A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Obstructive sleep apnea (OSA) is a condition characterized by upper airway obstruction during sleep causing intermittent hypoxia and nighttime awakening. It is a common condition in the United States that is often undiagnosed. It is a significant risk factor for decreased daytime productivity, quality of life, cardiovascular disease, and death. The current gold standard for diagnosis of OSA is laboratory‐based polysomnography (PSG). While PSG is necessary for the diagnosis and monitoring of OSA, many patients have limited access to PSG due to wait times at PSG laboratories or economic or geographic limitations. Portable sleep monitoring has been studied as a possible solution for patients who do not have access to timely PSG. This study aimed to use the Zephyr BioHarness 3, a chest‐worn physical activity monitor that records movement and physiologic data in real‐time, to detect apnea events in patients with suspected OSA undergoing single‐night laboratory PSG. Twenty patients underwent single‐night laboratory‐based PSG while simultaneously wearing the Zephyr BioHarness 3. The Zephyr BioHarness 3 data was analyzed using three methods. First, apnea events were identified in 10‐second windows of Zephyr data via support vector machine, logistic regression, and neural network (sensitivity = 76.0 ± 0.3%, specificity = 62.7 ± 0.2%, accuracy = 63.7 ± 0.1%). Second, apnea events were identified using the mean, median, and variance of the 10‐second windows (sensitivity = 72.3 ± 0.3%, specificity = 69.4 ± 0.1%), accuracy 69.6 ± 0.1%). Third, apnea events were identified using phase‐space transformation of the Zephyr BioHarness 3 data (sensitivity = 76.9 ± 0.3%, specificity = 77.9 ± 0.1 %, accuracy = 77.9 ± 0.1%). The Zephyr BioHarness shows initial promise as a possible OSA screening tool for patients suspected of OSA but who lack access to timely laboratory‐based PSG.

Uno de los pilares fundamentales en el tratamiento de las patologías respiratorias es la oxígenoterapia, por lo cual, es de suma importancia determinar el dispositivo de administración de oxígeno (O2) que se utilizará. También es fundamental determinar qué dispositivo es mejor, en función del estado de la patología, y cuando es conveniente realizar una transición de un sistema de administración a otro. Este estudio, prospectivo, transversal y experimental, tiene como objetivo determinar los efectos de la transición desde el halo a la cánula nasal en pacientes lactantes menores con patología respiratoria, y medir estos efectos a través de cambios en parámetros funcionales. La hipótesis planteada fue que la transición de halo a cánula nasal no genera un deterioro en la condición del paciente con patología respiratoria al administrar una Fracción inspirada de O2 (FiO2) similar a la que se entrega por el sistema de alto flujo. Luego de realizar la transición, se redujo la cantidad de oxígeno administrado sin cambios significativos en la condición clínica de los pacientes, posiblemente debido al efecto CPAP que se produce al administrar oxígeno a través de una cánula nasal.

