Journal of Applied Physiology, Vol 61, Issue 4 1444-1448, Copyright © 1986 by American Physiological Society
Respiratory timing during NREM sleep in patients with occlusive sleep apnea
E. Onal and M. Lopata
To study respiratory timing mechanisms in patients with occlusive apnea,
inspiratory and expiratory times (TI and TE) were calculated from the
diaphragmatic electromyogram obtained in seven patients during
non-rapid-eye-movement (NREM) sleep. Peak diaphragmatic activity (EMGdi)
had a curvilinear relationship with TI during the ventilatory and occlusive
phases such that TI shortened as EMGdi decreased during the ventilatory
phase (r = 0.87, P less than 0.05) and it prolonged as EMGdi increased
during the occlusive phase (r = 0.89, P less than 0.02). However, EMGdi vs.
TI for the occlusive phase was shifted to the right of that for the
ventilatory phase, reflecting the relatively longer TI during upper airway
occlusion. TI also had a linear relationship with pleural pressure (r =
0.94, P less than 0.001) that remained unchanged during the ventilatory and
occlusive phases such that it prolonged as negative inspiratory pressure
increased. These results indicate that respiratory timing is continuously
modified in patients with occlusive apnea as inspiratory neural drive
fluctuates during NREM sleep and suggest that this modification is due to
the net effects of changing inspiratory neural drive and afferent input
predominantly from upper airway mechanoreceptors.
