Gaseous Microemboli Sizing in Extracorporeal Circuits Using Ultrasound Backscatter

Lynch, John E.; Pouch, Alison M.; Sanders, Randi; Hinders, Mark K.; Rudd, Kevin; Sevick, John

doi:10.1016/j.ultrasmedbio.2007.04.008

Cited by 38 publications

(42 citation statements)

References 22 publications

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“…HItS detected using tcd result from an increase in the ul-successive pulses. detectable microemboli diameters range from 10 um to the diameter of the connector element itself (47). the edAc Quantifier was able to detect GeM as small as 10 um in diameter at post-arterial filter sites; these microemboli are below the threshold for detection by conventional tcd and would enter the systemic circulation without notice.…”

Section: Transcranial Cranial Doppler (Tcd)mentioning

confidence: 95%

“…Increased sensitivity of the edAc system would provide surgeons and perfusionists with more frequent opportunities to locate sources of air uptake (19). the edAc Quantifier is also able to categorize individual microemboli by diameter (10-200 um) (47). Although the edAc Quantifier has a higher sensitivity than conventional tcd, its use is limited to the detection of circuit microemboli and cannot be used for systemic microemboli detection.…”

Section: Transcranial Cranial Doppler (Tcd)mentioning

confidence: 99%

“…As many microbubbles may be present at once in the measurement beam, counting and classification of emboli is performed using a multiple target echo-tracking algorithm adapted from algorithms used in SOnAr and rAdAr applications (48). the edAc Quantifier is able to reliably measure up to 1,000 microemboli per second at flow rates ranging from 0.2 L/min to 6.0 L/min (47). despite the improvement, acoustic GMe counters still do not count all microbubbles when too many microbubbles appear at the same time in the measuring window.…”

Section: Transcranial Cranial Doppler (Tcd)mentioning

confidence: 99%

“…the emboli detection and classification (edAc) Quantifier was approved by the Food and drug Administration and introduced into clinical service in 2007, which is the only fixedbeam ultrasonic imaging device available for detecting and sizing gaseous microemboli in the bypass circuit (47). edAc uses a series of broadband ultrasound pulses with a center frequency of 4 MHz to detect and track microemboli in cPB circuits.…”

Section: Emboli Detection and Classification (Edac)mentioning

confidence: 99%

“…edAc uses a series of broadband ultrasound pulses with a center frequency of 4 MHz to detect and track microemboli in cPB circuits. this is in contrast to narrowband doppler ultrasound systems, which have been used extensively for more than 25 years to detect gas emboli in the blood flow (47). edAc eliminates doppler processing and instead uses motion tracking algorithms to detect echo signatures from individual emboli.…”

Section: Emboli Detection and Classification (Edac)mentioning

confidence: 99%

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Generation, Detection and Prevention of Gaseous Microemboli during Cardiopulmonary Bypass Procedure

Lou

Liu

et al. 2011

Int J Artif Organs

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Neuropsychological injury after cardiopulmonary bypass (CPB) is one of the most serious and costly complications arising from the procedure. Gaseous microemboli (GME) have long been implicated as one of the principal causes. There are two major sources of GME: surgical and manual manipulation of the heart and arteries; and the components of the extracorporeal circuit, including the type of pump, different perfusion modes, the design of the oxygenator and reservoir, and the use of vacuum assisted venous drainage (VAVD), all of which have a great impact on the delivery of existing GME to the patients. Transcranial Cranial Doppler (TCD) has been used for more than two decades to assess and monitor the quality of extracorporeal perfusion with regard to the blood flow velocity of the middle cerebral arteries (MCA) and emboli detection, contributing to the achievement of better perfusion results. The Emboli Detection and Classification (EDAC) Quantifier has been able to detect and track microemboli in CPB circuits up to 1,000 microemboli per second at flow rates ranging from 0.2 L/min to 6.0 L/min. The deleterious effects of GME are multiple, including damage to the cerebral vascular endothelium, disruption of the blood-brain barrier, complement activation, leukocyte aggregation, increased platelet adherence, and fibrin deposition in the micro-vasculature. Improvements in perfusion equipment and in perfusion and surgical techniques have led to a dramatic reduction in the occurrence of GME during cardiac surgery. Although the clinical relevance of cerebral air embolization in causing neurological damage is unclear, every single person involved in perfusion and surgical technology should be aware of the risk of embolization and strictly regulate clinical behavior. Related research should also be done to improve the design of circuit components and clinical practice with a view to eliminating air bubbles during CPB procedure.

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Section: Transcranial Cranial Doppler (Tcd)mentioning

confidence: 95%

Section: Transcranial Cranial Doppler (Tcd)mentioning

confidence: 99%

Section: Transcranial Cranial Doppler (Tcd)mentioning

confidence: 99%

Section: Emboli Detection and Classification (Edac)mentioning

confidence: 99%

Section: Emboli Detection and Classification (Edac)mentioning

confidence: 99%

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Generation, Detection and Prevention of Gaseous Microemboli during Cardiopulmonary Bypass Procedure

Lou

Liu

et al. 2011

Int J Artif Organs

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Elimination of Gaseous Microemboli From Cardiopulmonary Bypass Using Hypobaric Oxygenation

Gipson

Rosinski

Schonberger

et al. 2014

The Annals of Thoracic Surgery

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Background Numerous gaseous microemboli (GME) are delivered into the arterial circulation during cardiopulmonary bypass (CPB). These emboli damage end organs through multiple mechanisms that are thought to contribute to neurocognitive deficits following cardiac surgery. Here, we use hypobaric oxygenation to reduce dissolved gases in blood and greatly reduce GME delivery during CPB. Methods Variable subatmospheric pressures were applied to 100% oxygen sweep gas in standard hollow fiber microporous membrane oxygenators to oxygenate and denitrogenate blood. GME were quantified using ultrasound while air embolism from the surgical field was simulated experimentally. We assessed end organ tissues in swine postoperatively using light microscopy. Results Variable sweep gas pressures allowed reliable oxygenation independent of CO2 removal while denitrogenating arterial blood. Hypobaric oxygenation produced dose-dependent reductions of Doppler signals produced by bolus and continuous GME loads in vitro. Swine were maintained using hypobaric oxygenation for four hours on CPB with no apparent adverse events. Compared with current practice standards of O2/air sweep gas, hypobaric oxygenation reduced GME volumes exiting the oxygenator (by 80%), exiting the arterial filter (95%), and arriving at the aortic cannula (∼100%), indicating progressive reabsorption of emboli throughout the CPB circuit in vivo. Analysis of brain tissue suggested decreased microvascular injury under hypobaric conditions. Conclusions Hypobaric oxygenation is an effective, low-cost, common sense approach that capitalizes on the simple physical makeup of GME to achieve their near-total elimination during CPB. This technique holds great potential for limiting end-organ damage and improving outcomes in a variety of patients undergoing extracorporeal circulation.

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Quantification of Embolic Showers Using Radio-Frequency Based TCD Analysis

Lipperts

Sauren

Hoeks

et al. 2009

Ultrasound in Medicine & Biology

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Gaseous Microemboli Sizing in Extracorporeal Circuits Using Ultrasound Backscatter

Cited by 38 publications

References 22 publications

Generation, Detection and Prevention of Gaseous Microemboli during Cardiopulmonary Bypass Procedure

Generation, Detection and Prevention of Gaseous Microemboli during Cardiopulmonary Bypass Procedure

Elimination of Gaseous Microemboli From Cardiopulmonary Bypass Using Hypobaric Oxygenation

Quantification of Embolic Showers Using Radio-Frequency Based TCD Analysis

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