Differential diagnosis of alterations in arterial flow and tissue oxygenation on venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) may be life-saving in several clinical situations, but it is also one of the most invasive therapeutic procedures, with significant potential for life-threatening complications. Pulse pressure waves are typically very small or even absent at the onset of ECMO therapy, and will reappear with the improvement of cardiac function. A low pulse pressure may indicate low cardiac output due to heart failure during sustained ECMO support. A sudden loss of pulse pressure during ECMO therapy, however, may reveal complications like pericardial tamponade, hemothorax or pneumothorax. Near infrared spectroscopy (NIRS) has been shown to be useful in detecting cerebral and lower limb ischemic events during ECMO therapy and could furthermore improve differential diagnosis in the event pulsatility of the arterial pressure trace is lost.

METHODS: We are reporting on 3 different complications of ECMO and their impact on arterial pulse pressure, arterial oxygen tension and regional tissue oxygenation measured by NIRS.

RESULTS: Pericardial hematoma, overinflation of the lung, and tension pneumothorax may impede cardiac output during VA-ECMO and cause a loss of pulse pressure. Monitoring of regional tissue oxygenation using NIRS, in addition to arterial and mixed venous oxygen tension, may allow early recognition and treatment of ECMO complications.

CONCLUSIONS: Together with the appearance of a flat, non pulsatile arterial pressure trace as well as a reduction in mixed venous oxygen saturation the improvement of upper body rSO2 measured by NIRS enables timely recognition of complications that interfere with natural cardiac output during VA-ECMO.