Received July 25, 2007
Revised August 31, 2007
Accepted after revision October 12, 2007
The genioglossus response to negative airway pressure: stimulus timing and route of delivery
Liam S Doherty 1*,
John P Cullen 1,
Phillip Nolan 2,
Walter T McNicholas 1
1 St.Vincent's University Hospital, Dublin
2 University College Dublin
* To whom correspondence should be addressed. E-mail: lsdoherty1{at}hotmail.com.
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Abstract |
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The genioglossus reflex response to sudden onset pulses of negative airway pressure (NAP) in humans is reported to occur more commonly at end rather than onset of expiration when delivered via mouthpiece. We examined whether this response was modulated by route of stimulus delivery throughout the respiratory cycle. The genioglossus surface EMG (GGsEMG) response to NAP delivered randomly throughout the respiratory cycle was measured in two experiments; (i) 40 stimuli of NAP at -5, -7.5 and -10 cmH2O applied to 8 healthy, awake, supine males via nose mask, (ii) 60 stimuli of -7.5 H2O NAP applied to 15 subjects via both nose-mask mask and mouthpiece in random order. Despite similar pressure changes detected in the epiglottis during both routes of stimulus delivery, far lower pressure changes were measured at the nasal choanae during mouthpiece compared to nose-mask delivery. There were no significant differences between the responses during any phase of respiration, nor when NAP was delivered via nasal-mask or mouthpiece. We conclude that the sensitivity of the GG sEMG response to NAP in humans does not vary significantly with phase of respiration or route of breathing.
Key Words:
EMG, Muscle contraction, Reflex
