Introdução: Apneia obstrutiva do sono (AOS) é uma doença comum em pacientes com cardiomiopatia hipertrófica (CMH) e está associada de forma independente a piora nos seus parâmetros cardíacos. O tratamento da AOS com CPAP (continuous positive airway pressure) é considerado benéfico em pacientes sem CMH. Contudo, o CPAP pode agudamente piorar o desempenho cardíaco em pacientes com CMH e obstrução na via de saída do ventrículo esquerdo (VSVE). Métodos: Foram estudados 26 pacientes com CMH, estáveis, divididos em 12 não-obstrutivos (CMHN-Obst) e 14 obstrutivos (CMHObst), de acordo com seu gradiente de VSVE menor ou maior que 30mmHg, respectivamente. Pacientes foram continuamente monitorados pela pressão arterial (PA) batimento-a-batimento e eletrocardiograma, em vigília e posição supina. Um ecocardiograma bidimensional foi realizado durante o repouso (Basal) a após 20 minutos de CPAP nas pressões de 1,5cmH2O e 10cmH2O, que foram aplicadas em ordem randomizada, interpostas por 10 minutos de intervalo sem CPAP. Em outra data os pacientes foram submetidos a uma polissonografia completa para diagnóstico de AOS. Resultados: Variáveis hemodinâmicas como PA, débito cardíaco, volume sistólico, frequência cardíaca, fração de ejeção do ventrículo esquerdo e gradiente de VSVE permaneceram estáveis ao longo do estudo em ambos os grupos. Em pacientes não-obstrutivos, o CPAP em 10cmH2O reduziu área do átrio direito, a complacência do ventrículo esquerdo, bem como o relaxamento de ambos os ventrículos. Nos pacientes obstrutivos, o CPAP em 10cmH2O provocou efeitos similares no coração direito e também elevou as pressões na artéria pulmonar. No coração esquerdo, houve uma redução na área e volume do átrio esquerdo, com aumento nas áreas e volumes do jato e frações regurgitantes. A polissonografia completa demonstrou que a AOS (índice de apneia e hipopneia >= 15 eventos/hora) estava presente em 58% dos pacientes. Conclusões: O CPAP se mostrou uma alternativa segura para tratar AOS em pacientes com CMH, pois não alterou agudamente a hemodinâmica. Contudo, provocou algumas alterações na dinâmica cardíaca de pacientes obstrutivos, que devem ser considerados com cautela / Background: Obstructive sleep apnea (OSA) is a common disease and is independently associated with a worse in cardiac parameters among patients with hypertrophic cardiomyopathy (HCM). The treatment of OSA with CPAP (Continuous positive airway pressure) is beneficial among patients without CMH. However, CPAP may acutely impair cardiac performance in patients with HCM and left ventricular outflow tract (LVOT) obstruction. Methods: We studied 26 stable HCM patients divided in 12 nonobstructive-HCM and 14 obstructive-HCM according to their LVOT pressure gradient lower or higher than 30 mmHg, respectively. Patients were continuously monitored by beatto- beat blood pressure (BP) and electrocardiogram in the supine position while awake. A 2-dimensional echocardiography was performed at resting (Baseline) and after 20 minutes of nasal CPAP at 1.5cmH2O and 10cmH2O, that was applied in a random order interposed by 10 minutes without CPAP. In another day all patients underwent full Polysomnography for OSA diagnosis. Results: Hemodynamic variables such as BP, cardiac output, stroke volume, heart rate, left ventricular ejection fraction and LVOT gradient did not change along the study period in both groups. CPAP at 10cmH2O in nonobstructive-HCM patients decreased right atrial area, left ventricular compliance, right and left ventricular relaxation. In obstructive-HCM patients, CPAP at 10cmH2O promoted similar effects in the right heart, and also raised pulmonary artery pressure. In the left heart, there was a decrease in left atrial area and volume with increased area and volume of both, regurgitant jet and regurgitant fraction. Full Polysomnography showed that OSA (apneahypopnea index >=15 events/h) was present in 58% of HCM patients. Conclusions: CPAP showed to be safe to treat OSA and did not acutely change hemodynamics in patients with HCM. However, CPAP may acutely impair cardiac dynamics in obstructive-HCM patients and this finding should be carefully considered

