Comparison of conventional extracorporeal circulation and minimal extracorporeal circulation with respect to microbubbles and microembolic signals

Abstract

The intention of minimal extracorporeal circulation (MECC) is to reduce priming volume and minimize contact of blood with polymers and air in a closed system. In contrast to conventional extracorporeal circulation (ECC), a venous reservoir is missing. Thus, air trapping is limited and avoidance of bubble embolism is a major concern. This study investigates microbubbles (MBB) number and size in the venous and arterial lines of ECC and MECC compared to the number of microembolic signals (MES) in the right and left middle cerebral artery (MCA). Twenty patients undergoing coronary surgery were operated either with conventional ECC (cardiotomy reservoir, Rotaflow pump, Quadrox oxygenator, Quart filter) or MECC (Quart filter, Rotaflow pump, Quadrox oxygenator). Number and size of MBB were monitored in the venous and arterial lines with an ultrasound Doppler system. MES in right and left MCAs were measured by transcranial Doppler (TCD) monitoring. Patients undergoing MECC had additional sealing of the venous cannula by a ligature at the site of its insertion into the right atrium. There were no significant differences between groups with respect to age, X-clamping, bypass time and number of distal anastomoses. The number of MES and MBB in the arterial line was comparable between the groups. On the venous side, MECC-perfusion shows a significantly lower number of MBB. This could be explained with the additional sealing of the venous cannula. Furthermore, our data indicate that the MBB-volume reaching the pump will also appear in the arterial outflow and into the patient's MCA. For this reason, the avoidance of air contamination is a major concern for surgeons, anaesthesiologists and perfusionists.

Cerebral Microembolization During Aortic Valve Replacement Using Minimally Invasive or Conventional Extracorporeal Circulation: A Randomized Trial

“…In contrast to these experimental and our clinical findings, a reduction of cerebral microembolic load with MiECC has been demonstrated during CABG surgery (39,40). A similar trend was observed by a group studying the incidence of retinal microembolism in patients undergoing SAVR with CECC or MiECC.…”

Clinical advantages of using mini-bypass systems in terms of blood product use, postoperative bleeding and air entrainment: an in vivo clinical perspective☆

“…Less arterial GME volume is seen in the mini-bypass system as compared to a conventional system, confirming the importance of having an active air management system on the venous side in any mini-bypass circuit. It should be noted that the same trend of GME at the outlet of the reservoir has been seen by our institution regardless of the type of open venous reservoir used [25].…”

Air Removal Efficiency of a Venous Bubble Trap in a Minimal Extracorporeal Circuit During Coronary Artery Bypass Grafting

“…In contrast, two recent studies reported a lower embolic load in patients perfused with a MECC system as compared to a conventional CPB system during CABG (10,11).…”