Data collection
A manual review of patient charts was then undertaken to confirm the diagnosis and to obtain preoperative, perioperative, and postoperative variables and outcomes. At hospital or ICU admission, we collected the following information: demographics, presence of venous-thromboembolic risk factors; Simplified Acute Physiology Score (SAPS) II9 and Sequential Organ Failure Assessment (SOFA) score10.
During the pre-ECMO period, the inotrope score11, defined as dobutamine dose (γ/kg/min) + [norepinephrine dose (γ/kg/min) + epinephrine dose (γ/kg/min)] × 100; cardiopulmonary arrest with its related “low-flow” and “no-flow” situations; and troponin level and blood gas analyses were noted. The echocardiography variables which includes; left ventricular ejection fraction (LVEF), RV/LV dimension ratio and visualization of a pulmonary arterial thrombus were also recorded before ECMO insertion. RV dysfunction (none, mild, moderate, or severe) was recorded according to a preoperative and postoperative transthoracic echocardiogram by an independent cardiologist, who both quantitatively and qualitatively assessed RV function.
The pulmonary angiography was independently reviewed for quantification of pulmonary emboli by one observer who was blinded to the clinical course. We applied an embolic burden scoring system in our study: observer scored main, lobar, right interlobar and segmental pulmonary arteries for the presence of emboli and also graded whether emboli were occlusive12.