Introdução: Apneia obstrutiva do sono (AOS) é uma doença comum em pacientes com cardiomiopatia hipertrófica (CMH) e está associada de forma independente a piora nos seus parâmetros cardíacos. O tratamento da AOS com CPAP (continuous positive airway pressure) é considerado benéfico em pacientes sem CMH. Contudo, o CPAP pode agudamente piorar o desempenho cardíaco em pacientes com CMH e obstrução na via de saída do ventrículo esquerdo (VSVE). Métodos: Foram estudados 26 pacientes com CMH, estáveis, divididos em 12 não-obstrutivos (CMHN-Obst) e 14 obstrutivos (CMHObst), de acordo com seu gradiente de VSVE menor ou maior que 30mmHg, respectivamente. Pacientes foram continuamente monitorados pela pressão arterial (PA) batimento-a-batimento e eletrocardiograma, em vigília e posição supina. Um ecocardiograma bidimensional foi realizado durante o repouso (Basal) a após 20 minutos de CPAP nas pressões de 1,5cmH2O e 10cmH2O, que foram aplicadas em ordem randomizada, interpostas por 10 minutos de intervalo sem CPAP. Em outra data os pacientes foram submetidos a uma polissonografia completa para diagnóstico de AOS. Resultados: Variáveis hemodinâmicas como PA, débito cardíaco, volume sistólico, frequência cardíaca, fração de ejeção do ventrículo esquerdo e gradiente de VSVE permaneceram estáveis ao longo do estudo em ambos os grupos. Em pacientes não-obstrutivos, o CPAP em 10cmH2O reduziu área do átrio direito, a complacência do ventrículo esquerdo, bem como o relaxamento de ambos os ventrículos. Nos pacientes obstrutivos, o CPAP em 10cmH2O provocou efeitos similares no coração direito e também elevou as pressões na artéria pulmonar. No coração esquerdo, houve uma redução na área e volume do átrio esquerdo, com aumento nas áreas e volumes do jato e frações regurgitantes. A polissonografia completa demonstrou que a AOS (índice de apneia e hipopneia >= 15 eventos/hora) estava presente em 58% dos pacientes. Conclusões: O CPAP se mostrou uma alternativa segura para tratar AOS em pacientes com CMH, pois não alterou agudamente a hemodinâmica. Contudo, provocou algumas alterações na dinâmica cardíaca de pacientes obstrutivos, que devem ser considerados com cautela / Background: Obstructive sleep apnea (OSA) is a common disease and is independently associated with a worse in cardiac parameters among patients with hypertrophic cardiomyopathy (HCM). The treatment of OSA with CPAP (Continuous positive airway pressure) is beneficial among patients without CMH. However, CPAP may acutely impair cardiac performance in patients with HCM and left ventricular outflow tract (LVOT) obstruction. Methods: We studied 26 stable HCM patients divided in 12 nonobstructive-HCM and 14 obstructive-HCM according to their LVOT pressure gradient lower or higher than 30 mmHg, respectively. Patients were continuously monitored by beatto- beat blood pressure (BP) and electrocardiogram in the supine position while awake. A 2-dimensional echocardiography was performed at resting (Baseline) and after 20 minutes of nasal CPAP at 1.5cmH2O and 10cmH2O, that was applied in a random order interposed by 10 minutes without CPAP. In another day all patients underwent full Polysomnography for OSA diagnosis. Results: Hemodynamic variables such as BP, cardiac output, stroke volume, heart rate, left ventricular ejection fraction and LVOT gradient did not change along the study period in both groups. CPAP at 10cmH2O in nonobstructive-HCM patients decreased right atrial area, left ventricular compliance, right and left ventricular relaxation. In obstructive-HCM patients, CPAP at 10cmH2O promoted similar effects in the right heart, and also raised pulmonary artery pressure. In the left heart, there was a decrease in left atrial area and volume with increased area and volume of both, regurgitant jet and regurgitant fraction. Full Polysomnography showed that OSA (apneahypopnea index >=15 events/h) was present in 58% of HCM patients. Conclusions: CPAP showed to be safe to treat OSA and did not acutely change hemodynamics in patients with HCM. However, CPAP may acutely impair cardiac dynamics in obstructive-HCM patients and this finding should be carefully considered

