Effects of bubble size differences on the bubble-trapping performance of arterial line filters

Abstract

Microbubbles inside a cardiopulmonary bypass circuit are captured by a venous reservoir or by the artificial lung, and ultimately, an arterial line filter (ALF) prevents gaseous micro-emboli (GME) from getting injected into the patient’s body. In our study using ALFs with pore sizes of 40 μm (PS40) and 20 μm (PS20), bubbles with a mean bubble diameter of 50 μm, 100 μm, and 180 μm were injected into the ALF. Arterial line filter GME removal was examined using different bubble sizes.

In the bubble group with various bubble sizes, the number of bubbles and the rate of bubble removal were determined for 50 μm bubbles (PS40=44.5±0.7%, PS20=56.1±0.6%, P<0.001), 100 μm bubbles (PS40=13.7±1.9%, PS20=9.9±3.8%, P=0.205), and 180 μm bubbles (PS40=-7.0±1.5%, PS20=-29.3±1.8%, P<0.001). Air bubble shrinkage and bubble volume removal rates were significantly higher with PS20.

The bubble’s internal pressure becomes lower as the bubble size is larger, which suggests that air bubbles can easily change shape and disrupt. This suggests that GME removal capability increases when all microbubbles that flow into the ALF are maintained at a diameter of 40-50 μm or less.