Extended evaluation of the efficacy of a proactive forced oscillation technique-based auto-CPAP algorithm.

PURPOSE: Previous studies revealed substantially varying therapy efficacy of automatic continuous positive airway pressure (APAP) devices in the treatment of obstructive sleep apnea (OSA). We evaluated the efficacy of a new APAP device using the forced oscillation technique (FOT) to evaluate upper airway obstruction during apneas and flow contour analyses during hypopneas. METHODS: Forty-six initially diagnosed OSA patients were included and the pressure range was set from 5 to 20 hPa. Therapy efficacy was assessed based on the reduction of apnea-hypopnea index (AHI), improvement of objective sleep quality parameters, and the appropriateness of the device's pressure regulation. RESULTS: AHI and arousal index significantly decreased during APAP therapy (median [interquartile range]: AHI 36 [23-55] vs. 2 [1-6]/h, arousal index 30 [22-45] vs. 15 [10-19]/h, both p < 0.001). The amount of slow wave sleep (SWS) and rapid-eye-movement (REM) sleep significantly increased (SWS 20 [14-29] vs. 29 [19-34]%, REM 16 [11-21] vs. 24 [14-30]%, both p < 0.01). Most residual respiratory events during therapy were of central etiology and attributable to five patients, who presented with treatment-emergent central sleep apnea. The device's pressure regulation abolished most obstructive respiratory events (n = 6.7 residual obstructive events per patient). Of central respiratory events, 534/646 (83%) did not lead to pressure increases. CONCLUSION: This pilot study provides a proof of concept that the APAP device combining FOT and evaluation of flow contour allows for the suppression of obstructive events without relevant false reactions.

[Expert Meeting on COPD: Personalized Treatment of COPD - Wishful Thinking or Reality?] / Expertentreffen COPD: Personalisierte Therapie der COPD ­ Wunsch oder Wirklichkeit?

Chronic obstructive pulmonary disease (COPD) is considered to be a complex and heterogeneous disease comprising multiple components. Its clinical presentation, pattern of functional disturbance, disease presentation and pathology varies tremendously between individuals despite the common feature of incompletely reversible airflow obstruction. It is therefore widely accepted that COPD is characterized by discriminable phenotypes that represent specific patterns of these disease features. COPD phenotypes are believed to correlate with outcome parameters such as severity of symptoms, exacerbations, functional loss or death and to require different treatment algorithms.This survey is the result of presentations that were given during an expert conference. It highlights the significance of major comorbidities, genetic, morphologic and inflammatory COPD-phenotypes and their impact on disease progression and treatment modalities.

["Nutritional risk screening 2002"--in clinical pneumology]. / "Nutritional Risk Screening 2002" in der Hand des Pneumologen.

Malnutrition is a frequent problem for hospitalized patients. It is a relevant risk factor for morbidity and mortality. The aim of this study was to detect undernutrition and the risk of malnutrition (RM) in patients admitted to a university-affiliated respiratory care clinic. Undernutrition was assessed by body mass index (BMI<18.5 kg/m²) and RM by using the "Nutritional Risk Screening 2002" (NRS 2002) in 705 consecutive patients (BMI: measured in 689 patients/NRS: 680 patients assessed). Data was analysed with regard to age, sex, length of hospital stay as well as underlying pneumological disorders. In 14.3% of 680 patients, RM was detected by NRS. In 2.5% out of 689 patients, undernutrition was identified by BMI. In patients older than 65 years (n=365), these numbers were 19.6% (NRS) and 1.5% (BMI<18.5 kg/m²). Age was a significant risk factor for RM (OR 1.054 per year). Gender, however, was not associated with undernutrition or RM. In a sub-analysis, RM was more frequent in patients with pneumonia and chronic obstructive lung disease (23% and 16%, respectively). Patients with cancer were more frequently at RM as compared to patients with sleep-disordered breathing (OR: 2.33 in cancer, OR: 0.04 in sleep-disordered breathing). RM was associated with a significant increase in length of hospital stay (10.2 ± 9.5 vs. 5.4 ± 6.0 days). Besides the BMI, the NRS provides a valid tool for screening patients at RM.

[Consensus paper on the diagnosis and treatment of sleep disordered breathing]. / Konsensuspapier zur Diagnostik und Therapie schlafbezogener Atmungsstörungen bei Erwachsenen.

