Circulatory collapse, right ventricular dilatation, and alveolar dead space: A triad for the rapid diagnosis of massive pulmonary embolism

A triad of circulatory collapse, right ventricular dilatation, and large alveolar dead space is proposed for the rapid diagnosis and treatment of massive pulmonary embolism. A 17 year-old female on oral contraceptives collapsed at home becoming incoherent with shallow breathing. Paramedics initiated mechanical chest compression and transported the patient to our emergency department, arriving minimally responsive with undetectable blood pressure but having positive corneal reflexes and bradycardia with wide QRS. The trachea was intubated and goal-directed echocardiography revealed marked right ventricular dilatation with septal flattening. The arterial PCO2 was 40 mmHg with an end-tidal PCO2 of 8 mmHg, revealing a large alveolar dead space. Persistent hypotension, bradycardia, and fading alertness despite epinephrine and norepinephrine infusions prompted resumption of chest compression. Intravenous alteplase (10 mg bolus over 10 min followed by 90 mg over 110 min) begun 125 min after collapse improved hemodynamic function within 10 min allowing discontinuation of chest compression. Five and a half hours after starting alteplase, the patient was hemodynamically stable and had normal end-tidal PCO2. A CT-angiogram showed the pulmonary arteries free of emboli but a thrombus in the right common iliac vein. The patient recovered fully and was discharged home on warfarin 8 days later. Based on this and other reports, we propose a triad of circulatory collapse, right ventricular dilatation, and large alveolar dead space for the rapid diagnosis and treatment of massive pulmonary embolism, with systemic fibrinolysis as the first-line intervention.