Journal of sleep research
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Journal of sleep research · Mar 2010
Heart rate increment analysis is not effective for sleep-disordered breathing screening in patients with chronic heart failure.
Frequency domain analysis of heart rate variation has been suggested as an effective screening tool for sleep-disordered breathing (SDB) in the general population. The aim of this study was to assess this method in patients with chronic congestive heart failure (CHF). We included prospectively 84 patients with stable CHF, left ventricular ejection fraction (LVEF) <45% and sinus rhythm. ⋯ Receiver-operating characteristic curves constructed using various AHI cut-offs (5-30 h(-1)) failed to identify a %VLFI cut-off associated with SDB. The 2.4% VLFI cut-off recommended for the general population of patients with suspected SDB had low specificity (35%) and low positive and negative predictive values (35% and 54%, respectively). Heart rate increment analysis has several limitations in CHF patients and cannot be recommended as an SDB screening tool in the CHF population.
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Journal of sleep research · Mar 2010
Endogenous ouabain-like compounds in locus coeruleus modulate rapid eye movement sleep in rats.
Although the detailed mechanism of spontaneous generation and regulation of rapid eye movement sleep (REMS) is yet unknown, it has been reported that noradrenergic REM-OFF neurons in the locus coeruleus (LC) cease firing during REMS and, if they are kept active, REMS is significantly reduced. On the other hand, the activity as well as expression of Na-K ATPase has been shown to increase in the LC following REMS deprivation. Ouabain is a specific inhibitor of Na-K ATPase, and endogenous ouabain-like compounds are present in the brain. ⋯ The decrease in REMS was due to reduction in the mean frequency of REMS episode, which is likely due to increased excitation of the LC REM-OFF neurons. Control microinjections of normal IgG did not elicit this effect. These results support our hypothesis that interactions of naturally available endogenous ouabain-like compounds with the Na-K ATPase in the LC modulate spontaneous REMS.