Heart rate variability (HRV) represents one of the most promising markers of the autonomic nervous system (ANS) regulation. However, it requires the acquisition of the ECG signal in order to reliably detect the RR intervals, which is not always easily and comfortably available in personal health applications. Additionally, due to progress in single spot optical sensors, photoplethysmography (PPG) is an interesting alternative for heartbeat interval measurements, since it is a more convenient and a less intrusive measurement technique. Driven by the technological advances in such sensors, wrist-worn devices are becoming a commodity, and the interest in the assessment of HRV indexes from the PPG analysis (pulse rate variability - PRV) is rising. In this study, we investigate the hypothesis of using PRV features as surrogates for HRV indexes, in three different contexts: healthy subjects at rest, healthy subjects after physical exercise and subjects with cardiovascular diseases (CVD). Additionally, we also evaluate which are the characteristic points better suited for PRV analysis in these contexts, i.e. the PPG waveform characteristic points leading to the PRV features that present the best estimates of HRV (correlation and error analysis). The achieved results suggest that the PRV can be often used as an alternative for HRV analysis in healthy subjects, with significant correlations above 82%, for both time and frequency features. Contrarily, in the post-exercise and CVD subjects, time and (most importantly) frequency domain features shall be used with caution (mean correlations ranging from 68% to 88%).
Sex- and/or ethnic-appropriate echocardiographic reference values are indicated for many measurements of LA and LV size, LV mass, and EF. Reference values for LV volumes and mass also differ across the age range.
Pruritus is a major symptom of primary biliary cirrhosis, cholestatic autoimmune disease which affects mostly middle-age women. Often, it can be severe and refractory to multiple treatments, and mostly affecting the patient's health-related quality of life. Intense pruritus can be itself an indication to liver transplantation, in extreme cases leading to suicide. Its physiopathology has not yet been fully elucidated, but recent studies added the elevation of autotaxin and lysophosphatidic acid to the group of classic mechanisms already linked to cholestatic pruritus. In this case report we illustrate how ultraviolet B phototherapy appears to successfully control severe pruritus and contribute to the healing of pruritic skin lesions caused by intense scratching. There is limited medical literature concerning this therapeutic approach on cholestatic pruritus, but we hope that further randomised controlled trials will successfully establish it as an effective treatment in the near future.
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