Evidence for reflex upper airway dilator muscle activation by sudden negative airway pressure in man.

Abstract

SUMMARY1. To determine if negative upper airway pressure causes reflex pharyngeal dilator muscle activation, we used intra-oral bipolar surface electrodes to record genioglossus electromyogram (EMG) activity in response to 500 ms duration pressure stimuli of 0. -25.-5.-15, -25 and -35 cmH2O (0-90 % rise time < 30 ms) in ten normal, conscious, supine subjects.2. WN&ith the subjects relaxed at end-expiration, stimuli were applied in each of three conditions: (i) glottis open (GO), (ii) glottis closed (GC) and (iii) controls with the mouth and nose closed.3. Six rectified and integrated EMG responses were bin averaged for each pressure in each experimental condition. Response latency was defined as the time when the EMG activity significantly increased above pre-stimulus levels. Response magnitude was quantified as the ratio of the EMG activity for 80 ms post-stimulus to 80 ms prestimulus; data from after the subject's voluntary reaction time (for tongue protrusion) were not analysed.4. Negative airway pressure activated the genioglossus. The median latency of activation (34 ms) was much faster than the time for voluntary activation (184 ms) indicating a reflex response.5. Significant activation, compared to 0 cmH20 controls and controls with mouth and nose closed, occurred with pressures of at least -5 cmH2O (GC) and -15 cmH2O (GO). , responses with GO were significantly greater than with GC.6. The magnitude ('strength') of the responses differed between subjects; these differences were repeatable.7. WTe conclude that negative airway pressure causes reflex pharyngeal dilator muscle activation in man. Responses with GC suggest that upper airway receptors can mediate the response but larger responses with GO indicate a contribution from subglottal receptors.

Pathophysiology of Adult Obstructive Sleep Apnea

“…One such mechanism is the genioglossus negative pressure reflex, whereby the muscle is activated in response to rapid changes in negative intrapharyngeal pressure (i.e., pressures that are subatmospheric or suction pressure) (23). Consistent with the nature of OSA being a state-related disease, the genioglossus negative pressure reflex has been shown to be diminished during non-REM sleep in healthy individuals (24,25).…”

Central sleep apnoea, pathogenesis and treatment: an overview and perspective

“…It was also shown that genioglossus muscle responds to negative airway pressure by reflex activation during wakefulness [75]. This reflex activation is reduced or lost during NREM sleep [76].…”

Efeitos da terapia miofuncional orofacial em pacientes com ronco primário e apneia obstrutiva do sono na anatomia e função da via aérea

“…Já na expiração, ocorre a ativação tônica (contínua) mantendo assim, a espessura e tamanho da VAS. [42] A pressão negativa na faringe estimula as fibras proprioceptivas e aumenta sua resposta de ativação [43] Durante momentos de hipóxia e hipercapnia a ativação do genioglosso é aumentada. [44] Os músculos palatoglosso e palatofaríngeo aumentam sua ativação em respostas a breve pulsos de pressões negativas ou resistência inspiratória.…”