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Background: Selfadjusting CPAP therapy is mostly employed if constant CPAP does not sufficiently suppress respiratory disturbances or is not accepted by the patient. The number of respiratory disturbances and thus the pressure need varies with sleep stages and body position during sleep. However, the analysis of the pressure profile during automatic CPAP therapy indicates a relevant variability of treatment pressure which is independent of the above mentioned criteria. Therefore, we aimed to quantify the pressure variability and its significance in patients with obstructive sleep apnea syndrome (OSAS)., Methods: We analysed the pressure profile during a six-week treatment period with selfadjusting CPAP therapy based on the measurement of the impedance (APAP FOT ). The variability index (VI) was calculated from the deviations of the treatment pressure from the mean pressure. The variability was considered to be low and clinically irrelevant if the VI did not exceed 0.75 as a mean value and in more than 10 % of the nights., Patients: 20 patients (male 19, age 55.5 +/- 10.9 years, BMI 36.6 +/- 26.5 kg/m (2), AHI 36.9 +/- 21.3/h) who were treated with APAP FOT because of intolerance or inefficiency of constant CPAP., Results: The VI was 0.9 +/- 0.7 (range 0.27 +/- 0.05 to 1.95 +/- 0.83). The number of nights with a figure >/= 0.75 reached 17.6 +/- 13.8 (range 0 - 40). In 50 % of the patients the mean VI was lower than 0.75. However, in 7 of these 10 patients the VI exceeded 0.75 in more than 10 % of the nights (4 - 15). Only 3 of 20 patients fulfilled both criteria of pressure stability. The VI showed a significant correlation with P mean (r: 0.66, p < 0.001)., Conclusions: In most patients with difficult-to-treat OSAS a variability of the treatment pressure can be found.

Background and Objective: In patients with obstructive sleep apnea syndrome (OSAS) there is an increased comorbidity of internal diseases such as hypertension, coronary heart disease, chronic obstructive pulmonary disease and endocrine diseases. We analyzed prospectively frequency and consequences of pathological results in routine examinations of internal medicine in sleep laboratory., Methods: 250 patients with OSAS underwent routine bodyplethysmography, blood- gas analysis, electrocardiogram and laboratory studies after anamnesis and clinical examination. Prior to this we indicated, whether we based on history and physical examination deemed any of these examinations necessary. Frequency and kind of pathological results as well as the consequences were analyzed., Results: 129 results of bodyplethysmography and blood-gas analysis were pathological (51.6 % of all investigations), most frequently hypoxemia (22 %) and obstructive pattern (16.4 %). Further steps were necessary in 19 patients (7.6 %); the indication was seen before in 13 patients, therefore 6 results with consequences (2.4 %) were not expected. Laboratory studies were abnormal in 133 patients (53.2 % of all investigations), most of them hyperglycaemia (26.8 %) and elevated liver enzymes (20.4 %). 29 results (11.6 %) had consequences, of which 16 (6.4 %) were not expected. 82 electrocardiograms were pathological (32.8 % of all investigations), presenting most frequently as coronary heart disease (21.2 %). Further steps were necessary in 5 patients (2 %), while that was not expected in 3 patients (1.2 %)., Conclusions: Routine examinations of internal medicine in patients with OSAS frequently present pathological results, which seldom have further consequences. As most of the important results can be predicted by history and clinical investigation, pathological by chance diagnoses are rare. With the exception of blood sugar tests routine examinations for patients with OSAS should be considered critically.

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.