The Detection of Microemboli in the Middle Cerebral Artery during Cardiopulmonary Bypass: A Transcranial Doppler Ultrasound Investigation Using Membrane and Bubble Oxygenators
TL;DR: The ultrasound index for detecting gaseous microemboli (MEI) indicated the presence of suchmicroemboli in 22 of the 27 patients during insertion of the aortic cannula during cardiopulmonary bypass surgery, supporting the assumption that the MEI is providing quantitative information regarding the existence of gaseously emboli in the middle cerebral artery.
About: This article is published in The Annals of Thoracic Surgery.The article was published on 1987-09-01. It has received 269 citations till now. The article focuses on the topics: Bubble oxygenator & Membrane oxygenator.
Citations
More filters
2,115 citations
TL;DR: The major areas of change reflected in the update of the ACC/AHA Guidelines for Coronary Artery Bypass Graft Surgery are described in a format that can be read and understood as a stand-alone document.
1,805 citations
Cites background from "The Detection of Microemboli in the..."
...Type 2 neurological outcomes may be further reduced by routine use of the membrane oxygenator rather than the less-expensive bubble oxygenator, which is still used selectively in the United States (190,227,228)....
[...]
TL;DR: It is posited that impaired washout is an important but neglected concept that intertwines hypoperfusion, embolization, and brain infarction.
Abstract: Objective To explore the relationship between hypoperfusion, embolism, and brain infarction. Design We studied 4 situations in which brain infarction is related to hypoperfusion: extracranial and intracranial occlusive vascular disease, reduced functional vascular reserve in patients with carotid artery occlusive disease, reduced collateral blood flow in patients given thrombolytic treatment, and cardiac surgery. We reviewed results of emboli monitoring using transcranial Doppler ultrasonography. Results Hypoperfusion is strongly linked to brain ischemia and infarction. The evidence includes close correlation of (1) the severity of arterial stenosis with brain infarction; (2) impaired functional blood flow reserve in patients with carotid artery disease and subsequent brain infarction; (3) reduced collateral blood flow with poor prognosis after thrombolysis; and (4) stroke-related neurologic deficits after cardiac surgery to hypoperfusion during surgery. Microembolization is common in patients with severe symptomatic carotid artery stenosis and during and after cardiac surgery. Conclusions Hypoperfusion and embolism often coexist and their pathophysiological features are interactive. Arterial lumenal narrowing and endothelial abnormalities stimulate clot formation and subsequent embolization. Reduced perfusion limits the ability of the bloodstream to clear or wash out emboli and microemboli and reduces available blood flow to regions rendered ischemic by emboli that block supply arteries. The brain border zones are a favored destination for microemboli that are not cleared. We posit that impaired washout is an important but neglected concept that intertwines hypoperfusion, embolization, and brain infarction.
810 citations
TL;DR: It is suggested that neuropsychological deficits after routine cardiopulmonary bypass are related to the number of microemboli delivered during surgery, and the numbers of microEmboli may be reduced by including a 40‐&mgr;m filter on the arterial line.
Abstract: Microemboli have been implicated in the etiology of neuropsychological deficits after cardiopulmonary bypass. This study examined the incidence of high-intensity transcranial signals (microemboli) and their relation to changes in neuropsychological performance after surgery.Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood flow velocity and detect microemboli. The number of high-intensity transcranial signals was determined and related to a neurological examination and absolute changes in neuropsychological performance as well as the number of patients considered to exhibit a neuropsychological deficit. Data were available on 100 consenting patients undergoing routine cardiopulmonary bypass. Fifty of the patients were randomly assigned to a procedure that included a 40-microns arterial line filter, and 50 had the procedure without any arterial line filter.Significantly more patients were found to have neuropsychological deficits in the group without the arterial line fi...
720 citations
Cites methods from "The Detection of Microemboli in the..."
...However, the fact that fewer emboli are detected when membrane oxygenators replace bubble oxygenators suggests that many are microbubbles.(28) The relation between the number of high-amplitude signals and particles in an in vitro validation model using the present transcranial Doppler equipment(6) showed an effect of size that suggested that large emboli could give rise to more than one signal....
[...]
TL;DR: TCD is an efficient tool to access blood velocities within the cerebral vessels, cerebral autoregulation, cerebrovascular reactivity to CO(2), and neurovascular coupling in both physiological states and in pathological conditions such as stroke and head trauma.
