Gaseous Micro-Embolic Activity and Goal-Directed Perfusion Management in a Closed System for Cardiopulmonary Bypass and Minimally Invasive Extracorporeal Circulation during Coronary Artery Bypass Grafting

Background: Cardiopulmonary bypass (CPB) techniques are becoming minimally invasive in clinical practice. The literature describes various extracorporeal techniques which seek to eliminate air-blood contact and reduce both hemodilution and the contact surface such as in Minimally invasive Extracorporeal Circulation (MiECC) and closed systems for CPB. However, the delivery of micro-embolic activity in the circuit and metabolic activity in terms of oxygen delivery for Goal-Directed Perfusion (GDP) management, in relation to the patient's blood volume and central venous pressure, have never been related and correlated. In this report, we present a cohort study that investigated these aspects between the closed SVR2000 System and modular MiECC (both from Eurosets SRL, Medolla, Italy). Materials and Methods: Data were collected retrospectively and used to compare 60 consecutive patients who underwent isolated coronary artery bypass grafting (CABG) surgery by two surgeons using an SVR2000 oxygenator in 30 procedures, with a matched cohort of patients from the same period who underwent isolated CABG surgery by two other surgeons using a modular MiECC in 30 procedures. The primary endpoints collected were data on micro-embolic activity, including the number of gaseous micro-emboli in the circuit during the procedure, the mean maintenance value of oxygen delivery (DO2) and data relating to venous return volume and central venous pressure (CVP). Results: During the CPB procedures, the following values were recorded for the closed SVR2000 and MiECC groups, respectively: the average number of gaseous micro-emboli (GME) in the venous line, 833 ± 23 vs 1221 ± 45 (p = 0.028); GME in the outlet of the pump, 375 ± 45 vs 429 ± 76 (p = 0.89; GME in the arterial line, 189 ± 36 vs 205 ± 27 (p = 0.92), and the volume of GME in the arterial line (mL), 0.32± 12 vs 0.49± 17 (p = 0.93). The mean Indexed Oxygen Delivery (DO2i) during cross-clamp (ml/min/m2) was 319 ±12 vs 278 ±9 (p = 0.0019), respectively. The maximum mean volume of venous return in the soft-shell venous reservoir (ml) was 1801 ±128 vs 824 ±192 (p = 0.038). The mean central venous pressure (CVP) during cross-clamp (mmHg) was 0 ± 2 vs 6 ± 2 (p = 0.019). Conclusions: In this study, the results in the closed SVR2000 group were not statistically inferior to those in the modular MiECC group in terms of gaseous micro-embolic activity during CPB. Our analysis showed an important reduction of GME delivery in both systems. The closed SVR2000 group showed better management for GDP in terms of DO2i, associated with the flexibility of dynamic volume management and the absence of cavitation and regulation of the rate per minute and pump flow, which were reported in the MiECC group. The SVR2000 and modular MiECC systems were both safe and effective in perioperative practice without iatrogenic problems.