Många patienter med obstruktivt sömnapnésyndrom (OSAS) som behandlas med Continuous Positive Airways Pressure (CPAP) avbryter sin behandling i ett tidigt skede. Att inte vara följsam behandlingen kan innebära olika hälsorisker för patienten som kan få allvarliga konsekvenser. Kommunikationssituationen vid det initiala utprovningsbesöket kan därför påverka huruvida patienten inte blir följsam och fullföljer behandlingen. Syftet med denna studie var att belysa hur vårdpersonal beskriver sina erfarenheter av kommunikationssituationen vid det initiala utprovningsbesöket av CPAP. En kvalitativ intervjustudie genomfördes med 23 personer som alla möter denna grupp av patienter.  Som analysmetod användes induktiv innehållsanalys. Vid analysen av materialet framkom tre kategorier; Bygga en relation, Inta ett pedagogiskt förhållningssätt samt Stödja patientens delaktighet. Dessa tre kategorier mynnade ut i ett tema som visade på hur kommunikationssituationen beskrevs Skapa förutsättning för lärande hos patienten. Studien belyser vikten av en samskapande vård och ett personcentrerat förhållningssätt där patienten ses som en partner i de beslut som tas samt hur vårdpersonalens pedagogiska förhållningssätt påverkar kommunikations-situationen på olika sätt. Erfarenheterna som beskrevs i studien upplevdes påverka patientens möjligheter till lärande i situationen för en ökad följsam till sin CPAP-behandling. / Many patients with obstructive sleep apnea syndrome (OSAS) treated with Continuous Positive Airways Pressure (CPAP) interrupt their treatment at an early stage. Not having adherence to the treatment implies various health risks for the patient that can have serious consequences. Therefore, the communicationsituation at the initial testing visit may affect whether the patient does not follow up and completes the treatment. The purpose of this study was to illustrate how healthcare professionals describe their experiences of the communicationsituation at the initial visit testing CPAP. A qualitative interview study was conducted with 23 people who all meet this group of patients. As an analytical method, inductive content analysis was used. In the analysis of the material three categories was revealed; Build a Relationship, Take an Educational Approach and Support the Patient's Participation. These three categories emerged in a theme that demonstrated how the communication situation was described as Creating a prerequisite for learning for the patient. The study highlights the importance of a person-centered approach, a co-productive care where the patient is seen as a partner in the decisions and how the healthcare professionals' pedagogical approaches affect the communicationsituation in different ways. The experiences described in the study were perceived to affect the patient's ability to learn in the situation for an increased adherence to the CPAP treatment.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / IntroduÃÃo: A DoenÃa Pulmonar Obstrutiva CrÃnica (DPOC) caracteriza-se por graus variÃveis de bronquite crÃnica e enfisema pulmonar, tendo por conseqÃÃncia aprisionamento aÃreo e hiperinsuflaÃÃo dinÃmica. Essas alteraÃÃes predispÃem à fadiga muscular e à necessidade de suporte ventilatÃrio. A ventilaÃÃo nÃo invasiva com pressÃo positiva (VNI) à o suporte ventilatÃrio de escolha para tratamento da exacerbaÃÃo aguda da DPOC, com reduÃÃo da mortalidade. Os efeitos da aplicaÃÃo de diferentes nÃveis de pressÃo positiva contÃnua em vias aÃreas (CPAP) sobre a hiperinsuflaÃÃo sÃo controversos, podendo ocasionar agravamento, atenuaÃÃo ou nenhum efeito. Os mÃtodos de imagem podem contribuir para maior compreensÃo dos efeitos da CPAP nos pulmÃes de pacientes com DPOC, incluindo seus efeitos regionais no parÃnquima pulmonar. Pacientes e MÃtodo: Trata-se de um trabalho prospectivo, intervencionista que estudou 11 pacientes com DPOC. Todos foram submetidos a TCAR, sem VNI e com VNI-CPAP (5, 10 e 15 cmH2O) aplicada por mÃscara nasal. A seqÃÃncia das pressÃes foi randomizada e os cortes tomogrÃficos realizados em Capacidade Residual Funcional. Os cortes foram realizados em trÃs regiÃes, para cada nÃvel de pressÃo: Ãpice (2 cm acima do arco aÃrtico), hilo (1cm abaixo da carina) e base (2 cm acima do diafragma). As unidades com densidades menores que -950 UH foram consideradas hiperaeradas. Os resultados foram analisados agrupando-se todos os nÃveis de corte e por regiÃes: Ãpice, hilo e base; e ventral, medial e dorsal. Resultados: Houve reduÃÃo das densidades pulmonares e aumento do nÃmero de pixels nas Ãreas hiperaeradas, com aplicaÃÃo de nÃveis de CPAP de 10 e 15 cmH2O em todas as anÃlises (p<0,05). Na anÃlise dos cortes agrupados, a densidade mÃdia foi reduzida progressivamente, sendo -846 UH (sem CPAP), -849 UH (CPAP de 5 cmH2O), -859 UH (CPAP de 10 cmH2O) e -869UH (CPAP de 15 cmH2O) (p<0,05). Na subdivisÃo em regiÃes, comparado-se sem CPAP com CPAP de 15 cmH2O: em Ãpice houve reduÃÃo de -840 para -871UH (p<0,05), em hilo de -848 para -882 UH (p<0,05), em base de -848 para -876 UH (p<0,05), em regiÃo ventral de -859 para -885 UH (p<0,05), em regiÃo medial de -848 para -864 UH (p<0,05) e em regiÃo dorsal de -832 para -860UH (p<0,05) .Ocorreu aumento do percentual de pixels nas Ãreas hiperaeradas na maioria das anÃlises com CPAP de 10 e 15 cmH2O (p<0,05). Em 2 pacientes houve aumento da densidade pulmonar mÃdia e diminuiÃÃo da aeraÃÃo com CPAP de 5 cmH2O . Observou-se um padrÃo de aeraÃÃo pulmonar de forma nÃo homogÃnea sendo maior em Ãpice em relaÃÃo à base do pulmÃo e em regiÃo ventral em relaÃÃo a dorsal, que nÃo foi modificado com aplicaÃÃo de CPAP. ConclusÃo: A aplicaÃÃo da CPAP por VNI resultou em aumento da hiperaeraÃÃo pulmonar com CPAP de 10 e 15 cmH2O detectÃvel a TCAR. Este padrÃo de resposta nÃo foi homogÃneo, havendo um subgrupo de pacientes em que houve reduÃÃo da hiperaeraÃÃo com CPAP de 5 cmH2O. A distribuiÃÃo do grau de hiperaeraÃÃo induzida pela CPAP dentro do parÃnquima pulmonar segue a distribuiÃÃo heterogÃnea de hiperaeraÃÃo basal / Introduction: The Chronic Obstructive Pulmonary Disease (COPD) is characterized by different stages of chronic bronchitis and pulmonary emphysema with air trapping and dynamic hyperinflation. These conditions lead to respiratory muscles fatigue and need of ventilator support. Noninvasive positive pressure support ventilation (NIPPV) is the treatment of choice for COPD exacerbations with mortality reduction. Continuous positive airway pressure (CPAP) effects on hyperinflation is controversy; it can worsen, attenuate or have no effect. Imaging methods can facility the comprehension of CPAP effects on COPD patients, including regional effects on lung parenchyma. Objectives: To evaluate the effect of CPAP application by NIPPV-CPAP on pulmonary hyperinflation in COPD patients. Patients and Method: This is a prospective and interventionist study that evaluated 11 patients with COPD. All patients were evaluated by high resolution CT (HRCT), without and with NIPPV-CPAP (5, 10 and 15 cmH2O) applied by nasal mask. The pressures sequence was randomized and the HRCT images were done in Functional Residual Capacity. HRCT images were done in three regions for each level of pressure: apex (2 cm above the aortic arc), hilar (1cm below the carina) and basis (2 cm above the diaphragm). The units with densities lower than -950 UH were considered hyperinflated. For analysis the results were divided in full lung and in regions: apex, hilar and basis and ventral, medial and dorsal. Results: It was observed a pulmonary density reduction and an increase of pixels on hyperinflated areas with application of CPAP levels greater than 10 cmH2O in all analyses (p<0,05). In grouped lung analysis the mean density was reduced gradually from -846 UH (without CPAP), -849 UH (5 CPAP of cmH2O), -859 UH (10 CPAP of cmH2O) to -869UH (15 CPAP of cmH2O) (p<0,05). In subdivisions, comparing without CPAP and with CPAP of 15 cm cmH2O: in apex it was observed reduction from -840 to -871UH (p<0,05), in hilar region from -848 to -882 UH (p<0,05), in basis from -848 to -876 UH (p<0,05), in ventral region from -859 to -885 UH (p<0,05), in medial region from -848 to -864 UH (p<0,05) and in dorsal region from -832 to -860UH (p<0,05). It was also noted an increase of the percentage of pixels on hyperinflated areas in the majority of analyses with CPAP of 10 and 15 cmH2O (p<0,05). In 2 patients it was observed elevation of mean pulmonary density with CPAP of 5 cmH2O. It was observed that pulmonary parenchyma aeration was distributed in a non homogeneous way with predominance of the apex area comparing with basis of the lung and of the ventral area comparing with dorsal area. Conclusion: The CPAP application by NIPPV resulted in increase of pulmonary hyperinflation with levels of CPAP of 10 and 15 cmH2O detectable by HRCT. However this was not homogeneous, a subgroup of patients had aeration reduction with CPAP of 5 cmH2O. The distribution of aeration induced by CPAP is heterogeneous inside pulmonary parenchyma and follows the heterogeneous basal hyperaeration

No description available.

