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At least 19 recordsLinked to original sources
PubMed1999

The comparison between the cerebral blood flow directly measures and cerebral blood flow velocity in the middle and basilar cerebral arteries measured by transcranial Doppler ultrasonography.

Transcranial Doppler ultrasonography (TCD) may be useful for determining alterations in cerebral blood flow (CBF) during excessive hemodynamic changes by non-invasive measurement of the CBF velocity. The purpose of this study was to measure the correlation between CBF and the middle cerebral artery (MCA) and basilar artery (BA) flow velocities, as measured by TCD during excessive hemodynamic changes produced by hypertension and hypotension in adult dogs. The peak, diastolic, and mean flow velocities were measured by TCD. Arterial hypertension was induced by administration of dopamine at 5 and 15 microg/kg/min, and hypotension was induced by hemorrhage. During the hemodynamic changes, the BA velocity correlated more closely with the alteration in the CBF than the MCA velocity. In terms of percentages of the values during anesthesia, there was good correlation between CBF and the MCA and BA velocities. In conclusion, our findings indicate that MCA and BA velocity measurements, as a percentage of the values during anesthesia, both give an equally accurate indication of alterations in CBF during excessive hemodynamic changes.

Animals↗
PubMed1994

Transcranial Doppler ultrasonography.

Transcranial Doppler ultrasonography is an extremely useful adjunct in neurosurgical intensive care. Continuous improvements in TCD equipment as well as computer software have improved examination success and also vessel identification. Recent expanding applications of TCD have also allowed the study of disorders of control of the cerebral circulation. TCD can be used to detect vessel narrowing from a variety of causes, including vasospasm, and also can be used to detect cerebral emboli and to evaluate CO2 reactivity, autoregulation, and the response to certain medications, as well as to indicate progressive obstruction of the cerebral circulation as seen in conditions leading to brain death. In the future, TCD may offer the ability to estimate the ICP using noninvasive means by evaluating velocity in the middle cerebral artery and arterial blood pressure tracings. The noninvasive determination of cerebral autoregulation may be useful in evaluating strategies to improve cerebral autoregulation as well as aid in the optimal management of ICP control and preservation of optimal cerebral circulation.

Blood Flow Velocity↗
PubMed1996

Intraoperative use of transcranial Doppler ultrasonography.

Transcranial Doppler (TCD) ultrasonography is a diagnostic tool that is well established in the fields of neurology and neurosurgery. There are many potential applications of TCD ultrasonographic monitoring in the perioperative care of the patient at risk of cerebral ischemia, the most important of which are detailed in this article. The introduction of TCD ultrasonography has made it possible to monitor intraoperative CBF changes in a continuous, noninvasive manner. Further refinement in the technology will delineate its appropriate use as an intraoperative monitor.

Brain Ischemia↗
PubMedDate not supplied

[Doppler transcranial ultrasonography: a means of non-invasive monitoring at the patient's bedside].

A description was made of a new diagnostic technique used in patients with neurological disease who require admission to an intensive care unit, transcranial Doppler ultrasonography (TCD). TCD is carried out by the physician at the patient's bedside for the purpose of monitoring cerebral hemodynamics. A bibliographic review of TCD confirmed that little information is available on the nursing aspects of the technique. The aim of this article is to describe basic TCD concepts, parameters of normality/pathology, and the effects of this technique on nursing tasks.

Cerebrovascular Circulation↗
PubMed1999

Methodological parameters influence the detection of right-to-left shunts by contrast transcranial Doppler ultrasonography.

BACKGROUND AND PURPOSE: Contrast transcranial Doppler ultrasonography is a new method to detect intracardiac right-to-left shunts, such as the patent foramen ovale. However, the methodology of the procedure varies considerably among investigators. This study was undertaken to assess the influence of methodological parameters on the results of the contrast transcranial Doppler examination in the detection of right-to-left shunts. METHODS: A total of 72 patients (mean age, 58.2+/-14.7 years) had a contrast transcranial Doppler ultrasonography examination. To study the influence of methodological factors, patients with evidence of a right-to-left shunt underwent repeated examinations with modified procedures. Parameters under investigation were the timing of the Valsalva maneuver, the dose of the contrast medium, and the patient's posture during the examination. RESULTS: The median contrast signal count was 58.5 and 48.0 (P<0.001) and the median latency of the first intracranially detected contrast signal was 12.5 and 8.5 seconds (P=0.05) when the Valsalva maneuver was performed 5 and 0 seconds after the start of the injection, respectively. Reducing the contrast medium dose from 10 to 5, 2.5, and 1.2 mL resulted in a decline of the median signal count from 54.5 to 28.5, 20.5, and 12.0 (P<0.01), respectively, while the latency of the first contrast signal increased from 13.3 to 14.0, 14.6, and 15.0 seconds (P<0.05). The sitting position also produced a lower signal count than the supine position (P<0.02). CONCLUSIONS: This study demonstrates that several essential methodological parameters influence the results of the contrast transcranial Doppler ultrasonography examination. Therefore, it is necessary to standardize the procedure to permit comparable quantitative assessments of the shunt volume. The findings of the present study suggest that 10 mL of contrast medium be injected with the patient in the supine position and that the Valsalva maneuver be performed 5 seconds after the start of the injection.

Adult↗
PubMed2001

Cerebral blood flow velocity changes during dichotic listening with directed or divided attention: a transcranial Doppler ultrasonography study.

