Hemodynamic Responses to Fluid and Vasopressor Resuscitation Strategies in Experimental Septic Shock: A Randomized Porcine Model Research Protocol

Introduction Septic shock is a condition resulting from an uncontrolled immune response to infection, leading to multi-organ failure. Fluid resuscitation is the primary initial therapy, but an aggressive approach risks fluid overload and increased extravascular lung water (EVLW). To date, direct comparative evidence between fluid-based resuscitation strategies, vasopressors, or a combination of both on hemodynamic changes is limited. This study aims to compare hemodynamic responses to three resuscitation strategies in a randomized porcine model of endotoxin-induced septic shock. Methods This experimental protocol will include 15 male Sus scrofa domestica aged 16–20 weeks and weighing 40–60 kg, together with three non-septic controls as described in the source protocol. Septic shock will be induced by intravenous lipopolysaccharide from Escherichia coli O111:B4 until mean arterial pressure falls below 65 mmHg. Animals will be randomized to fluid-first, vasopressor-first, or combined resuscitation. Subjects were stratified into three groups: fluid first, vasopressor first, and combined. The main parameters assessed were MAP ≥65 mmHg, hemodynamic parameters (MAP, CI, SVRI, SVI, GEDVI, ELWI), laboratory biomarkers and oxygen transport parameters (DO2 and CaO2). Statistical analyzes were performed according to data distribution at a significance level of p<0.05. This study is expected to provide mechanistic understanding of the interaction between intravascular volume, vascular tone, and tissue perfusion in septic shock. Anticipated limitations include intersubject variation in intravascular volume and a relatively small sample size. Conclusion This protocol aims to generate controlled experimental data of interaction between intravascular volume, vascular tone and tissue perfusion in septic shock.