Effects of Anisodamine on Sublingual Microcirculation and Vascular Waterfall Phenomenon in Patients With Septic Shock

This prospective, multicenter, single-arm, open-label interventional pilot study aims to evaluate the short-term physiological effects of intravenous anisodamine on sublingual microcirculation and vascular-waterfall parameters in adult patients with septic shock. Eligible patients will have septic shock according to Sepsis-3 criteria, will require norepinephrine support after adequate fluid resuscitation, and will be receiving invasive mechanical ventilation and PiCCO-based hemodynamic monitoring. After baseline assessment, participants will receive intravenous anisodamine according to the study protocol. Anisodamine will be administered as a loading dose of 0.5 mg/kg within 3 minutes, with a minimum dose of 20 mg and a maximum dose of 40 mg, followed by continuous infusion at 0.02-0.1 mg/kg/hour, with a maximum total daily dose of 200 mg. Sublingual microcirculatory variables, including microvascular flow index, perfused vessel density, proportion of perfused vessels, and heterogeneity index, as well as vascular-waterfall parameters, including estimated critical closing pressure, estimated mean systemic filling pressure, and the Pcc-Pmsf gradient, will be measured at baseline, 3 hours, and 6 hours after initiation of anisodamine. Systemic hemodynamic, perfusion, vasopressor, PiCCO-derived variables, and safety outcomes will also be collected. The primary objective is to characterize immediate changes in sublingual microcirculation and vascular-waterfall physiology after anisodamine administration and to provide preliminary data for future controlled studies.