{'fraction_non_alphanumeric': 0.024189646831156264, 'fraction_numerical': 0.011127237542331882, 'mean_word_length': 5.173134328358209, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Reduced cardiac beat-to-beta variation in chronic renal failure: a ubiquitous marker of autonomic neuropathy.

Volume unresponsive hypotension is being reported more frequently in chronic haemodialysis patients [ 11 and several studies have ascribed this to autonomic neuropathy 12, 31. While methods are available for localizing defects to afferent or efferent limbs of the autonomic nervous system [41, many of these investigations are invasive and complex and do not correlate with the presence of volume unresponsive hypotension. Cardiac beatto-beat variation is a simple non-invasive means of assessing the integrity of cardiac autonomic control [51 and we have used this method to determine the incidence of autonomic neuropathy in chronic renal failure and whether volume unresponsive hypotension was predictable. Twenty patients on maintenance haemodialysis were studied prospectively over a 4 month period. We excluded patients with diabetes mellitus, amyloidosis, overt cardiac disease and those taking antihypertensive agents. No patient was anephric. They were then allocated into one of two groups based on the frequency of volume unresponsive hypotension while on dialysis: (a) group A (14 patients) rarely had volume unresponsive hypotension ( 50% of haemodialyses) resulting usually in a fall in mean arterial pressure to 70 mmHg and bradycardia in 85% of cases. These episodes occurred at a variable time after starting haemodialysis. Both groups were comparable in terms of mean age, diet, dialyser, length of time on dialysis, haemoglobin and serum urea and creatinine levels. R-R studies were performed on a non-dialysis day, resting with four standard ECG limb leads attached. A pulse rate recorder determined the time interval between 600 successive R waves and these data were then analysed by computer. The R-R interval variation was calculated as 1 SD from the mean R-R interval in ms. Because heart rate variability is reduced by increased heart rate, the R-R interval was also expressed as a coefficient of variation (cRRIV), where: cRRIV =