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Gaseous microemboli in a pediatric bypass circuit with an unprimed venous line: an in vitro study
Andrea Hudacko1, Alicia Sievert, Joseph Sistino
1Medical University of South Carolina, Charleston, South Carolina, USA. ahudacko@cnmc.org
Abstract:
Miniaturizing cardiopulmonary bypass (CPB) circuits to reduce hemodilution and allogenic blood product administration is common in cardiac surgery. One major concern associated with smaller CPB circuits is a possible increase in gaseous microemboli (GME) sent to the cerebral vasculature, which is exacerbated by vacuum-assisted venous drainage (VAVD). The use of VAVD has increased with smaller venous line diameter and venous cannulae. This study examines the effects of CPB initiation with an unprimed venous line and VAVD in a pediatric circuit. A CPB circuit was set up with reservoir, oxygenator, and arterial filter with a bag reservoir to simulate the patient. All trials were done in vitro, and GME were measured using the EDAC Quantifier by Luna Innovations. EDAC sensors were placed proximal and distal to the oxygenator and distal to the arterial filter. Group 1 was the control group with no VAVD and a primed venous line. Groups 2, 3, and 4 used an unprimed venous line and VAVD of -40, -20, and -10 mmHg, respectively. Total microemboli counts and total embolic load in micrometers were measured at each sensor. Groups 2 (12,379.00 +/- 3180.37) and 3 (8296.67 +/- 2818.76) had significantly more microemboli than group 1 (923.33 +/- 796.08, p < .05) at the pre-oxygenator sensor. Group 2 (57.33 +/- 25.01, p < .05) had significantly more microemboli than group 1 (5.33 +/- 3.21) at the post-oxygenator sensor. No other findings were statistically significant. The results suggest that, if an oxygenator and arterial filter with sufficient air handling capabilities are used, this method to reduce prime volume may not increase GME in the arterial line distal to the arterial filter.
Insights
Reducing cardiopulmonary bypass (CPB) prime volume with vacuum-assisted venous drainage (VAVD) may increase gaseous microemboli (GME) before the oxygenator. However, with adequate equipment, GME in the arterial line may not increase, ensuring patient safety.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Medical Devices
Background:
- Minimizing cardiopulmonary bypass (CPB) circuits reduces hemodilution and blood product use in cardiac surgery.
- Smaller circuits raise concerns about increased gaseous microemboli (GME) to the brain, especially with vacuum-assisted venous drainage (VAVD).
- VAVD use is rising due to smaller venous lines and cannulae.
Purpose of the Study:
- To investigate the impact of initiating CPB with an unprimed venous line and VAVD on GME in a pediatric circuit.
- To assess GME levels at various points within the CPB circuit under different VAVD pressures.
Main Methods:
- An in vitro pediatric CPB circuit model was used, simulating patient circulation.
- Gaseous microemboli were quantified using EDAC sensors placed pre- and post-oxygenator and post-arterial filter.
- Experimental groups included a control (primed line, no VAVD) and three VAVD groups (-40, -20, -10 mmHg) with an unprimed line.
Main Results:
- Significantly higher GME counts were observed pre-oxygenator in VAVD groups (-40 and -20 mmHg) compared to the control.
- GME counts post-oxygenator were significantly higher in the -40 mmHg VAVD group versus the control.
- No other statistically significant differences in GME were found at other sensor locations.
Conclusions:
- Initiating CPB with an unprimed venous line and VAVD can increase GME upstream of the oxygenator.
- The use of an oxygenator and arterial filter with effective air handling capabilities may mitigate GME increase in the arterial line.
- This strategy for prime volume reduction may be feasible without compromising arterial GME levels if appropriate equipment is utilized.
