Document Detail

Autonomic cardiac regulation in obstructive sleep apnea syndrome: evidence from spontaneous baroreflex analysis during sleep.
MedLine Citation:
PMID:  9488213     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To assess spontaneous baroreceptor-heart rate reflex sensitivity during sleep in patients with obstructive sleep apnea syndrome, a condition associated with increased cardiovascular morbidity and mortality and characterized by marked sympathetic activation, which is believed to originate from hypoxic chemoreceptor stimulation, although little is known of other possible mechanisms such as baroreflex impairment. DESIGN AND METHODS: In 11 patients with severe obstructive sleep apnea syndrome (mean+/-SD age 46.8+/-8.1 years, apnea/hypopnea index 67.9+/-19.1 h), who were normotensive or borderline hypertensive during wakefulness by clinic blood pressure measurements, finger blood pressure was monitored beat-by-beat non-invasively (Finapres) at night during polysomnography. Periods of wakefulness and sleep were identified based on electroencephalographic recordings. Baroreflex sensitivity was assessed by the sequence technique, as the slope of the regression line between spontaneous increases or reductions in systolic blood pressure (SBP) and the related lengthening or shortening in the RR interval, occurring over spontaneous sequences of four or more consecutive beats. The number of these sequences was also computed, as an additional index of baroreflex engagement by the spontaneous blood pressure fluctuations. The controls were age-related normotensive or borderline hypertensive subjects without sleep apnea who had been investigated in previous studies; in these subjects blood pressure was recorded intra-arterially over 24 h in ambulatory conditions and spontaneous baroreflex sensitivity was assessed by the sequence technique. RESULTS: In our patients the lowest nocturnal arterial oxygen saturation was 78.6+/-12.1% (mean+/-SD). During sleep, the number of pooled +RR/+SBP and -RR/-SBP sequences per hour was 20.3+/-2.7 per h in patients with sleep apnea and 27.1+/-2.1 /h in controls (means+/-SEM). The average baroreflex sensitivity during sleep periods was 7.04+/-0.8 ms/mmHg in sleep apnea patients and 10.05+/-2.1 ms/mmHg in controls. Both the pooled number of sequences and baroreflex sensitivity values of the sleep apnea patients were significantly (P < 0.01) less than the corresponding night values of control subjects. In the sleep apnea patients, at variance from controls, baroreflex sensitivity did not show any increase during sleep compared with its values during wakefulness (6.9+/-1.0 ms/mmHg). CONCLUSIONS: Our data provide evidence that spontaneous baroceptor reflex sensitivity is depressed in severe obstructive sleep apnea syndrome. This suggests that in such patients baroreflex dysfunction and not only chemoreceptor stimulation by hypoxia may be involved in the sympathetic activation which occurs during sleep. Such dysfunction may contribute to the higher rate of cardiovascular morbidity and mortality reported in these patients.
G Parati; M Di Rienzo; M R Bonsignore; G Insalaco; O Marrone; P Castiglioni; G Bonsignore; G Mancia
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of hypertension     Volume:  15     ISSN:  0263-6352     ISO Abbreviation:  J. Hypertens.     Publication Date:  1997 Dec 
Date Detail:
Created Date:  1998-04-02     Completed Date:  1998-04-02     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8306882     Medline TA:  J Hypertens     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1621-6     Citation Subset:  IM    
Istituto Scientifico Ospedale S. Luca, University of Milan, Italy.
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MeSH Terms
Autonomic Nervous System / physiopathology*
Baroreflex / physiology*
Blood Pressure
Blood Pressure Monitoring, Ambulatory
Chemoreceptor Cells / physiology
Heart / innervation*,  physiopathology
Heart Rate
Hypertension / physiopathology
Middle Aged
Sleep Apnea Syndromes / physiopathology*

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

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