Mj. Morrell et al., THE ASSESSMENT OF UPPER AIRWAY PATENCY DURING APNEA USING CARDIOGENICOSCILLATIONS IN THE AIR-FLOW SIGNAL, Sleep, 18(8), 1995, pp. 651-658
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.