Application of Micropore Filter Technology: Exploring the Blood Flow Path in Arterial-Line Filters and Its Effect on Bubble Trapping Functions.
Conventional arterial-line filters commonly use a large volume circular shaped housing, a wetted micropore screen, and a purge port to trap, separate, and remove gas bubbles from extracorporeal blood flow. Focusing on the bubble trapping function, this work attempts to explore how the filter housing shape and its resulting blood flow path affect the clinical application of arterial-line filters in terms of gross air handling. A video camera was used in a wet-lab setting to record observations made during gross air-bolus injections in three different radially designed filters using a 30-70% glycerol-saline mixture flowing at 4.5 L/min. Two of the filters both had inlet ports attached near the filter-housing top with bottom oriented outlet ports at the bottom, whereas the third filter had its inlet and outlet ports both located at the bottom of the filter housing. The two filters with top-in bottom-out fluid paths were shown to direct the incoming flow downward as it passed through the filter, placing the forces of buoyancy and viscous drag in opposition to each other. This contrasted with the third filter's bottom-in bottom-out fluid path, which was shown to direct the incoming flow upward so that the forces of buoyancy and viscous drag work together. The direction of the blood flow path through a filter may be important to the application of arterial-line filter technology as it helps determine how the forces of buoyancy and flow are aligned with one another.
Pre-clinical laboratory evaluation of the new ‘AF’ arterial line filter range
Introduction: The presence of emboli was recognised relatively early in the history of open heart surgery. The emboli produced during cardiopulmonary bypass have the predisposition to distribute into, and ultimately obstruct, microvessels of all tissues. The Sorin Group has recently developed a new range of arterial line filters. Before the Sorin AF range of filters was released for pre-launch clinical trials, our group performed in vitro laboratory testing of the AF range against a selection of commercially available filters on the global market. Results: The Sorin AF620 and AF640 demonstrate both the smallest prime volume and smallest surface contact area (92ml and 290cm2, respectively).The results of the GME Handling Efficiency experiments ranged by 39.6%, from 95.9% to 56.3%. In terms of an air bolus handling, the results of the Limit Bolus experiment ranged by 97ml, from 147.5ml down to 50ml. The pressure drop across all the filters was measured under steady state experimental conditions. All of the above investigations were considered against surface area and prime volume. Conclusion: It is clear from the results that some commercially available arterial line filters perform better than others, not only in overall performance, but also with regard to individual characteristics. Evaluating arterial line filters for hospital-specific use has to balance pressure drop, surface area, micro air handling, prime volume and gross air handling; all points need to be considered. In the AF620 and AF640, Sorin boast that they are the two smallest prime and smallest surface area filters commercially available on the global market. The Sorin AF filter range performs well in all of the areas we investigated and will be a competitive option for centres, irrespective of which characteristics they use to evaluate and select their arterial line filter.
Randomized trial of the Terumo Capiox FX05 oxygenator with integral arterial filter versus Terumo Capiox Baby RX05 and Terumo Capiox AF02 arterial filter in infants undergoing cardiopulmonary bypass.
UNLABELLED
The purpose of this clinical trial was to evaluate the effect of the Terumo Capiox FX05 oxygenator with integrated arterial filter during cardiopulmonary bypass (CPB) compared with the Terumo Capiox RX05 Baby RX and arterial filter on inflammatory mediators and blood product utilization. Forty patients weighing less than 10 kg who underwent congenital heart surgery utilizing cardiopulmonary bypass were randomized into either oxygenator group. The endpoints included measuring inflammatory markers at six different time points (preoperative baseline, CPB circuit being primed, 15 minutes after CPB initiation, status post protamine administration, prior to transport to intensive care unit, and within 12 to 24 hours post surgery), blood product utilization, extubation time, and days until discharge. The inflammatory mediators showed no significant differences between oxygenators at any time points. However, looking at the inflammatory mediators of both the FX and RX groups combined, a statistically significant difference was seen in interleukin (IL)-6 at 12/24 hour post surgery (p < .001) versus baseline and all other time points. IL-8 at status post protamine (p < .001) and 12/24 hours post surgery (p < .001) demonstrated significant differences versus all other time points, and IL-10 at status post protamine (p < .001) and prior to leaving the operating room (p < .001) were statistically different compared to all other time points. Cardiopulmonary bypass stimulates the systemic inflammatory response through various components of the extracorporeal system. This investigation did not find significant differences in cytokines interferon-gamma, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12 p70, tumor necrosis factor (TNF)-alpha, and TNF-beta when comparing these two oxygenators. It is well known that various mechanisms contribute to the levels of cytokines circulating in a patient's blood volume and many manipulations throughout cardiac surgery have the ability to demonstrate anti-inflammatory interventions. Further investigation is needed as to how modification of the extracorporeal circuit may minimize increases in inflammatory mediators.


KEYWORDS
infant, bypass, cytokines, blood, infant perfusion strategy.