Gaseous microemboli have been associated with post operative neurological deficits in patients undergoing cardiopulmonary bypass. Creating an optimal perfusion system that minimizes microemboli production and has enhanced abilities to sequester entrained air during the bypass procedure has been an important focus. This study examines the air-handling capabilities of a cardiopulmonary bypass circuit and correlates blood temperatures with microemboli loads proximal and distal to the arterial line filter within the circuit. Utilizing a Capiox RX25R oxygenator, Capiox 37 micron arterial filter, vacuum assisted venous return, and emboli detectors, 30 mL of air were injected into the venous line of a bypass circuit at eight different temperatures. Emboli were counted distal to the arterial line filter by the EDAQ® Quantifier (Emboli Detection and Classification). The average number of emboli detected distal to the arterial filter progressively increased as the perfusate temperature was dropped. At 37.0°C an average of 1.4 emboli was observed distal to the arterial filter within 90 seconds of the air injection. At 23.0°C an average of 49.8 emboli was detected. Air introduced into the venous side of the bypass circuit resulted in showers of microemboli being sent past the arterial line filter. In addition, as the bovine blood was cooled, the air handling capability of the circuit was diminished.
Numerous researchers and clinicians have shown that cardiopulmonary bypass (CPB) plays a large role in the initiation of the systemic inflammatory response during cardiac surgery. The activation of leukocytes during this process has been implicated as one of the major contributors to multi-organ dysfunction experienced by some patients after cardiac surgery. Thus, in an attempt to attenuate the systemic inflammatory response and to reduce the amount of activated leukocytes from the systemic circulation during CPB, leukocyte-depleting filters were developed in the early 1990s. Since the clinical introduction of these filters into the CPB circuit, several articles have been published evaluating the effectiveness of leukocyte filtration; however, the results have been conflicting. This article will review some of the most recent literature, ∼40 papers published within the past 10 years, regarding the use of leukocyte-depleting filters during CPB and its effectiveness in preserving organ function. In addition, the effect of different filtration strategies and the effectiveness of the filter to attenuate the systemic inflammatory response in combination with other mechanical and pharmaceutical strategies will be reviewed.
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 non-coated. 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.
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