No change in autonomic function tests during uncomplicated haemodialysis

Abstract

Uraemic autonomic dysfunction is reckoned to participate in dialysis hypotension, but a clear relationship has not been established. However, autonomic function is usually tested at rest, and possibly autonomic dysfunction arises or worsens during dialysis. We therefore performed easily repeatable tests of efferent sympathetic function, that is static exercise test and parasympathetic function, that is heart rate variability during Valsalva manoeuvre and deep breathing, at successive stages of a standard haemodialysis session; before dialysis, 20 min after dialysis without ultrafiltration, after 3 h of dialysis combined with ultrafiltration, and 20 min after dialysis. Studies were performed in 22 patients on chronic haemodialysis on a cuprophane dialyser. The mean ultrafiltration volume was 2.2 +/- 0.61. We found that blood pressure elevation upon static exercise, and heart rate variability during Valsalva or deep breathing test remained unaltered at the various stages of dialysis. On past performance the patients were divided into hypotension prone (n = 6) or resistant (n = 16). Hypotension prone patients showed a greater blood pressure drop during dialysis, but also showed an appropriately enhanced heart rate acceleration. The occurrence of autonomic dysfunction was not elevated in this group, nor did such dysfunction develop along dialysis. Predialysis parasympathetic function tests were abnormal in 10 patients. These patients also showed an augmented intradialytic blood pressure decrease, but no enhanced acceleration in heart rate. Their parasympathetic dysfunction did not worsen during dialysis. Based upon the predialysis exercise test, low responding patients (blood pressure increase 5 +/- 2 mmHg, n = 11) were distinguished. These subjects were not characterized by a greater blood pressure decrease or different heart rate acceleration. Generally, the responses upon exercise, whether low or high, remained unaltered during dialysis. we conclude that haemodialysis has no systematic effect on autonomic function. Hypotension-prone patients are not distinguished by a disturbed predialytic or intradialytic autonomic blood pressure control.

Autonomic neuropathy in hemodialysis patients: questionnaires versus clinical tests

“…According to some authors, in non-diabetic patients with ESRD, parasympathetic nervous system dysfunction is the most common but usually subsides with increasing time on dialysis, in contrast with diabetic AN, the signs and symptoms of which tend to increase with time [6,7]. Therefore the lower prevalence of AN in our study than in other studies may be explained by the longer dialysis vintage in our patients and the exclusion of subjects with diabetic nephropathy [4,6]. Similarly, the lack of significant differences between the study group and healthy subjects in both HR and BP changeability indexes could be explained by the adequately dosed hemodialysis and strict selection criteria.…”

“…Autonomic and peripheral nervous system dysfunction is a well-known complication of chronic uremia and nearly 70% of uremic patients fulfill electrodiagnostic criteria for polyneuropathy including AN [4,5]. AN is a common problem in that population, because in some of the studies the incidence of AN was as high as 46% [1].…”

“…Others, for example QT interval prolongation observed as heart rate decreases with hypotension, have been linked to increased risk of sudden death [1][2][3]. It is of note that subjective manifestation of autonomic nervous system damage is highly variable [4]. Therefore it is still unclear whether there is any correlation between uremic AN and the presence of specific complaints.…”

Hypotension During Haemodialysis: Aetiology, Risk Factors and Outcome

“…It occurs in nearly 25% of dialysis sessions 4 and often requires aggressive resuscitative measures and sometimes premature termination of hemodialysis. It is also a significant independent factor affecting mortality in hemodialysis patients 4,5 .…”

The Role of Autonomic Neuropathy in the Genesis of Intradialytic Hypotension

“…Organic damage to the autonomic nervous system has been suggested by some authors as one of the major causes [1,6]. However, other authors have shown no association between autonomic dysfunction and genesis of intradialytic hypotension [7,8]. Therefore, it is unclear whether sympathetic or parasympathetic dysfunction contributes to the pathogenesis of intradialytic hypotension.…”