Between 2%-4% of adult population suffers from obstructive sleep apnea (OSAS)(1), which is
characterized by obstructive snoring, repetitive apnea and hypopnea in sleep, repetitive
cyclic oxygen saturation, as a result from sleep fragmentation related to the arousals in
sleeping profile and clinical consequences like day drowsiness, neuropsychological deficits,
raised danger of accidents and cardiovascular disease. (1-6). The therapy of choice is the
application of nasal continuous positive airway pressure (CPAP) (7-9).
Increasing relevance obtain the combined sleep-related breathing disturbances, where the
patient shows an obstructive sleep apnea syndrome and some central breathing disturbances in
the polysomnography at night. Those patients frequently present with cardiovascular diseases.
These combined night breathing disturbances are frequently insufficient to be mitigated
exclusively with a CPAP therapy.
Some modifications of nCPAP therapy were developed in order to optimize the
therapy-compliance and the effectiveness of the therapy. Bi-level-CPAP-devices produce two
pressure levels: one for inspiration and another for expiration, so that the patients are
able expire against a constant low pressure. An increase in the use of this application in
comparison between the conventional or the automatic CPAP therapy could not be proved in
early studies. (12, 13) The principle of the automatic nCPAP therapy is to recognize the
patient's current need of pressure and to alter the pressure within a set range by applying
different algorithms. Some studies have shown that this therapy increased compliance and
comfort (14-16), while other studies could not confirm these results. (17, 18)
The result of the current study should prove if the treatment of a new algorithm therapy
based on an automatic bi-level-system for patients with sleep-related respiratory disorders
is as effectively and subjective more comfortable as the conventional CPAP therapy.
Patients with a particularly high need of pressure should experience a clear expiratory
pressure relief and a higher comfort. Therefore a better compliance is to expect. In the same
way patients with additional central respiratory disturbances should obtain a benefit from
the bi-level modus. This new treatment would help particularly such "critical patients", who
are not responding well to the CPAP therapy or find it uncomfortable.