This study aims to explore the feasibility and scientific validity of carotid-jugular Doppler in evaluating volume tolerance in shock patients (with the VExUS score as an important reference standard), and to conduct an in-depth analysis of the correlation between its monitoring indicators and patient prognosis.The primary endpoint is comparison of the agreement between hands-free carotid-jugular Doppler and the VExUS score in evaluating volume tolerance.The secondary endpoint is correlation between volume tolerance assessed by hands-free carotid-jugular Doppler and the clinical outcomes of shock patients.

Inclusion Criteria:

• Shock patients admitted to the ICU are defined as those with persistent hypotension (systolic blood pressure < 90 mmHg or a decrease of ≥ 40 mmHg from the baseline blood pressure) accompanied by signs of tissue hypoperfusion.
• Age ≥ 18 years old.
• The patient or their legal representatives signed the informed consent form.

Exclusion Criteria:

• Patients with severe pulmonary circulatory disorders such as severe pulmonary hypertension and acute pulmonary embolism.
• Patients with right ventricular myocardial infarction or severe tricuspid regurgitation.
• Patients with severe neck trauma or deformity that affects Doppler examination of cervical arteries and veins, or those with anatomical contraindications preventing evaluation of at least one cervical artery or vein.
• Pregnant or lactating women.
• Patients with diseases that may interfere with abdominal ultrasound examination.

Patients admitted to the ICU