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An in vitro quantitative analysis of gaseous microemboli production using a centrifugal pump in pulsatile mode / Kirsten Kallies.

by Kallies, Kirsten

Centrifugal pumps

Blood -- Circulation, Artificial

159 leaves : ill. ; 29 cm.

Thesis advisor: Dr. Samantha Richerson

Committee members: Dr. Larry Fennigkoh, Scott M. Brown

Introduction -- Background -- Materials and methods -- Results -- Discussion and conclusions -- Future recommendations -- A: Milwaukee School of Engineering IRB documents -- B: BloodCenter of Wisconsin, Inc. IRB documents -- C: Raw data -- D: Full statistical results.

A significant amount of research has been dedicated to the debate over the benefits of pulsatile perfusion. Similarly, much research has focused on the debate over which type of arterial pump head should be utilized for cardiopulmonary bypass (CPB) -- roller pump or centrifugal pump. However, no experiments have combined these two highly debated areas in order to study the possibility of air production when a centrifugal pump is used to impart pulsatile perfusion. Therefore, the purpose of this experiment was to employ a pulsatile waveform architecture in order to observe any air produced within the experimental CPB circuit.

Consistent with similar studies conducted with roller pump heads, the independent variables chosen to be maniuplated in order to observe their effect on air production, were mean flow and baseline percentage. Additionally, these were the only two variables which could be manipulated on the Sarns Centrifugal System control module to alter the pulsatile waveform generated. The dependent variables, monitored via the embolus detection and classifier (EDAC) QUANTIFIER manufactured by Luna Innovations, Inc., were the volume of air produced and the number of gaseous microemboli (GME) detected. Additionally, pre-pump head pressure was monitored via a BioTek DPM-2 Digital Pressure Meter and recorded onto a laptop computer with Biobench software. The pressure data were then used to calculate average and minimum pressures during each trial in order to conclude whether there was a possibility for cavitation to occur in the system.

For the experimental materials and methods used in this study, the independent variables of mean flow and baseline did not have a statistically significant effect on either the total volume of air or total bubble count. However, mean flow did have a statistically significant effect on both the average and minimum pressures measured at the pre-pump pressure port. Additionally, both the average and minimum pressures were significantly lower (more negative) at the higher mean flow setting of 5.5 L/min. Baseline did not significantly influence either set of pressure data.

In conclusion, for the experimental materials and methods used in this study, the independent variable of baseline had no statistically significant effect on any of the dependent variables observed in this study. These results were consistent with the results of similar studies conducted with roller pump heads. Therefore, clinicians can conclude that no matter the type of arterial pump head, the baseline setting does not affect the number of GME produced in the CPB circuit.

Further, mean flow exhibited an effect on the pressure data, but it did not have an effect on GME production. Therefore, clinicians must keep in mind, when using a centirfugal pump head, that increasing flows will cause a decrease in pressure at the pump inlet, and thus, a potential for cavitation to occur.

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