Hypoxia, Not the Frequency of Sleep Apnea, Induces Acute Hemodynamic Stress in Patients With Chronic Heart Failure

Received 26 June 2009; received in revised form 26 August 2009; accepted 30 August 2009.

Refers to article:

Stressful Sleeping⁎
Lee R. Goldberg
Journal of the American College of Cardiology
27 October 2009 (Vol. 54, Issue 18, Pages 1713-1714)
Full Text | Full-Text PDF (109 KB)

Objectives

This study was conducted to evaluate whether brain (B-type) natriuretic peptide (BNP) changes during sleep are associated with the frequency and severity of apneic/hypopneic episodes, intermittent arousals, and hypoxia.

Background

Sleep apnea is strongly associated with heart failure (HF) and could conceivably worsen HF through increased sympathetic activity, hemodynamic stress, hypoxemia, and oxidative stress. If apneic activity does cause acute stress in HF, it should increase BNP.

Methods

Sixty-four HF patients with New York Heart Association functional class II and III HF and ejection fraction <40% underwent a baseline sleep study. Five patients with no sleep apnea and 12 with severe sleep apnea underwent repeat sleep studies, during which blood was collected every 20 min for the measurement of BNP. Patients with severe sleep apnea also underwent a third sleep study with frequent BNP measurements while they were administered oxygen. This provided 643 observations with which to relate apnea to BNP. The association of log BNP with each of 6 markers of apnea severity was evaluated with repeated measures regression models.

Results

There was no relationship between BNP and the number of apneic/hypopneic episodes or the number of arousals. However, the burden of hypoxemia (the time spent with oxygen saturation <90%) significantly predicted BNP concentrations; each 10% increase in duration of hypoxemia increased BNP by 9.6% (95% confidence interval: 1.5% to 17.7%, p = 0.02).

Conclusions

Hypoxemia appears to be an important factor that underlies the impact of sleep abnormalities on hemodynamic stress in patients with HF. Prevention of hypoxia might be especially important for these patients.

Key Words: brain natriuretic peptide, sleep apnea, hypoxia

Abbreviations and Acronyms: AHI, apnea-hypopnea index, BNP, brain (B-type) natriuretic peptide, CSA, central sleep apnea, HF, heart failure, OSA, obstructive sleep apnea, SaO2, oxygen saturation, t90, percentage of time spent during each epoch at oxygen saturation levels <90%

⁎ Harvard University, Cambridge, Massachusetts

† Johns Hopkins Bayview Medical Center, Baltimore, Maryland

‡ University of Maryland School of Medicine, Baltimore, Maryland

§ Medstar Research Institute, Baltimore, Maryland

∥ University of Virginia, Charlottesville, Virginia

¶ National Institute on Aging, National Institutes of Health, Baltimore, Maryland

Reprint requests and correspondence: Dr. Stephen S. Gottlieb, University of Maryland, 22 South Greene Street, Baltimore, Maryland 21201

This study was supported by grant #R01 HL071506 from the National Heart, Lung and Blood Institute, National Institutes of Health (NIH), and by grant #M01-RR02719 from the National Center for Research Resources (NCRR), a component of NIH, and NIH Roadmap for Medical Research.

Its contents are solely the responsibility of the authors and do not necessarily represent the official view of the NCRR or NIH. Information on NCRR is available at http://www.ncrr.nih.gov/. Information on Re-engineering the Clinical Research Enterprise can be obtained from http://nihroadmap.nih.gov/clinical research/overview-translational.asp.

This study was supported, in part, by the Intramural Research Program of the National Institute on Aging, NIH, a portion of which was through a Research and Development Contract with MedStar Research Institute. The BNP assays were provided by Biosite, Inc., San Diego, California.

Drs. Najjar and Gottlieb contributed equally to this paper.

PII: S0735-1097(09)02920-9

doi:10.1016/j.jacc.2009.08.016

*Note: Add-ons open in a new browser window. Please disable any pop-up blocking software before viewing Add-ons.

9 of 17