Driver sleepiness is known to be a major contributor to road traffic incidents (RTIs). An initial literature review identified many studies reporting untreated obstructive sleep apnoea (OSA) sufferers as having impaired driving performance and increased RTI risk. It is consistently reported that treatment with continuous positive air pressure (CPAP) improves driving performance and decreases RTI risk, although most of these studies are conducted less than one year after starting treatment. UK law allows treated OSA patients to continue driving if their doctor states that treatment has been successful. Despite the wealth of publications surrounding OSA and driving, 6 key areas were identified from the literature review as not fully investigated, the: (i) prevalence of undiagnosed OSA in heavy goods vehicle (HGV) drivers in the UK; (ii) impact of sleep restriction on long term CPAP treated OSA compared with healthy controls; (iii) ability of treated OSA participants to identify sleepiness when driving; (iv) impact of one night CPAP withdrawal on driving performance; (v) individual difference in driving performance of long term CPAP treated OSA participants; (vi) choice of countermeasures to driver sleepiness by two groups susceptible to driver sleepiness, OSA and HGV drivers. Key areas (i) and (vi) were assessed using questionnaires. 148 HGV drivers were surveyed to assess OSA symptoms and preference of countermeasures to driver sleepiness. All participants completing the driving simulator study were also surveyed. 9.5% of HGV drivers were found to have symptoms of suspected undiagnosed OSA. Additionally the OSA risk factors were more prevalent for HGV drivers than reported in national statistics reports for the general population. The most effective countermeasures to driver sleepiness (caffeine and a nap) were not the most popular. Being part of a susceptible group (OSA or HGV driver) and prior experience of driver sleepiness did not promote effective choice of countermeasure. Key areas (ii) to (v) were assessed using a driving simulator. Driving simulators present a safe environment to test participants in a scenario where they may experience sleepiness without endangering other road users.

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is characterised by repeated cycles of upper airway obstruction during sleep, leading to diurnal symptoms. Individuals with Down syndrome (DS) are predisposed to this as the DS phenotype overlaps with OSAHS risk factors. Around 2-4% of the general adult population and 55% of children with DS have OSAHS but, to date, no large-scale study has assessed OSAHS prevalence or efficacy of treatment in DS adults. This study aimed to: 1) Systematically assess subjective and objective OSAHS prevalence; 2) Assess the effectiveness of continuous positive airway pressure (CPAP) in an adult DS population. Standard questionnaires including pictorial Epworth Sleepiness Scale (pESS) and Developmental Behaviour Checklist for Adults (DBC-A) were sent to UK adults aged ≥16yr with DS and their caregivers. All questionnaire responders were invited to undergo home polygraphy. Symptomatic adults with DS with ≥10 apnoeas/hypopnoeas per hour in bed (AH) on home polygraphy were invited to participate in a prospective randomised controlled trial (RCT) of CPAP v. lifestyle advice, with review at 1, 3, 6 and 12m. Participants in the lifestyle arm were offered CPAP at 1m. Standard measurements of sleepiness, behaviour, cognitive function and general health were undertaken. Standard statistical analyses were conducted, with significance set at p < 0.001 to control for multiple testing. Of 5270 questionnaires sent, 1105 responses were valid (21%). Responders (55% males) were overweight/obese young adults: mean BMI 29.0±6.8kg/m2; mean age 28±9 years. Women had a higher BMI (p < 0.0001), but collar size was greater in men (p < 0.0001). Mean pESS scores were broadly within the normal range (7±5/24). No significant gender differences in OSAHS symptoms were noted. Individuals with probable OSAHS had higher pESS and DBC-A scores, and significantly more symptoms of OSAHS. Subjective OSAHS prevalence was estimated at 35%. Of the 790 individuals invited, 149 underwent polygraphy, with 134 valid studies obtained: mean AH 21.8(10.9-42.7); mean oximetry desaturation index (ODI) 6.6(2.3-20.0). No significant gender differences were observed. Forty-two percent of participants met standard clinical diagnostic criteria for OSAHS. Twenty-eight eligible adults with DS (19 male) were randomised: age 28±9yr; BMI 31.5±7.9kg/m2; AH 28.6(14.8-47.9); ODI 7.3(1.8-21.9); pESS 11±6/24. Groups did not differ significantly at baseline. By 12m, 4 participants had withdrawn (all remaining participants on CPAP). The pESS (p=0.001), DBC-A Disruptive (p < 0.0001) and Kaufmann Brief Intelligence Test verbal subscale (p=0.001) scores improved significantly. This first large study of OSAHS prevalence in the adult DS population estimates a prevalence of 35-42% - around 10 times higher than in the general adult population. Sustained, significant improvements in sleepiness, cognitive function and behavioural/emotional outcomes with CPAP use over a 12m period were demonstrated during this first RCT of CPAP in adults with DS. A larger trial of CPAP in this population is warranted.

