Rapid dynamic bedside assessment of pulmonary perfusion defect by electrical impedance tomography in a patient with acute massive pulmonary embolism

Several animal studies have shown that regional lung perfusion could be effectively estimated by the hypertonic saline contrast electrical impedance tomography method. Here, we reported an application of this method to dynamically assess regional pulmonary perfusion defect in a patient with acute massive pulmonary embolism. A 68-year-old man experienced sudden dyspnea and cardiac arrest during out-of-bed physical activity on the first day after partial mediastinal tumor resection. Acute pulmonary embolism was suspected due to acute enlargement of right heart and fixed inferior venous cava measured with bedside ultrasound. The computed tomography pulmonary angiography further confirmed large embolism in both left and right main pulmonary arteries and branches. The regional time impedance curves, which were obtained by a bolus of 10 ml 10% NaCl through the central venous catheter, were then analyzed to quantitatively assess regional perfusion. Normal ventilation distribution with massive defects in regional perfusion in both lungs was observed, leading to a ventilation-perfusion mismatch and low oxygenation index (PaO₂/FiO2 = 86 mmHg) at the first day of pulmonary embolism. The anticoagulation was performed with heparin, and the patient's condition (such as shock, dyspnea, hypoxemia, etc.), regional lung perfusion defect, and ventilation-perfusion mismatch continuously improved in the following days. In conclusion, this case implies that electrical impedance tomography might have the potential to assess and monitor regional perfusion for rapid diagnosis of fatal pulmonary embolism in clinical practice.