Electrochemical skin conductance is associated with peripheral tissue hypoperfusion in septic patients.

Background: Autonomic nervous system (ANS) dysfunction contributes to the pathophysiology of sepsis. However, studies using reliable methods for ANS activity monitoring and evaluating its association with outcomes in sepsis patients are scarce. The Sudoscan^® device offers a non-invasive method to evaluate sympathetic function by measuring electrochemical skin conductance (ESC), but its clinical relevance in sepsis remains unclear. This study aimed to assess autonomic sympathetic activity in septic patients using the Sudoscan^® technology and explore its relationship with peripheral perfusion and outcomes.

Methods: This prospective, observational, single-center study included 97 consecutive adult ICU septic patients without or with shock. Sudoscan^® measurements were performed at admission and serially for 72 h, alongside standard hemodynamic and peripheral perfusion assessments (e.g., knee capillary refill time [CRT], mottling, cardiac output). Associations between ESC ("sudoscore"), clinical parameters, and mortality at day-28 were analyzed.

Results: Of the 97 septic patients included, 37% had shock. Mottling was frequent (53%), and mean knee CRT was 3.3 ± 2.5 s. The mean admission Sudoscore was 31.2 ± 21 µS and was significantly higher in patients with peripheral perfusion abnormalities, such as mottling compared to no mottling (35.7 ± 21 vs 28.5 ± 19.5 µS, P = 0.04) and prolonged knee CRT > 5 s compared to CRT < 5 s (44.2 ± 25 vs 29.6 ± 18.6 µS, P = 0.03). Additionally, Sudoscore positively correlated with CRT (P = 0.01, R = 0.27). There was no difference in Sudoscore between patients receiving vasopressors or not, and between patients receiving sedative drugs or not. Longitudinally, the Sudoscore course was significantly lower over the first 72 h in survivors compared to non-survivors (P = 0.04, two-way ANOVA mixed model effect).

Conclusion: Electrochemical skin conductance measured via Sudoscan^® may serve as a surrogate marker of autonomic sympathetic hyperactivation during sepsis and is associated with peripheral circulatory impairment. Although admission values were not independently predictive of mortality, elevated and persistently high Sudoscores are associated with death at day 28. Sudoscan^® may offer a non-invasive window into sympathetic activity during septic shock and warrants further investigations.