Document Detail

Overnight shift from obstructive to central apneas in patients with heart failure: role of PCO2 and circulatory delay.
MedLine Citation:
PMID:  11208683     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Obstructive (OSA) and central sleep apnea (CSA) can coexist in patients with congestive heart failure (CHF). However, the reason why OSA events occur at one time and CSA events at another has not been determined. We hypothesized that a change in PCO(2) would be associated with an alteration in apnea type: a decrease in PCO(2) should lead to CSA. METHODS AND RESULTS: To test this hypothesis, we evaluated minute ventilation (V(I)), transcutaneous PCO(2) (PtcCO(2)), circulation time, and periodic breathing cycle length during overnight polysomnography in 12 patients with CHF and coexisting OSA and CSA. V(I) was significantly greater (mean+/-SEM, 9.4+/-1.3 versus 8.0+/-0.9 L/min; P:<0.05) and PtcCO(2) was lower (39.4+/-1.0 versus 41.9+/-1.1 mm Hg, P:<0.01) during episodes of CSA than of OSA. These changes were associated with significant lengthening of circulation time (23.6+/-3.7 versus 21.1+/-3.6 seconds, P:<0.01) and periodic breathing cycle length (53.7+/-3.5 versus 49.6+/-2.9 seconds, P:<0.01). In addition, the proportion of obstructive events decreased (from 68.5+/-11.4% to 22.5+/-7.2%, P:<0.001) and of CSA events increased (from 31.5+/-11.4% to 77.5+/-7.2%, P:<0.001) from the first to the last quarter of the night in association with a significant decrease in PtcCO(2) (from 42.6+/-0.9 to 40.8+/-0.9 mm Hg, P:<0.01). CONCLUSIONS: In patients with CHF, the shift from OSA to CSA is associated with a reduction in PCO(2). This appears to be related to an overnight deterioration in cardiac function as suggested by the concurrent lengthening of circulation time. Therefore, in CHF patients, alterations in cardiac function may influence apnea type.
R Tkacova; M Niroumand; G Lorenzi-Filho; T D Bradley
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Circulation     Volume:  103     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  2001 Jan 
Date Detail:
Created Date:  2004-07-08     Completed Date:  2004-07-29     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  United States    
Other Details:
Languages:  eng     Pagination:  238-43     Citation Subset:  AIM; IM    
Sleep Research Laboratory of the Toronto Rehabilitation Institute and the Department of Medicine of the Toronto General Hospital/University Health Network, University of Toronto, Toronto, Ontario, Canada.
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MeSH Terms
Blood Circulation*
Carbon Dioxide*
Circadian Rhythm*
Heart Failure / complications*
Middle Aged
Partial Pressure
Respiratory Mechanics
Sleep Apnea, Central / etiology*,  physiopathology
Sleep Apnea, Obstructive / etiology*,  physiopathology
Time Factors
Reg. No./Substance:
124-38-9/Carbon Dioxide

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