THE ASSESSMENT OF UPPER AIRWAY PATENCY DURING APNEA USING CARDIOGENICOSCILLATIONS IN THE AIR-FLOW SIGNAL

We investigated the relationship between airway patency and the occurr ence of cardiogenic related oscillations in the airflow signal during 67 apneas occurring in non-rapid eye movement sleep in eight subjects. Spontaneously occurring apneas and apneas induced by mechanical venti lation were analyzed, Airway occlusion was determined by direct observ ation of the pharyngeal lumen using fiberoptic endoscopy. The presence or absence of cardiogenic oscillations was determined from an expande d airflow signal by an investigator blinded to the airway patency. Of the total 67 apneas, complete airway occlusion occurred during 51, and the airway remained patent throughout in 16. Cardiogenic oscillations were seen throughout 39 of the 51 occluded apneas and throughout 9 of the 16 apneas with the airway patent. There was no relationship betwe en the occurrence of cardiogenic oscillations and airway patency. In a ddition, in a canine model where the upper airway was anatomically iso lated, cardiogenic oscillations were evident during apneas in pressure signals recorded from the isolated upper airway and in airflow signal s at the tracheal stoma. We conclude that cardiogenic oscillations can not be used to predict airway patency during apnea.