Saline Contrast Electrical Impedance Tomography Method for Diagnosis of Acute Pulmonary Embolism

Inclusion Criteria: 1. Patients with clinically suspected or confirmed acute pulmonary embolism (PE) presenting with acute respiratory failure; 2. Availability of CTPA results within 24 hours or scheduled to undergo CTPA within the next 24 hours; 3. Age \>18 years; no gender restrictions; 4. Presence of central venous access (internal jugular or subclavian vein) or peripheral forearm venous access; 5. Willingness to participate with signed informed consent from either the patient or legal guardian. Exclusion Criteria: 1. Pregnancy or lactation; 2. Relative contraindications to EIT examination (e.g., chest wall wounds at electrode belt placement site, presence of pacemakers); 3. Severe hypernatremia (serum sodium \>155 mmol/L); 4. Inability to maintain expiratory breath-hold for ≥8 seconds; 5. BMI \>50 or severe thoracic deformities; 6. Current extracorporeal membrane oxygenation (ECMO) therapy.