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

"This study will enroll patients with clinically suspected or confirmed acute pulmonary embolism (PE) presenting with acute respiratory failure, who undergo electrical impedance tomography (EIT) with saline contrast within 24 hours before or after computed tomography pulmonary angiography (CTPA). The EIT procedure is performed as follows:~1. Breath-Hold Maneuver: (1)Spontaneous breathing patients: Supine position, instructed to hold expiration for ≥8 seconds. (2)Mechanically ventilated patients: Expiratory hold (\>8 sec) achieved via ventilator; deeper sedation will be applied when feasible to prolong breath-hold.~2. Venous Access: (1)Preferred: Central venous catheter (internal jugular or subclavian vein).(2)Alternative: Peripheral forearm vein (preferably the median cubital vein).~3. Contrast Administration:(1)Central venous route: 10 mL of 10% NaCl.(2)Peripheral venous route: 15 mL of 5% NaHCO₃."

Patients who meet the inclusion criteria will undergo CTPA examination using conventional clinical diagnostic methods.