Diagnosis and treatment of sleep disordered breathing (SDB) undergo substantial changes, both in terms of increasing scientific knowledge and also in terms of patient provision and socio-economic aspects. Increasing evidence shows the relevance of SDB on morbidity and mortality of affected patients. The precise differentiation of different phenotypes of SDBs has improved substantially in recent years. These proceedings influence the approach to the patients suspected of suffering from SDB. The scientific advances on the one hand are facing intentions to simplify diagnostical processes and treatment initiation and intentions to translate duties of physicians to non-medical personnel on the other hand. This consensus paper presents the principals of diagnosis, treatment initiation and provision, including the role of different participants of the healthcare system, and compares different treatment options. Major aspects include the differentiation of the diagnostical process in screening, affirmation of diagnosis and differential diagnosis. In addition, it focusses on the relevance of the pretest probability and describes a therapeutical algorithm.

Medication-Induced Central Sleep Apnea: A Unifying Concept.

Medication-induced central sleep apnea (CSA) is one of the 8 categories of causes of CSA but in the absence of awareness and careful history may be misclassified as primary CSA. While opioids are a well-known cause of respiratory depression and CSA, non-opioids medications including sodium oxybate, baclofen, valproic acid, gabapentin and ticagrelor are less well-recognized. Opioids-induced respiratory depression and CSA are mediated primarily by µ-opioid receptors, which are abundant in the pontomedullary centers involved in breathing. The non-opioid medications, sodium oxybate, baclofen, valproic acid and gabapentin, act upon brainstem gamma-aminobutyric acid (GABA) receptors, which co-colonize with µ-opioid receptors and mediate CSA. The pattern of ataxic breathing associated with these medications is like that induced by opioids on polysomnogram. Finally, ticagrelor also causes periodic breathing and CSA by increasing central chemosensitivity and ventilatory response to carbon dioxide. Given the potential consequences of CSA and the association between some of these medications with mortality, it is critical to recognize these adverse drug reactions, particularly because discontinuation of the offending agents has been shown to eliminate CSA.

Feasibility of noninvasive single-channel automated differentiation of obstructive and central hypopneas with nasal airflow.

BACKGROUND: The identification of obstructive and central hypopneas is considered challenging in clinical practice. Presently, obstructive and central hypopneas are usually not differentiated or scores lack reliability due to the technical limitations of standard polysomnography. Esophageal pressure measurement is the gold-standard for identifying these events but its invasiveness deters its usage in daily practice. OBJECTIVES: To determine the feasibility and efficacy of an automatic noninvasive analysis method for the differentiation of obstructive and central hypopneas based solely on a single-channel nasal airflow signal. The obtained results are compared with gold-standard esophageal pressure scores. METHODS: A total of 41 patients underwent full night polysomnography with systematic esophageal pressure recording. Two experts in sleep medicine independently differentiated hypopneas with the gold-standard esophageal pressure signal. Features were automatically extracted from the nasal airflow signal of each annotated hypopnea to train and test the automatic analysis method. Interscorer agreement between automatic and visual scorers was measured with Cohen's kappa statistic (ĸ). RESULTS: A total of 1,237 hypopneas were visually differentiated. The automatic analysis achieved an interscorer agreement of ĸ = 0.37 and an accuracy of 69% for scorer A, ĸ = 0.40 and 70% for scorer B and ĸ = 0.41 and 71% for the agreed scores of scorers A and B. CONCLUSIONS: The promising results obtained in this pilot study demonstrate the feasibility of noninvasive single-channel hypopnea differentiation. Further development of this method may help improving initial diagnosis with home screening devices and offering a means of therapy selection and/or control.

[Non-CPAP therapies in obstructive sleep apnoea: an overview]. / Die Nicht-CPAP-Therapie des obstruktiven Schlafapnoe-Syndroms: ein Überblick.

Optimal treatment of the obstructive sleep apnoea syndrome (OSAS) requires an individually designed and interdisciplinary approach. Continuous positive airway pressure (CPAP) is accepted as the first line therapy for patients with OSAS. However, non-CPAP therapies may be indicated as supportive therapeutical approach in CPAP failure or as an alternative approach in CPAP intolerance. Overall, the level of evidence for the majority of non-CPAP therapies is low. Mandibular advancement devices as a medical non-CPAP treatment have proven to reduce respiratory disturbances to a level which may be sufficient in mild to moderate sleep apnoea. Apnoea triggered neurostimulation of upper airway muscles is an innovative approach that has shown promising results in preclinical studies. Surgical treatment has previously been performed as single level surgery of the nasal, the oropharyngeal or hypopharyngeal level. However, only tonsillectomy in the presence of tonsillar hypertrophy and maxillomandibular advancement are recommended in carefully selected cases. Due to low success rates for single level surgery, multilevel surgery has been proposed as the surgical approach for the future.

