T. Rath et al.: J Extra Corpor Technol 2026, 58, 19 – 31 25
Table 3. Statistical analysis for the“ venous” GME sensor for all test reservoirs combined. This shows post-hoc comparisons of the average difference in GME number by reservoir level( 200 mL, 500 mL, 1,000 mL) at a constant suction speed of 25 RPM( 0.32 L / min), 50 RPM( 0.65 L / min), 75 RPM( 0.99 L / min), and 100 RPM( 1.32 L / min). Statistically significant differences are denoted by p <. 05 and are shown in bold, with adjustments made using the Tukey HSD method.
Suction speed |
Reservoir level 1 |
Reservoir level 2 |
Difference in average GME number |
Adjusted P-value |
25 RPM |
200 mL |
500 mL |
814.793 |
0.999 |
25 RPM |
500 mL |
1000 mL |
234.391 |
1 |
25 RPM |
200 mL |
1000 mL |
1049.184 |
0.994 |
50 RPM |
200 mL |
500 mL |
2117.522 |
0.528 |
50 RPM |
500 mL |
1000 mL |
745.217 |
1 |
50 RPM |
200 mL |
1000 mL |
2862.739 |
0.109 |
75 RPM |
200 mL |
500 mL |
4056.981 |
0.002 |
75 RPM |
500 mL |
1000 mL |
2765.044 |
0.164 |
75 RPM |
200 mL |
1000 mL |
6822.024 |
0 |
100 RPM |
200 mL |
500 mL |
4784.544 |
0 |
100 RPM |
500 mL |
1000 mL |
5979.913 |
0 |
100 RPM |
200 mL |
1000 mL |
10764.457 |
0 |
and 200 – 1000 mL. At a suction speed of 100 RPM, all changes in level produced significant differences in bubble numbers.
Arterial GME count
Summary statistics describing the total number of GME measured over 3 min( 180 s) by the“ arterial” sensor are presented( Figure 5), accompanied by a box plot illustrating data from all reservoirs tested( Medtronic Affinity Fusion, LivaNova SORIN Inspire 8F, and Terumo CAPIOX FX25) combined. Box plots were made to visualize the group differences in mean and variability. The independent variables, four suction flow rates( 25 RPM( 0.32 L / min), 50 RPM( 0.65 L / min), 75 RPM( 0.99 L / min), and 100 RPM( 1.32 L / min) and three reservoir levels( 200, 500, 1000) mL are shown on the x-axis with GME number on the y-axis. Note the scaling difference between Figures 4 and 5: the amount of GME flowing past the arterial sensor( post-oxygenator / arterial filter) was significantly less than that found with the venous sensor( post-reservoir).
As with the venous GME number, this data was not statistically normal; however, given the large sample size of 284 observations, a two-way ANOVA was used to statistically evaluate GME number differences between suction flow rates and reservoir levels. Unlike the venous GME sensor, the data from the arterial GME sensor revealed no statistical interaction between suction flow rate and reservoir level( p-value = 0.9946) or between reservoir level and GME count( p-value = 0.2919). Changes in suction flow rate overall( 25 – 100 RPM) did, however, affect the GME number from the arterial sensor( p-value = 0.0005).
Table 4 shows the post hoc comparisons using Tukey HSD to compare suction flow rates. The adjusted p-values in bold are statistically significant, with an adjusted p-value of less than 0.05. Significant differences in average bubble number were only noticed between 25 – 100 RPM and 50 – 100 RPM.
GME size analysis
Venous and arterial GME size and amount were recorded for all reservoir types( Medtronic Affinity Fusion, LivaNova
SORIN Inspire 8F, and Terumo CAPIOX FX25), levels( 200 mL, 500 mL, and 1,000 mL) and suction flow rates( 25 RPM( 0.32 L / min), 50 RPM( 0.65 L / min), 75 RPM( 0.99 L / min) and 100 RPM( 1.32 L / min)) for all trials. The total venous( Figure 6A) and arterial( Figure 6B) GME data were categorized by size, ranging from 0 to 300 lm, and averaged across all 25 trials.
Discussion Summary of findings
One of this project’ s goals was to develop an in vitro model that is both explanatory and predictive of GME presence and transmission in a cardiopulmonary bypass circuit. After completing 25 trials and examining the resultant data, the model described in this study helped explain how varying“ circulation factors,” as designated by Miyamoto et al. [ 36 ], can influence a measurable consequence( GME count). This study focused on the influence of two factors; however, the developed model can be adapted to many experimental protocols.
Another goal of this study was to replicate previous investigations examining the relationship between two modifiable interventions – suction speed and reservoir level – and their influence on GME count measured in both venous( postreservoir) and arterial( post-oxygenator) lines. We selected disposable components from three manufacturers commonly used in the United States today and the state-of-the-art bubble counter( Gampt BCC300) to enhance the applicability to current perfusion practice.
When keeping other“ circulation factors” constant, we found that both reservoir level and suction speed influenced GME count, as measured by the venous( post-reservoir) and arterial( post-oxygenator) sensors. Notably, we found a statistical interaction between these variables at the venous sensor, indicating that suction speed and level interact combinatorially. The effect of suction speed influenced the impact of the level and vice versa. This suggests, in a general sense, that as the reservoir level lowers, it would be prudent to monitor closely and, if possible, minimize suction speed to prevent