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Medical Science Monitor Basic Research


Worsening Hypoxemia in the Face of Increasing PEEP: A Case of Large Pulmonary Embolism in the Setting of Intracardiac Shunt

Unusual or unexpected effect of treatment, Rare co-existance of disease or pathology

Glen T. Granati, Getu Teressa

USA Department of Internal Medicine, Health Science Center, Stony Brook University Hopsital, Stony Brook, NY, USA

Am J Case Rep 2016; 17:454-458

DOI: 10.12659/AJCR.898521

Available online: 2016-07-05

Published: 2016-07-05


BACKGROUND: Patent foramen ovale (PFO) are common, normally resulting in a left­to­right shunt or no net shunting. Pulmonary embolism (PE) can cause sustained increased pulmonary vascular resistance (PVR) and right atrial pressure. Increasing positive end-expiratory pressure (PEEP) improves oxygenation at the expense of increasing intrathoracic pressures (ITP). Airway pressure release ventilation (APRV) decreases shunt fraction, improves ventilation/perfusion (V/Q) matching, increases cardiac output, and decreases right atrial pressure by facilitating low airway pressure.
CASE REPORT: A 40-year-old man presented with dyspnea and hemoptysis. Oxygen saturation (SaO2) 80% on room air with A­a gradient of 633 mmHg. Post-intubation SaO2 dropped to 71% on assist control, FiO2 100%, and PEEP of 5 cmH20. Successive PEEP dropped SaO2 to 60–70% and blood pressure plummeted. APRV was initaiated with improvement in SaO2 to 95% and improvement in blood pressure. Hemiparesis developed and CT head showed infarction. CT pulmonary angiogram found a large pulmonary embolism. Transthoracic echocardiogram detected right-to left intracardiac shunt, with large PFO.
CONCLUSIONS: There should be suspicion for a PFO when severe hypoxemia paradoxically worsens in response to increasing airway pressures. Concomitant venous and arterial thromboemboli should prompt evaluation for intra­cardiac shunt. Patients with PFO and hypoxemia should be evaluated for causes of sustained right-to­left pressure gradient, such as PE. Management should aim to decrease PVR and optimize V/Q matching by treating the inciting incident (e.g., thrombolytics in PE) and by minimizing ITP. APRV can minimize PVR and maximize V/Q ratios and should be considered in treating patients similar to the one whose case is presented here.

Keywords: Disease Progression, computed tomography angiography, Cardiac Surgical Procedures, Adult, Echocardiography, Transesophageal, Foramen Ovale, Patent - surgery, Hypoxia - etiology, Oxygen - blood, Positive-Pressure Respiration - adverse effects, Pulmonary Embolism - diagnosis