[Video-endoscopic recording of the pharynx before and following nasal continuous positive airway pressure therapy in patients with obstructive sleep apnea].

The action mechanism of nCPAP in the treatment of obstructive sleep apnea is not adequately known. We took video endoscopic pictures (chip video camera manufactured by Videotronik) of the pharynx in five patients with SA in the awake state, during apnea during sleep, and under nCPAP treatment during sleep. The patients were all in the supine position. Simultaneously with video-endoscopy, polysomnography was performed. Qualitatively good pictures were obtained in 3 patients. In the awake state, a relatively narrow pharynx was observed which, however, was completely patent during the entire respiratory cycle. During apnea and hypopnoea, a concentric collapse of the oropharynx was observed, with involvement of the lateral and posterior walls of the pharynx and the tongue, together with the soft palate over a length of several centimetres to above the epiglottis. During the hyperventilation phase following apnea, the occlusion opened up again, the diameter of the pharynx then being appreciably greater than that seen in the awake state. Under increasing CPAP pressure, occlusion became progressively less complete; when the effective pressure had been attained, the diameter of the pharynx was roughly comparable to that seen in the hyperventilation phase, that is, appreciably wider than in the awake state. During inspiration, however, even under effective nCPAP pressure, a discrete decrease in pharyngeal diameter occurred. On the basis of the visual impression, we believe that the effect of CPAP is based on a passive "pneumatic splinting" of the pharyngeal musculature.