BOSTON, MASSACHUSETTS. Heart rate variability (the variation in the interval between heart beats) is a powerful indicator of the state of the autonomic nervous system (ANS). The variation in the heart beat interval is usually measured via a 5-minute electrocardiogram or 24-hour Holter monitoring. The original and still commonly used measure for the variation is referred to as SDNN which is the standard deviation of the heart beat intervals, that is, the square root of the variance. Most scientific work on heart rate variability (HRV) now uses power spectral density (PSD) analysis to relate the relatively simple measurement of beat to beat variability to the state of the autonomic nervous system. PSD analysis uses a mathematical technique (fast Fourier transform) to determine how the power (variance in heart beat interval) is distributed across different frequency bands. There is now general agreement that the power in the low frequency band (LF) from 0.04 to 0.15 Hz (cycles/second) is an indication of sympathetic (adrenergic) branch activity and that the power in the high frequency band (HF) from 0.15 to 0.40 Hz is primarily an indication of parasympathetic (vagal) activity. It follows that the ratio of LF/HF is a measure of the balance of the autonomic nervous system with a higher number indicating an excess of adrenergic activity and a lower number indicating an excess of vagal activity.
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Lactulose improves quality of life in patients with cirrhosis who have minimal hepatic encephalopathy September 15
A study on patients with cirrhosis who had minimal hepatic encephalopathy (MHE), a condition in which behavioral, psychological and neurological changes are associated with advanced liver disease, found that cognitive function and health related quality-of-life improved when they took lactulose. Lactulose is a drug used to help eliminate toxins such as ammonia that are normally cleared by the liver.
The results of this study appear in the March 2007 issue of Hepatology, the official journal of the American Association for the Study of Liver Diseases (AASLD).
MHE is the mildest form of hepatic encephalopathy (HE), a condition marked by impaired intellectual functioning, personality changes, altered levels of consciousness, and neuromuscular dysfunction. Although MHE has no recognizable symptoms, patients who have it show mild cognitive and psychomotor deficits. These can impair their daily functioning and health related quality-of-life (HRQOL) to the extent that they may not be able to work or drive a car. MHE can also lead to the development of more severe HE, and can be associated with a poor prognosis.
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