2014 Volume 41 Issue 2 Pages 131-138
In this study, we examined the causes and coping methods of microbubble generation during cardiopulmonary bypass(CPB)using a basic experiment and by evaluation of clinical data, and discuss the prevention of microbubble generation. In the basic experiment, mock circuit was established by using CPB components of clinical grade, and filled with bovine blood. After a regulated state of the blood had been accomplished, we mixed air using a roller pump into the blood removal circuit. Microbubbles were measured using a CMD20 microbubble counter at the inlet and outlet of the CPB components. We found that microbubbles were released regardless of the venous reservoir level for all venous blood reservoirs. Moreover, the oxygenator released microbubbles regardless of the priming volume, and the removal efficiency of the microbubbles positively correlated with pressure loss. Arrangement of the arterial filter downstream of the oxygenator resulted in a reduction of microbubbles mixed into the arterial circuit. The microbubble removal rate with the oxygenator decreased with the increase of mixed air. On the basis of these results, we next evaluated our clinical data. As with the basic experiment, microbubbles mixed into the arterial circuit were found to be increased at the start of CPB during various procedures such as right atriotomy and heart retraction. Microbubbles can enter the blood flow easily owing to their low buoyancy, and the dissolution speed is extended in the blood. Consequently, the microbubbles, which are known to cause gaseous microemboli, may influence the clinical outcomes. Therefore, during surgical procedures, specific care must be taken to prevent air from getting into the blood removal circuit of CPB.