Introduction: Obstructive sleep apnoea (OSA) is common and is caused by repetitive obstruction of the upper airway during sleep. OSA is associated with increased cardiovascular morbidity and mortality and is an independent risk factor for hypertension. The immediate physiological effects of OSA include intermittent hypoxia, repeated arousal from sleep and intra-thoracic pressure swings. The resulting activation of the sympathetic nervous system, systemic inflammation and oxidative stress may result in increased arterial stiffness and endothelial dysfunction, potentially explaining any causal link between OSA and cardiovascular disease (CVD). Continuous positive airway pressure (CPAP) therapy improves excessive daytime sleepiness (EDS) and in non-randomised studies, reduces cardiovascular mortality. Prior to starting this study, there was a limited amount of evidence suggesting that CPAP therapy improved arterial stiffness and endothelial function, but the effects in subjects without pre-existing CVD were unclear. Aims: i) to determine whether CPAP therapy has an effect upon measures of arterial stiffness and endothelial function in patients with OSA, in the absence of known CVD. ii) To compare arterial stiffness and endothelial function in a subset of patients with OSAHS (defined as OSA and EDS), with a group of well-matched control subjects. Methods: Fifty three patients with OSA, defined as an apnoea/hypopnoea index of ≥15, and without known CVD, entered a double-blind placebo-controlled crossover trial of 12 weeks CPAP therapy, of whom forty three completed the study protocol. Sham CPAP was used in the placebo arm of the study and vascular assessments were made at baseline and after each arm of the study. Arterial stiffness was determined by measuring aortic distensibility using cardiovascular magnetic resonance imaging and by measuring the augmentation index (AIx) and aortic pulse wave velocity (PWV) by applanation tonometry. Endothelial function was assessed non-invasively by measuring vascular reactivity after administration of salbutamol and glyceryl trinitrate. In a subset of twenty patients with OSAHS, arterial stiffness and endothelial function at baseline were compared to readings obtained from healthy control subjects, matched on a one-to-one basis for age, sex and BMI. Results: Patients with OSAHS (n=20) had increased arterial stiffness [AIx 19.3(10.9) vs. 12.6(10.2) %; p=0.017] and impaired endothelial function, measured as the change in AIx following salbutamol [-4.3(3.2) vs. -8.0(4.9) %; p=0.02] compared to controls. Twelve weeks of CPAP therapy had no significant effect upon any measure of arterial stiffness or endothelial function in patients with OSA (n=43). A trend towards a reduction in AIx following CPAP therapy was seen, but this was non-significant. There was a reduction in systolic blood pressure following CPAP therapy [126(12) vs. 129(14) mmHg]. Sub group analysis showed CPAP to have no effect on arterial stiffness or endothelial function in patients with EDS or in patients using CPAP for ≥4 hours per night. Conclusions: This study demonstrates that even in the absence of known CVD, patients with OSAHS have evidence of increased arterial stiffness and impaired endothelial function. However, in patients with OSA, free from CVD, CPAP therapy did not lead to an improvement in any measure of arterial stiffness or endothelial function after 12 weeks.

