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2009

Protecting the brain from gaseous and solid micro-emboli during coronary artery bypass grafting: a randomized controlled trial

Tibo Gerriets, Niko Schwarz, Gebhard Sammer, Jeanette Baehr, Erwin Stolz, Manfred Kaps, Wolf-Peter Kloevekorn, Georg Bachmann and Markus Schoenburg
European Heart Journal Advance Access; 06/18/2009

Aims: The purpose of the study was to investigate whether intra-operative filter devices protect the brain during coronary artery bypass grafting (CABG) and to determine the impact of solid and gaseous micro-emboli on neuropsychological functioning.

Conclusion: Gaseous micro-embolization contributes to neuropsychological decline, which is measurable three months post-operatively. No filter device could protect the brain during CABG completely. However, the use of the DBT tends to improve the cognitive outcome after CABG. Gas filters are recommendable for neuroprotection during cardiac surgery.

2006

Dynamic bubble trap can replace filter during cardiopulmonary bypass surgery

Stefan Göritz, Helmut Schelkle, Joachim-Gerd Rein and Simon Urbanek
Perfusion 2006; Vol. 21: 367 371

Objective: The arterial filter (AF) and the dynamic bubble trap (DBT) reduce the number of air microbubbles passing through these devices. The aim of the study was to confirm that the DBT diminishes microbubbles in the arterial line similar to, or better than, the AF, and can replace it.

Conclusion: The use of the DBT instead of the AF yields higher air microbubble removal efficacy, allowing replacement of the AF, assuming the AF is used for air removal purpose only.

2005

Use of a dynamic bubble trap in the arterial line reduces microbubbles during cardiopulmonary bypass and microembolic signals in the middle cerebral artery

Mathias Perthel, Samer Kseibi, Andreas Bendisch, Joachim Laas
Herz-Kreislauf-Klinik Bevensen, Department for Cardiothoracic Surgery, Bad Bevensen, Germany
Perfusion 2005, Vol. 20, No. 3, 151-156

Neurological complications remain an important cause of morbidity and mortality of patients following cardiopulmonary bypass (CPB). Microemboli, as well as cerebral hypoperfusion, are the main postulated mechanisms. This study demonstrates that the insertion of a dynamic bubble trap (DBT) into the curcuit reduces microbubbles in the arterial line and microembolic signals (MES) in the middle cerebral arteries (MCAs). We investigated 12 patients during coronary artery bypass grafting (CABG). The DBT was inserted between the arterial filter and the arterial cannula. For detection of microemboli before and after the DBT, a special ultrasound Doppler device was used. MES were detected by transcranial Doppler monitoring in both MCAs of the patients. Microbubbles and MES were counted during bypass. These data were compared to 12 patients who were operated in a previous period without the use of a DBT. There were no significant differences in both groups with respect to gender, age, crossclamp and bypass time and number of anastomoses. In the group without a DBT in the circuit, a mean of 6311 microbubbles per operation could be observed distal to the arterial filter, corresponding to 282 MES. After inclusion of a DBT, we could register, in the second group, 8496 microemboli proximal and 2915 distal of the DBT, corresponding to 89 MES per operation. The reduction rate of microbubbles in the tubing was 65.7%, corresponding to a reduction in MES of about 86.2%. We conclude that the insertion of a DBT in the arterial line of CPB circuit protects the cerebrovascular system from microembolic events, as demonstrated by lower MES counts.

2004

Die Entstehung, Bedeutung und Vermeidung von Mikrobläschen in den verschiedenen Formen des EKZ-Managements

Schmidt V, Kanig R, Tugtekin SM, Knaut M, Matschke K
Herzzentrum Dresden
Kardiotechnik 2004

Objective: Die Markteinführung der Dynamischen Bläschen Falle (Dynamic Bubble Trap; DBT) rückte das Thema Mikrobläschen in der Extrakorporalen Zirkulation eindrucksvoll erneut in den Focus der Betrachtung. In Verbindung mit einem neuartigen Ultraschall Messgerät (UBC Ultrasound Bubble Counter), entwickelt in Zusammenarbeit mit der Martin Luther Universität Halle, wurde vielerorts zum ersten Mal den Anwendern die Dringlichkeit einer neuen Auseinandersetzung mit diesem wichtigen Thema demonstriert.

