The Journal of ExtraCorporeal Technology No 58-1 | Page 25

J Extra Corpor Technol 2026, 58, 19 – 31 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / ject / 2025067

Available online at: ject. edpsciences. org

ORIGINAL ARTICLE

The effect of surgical field suction flow rate and venous reservoir levels on gaseous microemboli transmission w

Thomas Rath( MPS) 1,*, Marisa Sugden( MS) 2, Edward Evans( MA) 3, Kyle Dana( DC) 1, Mitchell Rentschler( BA) 4, Charlotte Bolch( PhD) 5, and Nathaniel H. Darban( PhD) 1

1 College of Health Sciences, Midwestern University, 19555 N. 59th Avenue, Glendale, AZ 85308, USA 2 College of Graduate Studies, Midwestern University, 19555 N. 59th Avenue, Glendale, AZ 85308, USA 3 Cardiovascular Perfusion Program, Lipscomb University, 1 University Park Dr, Nashville, TN 37204, USA 4 Arizona College of Osteopathic Medicine, Midwestern University, 19555 N. 59th Avenue, Glendale, AZ 85308, USA 5 Office of Research & Sponsored Programs, Midwestern University, 19555 N. 59th Avenue, Glendale, AZ 85308, USA Received 27 April 2025, Accepted 14 November 2025

Abstract – Background: Minimizing Gaseous microemboli( GME) introduced into the CPB circuit can help alleviate neurologic injury. This study focuses on understanding how suction flow rate and the reservoir level can influence the introduction of GME past the venous reservoir during CPB. Methods: An in vitro mock CPB loop filled with bovine blood was used to simulate adult CPB. A Gampt BCC-300 bubble detector measured bubble size, volume, and count at three locations: post-reservoir( venous), post-oxygenator / arterial filter( arterial), and the venous inlet to the reservoir( recirculation). Room air was added into the suction line at 200 mL / min and mixed with blood to simulate aerated suction return. Bubble transmission was measured for three minutes at three reservoir levels, 200 mL, 500 mL, and 1000 mL, and at four pump sucker 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). GME count data were pooled from three commonly used, coated, disposable reservoirs / oxygenator combinations: Medtronic Affinity Fusion, Terumo CAPIOX FX25, and Sorin Inspire 8F. Results: A total of 284 measurements were conducted, and the data from all reservoir manufacturers were analyzed and averaged. A statistically significant interaction was noticed between roller pump suction rate and reservoir level( p-value < 0.0001) at the venous sensor. As the suction flow rate increased, the reservoir level decreased, or a combination of the two occurred, a significant increase in GME count was observed at the post-reservoir sensor. Analysis of the GME count from the post-oxygenator / filter sensor revealed a significant increase as the suction flow rate increased from 25 RPM to 100 RPM. Conclusion: A minimum effective suction flow rate and maximum practical reservoir level are recommended to prevent the transmission of GME through the cardiopulmonary bypass circuit and potentially to the patient. Care should be taken to continuously monitor these variables throughout the case and adjust them accordingly.

Key words: Cardiopulmonary bypass, Gaseous microemboli, Perfusion, Venous reservoir, Cardiotomy suction.

Introduction

The presence of iatrogenic gaseous micro-emboli( GME) introduced into the circulatory system during cardiac surgery is ubiquitous and well-documented in the literature. GME is defined as air that the naked eye cannot see. In vivo clinical studies and in vitro benchtop work demonstrate that“ air is there” and that we can do better for our patients.

Clinical( in vivo) studies utilizing transcranial doppler( TCD) ultrasonography of the middle cerebral artery of patients

undergoing cardiopulmonary bypass( CPB) are informative because they document emboli entering the cerebral vasculature in the form of high-intensity transcranial signals( HITS). Pugsley and colleagues used this technology to demonstrate the importance of arterial line filters [ 1 ]. Other investigators have shown cerebral air associated with aortic cannula placement and perfusionist interventions [ 2 – 5 ], surgical events such as CPB initiation and aortic cross-clamp removal [ 6 ], and increased cerebral air with open-chamber cardiac procedures compared to closed-chamber procedures [ 7 ]. TCD also has the potential to reveal a link between cerebral emboli and poor neurologic outcomes [ 8 ].

The placement of ultrasonic bubble measuring devices at various positions on the CPB circuit during cardiac surgery

This is an Open Access article distributed under the terms of the Creative Commons Attribution License( https:// creativecommons. org / licenses / by / 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.