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

This prospective, multicenter, single-arm interventional pilot study aims to evaluate the short-term physiological effects of intravenous esmolol on sublingual microcirculation and vascular-waterfall parameters in adult patients with septic shock. Eligible patients will have septic shock according to Sepsis-3 criteria, persistent tachycardia after initial hemodynamic optimization, ongoing norepinephrine support, adequate volume status or absence of significant fluid responsiveness, and preserved or hyperdynamic cardiac function. Approximately 20 patients will be enrolled from participating intensive care units. After baseline assessment, participants will receive continuous intravenous esmolol infusion according to the study protocol and clinical safety criteria. 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 and at 3, and 6 hours after esmolol initiation. Additional systemic hemodynamic, perfusion, vasopressor, and safety variables will also be collected. The primary objective is to characterize immediate changes in sublingual microcirculation and vascular-waterfall physiology after esmolol administration and to provide preliminary data for the design of future controlled studies.