Phasic mechanoreceptor stimuli can induce phasic activation of upper airway muscles in humans

摘要: Upper airway dilator muscles are phasically activated throughout breathing by respiratory pattern generator neurons. Studies have shown that non-physiological upper mechanoreceptive stimuli (e.g. rapidly imposed pulses of negative pressure) also activate these muscles. Such reflexes may become during conditions alter resistance in order to stabilise patency. To determine the contribution ongoing phasic activity dilators, we assessed genioglossal electromyogram (GG EMG: rectified with moving time average 100 ms) slow (physiological) oscillations pressure generated spontaneously and passively (negative ventilator). Nineteen healthy adults were studied while awake, passive mechanical ventilation across normal physiological ranges rates (13–19 breaths min−1) volumes (0.5–1.0 l) spontaneous range end-tidal carbon dioxide (PET,CO2; 32–45 mmHg). Within-breath changes mechanoreceptor or flow) highly correlated within-breath activation, probably representing a robust reflex. These reflex relationships largely unchanged alterations central drive pump rate within studied. A multivariate model revealed tonic GG EMG, PET,CO2 breath duration provided no significant independent information prediction inspiratory peak EMG beyond epiglottic pressure, which alone explained 93 % variation all conditions. The overall relationship was: Peak = 79.7 − (11.3 x pressure), where is measured as percentage baseline, cmH2O. These data provide strong evidence can be inspiration via reflexes. feedback mechanism likely active on basis protect patency awake humans. This could mediate increased observed patients obstructive sleep apnoea (i.e. compensation for an anatomically smaller airway). Obstructive (OSA) common disease characterised repeated pharyngeal collapse sleep. depends balance between dilating force collapsing intra-luminal (generated ‘pump’ muscles) (Remmers et al. 1978). Many breathing, yet uncertain whether muscle activation emanates from primarily product If predominate, this would whereby local directly affect each breath. Numerous studies demonstrated imposing large, rapid (Horner 1991a, b; Wheatley 1993). principal aim research was not breathing. Our three specific aims determine: (i) effects slow, at frequencies tidal volumes), (ii) such induce when diaphragm relatively quiescent, (iii) affects activation. For (i), ventilator used apply frequencies. (ii), lessen drive, subjects hypocapnia being mechanically ventilated, associated reduction cessation (Shea, 1996). (iii), hypercapnia induced increase drive. We chose study genioglossus (GG), one 1978; Kobayashi responsible expect persist ventilation, magnitude related level similar On other hand, if activity, little becomes stimulated hypercapnia.