Das Ziel der vorliegenden Studie war die Erhebung der Ursachen für ein Therapieversagen der nCPAP-Therapie. Der Therapieerfolg bei Vorliegen eines obstruktiven Schlafapnoesyndroms wird im Wesentlichen durch den individuellen Leidensdruck und die Nebenwirkungen der nCPAP-Therapie beeinflusst. Patienten mit einer milderen Form des obstruktiven Schlafapnoesyndroms haben einen geringeren Nutzen von der nCPAP-Therapie als Patienten mit einem höheren Leidensdruck. Die Schwere der Krankheit zeigt sich z. B. in einem höheren RDI und einer schlechteren Sauerstoffsättigung vor Therapie. Es zeigte sich ein Trend, dass die Therapieversager bei besseren Ausgangswerten eine geringere Verbesserung unter der Therapie als die ausreichend Therapierten erfuhren. Die Therapieversager profitierten objektiv und subjektiv weniger von der Therapie, so dass sie weniger bereit waren, Nebenwirkungen zu akzeptieren und diese als störender bewerteten. Sie klagten vermehrt über lokale Probleme durch die Maske. Die maximal tolerierten Beatmungsdrücke lagen unter denen der ausreichend Therapierten. Die Verbesserung der Tagesmüdigkeit war bei den Therapieversagern signifikant schlechter. Sie erfuhren seltener eine Steige-rung der Lebensfreude und verzeichneten häufiger eine Zunahme sozialer Probleme. So empfinden sie die Therapie als störenden Einschnitt in ihre Le-bensführung und nicht als Hilfe. Durch diese Unzufriedenheit brechen sie die Therapie ab oder greifen zu Hilfsmitteln, wie z. B. der Rampenfunktion, einem Luftbefeuchter oder Alternativtherapien wie Nasenpflaster oder Protrusions-schienen. Letztendlich wurde diese Unzufriedenheit der Therapieversager in der signifi-kant schlechteren Bewertung von Maske, Gerät und nCPAP-Therapie insge-samt deutlich. Obwohl viele Autoren ähnlicher Studien davon ausgehen, dass keine höhe-ren Erfolgsquoten mehr zu erzielen sind, muss eine weitere Minimierung der Nebenwirkungen, wie z. B. durch eine intensive individuelle Betreuung mit Beobachtung und Behebung der Nebenwirkungen und Verwendung von Hilfsmitteln das Ziel sein. Davon profitieren sowohl die ausreichend Therapierten als auch die Therapieversager. / The aim of this study was to evaluate the reasons for incompliance with treatment of obstructive sleep apnea syndrome (OSAS) with nasal continuous airway pressure (nCPAP). The overall compliance was 65,4 %. The success of the nCPAP-Therapy in patients with OSAS is basically influenced by the individual level of psychological stain and the side effects of nCPAP-Therapy. Patients with less OSAS have less benefit from the nCPAP-Therapy than patients with a high level of psychological stain. The severity of OSAS was shown in a high respiratory disturbance index (RDI) or a low arterial oxygen saturation. The severe OSAS group experienced a larger improvement. The incompliant group had less objective and subjective benefit. They did not tolerate the side effects in the same way as the sever OSAS group did. They complained more about local disturbances from the nasal mask and had a significant less improvement of daytime sleepiness (p=0,004). The increasing quality of live, as the severe group showed, was not found in these patients. Incompliant patients are dissatisfied with the therapy. They make use of humidification or a steady increase of the ventilation pressure to make it more comfortable. However they do not reach the same level of satisfaction as the compliant group. Finally, the dissatisfaction of the incompliant group leads to a significant worse evaluation of the nasal mask (p=0,009), respirator (p=0,003) and the nCPAP-therapy all in all.

No description available.

Bakgrund: Continuous Positive Airway Pressure (CPAP) är en non-invasiv behandling som bland annat används vid respiratorisk svikt. CPAP-behandling utförs inte bara på intensivvårdskliniker, vilket ställer högre utbildningskrav på sjuksköterskor verksamma inom slutenvården. Otillräcklig kunskap bland personalen leder till minskad möjlighet att tillgodose patienternas behov. I dagens sjukvård där allt fler sjuka patienter vårdas utanför intensivvårdskliniker krävs det därför regelbunden utbildning för sjuksköterskor för att kunna upprätthålla en säker vård. Syfte: Att beskriva sjuksköterskors erfarenhet av att utföra CPAP-behandling på en medicinsk slutenvårdsavdelning. Design: Kvalitativ studie med induktiv ansats Metod: Femton sjuksköterskor intervjuades på två sjukhus i Mellansverige. Den transkriberade datan analyserades med hjälp av en konventionell innehållsanalys. Fynd: Huvudfyndet i denna studie visar att sjuksköterskans erfarenhet av CPAPbehandling kännetecknas av blandade känslor. Det framkommer att sjuksköterskans utförande av CPAP-behandling påverkas av såväl frustration och osäkerhet som trygghet och säkerhet vilket är länkat till erfarenheten. Trots dessa blandade känslor leder sjuksköterskan teamet med mål att skapa en säker vård för patienten. Konklusion: Det behövs en kontinuerlig utbildning kring CPAP-behandling och ett regelbundet användande för att sjuksköterskor ska känna sig säkra och främja patientsäkerheten. / Background: Continuous Positive Airway Pressure (CPAP) is a non-invasive treatment which is useful to treat respiratory failure. CPAP-treatment is not only performed at the intensive care units, and that leads to higher demands of education for nurses in clinical wards. Insufficient knowledge among the health care staff leads to reduced ability to satisfy the patient´s needs. In today’s health care with more complex patients in general wards is regular education important for nurses to maintain quality and safety. Aim: To describe nurses´ experience of performing CPAP-treatment in medical hospital care. Design: A qualitative study, inductive. Method: Fifteen nurses were interviewed in two hospitals in Sweden. The transcribed data where analysed with qualitative content analysis. Findings: The main finding where that nurses had both positive- and negative experience of CPAP-treatment. The study shows that nurses experience feelings such as frustration and insecurity as well as safety around CPAP-treatment. Despite the mixed feelings the nurse could be a team leader with focus on quality and safety. Conclusion: A regular education and regular use of CPAP-treatment is important so the nurses feels secure and to maintain the patient safety.

