Severe lung dysfunction and pulmonary blood flow during extracorporeal membrane oxygenation

Background: Extracorporeal membrane oxygenation (ECMO) is indicated for patients with respiratory and/or circulatory failure. The standard technique to visualize the extent of pulmonary damage during ECMO is computed tomography (CT). Purpose: This single centre retrospective study aimed to investigate whether pulmonary blood flow (PBF) measured with echocardiography may assist in the assessment of the extent of pulmonary damage and whether echocardiography and CT findings are associated with patient outcome. Methods: All patients (>15 years of age) commenced on ECMO between 2011 and 2017 with septic shock with a pulmonary origin, and a treatment time >28 days were screened. Of 277 eligible patients, nine were identified where both CT and echocardiography had been consecutively performed. Results: CT failed to indicate any differences in viable lung parenchyma within or between survivors and non-survivors at any time over the course of ECMO. At initiation of ECMO the survivors (n=5) had a mean PBF of 3.8 L/min and the non-survivors (n=4) 3.5 L/min, p=0.78. Survivors showed no change over time concerning PBF (3.8±2.1 at ECMO start vs. 7.9±4.3 L/min at the end of treatment, p=0.12). The non-survivors showed a significant deterioration in PBF from the ECMO start to the end of support (3.5±1.0 L/min vs. 1.0±1.1, respectively, p=0.029). Conclusions: Although CT is widely used to examine pulmonary viability and recovery, our results do not support CT as a prognostic tool. However, this hypothesis-generating investigation supports echocardiography as a tool to predict pulmonary recovery via assessment of PBF at early to later stages of ECMO treatment. Prospective studies are needed.