Genioglossus and breathing responses to airway occlusion: effect of sleep and route of occlusion

Abstract

We examined the effect of sleep state on the response of genioglossus muscle (EMGgg) activity to total airway occlusion applied at 1) nasal (N) airway [and thus exposing the upper airway (UAW) to pressure changes] and 2) tracheal (T) airway (thus excluding UAW from pressure changes). A total of 233 tests were performed during wakefulness (W), 98 tests in slow-wave sleep (SWS), and 72 tests in rapid-eye-movement (REM) sleep. Prolongation of inspiratory time (TI) of the first occluded effort occurred in all tests irrespective of behavioral state, with the greatest increase seen in awake N tests. Nasal tests augmented EMGgg activity in the first occluded breath and produced a linear increase in EMGgg during occlusion. The EMGgg activity at any given time during nasal occlusion in SWS was less than that recorded during W tests. There was a marked reduction in EMGgg response to N occlusion during REM sleep. The EMGgg activity during awake T tests was significantly less than that of N tests at any given time during occlusion. There was no relationship between the level of EMGgg activity and asphyxia in T tests performed during SWS and REM sleep. Nasal tests decreased the force generated by the inspiratory pump muscles and the central drive to breathing compared with T tests. These results confirm the important role of the UAW in regulating breathing pattern and indicate that both immediate and progressive load-compensating responses during nasal occlusion are influenced by information arising from the UAW.

Determinants of effective ventilation during nasal intermittent positive pressure ventilation

“…Alternatively, the response to increases in flow may result from changes in airway pressure likely to result from shortening of tI for a constant delivered VT. Pressure receptors are also known to exist in the larynx and their response to negative pressure has been studied. Contrary to our observations, sleep reduces the laryngeal response to application of negative pressure in the airway [23]. Positive pressure is known to be a less intense stimulus than negative pressure [24].…”

Effect of route of breathing on the ventilatory and arousal responses to hypercapnia in awake and sleeping dogs.

“…However, these changes allowed larger tidal volumes to be generated during nasal breathing. These results are similar to those reported in the awake and sleeping dogs during externally applied nasal occlusion tests (Issa et al 1988), and suggest that the change in breathing pattern during nasal breathing serves to protect the upper airway from narrowing, particularly during sleep. Several respiratory stimuli induce arousal, including hypoxia (Bowes et al 1981;Berthon-Jones & Sullivan, 1982;Hedemark & Kronenberg, 1982), hypercapnia (Berthon-Jones & Sullivan, 1984), negative intrathoracic pressure (Gleeson et al 1990), upper airway mechanoreceptors (Issa & Sullivan, 1983;Issa et al 1987), and stimuli from thoracic pump muscles (Vincken et al 1987).…”

“…The results of these studies indicated that breathing through the nares is different from that during tracheal breathing. The dissimilarity was not due to differences in dead space or airway resistance since both these variables were matched (McNamara et al 1986;Issa et al 1988;Plowman et al 1990). The present study confirms these findings and extends the results to both NREM and REM sleep.…”

“…In addition to maximizing flow of air into the lungs by widening the upper airway, pharyngeal stimulation prolongs inspiration and influences the central respiratory drive to thoracic pump MS 1597 muscles (Mathew, Abu-Osba & Thach, 1982;Issa et al 1988). Furthermore, upper airway receptor activity influences breathing pattern in wakefulness and sleep, and may also interrupt the sleep process itself (Issa & Sullivan, 1983;Issa et al 1987).…”

Pathophysiology of Adult Obstructive Sleep Apnea

“…Some patients have OSA only during REM sleep (123). Although human physiological data are challenging to obtain and the available literature is relatively scarce, REM sleep is associated with decreased upper airway muscle tone (124,125), impaired genioglossus reflex responsiveness to negative pressure (26,126,127), and reduced chemosensitivity (128,129). These factors may worsen apnea during REM sleep.…”