Non-CPAP therapies in obstructive sleep apnoea.

In view of the high prevalence and the relevant impairment of patients with obstructive sleep apnoea syndrome (OSAS) lots of methods are offered which promise definitive cures for or relevant improvement of OSAS. This report summarises the efficacy of alternative treatment options in OSAS. An interdisciplinary European Respiratory Society task force evaluated the scientific literature according to the standards of evidence-based medicine. Evidence supports the use of mandibular advancement devices in mild to moderate OSAS. Maxillomandibular osteotomy seems to be as efficient as continuous positive airway pressure (CPAP) in patients who refuse conservative treatment. Distraction osteogenesis is usefully applied in congenital micrognathia or midface hypoplasia. There is a trend towards improvment after weight reduction. Positional therapy is clearly inferior to CPAP and long-term compliance is poor. Drugs, nasal dilators and apnoea triggered muscle stimulation cannot be recommended as effective treatments of OSAS at the moment. Nasal surgery, radiofrequency tonsil reduction, tongue base surgery, uvulopalatal flap, laser midline glossectomy, tongue suspension and genioglossus advancement cannot be recommended as single interventions. Uvulopalatopharyngoplasty, pillar implants and hyoid suspension should only be considered in selected patients and potential benefits should be weighed against the risk of long-term side-effects. Multilevel surgery is only a salvage procedure for OSA patients.

["Common variable immunodeficiency"--first diagnosis of a rare pneumological disease]. / "Common variable Immunodeficiency" - Eine seltene pneumologische Differenzialdiagnose.

Common variable immunodeficiency (CVID) is generally used synonymously with "late onset hypogammaglobulinaemia", which is already indicative of the central pathological finding. Patients with CVID produce specifically less immunoglobulins, thus reducing their immunological competence. Our patient showed the typical medical history of undetected CVID. After excluding differential pneumological diseases, the suspected diagnosis was confirmed. This case report examines the complex of CVID as a cause for recurrent pneumological infections. It is the most prevalent form of severe antibody deficiency in children and adults and occurs with a probability of 1:25,000 in the population.

[Recommendations for invasive home mechanical ventilation]. / Durchführungsempfehlungen zur invasiven außerklinischen Beatmung.

Due to chronic respiratory failure, a proportion of patients require long-term home ventilation therapy. The treating doctors, nurses and therapists, as well as employees of the health insurance provider, all require specialized knowledge in order to establish and monitor home ventilation. The following document represents a consensus formed by the participating specialist societies, the health insurers and their medical advisory services. The recommendations for accomplishing home mechanical ventilation are based on the "S2 Guidelines for Non-Invasive and Invasive Mechanical Ventilation for Treatment of Chronic Respiratory Failure", and provide advice about the necessary qualifications of medical and nursing practitioners working in specialised ventilation centres or in the home setting. Management of transfer, which comprises the medical, technical and organisational requirements for releasing the patient from hospital care, is of paramount importance. In outpatient care, the requirements for the recruitment of resources, monitoring of procedures, adjustment of ventilation, and frequency of check-ups are each addressed. The recommendations are supplemented by appendices which include patient transfer forms, checklists for the supply of basic resources for home ventilation, as well as a template for the letter of discharge from hospital.

[Pathophysiology of the obesity hypoventilation syndrome]. / Obesitas-Hypoventilationssyndrom--Pathophysiologische Aspekte.

