This prospective single-center clinical trial aims to evaluate the circulatory and microcirculatory effects of Shenfu Injection in patients with septic shock. The study focuses on the vascular waterfall phenomenon, which describes the relationship between arterial and venous pressures in the microcirculation.

Eligible participants with septic shock will receive an intravenous infusion of 100 mL Shenfu Injection (manufactured by China Resources Sanjiu Pharmaceutical Co., Ltd.). Hemodynamic and oxygen metabolism parameters will be measured before and 3 hours after treatment. The main goal is to determine whether Shenfu Injection influences the vascular waterfall difference, expressed as the gap between critical closure pressure and mean systemic filling pressure.

This study will also record changes in cardiac index, systemic vascular resistance, blood lactate, venous oxygen saturation, and norepinephrine requirement. Findings will provide preliminary clinical evidence about the role of Shenfu Injection in circulatory regulation during septic shock and help design future randomized controlled studies.

his prospective single-center interventional pilot study aims to evaluate the hemodynamic and microcirculatory effects of Shenfu Injection in septic shock patients, focusing on the vascular waterfall phenomenon quantified by Critical Closure Pressure (Pcc) and Mean Systemic Filling Pressure (Pmsf).

After achieving hemodynamic optimization according to Surviving Sepsis Campaign guidelines, qualified participants will receive a single intravenous infusion of 100 mL Shenfu Injection, diluted and administered over 1 hour. Hemodynamic and oxygen metabolism parameters will be recorded at baseline (within 30 minutes before infusion) and 3 hours after infusion.

Pcc and Pmsf will be determined using the inspiratory hold maneuver method via ventilator (plateau pressures of 5, 15, 25, and 35 cm H₂O). Ventricular Output (VO) and Venous Return (VR) curves will be constructed, and linear regression will yield intercepts representing Pcc and Pmsf.

The primary analysis will compare pre- and post-infusion Pcc-Pmsf differences to determine restoration or augmentation of the vascular waterfall phenomenon. Secondary parameters such as CI, SI, MAP, CVP, ScvO₂, Pcv-aCO₂, and blood lactate will be observed to evaluate overall circulatory and metabolic response.

nclusion Criteria Septic shock diagnosed according to Sepsis-3 criteria after adequate fluid resuscitation.

Age ≥ 18 years. Within 24 hours of ICU admission. Receiving norepinephrine ≥ 0.10 µg/kg/min to maintain mean arterial pressure ≥ 65 mmHg.

Hemodynamically stable without vasopressor dose adjustment for ≥ 30 minutes before baseline measurement.

Endotracheal intubation with controlled mechanical ventilation under continuous sedation and analgesia.

Presence of both arterial and central venous catheters with PiCCO monitoring capability.

Written informed consent obtained from the patient or legally authorized representative.

Exclusion Criteria Cardiogenic shock as primary diagnosis or cardiac index < 2.2 L/min/m² after optimization.

Severe pulmonary bullae, pneumothorax, or conditions precluding safe inspiratory hold maneuvers.

Pregnancy or lactation. Expected ICU stay < 48 hours or limitation of life-sustaining therapy. Known allergy or contraindication to Shenfu Injection or its ingredients (e.g., ginseng, aconitum).