ABSTRACT Patients with respiratory failure secondary to acute asthma exacerbation (AAE) frequently present at emergency units. Some patients may develop respiratory muscle fatigue. Current guidelines for the treatment of an AAE center on pharmacological treatment and invasive mechanical ventilation. Noninvasive positive pressure ventilation (NPPV) has an established role in COPD exacerbations. The role it can play in an AAE remains unanswered although it is frequently used in the clinical setting. Aims: The present study proposed to investigate if the early use of NPPV in the forms of continuous positive airway pressure (CPAP) or bilevel positive pressure ventilation (BPPV) together with standard medical therapy in AAE can decrease time of response to therapy compared to standard medical therapy alone. We further tested the effect of BPPV against CPAP. Methods: Asthmatic patients who presented with a severe AAE (PEFR % predicted < 60 %) at the emergency unit were randomized to either standard medical therapy (ST), ST and CPAP or ST and BPPV. Thirty patients fulfilled the inclusion criteria for the study. Groups presented similar baseline characteristics. The mean age for the group was 42.1 ± 12.6 years. Mean baseline PEFR % predicted was 35.2 ± 10.7 % (ST), 30.5 ± 11.7 % (ST + CPAP) and 33.5 ±13.8 % (ST + BPPV). Results: Hourly improvement (Δ) in respiratory rate and sensation of breathlessness was significantly better in the BPPV intervention group. Improvement (Δ) from baseline to end of treatment in respiratory rate and sensation of breathlessness was significant for both CPAP and BPPV (p = 0.0463; p = 0.0132 respectively) compared to ST alone. Lung function was significantly improved in the CPAP intervention group hourly and from baseline to end of treatment (p = 0.0403 for PEFR and p = 0.0293 for PEFR % predicted) compared to ST + BPPV and ST alone. The mean shift (Δ) in PEFR from baseline to 3 hours of treatment was 67.4, 123.5 and 86.8 L/min (p = 0.0445) for ST, ST + CPAP and ST + BPPV respectively. This corresponded to a 38.1, 80.8 and 51.7 % improvement in lung function respectively. Discussion: The effect of BPPV on the reduction of respiratory rate and sensation of breathlessness could be related to the inspiratory assistance provided by BPPV. The significant improvement in lung function in the CPAP group could be related to its intrinsic effect on the airway smooth muscle and / or on the airway smooth muscle load. Conclusion: The present results suggest that adding NPPV to standard treatment for an AAE not only improves clinical signs faster but also improves lung function faster. CPAP seems to have an intrinsic effect on the airway smooth muscle so rendering it more effective in ameliorating lung function.

CPAP is the most common treatment for moderate to severe sleep apnea in adults. Despite its efficacy, patients’ safety, comfort and compliance are issues to be considered and improved in CPAP design. The issues include condensation, carbon dioxide in inhaled air, humidity and temperature of inhaled air. When a CPAP user breaths deeply, there will be some air not fully expelled and may be driven back into the heated air delivery tube (HADT). An interest has existed in what impacts this so called reverse flow may bring about to the CPAP use. The main objectives of this research are to quantify the reverse flow and its influence on carbon dioxide re-breathing, delivered humidity to the patient and condensation in the HADT. Within this thesis, two computer models of the CPAP system have been constructed on Simulink™ in the Matlab™ environment. One is about the CPAP fluid dynamic performance and carbon dioxide re-breathing and the other is on thermodynamic performance. The models can predict the dynamic behaviour of the CPAP machine. They are able to mimic the breath induced airflow fluctuation, and flow direction changes over wide real working ranges of ambient conditions, settings and coefficients. These models can be used for future analysis, development, improvement and design of the machine. The fluid dynamic and thermodynamic models were experimentally validated and they have proved to be valuable tool in the work. The main conclusions drawn from this study are: • Reverse flow increases when breaths load increases and pressure setting decreases. • Reverse flow does not definitely add exhaled air to the next inhalation unless the reverse flow is relatively too much. • Mask capacity does not influence the reverse flow. • The exhaled air re-breathed is mainly due to that stays in the mask, therefore larger mask capacity increases the exhaled air re-breath and the percentage of exhaled air in next inhalation drops when the breath load increases. • Deep breathing does not significantly change the total evaporation in chamber. • When deep breathing induced reverse flow occurs, condensation occurs or worsens in the HADT near the mask. This happens only when the humidity of the airflow from the CPAP is much lower than that of the exhaled air and the tube wall temperature is low enough for condensation to occur. • The deep breathing and reverse flow do not significantly influence the average inhaled air temperature. • The overall specific humidity in inhaled air is lower under deep breathing. • Mask capacity does not influence the thermal conditions in the HADT and the inhaled air specific humidity. Also the mask capacity does not significantly influences the inhaled air temperature.