Results:
1. Die Dynamic Bubble Trap ist ein sicheres, zeitgemäßes und das effizientere Medium zur Eliminierung von Mikrobläschen. Füllvolumen und Fremdoberfläche unterscheiden sich kaum von dem eines blutführenden Schlauches des gleichen Durchmessers. Sie ist uneingeschränkt als Ersatz für den arteriellen Filter zu benutzen.
2. Schlecht durchgeführtes Priming der EKZ, venöse Luft während der EKZ, der Medikamentenport sowie Volumenzufuhr waren die hauptsächlichen Quellen für Mikrobläschen in der EKZ.
3. Aufgrund der nun möglichen Dokumentation des Verhaltens wurde ein neues Verhaltensmuster seitens der Kardiotechnik und seitens der Chirurgie entwickelt.
4. Die sogenannte Offene EKZ eliminiert Bläschen deutlich besser. Die neuen Mini- und Mikrozirkulationen bergen ein enormes Potential für ein Einschleusen teils enormer Mengen von Luft in den Kreislauf.

Conclusion: Mikrobläschen in der EKZ können allein durch Verhaltensänderungen zu einem Großteil vermieden werden. Das Bewusstsein der Entstehungsorte und Entstehungsmechanismen von Bläschen wurde durch die neuen Methoden bei allen Beteiligten enorm sensibilisiert. Der arterielle Filter kann heute durch verbesserte Techniken ersetzt werden. Das CO2 Flushing ist, bei richtiger Handhabung, überflüssig.

2003

The dynamic bubble trap reduces microbubbles in extracorporeal circulation and high intensity transient signals in the middle cerebral artery: a case report

Mathias Perthel, Samer Kseibi, Andreas Bendisch, Joachim Laas
Division of Cardiac Surgery, Herz-Kreislauf-Klinik, Bad Bevensen, Germany
Perfusion, Vol. 18, No. 5, 325-329 (2003)

Microemboli during extracorporeal circulation (ECC) might be a reason for postoperative neuropsychological dysfunction. This case report shows that reduction of microbubbles in the arterial line, as well as high intensity transient signals (HITS) in the middle cerebral artery (MCA), could be accomplished by use of a dynamic bubble trap (DBT) during routine coronary artery bypass graft (CABG) surgery in a 63-year-old male. The DBT was placed after the arterial filter, an ultrasound Doppler device was used for detection of microemboli before and after the DBT. HITS were measured by a transcranial ultrasound Doppler in both MCAs. For first 32 min of ECC, the DBT was excluded; 54 916 microbubbles and 507 HITS were counted. In the next 30 min, blood flow was directed through the DBT. This led to a significant reduction of microbubbles from 55 888 to 18 237; accordingly, only 120 HITS were registered. A DBT, integrated in ECC for routine CABG, effectively reduces air bubbles, thus protecting the cerebrovascular system from micro-embolization, as demonstrated by lower HITS counts.

The dynamic air bubble trap reduces cerebral microembolism during cardiopulmonary bypass

M. Schoenburg, MD(a),*, B. Kraus, MD(b), A. Muehling, MD(b), U. Taborski, MD(c), H. Hofmann, PhD(e), G. Erhardt, CCP(a), S. Hein, MD(a), M. Roth, MD(a), P. R. Vogt, MD, FETCS(d), G. F. Karliczek, MD(b), W.-P. Kloevekorn, MD(a)
(a) Department of Thoracic and Cardiovascular Surgery, Kerckhoff-Klinik, Bad Nauheim, Germany, (b) Department of Anesthesiology and Intensive Care Medicine, Kerckhoff-Klinik, Bad Nauheim, Germany, (c) Department of Hemostaseology and Transfusion Medicine, Kerckhoff-Klinik, Bad Nauheim, Germany, (d) Department of Cardiovascular Surgery, University of Giessen, Giessen, Germany, (e) Department of Statistics, Iowa State University, Ames, Iowa, USA
* Address for reprints: Markus Schoenburg, MD, Department of Thoracic and Cardiovascular Surgery, Kerckhoff-Clinic Foundation, Benekestrasse 2-8, 61231 Bad Nauheim, Germany
J Thorac Cardiovasc Surg 2003;126:1455-1460

OBJECTIVE: Neuropsychologic disorders are common after coronary artery bypass operations. Air microbubbles are identified as a contributing factor. A dynamic bubble trap might reduce the number of gaseous microemboli.

