Electrochemical Skin Conductance by Sudoscan

A New Tool to Predict Intradialytic Hypotension

Pauline Reach; Maxime Touzot; Yannis Lombardi; Catherine Maheas; Emmanuelle Sacco; Audrey Fels; Hélène Beaussier; Pablo Ureña-Torres; Gilles Chatellier; Christophe Ridel; Mathieu Zuber


Nephrol Dial Transplant. 2021;36(8):1511-1518. 

In This Article

Abstract and Introduction


Graphical Abstract

Background: Intradialytic hypotension (IDH), a common complication in haemodialysis (HD) patients, is associated with multiple risk factors including cardiac dysfunction and alterations of the peripheral autonomic nervous system. To what extent dysautonomia may contribute to the occurrence of IDH remains elusive. We sought to investigate the clinical utility of Sudocan®, a device that quantifies dysautonomia, in the prediction of IDH.

Methods: We conducted a prospective monocentric study in adult HD patients from July 2019 to February 2020. Dysautonomia was assessed by the measurements of hand and foot electrochemical skin conductance (ESC) using Sudocan®, before HD. The primary endpoint was the incidence of IDH (The National Kidney Foundation/Kidney-Dialysis Outcome Quality Initiative definition), according to the presence of a pathological hand and/or foot ESC value, during the 3-month study period.

Results: A total of 176 HD patients (64 ± 14 years old) were enrolled. Mean pre-dialysis HD hand and foot ESC was 45 ± 20 and 54 ± 22 μS, respectively. About 35% and 40% of patients had a pathological ESC at the hand and foot, respectively. IDH occurred in 46 patients. Logistic regression showed that pathologic pre-dialysis HD hand ESC was associated with an increased risk of IDH [odds ratio = 2.56, 95% CI (1.04–6.67), P = 0.04]. The cumulative risk incidence of IHD during the study was 5.65 [95% CI (2.04–15.71), P = 0.001] and 3.71 [95% CI (1.41–9.76), P = 0.008], with a pathological hand and foot ESC, respectively.

Conclusions: A pathological hand ESC, as assessed by a non-invasive Sudoscan® test, is associated with an increased risk of IDH.


Intradialytic hypotension (IDH) is a common complication in haemodialysis (HD) patients. Depending on the definition of IDH, a recent meta-analysis estimated that the prevalence was <15% (10.1% based on the nadir90 definition, or 11.7% based on with the European Best Practice guidelines).[1–3] Its occurrence is associated with cardiovascular or neurological events, reduced dialysis dose, vascular access thrombosis and increased risk of mortality.[4–6] Various definitions of IDH have been used across studies. The National Kidney Foundation/Kidney-Dialysis Outcome Quality Initiative (NKF/K-DOQI) defined IDH as a decrease in arterial systolic blood pressure (SBP) >20 mmHg, compared with the initial value, and associated with clinical signs (muscle cramps, abdominal pain, loss of consciousness and convulsions).[7] While this definition is widely accepted and used, another definition, the nadir of SBP of 90/100 mmHg, seems to be better correlated with mortality.[5]

Several clinical features have been proposed to predict the risk of IDH, including age, comorbidities [diabetes and coronary artery disease (CAD)], type of dialysis [HD or haemodiafiltration (HDF)], dialysis parameter [dry weight, ultrafiltration rate (UFR) and sodium conductivity in the dialysate fluid] as well as alterations of the autonomic nervous system, especially the sympathetic system.[1,2,8,9] Several mechanisms (e.g. alterations in central integration of the spinothalamic pathways, baroreceptor dysfunction) are responsible for BP fluctuations during dialysis.[8] These factors have already been studied in relation to HD and are directly correlated with the UFR.[1,8]

Over recent years, the study of vegetative functions has been facilitated by the use of Sudoscan® (Impeto, Paris, France). It is a simple non-invasive device that allows the measurement of electrochemical skin conductance (ESC) by chloride ions, and directly reflects the activity of small non-myelinated C nervous fibres that innervate the sweat glands.[10] Sudoscan® has been shown to have good sensitivity and specificity in the diagnosis of vegetative neuropathy in diabetic patients, and to be well correlated with autonomic cardiac neuropathy.[10,11] This sensitivity is comparable to that of quantitative sensitive tests and the correlation with cardiovascular dysautonomia tests is also acceptable. There is a good correlation between Sudoscan® results and the reduction in the density of intra-dermal nervous fibres measured on skin biopsies.[12,13] Additionally, this quick and easy test does not require the active participation of the patient.

HD patients are at risk of peripheral neuropathy not only because of an increasing incidence of diabetes (30–40%) but also because of the abnormal production and elimination of uraemic toxins.[14] Few studies have investigated the involvement of the vegetative nervous system on HD. A recent publication suggested a difference in nervous excitability depending on the type of HD (HD versus HDF).[15] However, to what extent dysautonomia may contribute to the occurrence of IDH is not known. Identifying patients at risk of discomfort during HD sessions could be useful in adapting HD protocols. In this study, we evaluated the potential of Sudoscan® as a tool to identify HD patients at risk for IDH.