The obesity hypoventilation syndrome (OHS) is defined by extreme overweight (BMI 30 kg/m2), daytime hypoventilation (PaCO2 > 45 mm Hg, the absence of other known causes of hypoventilation) and sleep-related breathing disorders. Obesity impairs breathing due to a restrictive ventilatory disorder, reduction of the capacity of respiratory muscles and diminishment of the ventilatory response. The restriction cannot serve as the only explanation of OHS because body weight or compliance on the one hand and hypoventilation on the other hand only correlate weakly. Obesity increases the work of breathing by greater body mass with its increased oxygen demand, impaired diaphragmatic mobility, upper airway obstruction, and oxygen desaturation which result in an inadequacy of oxygen demand and supply. The adjustment of the chemoreceptors can avoid the overload on the capacity of the respiratory muscles, at least in a number of patients or in the course of the disease. This disproportion results in hypercapnia. Furthermore, the level of leptin is an important factor in the pathophysiology of OHS. The blood level of leptin correlates with the body fat mass in humans. However, there seems to be a relative leptin deficiency in the brain in overweight humans. Therefore, in contrast to animals, leptin cannot sufficiently increase ventilation in man to avoid hypercapnia.

Self-adjusting nasal continuous positive airway pressure therapy based on measurement of impedance: A comparison of two different maximum pressure levels.

STUDY OBJECTIVE: Automatic titration using the forced oscillation technique (FOT) has recently been developed for the treatment of obstructive sleep apnea syndrome (OSAS). So far, it is not known if therapy with automatic nasal continuous positive airway pressure (nCPAP) using a preset upper pressure limitation or a free range (which might lead to higher mean pressure) is preferable with regard to obstructive events, sleep stages, and pressure characteristics. DESIGN: After diagnostic polysomnography, patients were randomly assigned to two settings with the self-adjusting nCPAP (APAP) device based on the FOT. In mode 1, the pressure variation ranged from 4 to 15.5 cm H(2)O, and in mode 2, the pressure variation ranged from 4 cm H(2)O to an individual upper pressure limit. PATIENTS: Eleven men, aged 53.0 +/- 6.8 years with a body mass index of 32.4 +/- 5.1 kg/m(2) and an apnea-hypopnea index (AHI) of 31.6 +/- 26.6/h. MEASUREMENTS AND RESULTS: Manually titrated pressure was at 9.3 +/- 2.1 cm H(2)O, the mean pressure in mode 1 was 5.4 +/- 1.0 cm H(2)O (p < 0.01), and the mean pressure in mode 2 was 5.1 +/- 0.7 cm H(2)O (p < 0.01). A reduction of respiratory events (baseline AHI, 31.6 +/- 26.6/h; AHI in mode 1, 3.4 +/- 4.5; AHI in mode 2, 5.0 +/- 7.2; each with p < 0.001) and an increase in the "rapid eye movement" stage of sleep (baseline, 13.0 +/- 5.5%; mode 1, 22.0 +/- 7.7 [p < 0. 05]; mode 2, 23.0 +/- 7.9 [p < 0.01]) were achieved. In mode 1, the mean pressure was below the manual pressure 91.7 +/- 9.3% of the time, and in mode 2, the mean pressure was below the manual pressure 90.4 +/- 6.3% of the time. The manual pressure was exceeded by 5.5 +/- 7.4% (mode 1) and by 5.2 +/- 3.1% (mode 2). CONCLUSION: We conclude that nCPAP therapy based on the FOT permits the adequate treatment of OSAS with significantly lower pressure than manually titrated nCPAP therapy does. A presetting of an upper pressure limit has no advantage compared to free range.

[Aspirin-exacerbated respiratory disease]. / Das Analgetika-Asthma-Syndrom.

Aspirin sensitivity is an important underlying disease in patients with nasal polyps, intrinsic asthma or urticaria. The terms "Aspirin- (or analgetics-) induced asthma" or "Aspirin-exacerbated respiratory disease" (AERD) describe the syndrome of chronic rhinosinusititis, polyposis nasi, asthma and acute reaction after ingestion of non-steroid antiinflammatory drugs (NSAID). The disease affects mainly women in the third decade or older. Nasal symptoms often appear many years previous to asthma and acute intolerance reactions. Nasal polyps not rarely require surgical interventions. However, polyps often relapse after weeks or few months after resection. The intrinsic asthma is difficult to control and patients often require treatment with oral steroids. The disease is not caused by the ingestion of NSAID, the sensitivity represents a phenomenon of the underlying metabolic disorder. Aspirin sensitivity is not an allergic disease based on IgE-mediated reactions. In contrast it is due to a metabolic overexpression of cysteinyl leucotrienes. Thus, skin tests and specific antibodies in the blood are always negative. Recent studies indicate that NSAID sensitivity may be proven and differentiated by sophisticated in vitro tests. However, nasal, bronchial, and oral provocation testing remains the standard of diagnosis. Aspirin desensitization is the most relevant therapeutical approach which improves nasal symptoms in the majority of patients and may stabilize intrinsic asthma.

