Gaseous microemboli reduction during cardiopulmonary bypass Impact of extracorporeal circuit design

During cardiac surgery using cardiopulmonary bypass (CPB) procedures, gaseous microemboli (GME) can originate from the extracorporeal circuit into the arterial bloodstream. These GME are thought to contribute to the adverse outcomes of cardiac surgery. The blood-air surface of GME can activate the complement system. In addition, GME may damage the endothelium and obstruct the blood flow in the capillary vessels, causing transient ischaemia of end-organs.
This thesis addresses the air removal properties of entire CPB circuits, their designs and their specific components. Besides, the clinical effects of GME on the cardiac patient are studied.
We conclude that, the source of GME is mainly caused by perfusionist interventions such as blood sampling, transfusing volume or injecting drugs, which means that almost all air is introduced into the venous side of the CPB system. Subsequently, air is reduced and fractionated by the different components of the CPB system. We suggest that the air removal properties of CPB systems may be best improved by adding an effective venous filter, which scavenges air before it is fractionated. Besides, with an oxygenator with excellent air removal properties, arterial filters could be omitted from the CBP circuit.
Micro-emboli seem to play a minor role in the adverse effects of present-day CPB, which is probably caused by the extremely small size of the GME released from the CPB circuit. However, more studies are warranted to compare the GME release of other CPB systems, which are used worldwide, with the CPB systems as used in our studies.