Ultrasound-Calibrated Pulse Contour Cardiac Output Monitoring: Value and Accuracy in Hemodynamic Care

This is a single-center prospective clinical study in the intensive care unit (ICU). Thirty adult patients with sepsis requiring hemodynamic monitoring and fluid resuscitation will be enrolled. All participants will undergo two hemodynamic monitoring modalities simultaneously: pulse indicator continuous cardiac output (PiCCO) (reference standard) and arterial pulse contour cardiac output (APCO, ultrasound-calibrated pulse-contour cardiac output). The study aims to evaluate the consistency of clinical decision-making for fluid resuscitation guided by APCO compared with PiCCO, and to verify the accuracy of cardiac output (CO) measured by APCO. No investigational drugs will be administered. A standardized fluid challenge will be performed based on clinical indications. Hemodynamic parameters, laboratory results, and adverse events will be collected throughout the ICU stay.

Inclusion Criteria: 1. Age ≥18 years, admitted to the intensive care unit; 2. Diagnosed with sepsis according to Sepsis-3 criteria: suspected or confirmed infection with an acute increase in SOFA score ≥2 points from baseline; 3. Requiring hemodynamic monitoring for volume assessment and fluid resuscitation due to sepsis; 4. Successfully inserted with central venous catheter and radial arterial catheter, meeting the technical requirements for PiCCO and APCO measurements; 5. Informed consent signed by the patient or legal surrogate. Exclusion Criteria: 1. Severe arrhythmia (e.g., atrial fibrillation, ventricular tachycardia) precluding pulse contour analysis; 2. Abnormal arterial access site (e.g., severe radial artery disease, arterial malformation) compromising the quality of invasive blood pressure measurement; 3. Contraindications to ultrasound examination (e.g., severe thoracic deformity, massive pleural effusion, large intrathoracic space-occupying lesion) that prevents acquisition of clear ultrasound images; 4. Contraindications for PiCCO monitoring (e.g., hemorrhagic disorders, aortic aneurysm, large-vessel vasculitis, pulmonary embolism, during extracorporeal circulation); 5. Expected ICU stay ≤ 48 hours; 6. Any other conditions judged unsuitable for enrollment by the investigator.