Detection and volume estimation of embolic air in the middle cerebral artery using transcranial Doppler sonography.

Bunegin, Leonid; Wahl, D.; Albin, Maurice S.

doi:10.1161/01.str.25.3.593

Cited by 33 publications

(10 citation statements)

References 27 publications

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“…5,10 For this reason it was decided to test the measurement of embolic duration as a parameter to help determine embolic composition, but in this study, despite improved temporal resolution, it was not Figure 2. ROC curves plotted for each of the four embolic parameters used to attempt to classify emboli.…”

Section: Discussionmentioning

confidence: 99%

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A Comparison of Four Methods for Distinguishing Doppler Signals From Gaseous and Particulate Emboli

Smith

Evans

Bell

et al. 1998

Stroke

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Background and Purpose-Many reports in the medical literature have proposed methods of differentiating between gaseous and particulate emboli detected with the use of transcranial Doppler ultrasound. The purpose of this study was to compare the previously published methods with our own sample volume length (SVL) parameter to assess the accuracy of each method in classifying emboli. Methods-A pure source of gaseous and particulate emboli was obtained from in vitro and in vivo studies, respectively, and recorded onto digital audiotape for off-line analysis. In total, 100 gaseous emboli and 215 particulate emboli were analyzed to measure four embolic parameters, namely, embolic duration, embolic velocity, relative signal intensity increase (measured embolic power [MEP]), and SVL of the embolic signal (ϭDurationϫVelocity). Receiver operator characteristic analysis was used to assess the optimum threshold for each parameter to differentiate between particulate and gaseous emboli, and levels of sensitivity and specificity were calculated. Results-Embolic duration and velocity produced the poorest levels of sensitivity and specificity compared with the MEP and SVL parameters. The optimum thresholds for embolic duration and velocity were 35 ms and 1 m/s, respectively, which produced a sensitivity (specificity) of 85.1% (87%) and 87% (67%), respectively. The optimum MEP and SVL thresholds were 30 dB and 12.8 mm, respectively, which produced a sensitivity (specificity) of 86.5% (95%) and 93% (97%), respectively. The SVL and MEP parameters were compared statistically ( 2 ) at chosen specificity values of 90%, 95%, 97%, 99%, and 100%, which showed that the SVL sensitivities were statistically greater than MEP sensitivities (PϽ0.01). Conclusions-SVL is the best parameter for differentiating between gaseous and particulate emboli but needs to be calculated with the use of a high-temporal-resolution spectral analyzer to measure embolic duration and velocity.

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Section: Discussionmentioning

confidence: 99%

“…A slight positive correlation was also found between embolic velocity and MEP in vivo but was not corroborated in vitro. Bunegin et al 10 described a method for estimating the volume of air in the middle cerebral artery using TCD. This was achieved by injecting controlled volumes of air (0.5 to 40 L) into the carotid arteries of monkeys.…”

mentioning

confidence: 99%

A Comparison of Four Methods for Distinguishing Doppler Signals From Gaseous and Particulate Emboli

Smith

Evans

Bell

et al. 1998

Stroke

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“…We did not differentiate gaseous from thrombofibrinous embolic material [17, 18, 19, 20, 21]because it is not yet known which type of microemboli will in fact lead to stroke and neuropsychologic deficits. While thrombofibrinous microthrombi have been shown to occlude retinal vessels during ECC [3]serving as a model for focal ischemic stroke, large numbers of gaseous microemboli may lead to diffuse encephalopathy [22, 23].…”

Section: Discussionmentioning

confidence: 99%

Cerebral Microembolus Generation in Different Extracorporeal Circulation Systems

Müllges

Berg²,

Babin‐Ebell³

et al. 1999

Cerebrovasc Dis

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Microemboli generated during extracorporeal circulation (ECC) are likely to induce neurological sequelae. This study examines whether the choice of a distinct type of ECC can reduce intracerebral emboli counts. Middle cerebral artery blood flow during coronary artery bypass grafting was monitored continuously by transcranial Doppler ultrasound in 45 patients. The ECC systems used were a roller pump (n = 16), a centrifugal pump (n = 18) and a combination of centrifugal pump and heparin-coated ECC system (n = 11). Patients’ characteristics as well as surgical and anesthesiological procedure did not differ between the groups. Total counts did not differ significantly between the three groups. Intraoperative events in individual patients may lead to massive embolus generation overcoming positive properties of a distinct ECC system.

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“…Doppler ultrasound attributes the high-intensity transient signal within the blood flow to emboli. The quality of this signal depends on the size and material of the embolus [20][21][22][23]. Both thrombofibrinous and gaseous emboli have been described during CPB [11].…”

Section: Discussionmentioning

confidence: 99%

Reduced release of tissue factor by application of a centrifugal pump during cardiopulmonary bypass

et al. 1998

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The application of a centrifugal pump might lead to a reduced release of tissue factor (TF) due to less blood cell damage. This could result in a decrease in activation of the extrinsic pathway of coagulation and embolus formation. In the present study, 60 patients undergoing coronary artery bypass grafting were randomly assigned to a centrifugal or a roller pump. Plasma concentrations of TF, thrombin-antithrombin complex (TAT), and prothrombin fragments F1 + 2 were investigated before, during, and after cardiopulmonary bypass (CPB). Embolus detection was performed at the arterial line of CPB and transcranially by Doppler ultrasound. The centrifugal pump group revealed a lower TF release (area under the curve during CPB) when compared with the roller pump group [5661 (696-10359) vs 12681 (6383-17538) microg x min/l; median (lower - upper quartiles); P = 0.009]. In contrast, TAT and F1 + 2 formation did not differ between the groups, and neither did the total embolus count of both Doppler systems. Embolus counts did not correlate with TAT or F1 + 2 formation. In conclusion, the reduction in TF release by the application of a centrifugal pump seems to have little consequence on total thrombin formation. Since the applied Doppler systems seem to detect mainly microbubbles, conclusions regarding differences between the two pumps in the formation of thrombofibrinous clots cannot be drawn.

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Detection and volume estimation of embolic air in the middle cerebral artery using transcranial Doppler sonography.

Cited by 33 publications

References 27 publications

A Comparison of Four Methods for Distinguishing Doppler Signals From Gaseous and Particulate Emboli

A Comparison of Four Methods for Distinguishing Doppler Signals From Gaseous and Particulate Emboli

Cerebral Microembolus Generation in Different Extracorporeal Circulation Systems

Reduced release of tissue factor by application of a centrifugal pump during cardiopulmonary bypass

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