An In Vitro Study of the Effectiveness of Carbon Dioxide Flushing of Arterial Line Filters

Abstract: Gaseous microemboli (GMEs) have been connected to neurologic impairment and other ischemic complications after surgery. The components of the extracorporeal circuit (ECC) have a large influence on GME production. This in vitro study investigates the use of carbon dioxide flushing of the 38-μm Medtronic Affinity CB351 and 38-μm Medtronic Affinity 351 arterial line filters (ALFs) to decrease GMEs and time for air to clear the ALF. An adult circuit was implemented with a silicone oxygenator for vacuum-assisted gas removal and to reduce air before ALF. The 48 filters were separated into four equal groups: flushed coated and non-coated and non-flushed coated and noncoated. Carbon dioxide flushing was performed at 6 L/min for 3 minutes. ALFs were retrograde primed at 200 mL/min. An Emboli Detection and Classification Quantifier (EDAC) was used to gather data. The average total emboli and time to clear (seconds) for flush coated were 20.25 ± 16.78 and 142.17 ± 174.80 seconds, respectively, flushed non-coated were 30.5 ± 34.65 and 124.17 ± 131.40 seconds, non-flushed coated were 162.08 ± 79.90 and 390.42 ± 84.36 seconds, and non-flushed non-coated were 163.67 ± 212.67 and 305.92 ± 179.36 seconds. Flushed filters had an average total emboli count of 25.375 ± 27.14 and an average time to clear of 133.167 ± 151.51 seconds. Non-flushed filters had an average total emboli count of 162.875 ± 157.11 and an average time to clear of 348.167 ± 143.70 seconds. Coated and non-coated filters for total emboli and time to clear had p values of .86 and .24, respectively. Flushed and non-flushed filters had total emboli and time to clear p values of <.001 and <.001, respectively. No significant difference was found between coated and non-coated filters involving total embolic count and time to clear. A significant difference was found in total embolic count and time to clear between flushed and non-flushed filters. This study shows that fewer emboli and faster embolic clearance time correlate with carbon dioxide flushing of the ALF.