460 citations
References
More filters
TL;DR: This transcranial Doppler method is of particular value for the detection of vasospasm following subarachnoid hemorrhage and for evaluating the cerebral circulation in occlusive disease of the carotid and vertebral arteries.
Abstract: In this report the authors describe a noninvasive transcranial method of determining the flow velocities in the basal cerebral arteries. Placement of the probe of a range-gated ultrasound Doppler instrument in the temporal area just above the zygomatic arch allowed the velocities in the middle cerebral artery (MCA) to be determined from the Doppler signals. The flow velocities in the proximal anterior (ACA) and posterior (PCA) cerebral arteries were also recorded at steady state and during test compression of the common carotid arteries. An investigation of 50 healthy subjects by this transcranial Doppler method revealed that the velocity in the MCA, ACA, and PCA was 62 +/- 12, 51 +/0 12, and 44 +/- 11 cm/sec, respectively. This method is of particular value for the detection of vasospasm following subarachnoid hemorrhage and for evaluating the cerebral circulation in occlusive disease of the carotid and vertebral arteries.
2,952 citations
TL;DR: It is concluded that the complement-derived inflammatory mediators C3a and C5a produced during extracorporeal circulation may contribute to the pathogenesis of "post-pump syndromes."
Abstract: We observed complement activation in 15 adults undergoing total cardiopulmonary bypass. Plasma levels of C3a were significantly elevated (P < 0.0001) at the beginning of the procedure, and they continued to increase steadily thereafter. At the end of the procedure, C3a levels were more than five times higher than preoperative levels. Plasma levels of C5a (a factor that binds avidly to neutrophils) did not change significantly during cardiopulmonary bypass. Instead, there was significant neutrophilia (P = 0.03) during bypass, and significant transpulmonary neutropenia (P = 0.0002) occurred when cardiopulmonary circulation was reestablished at partial bypass. The neutropenia is consistent with pulmonary-vascular sequestration of C5a-activated granulocytes. We also found that incubation of blood with the nylon-mesh liner of bubble oxygenators, as well as vigorous oxygenation of whole blood, promotes conversion of complement. We conclude that the complement-derived inflammatory mediators C3a and C5a produced during extracorporeal circulation may contribute to the pathogenesis of "post-pump syndromes."
1,131 citations
TL;DR: The end-tidal carbon dioxide partial pressure response curves for the flow velocity in the middle cerebral artery were studied in 31 normal subjects with transcranial Doppler techniques and an exponential curve with an exponent of 0.034 mm Hg−1 was found to be a good fit to the recorded data.
Abstract: The end-tidal carbon dioxide partial pressure (PCO2) response curves for the flow velocity in the middle cerebral artery were studied in 31 normal subjects with transcranial Doppler techniques. An exponential curve with an exponent of 0.034 mm Hg-1 was found to be a good fit to the recorded data. By means of this relationship, recordings of flow velocity in cerebral arteries can be normalized to a standard value of PCO2. Physiological aspects of cerebrovascular reactivity to PCO2 and the clinical implications of the PCO2 response curve are discussed. The normal material provides a reference for assessing pathological responses.
482 citations
TL;DR: Blood velocities have been measured transcranially, at small Doppler angles, in the middle cerebral artery of normal volunteers, and indicates that changes in middle cerebral blood velocity may be used to monitor changes in flow.
Abstract: Blood velocities have been measured transcranially, at small Doppler angles, in the middle cerebral artery of normal volunteers. Cerebral blood flow was changed by varying carbon dioxide tension. In four volunteers, the relationships between arterial pCO2 and percentage change in intensity weighted mean, median, and maximum Doppler-shifted frequencies in the internal carotid and middle cerebral arteries were linear with slopes of 2.5 and 2.8% per mm Hg change in pCO2. In 38 volunteers, the relationship between end-expiratory pCO2 and time-averaged maximum Doppler frequency was linear over the range of pCO2 20-60 mm Hg with slopes of 2.5 and 2.9 percentage change per mm Hg, for internal carotid and middle cerebral, respectively. These results are very similar to those reported using direct methods of measuring cerebral blood flow. As the transcranial Doppler method is reproducible, this indicates that changes in middle cerebral blood velocity may be used to monitor changes in flow.
268 citations
TL;DR: Several deleterious hematologic consequences of cardiopulmonary bypass can be minimized by the use of a membrane oxygenator, however, complement activation remains a potential risk factor even in membrane oxygenators patients and requires further investigation to obtain better hemocompatible materials for cardiopULmonary bypass circuits.
221 citations