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. 2013 Jun;45(2):94-106.

The effects of pressure on gases in solution: possible insights to improve microbubble filtration for extracorporeal circulation

Daniel P Herbst  1
Affiliations

The effects of pressure on gases in solution: possible insights to improve microbubble filtration for extracorporeal circulation

Daniel P Herbst. J Extra Corpor Technol. 2013 Jun.

Abstract

Improvements in micropore arterial line filter designs used for extracorporeal circulation are still needed because microbubbles larger than the rated pore sizes are being detected beyond the filter outlet. Linked to principles governing the function of micropore filters, fluid pressures contained in extracorporeal circuits also influence the behavior of gas bubbles and the extent to which they are carried in a fluid flow. To better understand the relationship between pressure and microbubble behavior, two ex vivo test circuits with and without inline resistance were designed to assess changes in microbubble load with changes in pressure. Ultrasound Doppler probes were used to measure and compare the quality and quantity of microbubbles generated in each test circuit. Analysis of microbubble load was separated into two distinct phases, the time periods during and immediately after bubble generation. Although microbubble number decreased similarly in both test circuits, changes in microbubble volume were significant only in the test circuit with inline resistance. The test circuit with inline resistance also showed a decrease in the rate of volume transferred across each ultrasound Doppler probe and the microbubble number and size range measured in the postbubble generation period. The present research proposes that fluid pressures contained in extracorporeal circuits may be used to affect gases in solution as a possible method to improve microbubble filtration during extracorporeal circulation.

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Conflict of interest statement

The author has stated that he has reported no material, financial, or other relationship with any healthcare-related business or other entity whose products or services are discussed in this paper.

Figures

Figure 1.
Figure 1.
Test circuit design showing flow direction to and from test section (test section not shown).
Figure 2.
Figure 2.
Test section (180 cm) used for experiment 1 with BCC200 probes attached.
Figure 3.
Figure 3.
Test section (180 cm) with resistor coils used for experiment 2 showingBCC200 probe positions.
Figure 4.
Figure 4.
Pressure monitoring system, showing setup to record from pressure 1 (P1).
Figure 5.
Figure 5.
Mean microbubble number and volume in microliters measured at each probe position in experiment 1.
Figure 6.
Figure 6.
Mean microbubble number and volume in microliters measured at each probe position in experiment 2.
Figure 7.
Figure 7.
Experiment 1 results for monitor 1 probe positions 1 (blue) and 2 (red). Bottom portion showing volume transfer (nL /sec) during bubble generation (gold cursor) and degassing periods (green cursor). Top portion showing histograms for bubble counts corresponding with bubble generation (gold) and degassing periods (green).
Figure 8.
Figure 8.
Experiment 1 results for monitor 2 probe positions 3 (blue) and 4 (red). Bottom portion showing volume transfer (nL /sec) during bubble generation (gold cursor) and degassing periods (green cursor). Top portion showing histograms for bubble counts corresponding with bubble generation (gold) for degassing periods (green).
Figure 9.
Figure 9.
Experiment 2 results for monitor 2 probe positions 1 (blue) and 4 (red). Bottom portion showing volume transfer (nL /sec) during bubble generation (gold cursor) and degassing periods (green cursor). Top portion showing histograms for bubble counts corresponding with bubble generation (gold) and degassing periods (green).
Figure 10.
Figure 10.
Experiment 2 results for monitor 1 probe positions 2 (red) and 3 (blue). Bottom portion showing volume transfer (nL /sec) during bubble generation (gold cursor) and degassing periods (green cursor). Top portion showing histograms for bubble counts corresponding with bubble generation (gold) and degassing periods (green).
Figure 11.
Figure 11.
Cumulative bubble counts by micron size in experiment 1 between probe positions 1 and 4.
Figure 12.
Figure 12.
Cumulative bubble counts by micron size in experiment 2 between probe positions 1 and 4.
See this image and copyright information in PMC

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