Abnormal electrochemical skin conductance in cystic fibrosis.

BACKGROUND: Electrochemical skin conductance measurement is an active electrophysiologic method in which incremental low direct voltage is applied on the skin. It generates a current due to reverse iontophoresis which previous studies suggested to be mostly related to chloride anion movements. As sweat chloride movements upon electric stimulation were likely to be impaired in cystic fibrosis (CF) patients, we designed a proof-of-concept study to measure electrochemical skin conductance in CF patients and control subjects and to test the ability of this method to discriminate CF from controls. METHODS: Electrochemical skin conductance was measured in 41 adult patients with classical CF and 20 healthy control subjects. Patients placed their hands and feet on nickel electrodes and an incremental low direct voltage was applied on the anode during 2min. The resulting voltage on the cathode and the current generated between anode and cathode were measured and from them, two electrochemical skin conductance variables were calculated: ESC, obtained when a low voltage of 1.6V was applied, and dESC which took into account electrochemical skin conductances obtained when low and high voltages were applied. RESULTS: ESC measurements on hands and feet were significantly different in CF patients (on feet: 75±10µSi), as compared with control subjects (62±13µSi, p<0.0001); dESC was also significantly different and more discriminative in CF patients (on feet: 34±24µSi), as compared with control subjects (93±24µSi, p<0.0001). dESC measurement provided a diagnostic specificity of 1 and a sensitivity of 0.93. CONCLUSIONS: These results show that electrochemical skin conductance which is easily and rapidly measured is abnormal in CF patients. Trial registry name in the European Clinical Trials Database (eudraCT): "EZSCAN MUCO1: Mesure de la conductance cutanée par chronoampérométrie", N°EUDRACT: 2007-A00221-52.

A new tool to detect kidney disease in Chinese type 2 diabetes patients: comparison of EZSCAN with standard screening methods.

BACKGROUND: EZSCAN(®) (Impeto Medical, Paris, France), a noninvasive device that assesses sweat gland dysfunction using reverse iontophoresis, also detects early dysglycemia. Given the interrelationships among dysglycemia, vasculopathy, and neuropathy, EZSCAN may detect kidney disease in diabetes (DKD). METHODS: An EZSCAN score (0-100) was calculated using a proprietary algorithm based on the chronoamperometry analysis. We measured the score in 50 Chinese type 2 diabetes patients without DKD (urinary albumin-creatinine ratio [ACR] <2.5 mg/mmol in men or ACR <3.5 mg/mmol in women and estimated glomerular filtration rate [eGFR] >90 mL/min/1.73 m(2)) and 50 with DKD (ACR ≥25 mg/mmol and eGFR <60 mL/min/1.73 m(2)). We used spline analysis to determine the threshold value of the score in detecting DKD and its sensitivity and specificity. RESULTS: EZSCAN scores were highly correlated with log values of eGFR (r=0.67, P<0.0001) and ACR (r=-0.66, P<0.0001). Using a cutoff value of 55, the score had 94% sensitivity, 78% specificity, and a likelihood ratio of 4.2 to detect DKD with a positive predictive value of 81% and a negative predictive value of 93%. On multivariable analysis, DKD was independently associated with EZSCAN score (ß=-0.72, P=0.02), smoking status (1=never, 0=current/former) (ß=-2.37, P=0.02), retinopathy (1=yes, 0=no) (ß=3.019, P=0.01), triglycerides (ß=2.56, P=0.013), and blood hemoglobin (ß=-0.613, P=0.04). Patients without DKD but low EZSCAN score (n=10) had longer duration of disease (median [interquartile range], 13 [9-17] vs. 8 [4-16] years; P=0.017) and were more likely to have retinopathy (36.7% vs. 5.1%, P=0.02), lower eGFR (98 [95.00-103] vs. 106 [98.5-115], P=0.036), and treatment with renin-angiotensin system blockers (81.8% vs. 25.6%, P=0.002) than those with a normal score. CONCLUSION: EZSCAN may detect high-risk subjects for DKD in Chinese populations.