent in Stage 1 non‐rapid eye movement sleep increased at 3500 m and higher (P < 0.001), time spent in slow‐wave sleep (SWS) decreased as altitude increased. Time spent in rapid eye movement (REM) sleep was well preserved. In subjects who developed periodic breathing during sleep at one or more altitudes (16 of 19), arousals because of periodic breathing predominated, contributing to an increase in the total arousal index. However, there were no differences in sleep architecture or sleeping oxyhaemoglobin saturation between subjects who developed periodic breathing and those who did not. As altitude increased, sleep architecture became progressively more disturbed, with Stage 1 and SWS being affected from 3500 m, while REM sleep was well preserved. Periodic breathing was commonplace at all altitudes, and while associated with increases in arousal indices, did not have any apparent effect on sleep architecture.

Non-invasive positive pressure ventilation during sleep at 3800 m: relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation.

Background and objective:  Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end‐expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep.

PP154. Relationship between recorded and reported snoring during pregnancy: Objective measurement versus questionnaire responses

INTRODUCTION Snoring is a common symptom of sleep disordered breathing (SDB), a condition that is present in 4% of the general population. SDB is identified by snoring and repetitive cessation of breathing during sleep accompanied by repetitive hypoxia and has been found to be associated with hypertension, stroke and heart attack. There is not depth of knowledge examining the association between SDB and pregnancy outcomes. OBJECTIVES To examine the prevalence of self reported snoring in pregnancy and the potential association between self reported snoring and the development of Hypertensive Disorders of Pregnancy (HDP) within a larger cohort from a prevalence of SDB in pregnancy study. METHODS Questionnaires were administered to pregnant women attending an outpatients antenatal clinic. The self reported snoring is a component of the Epworth scale. Pregnancy progression and outcome data were collected on all participants and analyse by IBM SPSS v.20™ utilising Chi-square analysis, Student T test and logistic regression analysis. HDP diagnoses were in alignment with the SOMANZ (2009) diagnostic criteria. RESULTS Questionnaires were administered and outcomes collected on 2023 pregnancies. Snoring was reported by 49.2% of women. HDP affected 10.1% of the cohort, 3.3% of whom were preeclamptic. Of the pregnancies affected by HDP self reported snoring occurred in 57.7% in comparison to 43.3% who do not report snoring (p<0.001). CONCLUSION This would indicate that there is an association between self reported snoring and the development of HDP. Further analysis will be undertaken to model the effect of other potential risk factors such as maternal age, parity, pre-pregnancy BMI and other co morbidities.

OS093. Prevalance of sleep disordered breathing in pregnancy

INTRODUCTION Snoring is a common symptom of Sleep Disordered Breathing (SDB), a condition that is present in 4% of the general population. SDB is identified by snoring and repetitive cessation of breathing during sleep accompanied by repetitive hypoxia and has been found to be associated with hypertension, stroke and heart attack.The general risk factors associated with severe preeclampsia significantly overlap with those reported to increase the risk of SDB syndromes. Further risk factors that need consideration include: multiple pregnancy, diabetes and chronic hypertension treatment. OBJECTIVES To determine the prevalence of SDB in the pregnant population in a metropolitan hospital and to examine self-reported snoring against actual snoring as determined by Sonomat

PP021 Outcomes for adolescent women and their pregnancies in greater Western Sydney

INTRODUCTION Hypertensive disorders in pregnancy (HDP) are a common complication of pregnancy. It is widely believed that this is a more common complication of adolescent pregnancies. Adolescent pregnancies are generally primiparous and result in earlier delivery, and these factors put them at a greater risk of preeclampsia. However, the generally lower blood pressure of the group should act as a protective measure against this. OBJECTIVES The aim of this investigation was to compare the adolescent age group (maternal age <20years at time of recruitment) to those in the 20-34years age group in terms of their change in blood pressure and diagnosis of HDP and preeclampsia. Immediate obstetric outcomes (gestation at delivery, birthweight and mode of delivery) were also compared. METHODS Questionnaires were administered to pregnant women at Campbelltown and Liverpool hospitals as part of a much broader study looking at sleep disordered breathing in pregnancy. Data collected included demographic information, pregnancy blood pressure readings, pregnancy complications, delivery type and neonatal outcomes. Adolescents (Group 1 age <20years) were compared to older women (Group 2 aged 20-34years) utilizing Students t-tests analysed with IBM SPSS v.19™. RESULTS Results were available on 2306 women, 108 in Group 1 and 2198 in Group 2. Adolescents had a lower booking systolic blood pressure (105mmHg and 109mmHg, p<0.005) and diastolic blood pressure (63mmHg and 65mmHG, p<0.002) than older women respectively. There was no statistical difference in the highest recorded systolic blood pressure antenatally (119mmHg and 121mmHg, p<0.06) nor the highest recorded diastolic blood pressure readings between Groups 1 and 2 respectively (74mmHg and 75mmHg, p=0.6). There was no difference in the rates of HDP between the groups (8.3% and 8.2%, p=0.8) nor the rates of preeclampsia (2.8% and 2.9%, p=1.0). CONCLUSION Although adolescents have lower booking blood pressures than their older peers, their highest antenatal blood pressure readings are similar and they have the same incidence of HDP and preeclampsia.