Clinical Impact of Computed Tomography Lung Density in Patients with Peripheral Extracorporeal Life Support Receiving Escalation of Mechanical Circulatory Support

Abstract

<h3>Purpose</h3> Peripheral veno-arterial extracorporeal membrane oxygenation (p-VA-ECMO) is an essential option for patients with cardiogenic shock, whereas several clinical issues remain due to its unphysiological hemodynamic conditions. Lung damage especially due to massive lung congestion is one of the critical complications related to p-VA-ECMO and has been also recognized as a trigger for escalation of mechanical circulatory support (MCS) using left ventricular (LV) venting. However, the prognostic impact of lung damage in patient with p-VA-ECMO has not been fully elucidated. <h3>Methods</h3> This is a single-center retrospective observational study, targeting patients with cardiogenic shock treated with p-VA-ECMO in our institution from 2013 to 2020. Fifty consecutive patients who underwent chest computed tomography (CT) on VA-ECMO followed by escalation to central ECMO with LV venting including LVAD assist devices were enrolled for this study. The average density of lung CT images [Hounsfield unit (HU)] in both upper field at the levels of bifurcation of trachea that indicates lung congestion were measured in all enrolled patients with region-of-interest methods. The primary endpoint of this study was 180-day mortality after escalation to central ECMO. <h3>Results</h3> Twenty-two patients (44%) developed primary endpoint during the follow-up period [169 (48-180) days]. According to the univariate and multivariable Cox proportional hazard analysis, age [hazard ratio (HR), 1.10; 95% confidential interval (CI), 1.05-1.18; <i>p</i> <0.001], ischemic etiology (HR, 2.91; 95% CI, 1.22-6.96; <i>p</i> =0.017) and high lung density (HR, 1.00; 95% CI, 1.00-1.01; <i>p</i> =0.004) were independently associated with the primary endpoint. Furthermore, optimal cutoff value of lung density to predict primary endpoint was determined as -481 HU. The 180-day overall survival rate after MCS escalation for patients with high lung density (≥ -481 HU) was significantly lower than that of patients with low lung density (40.0% vs. 72.0%, respectively, <i>p</i> =0.025). <h3>Conclusion</h3> This study demonstrates the important clinical implications of lung damages assessed by CT lung density as useful predictors of outcomes in patients with p-VA-ECMO requiring escalation of MCS.