Document Detail

Palatal muscle EMG response to negative pressure in awake sleep apneic and control subjects.
MedLine Citation:
PMID:  9310006     Owner:  NLM     Status:  MEDLINE    
The sleep apnea/hypopnea syndrome (SAHS) affects 1-4% of the middle-aged population and is caused by repeated occlusion of the upper airway mainly at the retropalatal level. It is unclear why SAHS patients obstruct their upper airways during sleep while others do not. We hypothesized that upper airway dilator muscle function may be impaired in SAHS patients and that chronic CPAP therapy may enhance upper airway function. We, therefore, examined the effects of upper airway negative pressure on reflex palatal muscle activity in 16 normal nonsnoring awake male subjects and 16 awake SAHS patients using electromyography. The application of negative upper airway pressure (0 to -12.5 cm H2O) caused increases in levator palatini (LP, p < 0.001) and palatoglossus (PG, p < 0.001) activity, 100 msec after pressure stimulus in normal subjects. Application of upper airway negative pressure in SAHS patients caused an increase in LP activity (p < 0.05) but not in PG activity. Reflex electromyographic response to negative pressure was reduced in SAHS patients compared to normal subjects for both muscles (p < 0.001). When the seven thinnest SAHS patients were compared with seven normal subjects matched for BMI and age, the SAHS patients still demonstrated impaired responses to negative pressure for both muscles (p < 0.001). A further eight SAHS patients were studied either while concurrently taking nightly CPAP therapy and also off CPAP (at least 3 nights). Chronic nightly CPAP therapy improved the reflex response of both LP (p < 0.001) and PG (p = 0.003) to nasal negative pressure application. Thus, untreated SAHS patients have impaired electromyographic responses to negative upper airway pressure suggesting impaired defence of the upper airway, which is improved by nightly CPAP therapy.
I L Mortimore; N J Douglas
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  156     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1997 Sep 
Date Detail:
Created Date:  1997-10-28     Completed Date:  1997-10-28     Revised Date:  2009-09-29    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  867-73     Citation Subset:  AIM; IM    
Department of Medicine, University of Edinburgh, Royal infirmary, Scotland, United Kingdom.
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MeSH Terms
Age Factors
Body Mass Index
Case-Control Studies
Palatal Muscles / physiopathology*
Positive-Pressure Respiration / methods*
Sleep Apnea Syndromes / physiopathology*,  therapy*
Ventilators, Negative-Pressure*
Grant Support
//Wellcome Trust

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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