A decrease in the level of CPAP required after prolonged treatment in patients with the obstructive sleep apnea syndrome

Application of continuous positive upper airway pressure (CPAP) is the treatment of choice in obstructive sleep apnea syndrome (OSAS). CPAP keeps the upper airway open by providing a "pneumatic splint" on the pharyngeal walls. However, it has been suggested that prolonged nasal CPAP treatment may also improve the physiopathological mechanisms responsible for OSAS by a variety of mechanisms such as the reduction of edema of the pharyngeal mucosa, modification of upper airway muscle dynamics; there may even be a reduction in the intensity of phenomena responsible for brief awakening and ending of apneic episodes. The objective of this study was to determine whether prolonged nasal CPAP is associated to a reduction of CPAP pressure required for eliminating apnea in patients with OSAS. We studied 22 patients (4 women) with OSAS diagnosed by conventional polysomnography, including study of neurological variables during sleep (electroencephalogram, ocular movement, submental electromyogram), respiratory variables (nasal air flow, thoracic-abdominal movement, O2 saturation in the blood), and others (electrocardiogram, leg movement). Treatment was exclusively with nasal CPAP. All 22 patients were middle-aged (52.3 +/- 10 years), presented a mean apnea/hypoapnea index of 65.2 +/- 24 per hour. CPAP levels needed to eliminate episodes of apnea, blood O2 desaturation and snoring at the time of diagnosis and after long-term treatment (8.5 +/- 4.6 months) were applied. Weight was recorder at both measurement times. Eighteen of the 22 patients (1 woman, mean age 53.1 +/- 11.4 years and apnea/hypopnea index 64.8 +/- 23.4 per hour) experienced no weight change during treatment.(ABSTRACT TRUNCATED AT 250 WORDS)