[Sleep medicine in pneumology]. / Pneumologische Schlafmedizin.

Diagnosis and treatment of sleep related breathing disorders have become an essential challenge of internal medicine. They are highly important clinically because of the impairment of daytime performance, attention and concentration with elevated risk of accidents in workplace and traffic and because of their consequences on cardiovascular and metabolic disorders. The obstructive sleep apnoea syndrome (OSAS) has proven to be one of the most important risk factors for arteriosclerosis, especially in the cerebral vessels. OSAS induces arterial hypertention and increases mortality due to cardiovascular diseases. Sleep related breathing disorders induce hyperglycemia and dyslipidemia. OSAS and the metabolic syndrome increase the cardiovascular risk additively. Moreover, cardiac disorders, such as arterial hypertention, heart failure and arterial fibrillation, can induce central breathing disturbances. This impairs the prognosis of affected patients substantially. Atypical symptoms of obstructive sleep apnoea (daytime sleepiness, snoring, witnessed apnoea) are often absent in these patients. In contrast patients often suffer from fatigue, reduced daytime performance, and depression which is a major challenge to diagnosis. This review presents new data on these aspects. Moreover, the association of sleep apnoea and pulmonary embolism and the question of optimal sleep duration are addressed.

[Automatic positive airway pressure in titration and treatment of the obstructive sleep apnea syndrome]. / Automatische kontinuierliche Positivdrucktherapie (Auto CPAP) in Titration und Behandlung des obstruktiven Schlafapnoesyndroms.

Although continuous airway pressure therapy (CPAP) represents the standard treatment for obstructive sleep apnea syndrome (OSAS) auto-adjusting CPAP (APAP) devices were developed which adapt the treatment pressure to the actual requirement of the patients. The aim of automatic CPAP therapy is to improve the patients' acceptance of positive pressure treatment. The devices react to respiratory flow, flattening of the inspiratory flow contour, snoring, generator speed or the upper airway impedance. In recent years several studies showed that auto CPAP effectively treats respiratory disturbances, improves sleep profile and the self-assessment of the patients equally as good as the gold standard constant CPAP. Moreover, APAP reduces the treatment pressure substantially. Although an improvement of the patient's compliance has not consistently been proven, most patients prefer APAP versus constant CPAP. APAP devices use different algorithms depending on the primary purpose of the application. Therefore, a clear distinction between automatic titration and treatment is of major relevance. While titration devices aim at the finding of one single pressure which is fixed to a constant CPAP device, automatic treatment means the chronic use of APAP at home for optimal adaptation of the treatment pressure to the actual requirements of the patient. A high constant CPAP level, huge pressure variability, insufficient compliance with constant CPAP may be indications for APAP treatment. The main reason for automatic titration is the standardisation of the initiation process.

A test for the determination of sustained attention in patients with obstructive sleep apnea syndrome.

BACKGROUND AND OBJECTIVES: To investigate the parameter daytime sleepiness in patients with the sleep apnea syndrome (SAS), a test for measurement of sustained attention was developed. The present studies were performed on volunteers undergoing preemployment medical examinations and SAS patients to determine the extent to which test results are in agreement with the symptoms of SAS and traffic accident reports, and also with daytime sleepiness, and whether learning or therapeutic effects can be seen with repeated tests prior to and following treatment with nasal continuous positive airway pressure (nCPAP). PARTICIPANTS: 125 healthy volunteers, and two groups of 28 SAS patients each. DESIGN: Study A: The volunteers underwent a single attention test and completed a questionnaire concerned with traffic accidents and symptoms of sleep-related breathing disorders. Study B: SAS patients underwent two attention tests before treatment. Study C: SAS patients underwent one attention test before and one after nCPAP therapy. RESULTS: Study A: The error rate in volunteers without symptoms of sleep-related breathing disorders (51 persons) was 4.7 +/- 4.3% (number of errors 14.1 +/- 12.9), 95% CI: 1.2 (number of errors 3.6). No dependence of the error rate on age, BMI or sex was found. In persons with a history of apneic events (n = 10), the error rate was 10.6 +/- 10.0% (number of errors 31.8 +/- 30), in those with more than two accidents during the last 5 years (n = 4), it was increased to 15.3 +/- 9.7% (number of errors 45.9 +/- 29.1). Study B: Among SAS patients, no significant learning effect was seen, and prolongation of the test duration beyond 30 min had no effect on the test results. Study C: The error rate improved significantly with nCPAP [10.6 +/- 13.5 vs. 6.4 +/- 8.9% (number of errors 31.8 +/- 40. 5 vs. 19.2 +/- 26.7), p < 0.001]. CONCLUSIONS: The attention test can be helpful for the measurement of daytime sleepiness, and CPAP therapy can improve test performance.

