The Journal of ExtraCorporeal Technology No 58-1 | Page 74

68 T. Benedict et al.: J Extra Corpor Technol 2026, 58, 65--72

Table 1. Median GME count by test type( N = 50).

trial when 1LPM of flow was obtained. All trials were conducted at 37 ° C for 3 min with an arterial line pressure between 130 and 150 mmHg. A flow of 5 LPM was acquired within 10 s of initiation, regardless of the initiation technique. EDAC sensors were placed post-reservoir, post-oxygenator, and posthypobaric oxygenator for every trial for GME measurements. Each trial was reset by clamping the arterial outlet of the oxygenator and forcing volume through the cardioplegia port and into the Medtronic reservoir until volume levels were back to baseline.

Trial groups

The first 10 trials were the control trials. These trials underwent the“ Instant Initiation” technique, with no negative pressure on the venous reservoir and a primed venous line. The second set of 10 trials used a dry venous line with instant initiation and a pressure of �20 mmHg on the venous reservoir(“ I( �20)”). The third set of 10 trials had the dry venous line with Instant Initiation and a pressure of �40 mmHg on the venous reservoir(“ I( �40)”). The fourth set of 10 trials had the dry venous line with delayed initiation and a pressure of �20 mmHg on the venous reservoir(“ D( �20)”). The fifth set of 10 trials had the dry venous line with delayed initiation and a pressure of �40 mmHg on the venous reservoir(“ D( �40)”).

Data analytic strategy

With the EDAC recording during the 3-minute circulation time, GMEs were counted by size and quantity in strategic locations on the circuit. The post-venous reservoir sensor counted and sized GME coming in from the venous line. The sensor post-oxygenator counted and sized GME, leaving the Inspire 8F oxygenator, which is indicative of GME transmission to the patient. The third sensor post-hypobaric oxygenator was necessary for reassurance that GME was exiting the circuit and that no GME was double counted in the trials. The measurements obtained from the EDAC were extrapolated into a data file and compared across a variety of analytical tests.

The results for all trials at each EDAC sensor location include average total GME count and size after 3 min of circulation; however, most GME detection occurred within the first few seconds of the trial. Given the small sample sizes and nonnormal distribution of data, differences were evaluated using the nonparametric Kruskal-Wallis test. To assess pairwise differences, the Dwass, Steel, Critchlow-Fligner( DSCF) test was conducted to adjust P-values to account for multiple comparisons. The level of significance was assessed at 5 %. Data was analyzed using SAS 9.4( SAS Institute, Cary, NC).

Figure 2. Distribution of post-oxygenator GME count by initiation type.

Table 2. Pairwise comparisons of median GME count by initiation type( N = 50).

* Dwass, Steel, Critchlow-Fligner( DSCF) test.

Results

The distribution of average post-oxygenator GME count varied across different experimental conditions, with a median count of 6.0 for control to 390.5 for I( �40). The highest counts were observed occurring consistently at pressures of �40 mmHg within instant and delayed initiation groups( Table 1). When comparing the average post-oxygenator GME count based on initiation types( Figure 2), there was a statistically significant difference in median count between types( p < 0.001). In post-hoc analyses via post oxygenator( Table 2), statistically significant differences were found between median GME counts in control vs. instant( 6.0 vs. 322.5, respectively; p < 0.0001), in control versus delayed( 6.0 vs. 177.0, respectively; p < 0.0001), and in instant vs. delayed( 322.5 vs. 177.0, respectively; p = 0.0275). Further analysis comparing GME counts across the different pressures post oxygenator( Figure 3) found there was a statistically significant difference in median GME count between pressures( p < 0.001). Posthoc analyses showed statistically significant differences between median GME counts in control vs. �20 mmHg( 6.0 vs. 193.0, respectively; p < 0.0001) as well as between control versus �40 mmHg( 6.0 vs. 338.5, respectively; p < 0.0001). However, no statistically significant differences were observed between �20 mmHg and �40 mmHg conditions( Table 3).

The distribution of post-oxygenator GME volume varied across different experimental conditions( Table 4). The median volume of 0.13 10 �7 for control, whereas the I( �40) condition had a median volume of 43.00 10 �7. Consistent with findings in GME counts, the highest GME volumes were observed at pressures of �40 mmHg within the instant and