METHODS: A total of 50 patients undergoing coronary artery bypass operation were recruited for this study. In 26 patients a dynamic bubble trap was placed between the arterial filter and the aortic cannula (group 1), and in 24 patients a placebo dynamic bubble trap was used (group 2). The number of high-intensity transient signals within the proximal middle cerebral artery was continuously measured on both sides during bypass, which was separated into 4 periods: phase 1, start of bypass until aortic clamping; phase 2, aortic clamping until rewarming; phase 3, rewarming until clamp removal; and phase 4, clamp removal until end of bypass. S100ß values were measured before, immediately after, and 6 and 48 hours after the operation and before hospital discharge.

RESULTS: The bubble elimination rate during bypass was 77% in group 1 and 28% in group 2 (P < .0001). The number of high-intensity signals was lower in group 1 during phase 1 (5.8 ± 7.3 vs 16 ± 15.4, P < .05 vs group 2) and phase 2 (6.9 ± 7.3 vs 24.2 ± 27.3, P < .05 vs group 2) but not during phases 3 and 4. Serum S100ß values were equally increased in both groups immediately after the operation. Group 2 patients had higher S100ß values 6 hours after the operation and significantly higher S100ß values 48 hours after the operation (0.06 ± 0.14 vs 0.18 ± 0.24, P = .0133 vs group 2). Age and S100ß values were correlated in group 2 but not in group 1.

CONCLUSION: Gaseous microemboli can be removed with a dynamic bubble trap. Subclinical cerebral injury detectable by increases of S100ß disappears earlier after surgical intervention.

In Vitro Biocompatibility Evaluation of the Dynamic Bubble Trap

*Uwe Taborski, †Petr Urbanek, *Gunther Erhardt, *Markus Schönburg, *Svetlana Basser, *Larisa Wohlgemuth, *Kathrin Heidinger, and *Wolf-Peter Klövekorn
*Kerckhoff-Klinik, Bad Nauheim; and †HPmedica, Augsburg, Germany
Artificial Organs, Vol. 27 Issue 8 Page 736 – August 2003

The goal of this study was to evaluate the biocompatibility of the dynamic bubble trap (DBT) prior to the clinical trial. It was set up as an in vitro model, which simulates physiological conditions. Twenty runs were performed (ten with the DBT, ten without the DBT) at a blood flow of 3 L/min, each lasting 180 min. Fifteen blood parameters (hemogram, hemostasis, complement system, and cytokines) were measured at five time intervals. None of the tested parameters showed a statistically significant difference between the DBT and control group. The data assessed in this in vitro model show that the DBT has no adverse influence on hemocompatibility. It may be concluded that the DBT is a safe tool to be used in vivo.

2001

Significant reduction of air microbubbles with the dynamic bubble trap during cardiopulmonary bypass

Schonburg M, Urbanek P, Erhardt G, Kraus B, Taborski U, Muhling A, Hein S, Roth M, Tiedtke HJ, Klovekorn WP
Perfusion. 2001 Jan, Vol. 16

Air microbubbles mostly occur unnoticed during cardiopulmonary bypass and are predominantly responsible for serious postoperative psychoneurological dysfunction. A dynamic bubble trap (DBT), which removes air microbubbles from the arterial blood, was tested in a clinical study. The aim was to evaluate the efficiency of microbubble removal under clinical conditions. As blood passes through the DBT, which is placed in the arterial line between the arterial filter and arterial cannula, it is converted into a rotating stream. The bubbles are directed to the centre of the blood flow and are collected in the distal end of the DBT, from where they are returned to the cardiotomy reservoir. Doppler ultrasonography was used to detect the microbubbles before and after the DBT, and also the number of high-intensity transient signals (HITS) in the right and left middle cerebral artery during extracorporeal circulation. A significant reduction of microbubbles in the arterial line (3,990 before DBT, 537 after, p < 0.001) and HITS in the brain (51 in the DBT group, 77 in the placebo group, p = 0.04) was measured.

2000

A dynamic bubble trap reduces microbubbles during cardiopulmonary bypass: a case study.

Schonburg M, Urbanek P, Erhardt G, Taborski U, Plechinger H, Hein S, Roth M, Klovekorn WP.
J Extra Corpor Technol. 2000 Sep;32(3):165-9

Microemboli passing to the cerebral circulation during cardiopulmonary bypass can contribute to postoperative neurologic dysfunction. Many studies conclude that air microbubbles predominantly are responsible for this problem. A dynamic bubble trap (DBT) was developed to diminish the number of microbubbles in the arterial line of extracorporeal circulation. The DBT is able to substantially reduce the number of air microbubbles, as shown in two patients undergoing coronary artery bypass grafting, where a high number of microbubbles was assessed. Although a 40-micron arterial filter was used, many bubbles larger than 40 microns occurred in the arterial line. The DBT reduced the number of large microbubbles from 2,267 to 67 in patient 1 and from 897 to 61 in patient 2.

