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Congestive Heart Failure Patients Suffer Acute Haemodynamic Stress From Hypoxia in Sleep Apnoea, Not Frequency of Episodes: Presented at HFSA
By Jennifer Reising
BOSTON -- September 16, 2009 -- Hypoxia in sleep apnoea increases brain natriuretic peptide (BNP) in congestive heart failure patients, but frequency of sleep-disorder breathing episodes does not relate to fluctuation of BNP, according to a study presented here at the 13th Annual Scientific Meeting of the Heart Failure Society of America (HFSA).
Researchers sought to determine whether BNP changes are related to the frequency and severity of apnoeic episodes, intermittent arousals, and hypoxia.
"Much to our surprise, we found that the BNP seemed to correlate with the percentage of time with hypoxia, but not with the frequency of the sleep apnoea," said Stephen S. Gottlieb, MD, University of Maryland, Baltimore, Maryland, on September 14. "I went into the study thinking that BNP would increase because of obstruction and direct physical effects, not hypoxia."
The analysis included 643 observations from 64 New York Heart Association class 2/3 heart failure patients with ejection fraction >40% who underwent 1 or more (based on apnoea severity) sleep studies. The study found that the severity of hypoxia (time spent with oxygen saturation <90%) significantly predicted BNP, and BNP increased by 9.6% (95% confidence interval, 1.5-17.7; P = .02) for each 10% increase in hypoxia duration.
The researchers concluded that hypoxia is a critical factor underlying the effect of sleep abnormalities on haemodynamic stress in heart failure patients and suggested that preventing hypoxia in these patients might be particularly important.
"It is possible that the hypoxia is working via pulmonary hypertension, but it is also possible that hypoxia is causing oxidative stress and has a more direct effect on BNP," said Dr. Gottlieb. "What the study does suggest is that people with obstructive sleep apnoea could possibly use oxygen supplementation, which might have beneficial effects on the heart, even if it does not treat the underlying obstruction."
[Presentation title: Hypoxia, Not the Frequency of Sleep Apnea, Causes Acute Hemodynamic Stress in Patients With Congestive Heart Failure. Abstract 030]
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