[Self-assessment by patients of impairment caused by obstructive sleep apnea syndrome]. / Beeinträchtigungen durch das obstruktive Schlafapnoe-Syndrom in der Selbsteinschätzung der Patienten.

BACKGROUND AND OBJECTIVE: The compliance of the nasal continuous positive airway pressure treatment (nCPAP) of the obstructive sleep apnea syndrome (OSAS) depends on the patients' awareness and improvement of the symptoms. Therefore, we studied the relevance of OSAS in different aspects of the quality of life and important aspects of daily life (driving performance, working place). METHODS: 352 patients with OSAS filled in a questionnaire of sociodemographic data and impairment of quality of life. The relevance of OSAS was evaluated with polysomnography and parameters of daytime sleepiness. RESULTS: The number of women was lower than expected from community related data. The apnea/hypopnea index was 29.9 +/- 23.4/h at baseline measurement and was reduced to 8.8 +/- 9.6/h with nCPAP (p < 0.001). The arousal index (baseline 26.6 +/- 15.3/h) fell with treatment significantly (17.7 +/- 9.2 Arousals/h, p < 0.001). The error rate in the driving simulator test was 7.8 +/- 8.9% (normal value 5.75 +/- 1.4). It was normalised with nCPAP (5.8 +/- 9.5, p < 0.001). 42.3% of patients reported about sleep apnea related symptoms for more than five years before diagnosis. The patients rated their physical fitness on a scale (0 to 6) at 2.9 +/- 1.3. It increased significantly with treatment to 3.4 +/- 1.3 an (p < 0.001). The mental activity improved significantly, too. The daytime sleepiness improved from 3.4 +/- 1.5 to 3.1 +/- 1.5 (p < 0.001). 32.3% of the patients reported that they fell asleep while steering at least once in the last month, 13.0% reported about more than five episodes/month. 5.3% of the patients thought their job in danger because of OSAS. 65.1% felt their performance in job to be impaired. CONCLUSION: OSAS impairs patients in different aspects of daily life, especially in the working place. The latency between the onset of symptoms and diagnosis is longer than expected. NCPAP treatment improves the symptoms of OSAS significantly both in criteria of polysomnography and self-assessment of the patients.

Autoadjusting CPAP therapy based on impedance efficacy, compliance and acceptance.

Constant continuous positive airway pressure (CPAP) is the treatment of choice for the obstructive sleep apnea syndrome (OSAS). To enable the pressure to be matched more accurately to actual requirements, and thus increase patient acceptance, an autoadjusting device based on the measurement of upper airway impedance was developed (APAP(FOT)). We investigated the efficacy and compliance in continuous use at home. Fifty-two patients were treated (randomized crossover) with CPAP and APAP(FOT) for 6 wk each. Respiratory disturbances, sleep profile, and arousals improved significantly with both modes (AHI: baseline, 35.1 +/- 26/h; APAP(FOT), 5.0 +/- 5.2; CPAP, 4.3 +/- 6.3; p < 0.001 baseline versus each mode). The mean pressure with APAP(FOT) was significantly reduced as compared with CPAP (CPAP, 7.8 +/- 1.5 cm H2O; APAP(FOT), 5.7 +/- 1.8 cm H2O; p < 0.001). Under APAP(FOT) the pressure was lower than that under CPAP for 81.5 +/- 21% of the time. Although overall use did not differ, 75% of the patients preferred APAP(FOT) for home treatment. We conclude that APAP(FOT) is as efficacious as constant CPAP in the treatment of OSAS. The treatment pressure can be reduced significantly, and sleep microstructure improved with APAP(FOT). These might be the reasons for patient preference of automatic therapy.