Arteriovenous shunt fraction as a marker for early diagnosis of acute respiratory distress syndrome against the background of cardiogenic pulmonary edema: a case report

Introduction. In recent years, there has been a trend towards an increase in the use of mechanical ventilation (MV) in patients with acute myocardial infarction and cardiogenic shock. Probably, currently there is an underdiagnosis of acute respiratory distress syndrome (ARDS) against the background of cardiogenic pulmonary edema, which does not allow timely use of effective treatment strategies. We propose to use the pulmonary shunt fraction (Qs/Qt) as an additional diagnostic method.

Case. A 70-year-old male patient entered the сardiovascular intensive care unit with acute ST-segment elevation myocardial infarction complicated by cardiogenic shock. Emergency percutaneous coronary intervention 50 minutes after hospitalization allowed revascularization of the infarct-related coronary artery and 1:1 intra-aortic balloon counterpulsation was initiated. Against the background of non-invasive ventilation, paraclinical signs of severe respiratory failure persisted  — S/F (SpO₂/FiO₂): 108, PaO₂/FiO₂ (Horowitz index): 78-103, Qs/Qt: 27,3-48,3%). Therefore, MV was started. According to the obtained data (24 hours from the admission), severe ARDS was verified. Renal replacement therapy session was started for non-renal indications. On the 4th day of hospitalization, therapy improved the patient’s condition. A  63-hour session of renal replacement therapy was completed. Against the background of gradual weaning from mechanical ventilation, the patient was extubated.

Conclusion. In the above case, the use of shunt fraction (Qs/Qt) contributed to the earliest possible verification of ARDS before the onset of full-scale clinical picture, an increase in biochemical markers and X-ray abnormalities, which made it possible to start targeted therapy in a timely manner.

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