Background: The use of pure oxygen during preoxygenation and induction of general anaesthesia is a major cause of atelectasis. The interaction between reduced lung volume, resulting in airway closure, and varying inspiratory fractions of oxygen (FIO2) in determining the risk of developing atelectasis is still obscure. Methods: In this thesis, computed tomography (in studies I and II during anaesthesia, in studies III and IV postoperatively) was used to investigate the area of atelectasis in relation to FIO2 and varying levels of continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP). Study I investigated the short-term influence of reducing FIO2 during preoxygenation and induction of general anaesthesia, and the time to hypoxia during apnoea. Study II focused on the long-term effect of an FIO2 of 0.8 for preoxygenation. Study III applied CPAP/PEEP with an FIO2 of 1.0 or 0.8 for pre- and postoxygenation until extubation. After extubation, CPAP with an FIO2 of 0.3 was applied before the end of mask ventilation. Study IV compared two groups given CPAP/PEEP during anaesthesia and an FIO2 of 1.0 or 0.3 during postoxygenation, but without CPAP after extubation. Results: Study I showed a reduction in atelectasis with an FIO2 of 0.8 or 0.6, compared with 1.0, but the time to hypoxia decreased. In study II, atelectasis evolved gradually after preoxygenation. In study III, atelectasis was reduced with an FIO2 of 1.0 and CPAP/PEEP compared with an FIO2 of 1.0 without CPAP/PEEP. The intervention failed in the group given an FIO2 of 0.8, this group had more smokers. Atelectasis and age were correlated. In study IV, no difference was found between the groups. Post hoc analysis showed that smoking and ASA class increased the risk for atelectasis. Conclusion, the effect of reducing FIO2 during preoxygenation to prevent atelectasis might be short-lived. A lower FIO2 shortened the time to the appearance of hypoxia. Increasing lung volume by using CPAP/PEEP also decreased the risk of atelectasis, but the method might fail; for example in patients who are heavy smokers. In older patients care must be taken to reduce a high FIO2 before ending CPAP.

CPAP is the most common treatment for moderate to severe sleep apnea in adults. Despite its efficacy, patients’ safety, comfort and compliance are issues to be considered and improved in CPAP design. The issues include condensation, carbon dioxide in inhaled air, humidity and temperature of inhaled air. When a CPAP user breaths deeply, there will be some air not fully expelled and may be driven back into the heated air delivery tube (HADT). An interest has existed in what impacts this so called reverse flow may bring about to the CPAP use. The main objectives of this research are to quantify the reverse flow and its influence on carbon dioxide re-breathing, delivered humidity to the patient and condensation in the HADT. Within this thesis, two computer models of the CPAP system have been constructed on Simulink™ in the Matlab™ environment. One is about the CPAP fluid dynamic performance and carbon dioxide re-breathing and the other is on thermodynamic performance. The models can predict the dynamic behaviour of the CPAP machine. They are able to mimic the breath induced airflow fluctuation, and flow direction changes over wide real working ranges of ambient conditions, settings and coefficients. These models can be used for future analysis, development, improvement and design of the machine. The fluid dynamic and thermodynamic models were experimentally validated and they have proved to be valuable tool in the work. The main conclusions drawn from this study are: • Reverse flow increases when breaths load increases and pressure setting decreases. • Reverse flow does not definitely add exhaled air to the next inhalation unless the reverse flow is relatively too much. • Mask capacity does not influence the reverse flow. • The exhaled air re-breathed is mainly due to that stays in the mask, therefore larger mask capacity increases the exhaled air re-breath and the percentage of exhaled air in next inhalation drops when the breath load increases. • Deep breathing does not significantly change the total evaporation in chamber. • When deep breathing induced reverse flow occurs, condensation occurs or worsens in the HADT near the mask. This happens only when the humidity of the airflow from the CPAP is much lower than that of the exhaled air and the tube wall temperature is low enough for condensation to occur. • The deep breathing and reverse flow do not significantly influence the average inhaled air temperature. • The overall specific humidity in inhaled air is lower under deep breathing. • Mask capacity does not influence the thermal conditions in the HADT and the inhaled air specific humidity. Also the mask capacity does not significantly influences the inhaled air temperature.