1999

Dynamic Bubble Trap – Method for the removal of microbubbles from the arterial blood during ECC
Dynamische Luftfalle: Methode zur Beseitigung von Luftmikrobläschen aus arteriellem
Blut während extrakorporaler Zirkulation

P. Urbanek, G. Erhardt*, U. Taborski*, M. Schönburg*, H.-J. Tiedtke, W.-P. Klövekorn
Kardiotechnik 1999, 4

Zusammenfassung:
Es werden Wirkungsweise und charakteristische Eigenschaften einer dynamischen Luftfalle (Dynamic Bubble Trap – DBT) beschrieben, die zur deutlichen Reduzierung von Mikroluftbläschen in arteriellem Blut dient. Diese Mikrobläschen entstehen weitgehend unbemerkt während eines kardiochirurgischen Eingriffes im extrakorporalen Kreislauf und können zu bleibenden Hirnschädigungen führen. Wenn das Blut durch die DBT fließt, die zwischen arteriellem Filter und arterieller Kanüle platziert ist, wird es in eine Drehbewegung versetzt. Die Mikrobläschen sammeln sich im zentralen Blutstrom, der beim Austritt aus der DBT herausgenommen wird. Dieser wird zum Kardiotomiereservoir zurückgeführt. Die Anzahl der Mikrobläschen wurde vor und nach der DBT mittels eines Zweikanal-Ultraschall-Doppler-Messgerätes ermittelt. Der Wirkungsgrad der DBT wurde anhand eines mathematischen Modells ermittelt und dann in der Praxis bei CABG (ACVB)- und AKE-Eingriffen bestätigt.

Air Embolism Pathophysiology

The pathophysiology of cerebral arterial gas embolism.

Mitchell S, Gorman D
J Extra Corpor Technol. 2002 Mar;34(1):18-23

Bubbles are introduced to the arterial circulation in many patients undergoing cardiac surgical procedures, and some of these distribute to the cerebral vessels. Larger bubbles may arrest in cerebral arterioles, causing ischemia and neuronal injury in the downstream territory. Smaller bubbles may redistribute through the cerebral circulation, but this is not a benign event. Their passage may cause transient ischemia and cause damage to endothelium. Margination and activation of leukoctyes follows, and may cause a secondary ischemia. Although the potential of large bubbles to cause cerebral injury is not disputed, there is controversy over the significance of exposure to small bubbles in cardiac surgery. It is known that postsurgical neuropsychological deficits do correlate positively with numbers of emboli to which patients are exposed, but to date, the technology to distinguish between gaseous and particulate emboli or to size emboli accurately is not readily available. Until this technology becomes available and is applied in large studies designed to determine the importance of small bubbles, it seems prudent to take all practical steps to prevent introduction of arterial bubbles in cardiac surgery.

Ultrasonic Bubble Counter (UBC)

Improved methods for measurement of gaseous microbubbles during extracorporeal circulation.

Urbanek S, Tiedtke HJ.
Perfusion. 2002 Nov;17(6):429-34

The detection and quantification of gaseous microbubbles in the arterial line of the extracorporeal circuit (ECC) are very important aims for quality assurance of perfusion. A system that allows a continuous measurement of microbubble distribution in the range of 10 and 120 microm was tested. The two-channel ultrasonic bubble counter (UBC) was based on a 2-MHz ultrasound Doppler system with propriety ultrasound probes. The bubble size was determined using the backscattered Doppler signal and was corrected by means of a reference signal based on measurement conditions. Our studies have shown that the quality of this signal can be negatively affected in the clinical environment. Different influences are involved, such as electrocoagulation or electromagnetic disturbances. Various algorithms were tested and new ones were developed in order to minimize the effect of such interferences on the accuracy of the bubble detection. The on-line data were recorded during the entire surgical time to allow an off-line evaluation with different algorithms. This allowed us to obtain more exact results. Two clinical studies with 91 patients were performed with microbubbles measured in the arterial line during coronary artery bypass grafting (CABG) and valve replacement. The results confirmed the expected occurrence of microbubbles during various phases of surgery. The measurement itself proved to be resistant to different external disturbances.