Correspondence and reprints:

A comparison was made between polysomnographic recordings and recordings of airflow pressures in the pharynx and respiratory pressures in the esophagus of 10 adult sleeping subjects with differing degrees of apnea. Pressure measurements were obtained by microsensors mounted on a 7F gauge flexible catheter which sited them in the epi, meso and hypopharynx and the esophagus. Digitized overnight pressure data were stored on a PC memory card and subsequently displayed for analysis by means of a notebook computer. In two patients examination of 200 obstructive, mixed and central apneic events showed no significant differences in recordings of their incidence, duration or classification between polysomnographic and either paryngeal or esophageal pressure techniques. Onset of apnea was demonstrated with particular clarity by computer integration of the pressure tracings. The multiple pressure sensor method offered a further important advantage in detecting the caudal limits of pharyngeal obstructions by steep elevation of pressure gradient in the pharyngeal segment between adjacent sensors in which the caudal limit of the obstruction was sited. The multiple pressure sensor technique provided reliable and comprehensive diagnostic information of breathing disorders in sleeping subjects and together with its miniaturized recording equipment the method commends itself as suitable for home monitoring. Key words: site of obstruction, multipe pressure recordings, polysomnography. 12