Background: Positive expiratory pressure (PEP) and continuous positive airway pressure (CPAP) are two forms of resistance breathing used in spontaneously breathing patients. With a threshold resistor or a flow resistor, both PEP and CPAP provide a positive (elevated) pressure level during the expiratory phase. With PEP, inspiratory pressure is negative, i.e. lower than ambient air pressure, as during a normal inspiration, but with CPAP, the inspiratory pressure is positive, i.e. higher than ambient air pressure. Methods: This thesis is based on four separate studies in which four different breathing devices, a PEP-bottle (threshold resistor device), a PEP-mask (flow resistor device), a threshold resistor CPAP and a flow resistor device were investigated. Paper I, II and III are based on studies in healthy volunteers. Paper IV is a bench study performed in a hypobaric chamber. Paper I examined differences between two PEP devices, the PEP-bottle and the PEP-mask. Paper II evaluated the performance of a flow resistor CPAP device, (Boussignac CPAP). Paper III investigated the effect of two PEP-devices, a PEP-bottle and a PEP-mask and two CPAP devices, a threshold resistor CPAP and a flow resistor CPAP, on inspiratory capacity (IC). In paper IV, the effect of changes in ambient pressure on preset CPAP levels in two different CPAP devices was compared. Results: With the PEP bottle, both expiration and inspiration began with a zero-flow period during which airway pressure changed rapidly. With the PEP-mask, the zero-flow period was very short and the change in airway pressure almost non-existent (paper I). During normal breathing with the Boussignac CPAP, changes in airway pressure were never large enough to reduce airway pressure below zero. During forced breathing, as airflow increased, both the drop in inspiratory airway pressure and the increase in expiratory airway pressure were potentiated (paper II). IC decreased significantly with three of the breathing devices, the PEP-mask and the two CPAP devices (paper III). With the threshold resistor CPAP, measured pressure levels were close to the preset CPAP level. With the flow resistor CPAP, as the altitude increased CPAP produced pressure levels increased (paper IV). Conclusion: The effect on airway pressure, airflow, IC and the effect of changes in ambient air pressure differ between different kinds of resistance breathing devices. These differences in device performance should be taken into consideration when choosing the optimal resistance breathing device for each patient.

Background: Compliance with CPAP treatment for OSA is not reliably predicted by the severity of symptoms or physiological variables. I conducted a series of studies to examine a range of factors that may affect compliance with CPAP. Methods: I performed a retrospective study examining association of demographic factors and OSA severity with long-term CPAP compliance. In a prospective study, I looked at the correlation of short and long-term CPAP compliance with socio-economic status, education, type D personality, demographics, disease severity, mood and clinician's prediction. I undertook a prospective, cross-over trial comparing the impact of Bi-level PAP therapy in individuals with low tolerance of CPAP. Results: In a retrospective analysis, an improvement in subjective daytime somnolence was correlated with optimal compliance. In the prospective study, median compliance with CPAP at 6 months was 5.6 (3.4- 7.1) hours/night with 73% of subjects using CPAP ≥ 4 hours/night. Compliance with CPAP was not found to be associated with socio-economic class for people in work, type D personality, education, sex, age, baseline sleepiness (ESS score) or disease severity (ODI). The clinician's initial impression had no predictive value for individual patients. Subjects who were long-term unemployed or reporting mood disorders (High Beck's Depression Index scores) were likely to have poor compliance and sub-optimal CPAP usage (OR 4.6, p = 0.011 and OR 1.4. p=0.04 respectively). Subjects experiencing side effects after the first night on treatment showed lower acceptance and subsequent compliance. In the cross-over trial, changing to Bi-level PAP in individuals with suboptimal compliance due to pressure related intolerance, did not lead to an improvement in CPAP compliance. In post-hoc analysis, compliance and comfort were better in the subgroup that complained of difficulty with exhalation on CPAP. Conclusion: My research as presented in this thesis, did not find an association between disease severity (ODI), socio-economic status (for people in employment), education or personality type and CPAP compliance. My research demonstrated that subjects with long-term unemployment, mood disorders and those experiencing side effects on the first night of treatment were likely to have sub-optimal compliance. Changing to Bi-level PAP is only likely to be useful for a sub-group of subjects experiencing pressure related intolerance. More research is needed to explore whether intensive support to individuals with OSA and long term unemployment, as well as mood disorders, may improve compliance.