title: Effects of sleep apnea on nocturnal free fatty acids in subjects with heart failure.
abstract: OBJECTIVE
  Sleep apnea is common in patients with congestive heart failure, and may contribute to the progression of underlying heart disease. Cardiovascular and metabolic complications of sleep apnea have been attributed to intermittent hypoxia. Elevated free fatty acids (FFA) are also associated with the progression of metabolic, vascular, and cardiac dysfunction. The objective of this study was to determine the effect of intermittent hypoxia on FFA levels during sleep in patients with heart failure.
  
  
  METHODS
  During sleep, frequent blood samples were examined for FFA in patients with stable heart failure (ejection fraction < 40%). In patients with severe sleep apnea (apnea-hypopnea index = 65.5 ± 9.1 events/h; average low SpO₂ = 88.9%), FFA levels were compared to controls with milder sleep apnea (apnea-hypopnea index = 15.4 ± 3.7 events/h; average low SpO₂ = 93.6%). In patients with severe sleep apnea, supplemental oxygen at 2-4 liters/min was administered on a subsequent night to eliminate hypoxemia.
  
  
  RESULTS
  Prior to sleep onset, controls and patients with severe apnea exhibited a similar FFA level. After sleep onset, patients with severe sleep apnea exhibited a marked and rapid increase in FFA relative to control subjects. This increase persisted throughout NREM and REM sleep exceeding serum FFA levels in control subjects by 0.134 mmol/L (P = 0.0038). Supplemental oxygen normalized the FFA profile without affecting sleep architecture or respiratory arousal frequency.
  
  
  CONCLUSIONS
  In patients with heart failure, severe sleep apnea causes surges in nocturnal FFA that may contribute to the accelerated progression of underlying heart disease. Supplemental oxygen prevents the FFA elevation.
authors: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors: Jonathan C
authors: JC
authors: Jun
authors: Luciano F
authors: LF
authors: Drager
authors: Samer S
authors: SS
authors: Najjar
authors: Stephen S
authors: SS
authors: Gottlieb
authors: Cynthia D
authors: CD
authors: Brown
authors: Philip L
authors: PL
authors: Smith
authors: Alan R
authors: AR
authors: Schwartz
authors: Vsevolod Y
authors: VY
authors: Polotsky
mesh_terms: D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000150:complications* / Q000628:therapy; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000150:complications / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000097:blood* / Q000150:complications* / Q000628:therapy
chemical_list: D005230:Fatty Acids, Nonesterified