Obstructive Sleep Apnoea (OSA) is a common sleep disorder for which Continuous Positive Airway Pressure Therapy (CPAP) is the standard treatment. Despite the effectiveness of this treatment, CPAP acceptance and adherence rates are generally suboptimal. The aim of this dissertation was to validate a new, inclusive Health Belief Model (HBM) for the prediction of CPAP acceptance and adherence. It was argued that the HBM could predict future adherence even before patients have experienced the treatment, thus providing valid intervention targets to improve CPAP acceptance as well as adherence. Modifiable constructs that are proximal to the decision making process for OSA patients, were identified from the literature (Chapter 1). Along with the generic HBM constructs of perceived benefits, barriers, severity, risk, self-efficacy and cues to action, additional predictors were incorporated in the OSA specific model. These included biomedical indices of objective disease severity and measures of psychological distress. Study One assessed 77 newly diagnosed, CPAP naïve OSA patients on a questionnaire battery at baseline (prior to CPAP treatment). The questionnaire included HBM measures which were available in the literature; benefits perception, self-efficacy, functional severity, and perceived risk of negative health outcomes. CPAP adherence was assessed at four month follow-up. This initial investigation found that health beliefs alone explained 21.8% of the variance in CPAP adherence, whilst health beliefs and biomedical indices together explained 31.8% of the variance in CPAP adherence. The greatest proportion of CPAP adherence was explained by higher benefits perception, greater severity and lower risk perception. Study Two reported on the development and validation of a measure of the barriers construct (as no measure of this existed). A sample of 113 newly diagnosed, CPAP naïve OSA patients completed a questionnaire containing potential items of the Barriers to CPAP Use questionnaire (BACQ) at baseline. Exploratory Factor Analysis (EFA) showed a two factor structure of the eight-item BACQ, with ‘Barriers’ and ‘Cost of Treatment’ subscales identified. The BACQ had an internal consistency of 0.82 and readability at a fifth grade reading level. The aim of Study Three was to develop a valid and reliable measure of the cues to action construct. A sample of 63 OSA patients (from the total 113 patients assessed in Study Two) completed a questionnaire containing potential items of the Cues to CPAP Use questionnaire (CCUQ) one month after being prescribed CPAP. EFA showed a three factor structure of the nine-item CCUQ, with ‘Health Cues’, ‘Partner Cues’ and ‘Health Professional Cues’ subscales identified. The CCUQ demonstrated modest internal consistency and split-half reliability, and readability at a seventh grade level. Study Four incorporated three sub-studies which assessed the accuracy of the fully articulated HBM (including the BACQ and CCUQ measures) in predicting CPAP adherence at two months. Study Four A reported on the same sample of 113 CPAP naïve patients (from Study Two). Structural Equation Modelling demonstrated the complex relationship between health beliefs, psychological variables, and biomedical indices in CPAP adherence. The full HBM predicted 24% of the variance in CPAP adherence at two months. Adherence was directly predicted by lower perception of treatment cost as a barrier to CPAP use, higher self-efficacy, and higher BMI. Study Four B reported on 63 patients who completed HBM questionnaires at one month. The model predicted 42% of the variance in CPAP adherence at two months. Adherence was directly predicted by greater benefits perception, greater psychological distress, and lower perception of the Health Professional as the important cue to action. Study Four C investigated changes in health beliefs between baseline and one month. By one month patients generally reported more positive attitudes to CPAP, and better overall functioning. These changes did not correlate with CPAP adherence. Those who used CPAP more than four hours per night demonstrated greater improvement in functional severity and in anxiety score. Study Five used the findings of the HBM studies in developing a theory-driven Motivational Intervention (MI) to target specific beliefs associated with poor adherence. 101 newly diagnosed, CPAP naïve OSA patients were randomly assigned to nurse-led MI + Standard Care (50 participants), or to Standard Care only (51 participants). MI patients received two sessions before starting CPAP, and one session one month after CPAP prescription. By three months, the MI group used CPAP 50% more of the time, and were six times less likely to reject CPAP. The MI group demonstrated greater self-efficacy and a lower perception of barriers to CPAP use. The findings were largely supportive of the HBM theory of CPAP adherence. The substantive findings of this dissertation were that patients do need relevant, timely and targeted support in order for them to effectively commence on CPAP and then continue to adequately adhere. At a minimum, psychological intervention, such as a Motivational Intervention, is likely to be needed for the subset of patients who report beliefs associated with poor adherence at pre-treatment.