[Nasal CPAP in sleep-related respiration disorders: patient profile, therapy compliance and influence of gas exchange...

A survey performed in 100 CPAP users indicated that irritation of the face, a painful nose and nasal obstruction were among the most frequently mentioned complaints in chronic CPAP users. In 132 normocapnic SAS patients a significant improvement of PaO2 was shown, with a decrease of the alveolo-arterial oxygen difference. This improved gas exchange was parallelled by a significant increase in the FRC and TLC. Maybe a modulation in force of the respiratory muscles may be involved. These data were more pronounced in obstructive sleep apnea than in central sleep apnea. In 50 chronic CPAP users we could show a lower AHI immediately after CPAP withdrawal after a previous prolonged treatment. These findings may support the insufflation theory as a mechanism of action of CPAP. Traditionally, mechanical splinting of the upper airway has been considered as the dominant mechanism of action. Other mechanisms like changes in regulation of breathing and decrease of the pharyngeal edema may be involved as well.