Simultaneous bilateral transcranial Doppler ultrasonography (TCD) monitoring of blood flow velocity (BFV) in the middle cerebral arteries was performed in 28 normal right-handed volunteers during linguistic dichotic listening tasks to investigate the effect of hemispheric specialisation and allocation of attention. A control task that required the repetition of monaurally presented words was followed by three randomised dichotic listening tasks in which the subjects were instructed to direct their attention to the word stimuli of the right ear, the left ear, or to divide their attention between both ears. Behavioural data indicated that the subjects used the required attentional strategies. A significant right ear advantage was not obtained in the divided attention condition due to a ceiling effect. Each task resulted in a significant bilateral increase in BFV. We found no significant lateralisation of BFV change for any of the tasks. We noted marked differences in BFV change between the different conditions that were significant in the right hemisphere, showed a borderline significance in the left hemisphere and appeared to be related with the difficulty of the task. We conclude that the hemodynamic changes caused by attentional strategies or hemispheric specialisation in processing dichotic stimuli over and above the effect of bilateral auditory stimulation, are too subtle to be detected as lateralised changes in BFV. Functional TCD could be used for the evaluation of a task's workload relative to other tasks, and may contribute to elucidate the role of the right hemisphere in attention and arousal.

Adult↗
PubMed1996

Comparison of transcranial Doppler ultrasonography and transesophageal echocardiography to monitor emboli during coronary artery bypass surgery.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasonography (TCD) is the standard technique for monitoring emboli in the cerebral circulation. Embolic signals have been detected with the use of this technique in most patients undergoing coronary artery bypass surgery. We previously reported that the majority of emboli are detected after release of aortic cross-clamps and partial occlusion clamps. In this study we compare the intraoperative use of TCD with transesophageal echocardiography (TEE) to monitor cerebral emboli. METHODS: We simultaneously monitored 20 patients undergoing coronary bypass surgery with TCD and TEE. All patients also underwent routine TEE examination of the aorta. RESULTS: Embolic signals were detected in all patients by both techniques. Mean total number of emboli was 535 +/- 109 by TEE compared with 133 +/- 28 by TCD. We found correlation between numbers of emboli detected by the two techniques at clamp placement and release (r = .65, P = .002). Clamp placement and release accounted for 84% of all emboli by TEE and 83% by TCD. By TEE, large, highly echogenic particles were detected after clamp release compared with small, barely echodense particles at the onset of bypass. No such distinction was apparent by TCD. We found correlation between severity of aortic atheroma and both TEE- (P = .003) and TCD-detected (P = .009) emboli. CONCLUSIONS: TEE and TCD can both be used to continuously monitor emboli during coronary artery bypass surgery. However, TEE is invasive and justified only if it is being performed for intraoperative assessment of aortic atheromatosis or cardiac function.

Aged↗
PubMed2000

Evaluation of intracranial pressure by transcranial Doppler ultrasonography in dogs with intracranial hypertension.

Transcranial Doppler ultrasonography (TCD) has been used to confirm changes in cerebral hemodynamics. In this study, we investigated whether the parameters for the basilar artery measured by TCD were correlated with the intracranial and cerebral perfusion pressures in extreme intracranial hypertension. An intracranial hypertension model was produced in seven dogs by inflating a balloon inserted into the epidural space. The resistance index was compared with the corresponding intracranial pressure and cerebral perfusion pressure values during intracranial hypertension. A significant correlation was recognized between the resistance index and cerebral perfusion pressure. Therefore, measurement of the basilar artery by TCD in the dog with intracranial hypertension is useful in estimating the intracranial circulation in cases where the measurement of intracranial pressure is not available or not indicated.

Animals↗
PubMed2006

Assessment of intra-cranial pressure after severe traumatic brain injury by transcranial Doppler ultrasonography.

PRIMARY OBJECTIVE: To investigate the potential of transcranial Doppler ultrasonography in estimating post-traumatic intra-cranial pressure early after severe traumatic brain injury. RESEARCH DESIGN: The group of 24 patients was analysed for the observation of an early post-traumatic cerebral haemodynamic by middle cerebral artery blood velocity measuring. METHODS AND PROCEDURES: The standard method of measuring the mean blood middle cerebral artery velocity by transcranial Doppler ultrasonic device was performed. MAIN OUTCOMES AND RESULTS: The increased duration of intra-cranial hypertension correlated to the middle cerebral artery low blood velocity (p = 0.042; r = -0.498) (n = 17) and to elevated pulsatility indices (p = 0.007; r = 0.753) (n = 11) significantly. The increased duration of lowered cerebral perfusion pressure correlated to the middle cerebral artery low blood velocity significantly (p = 0.001; r = -0.619) (n = 24). CONCLUSIONS: The significance of transcranial Doppler ultrasonography as a method to estimate an early post-traumatic intra-cranial pressure after severe brain injury was confirmed. This simple and non-invasive technique could be easily used in daily clinical practice and precede intra-cranial pressure monitoring in selected patients.

Adolescent↗
PubMed2001

Transcranial Doppler ultrasonography in the neurologic intensive care unit.

Transcranial doppler ultrasonography (TCD) is a noninvasive monitoring tool which allows imaging of blood flow velocities in intracranial blood vessels. It is safe, portable, easy to perform and provides accurate information regarding underlying physiology which may help to guide therapy in critically ill neurologic patients. It has significantly contributed to the management of vasospasm related to subarachnoid hemorrhage in the neurologic intensive care unit. TCD is also helpful in the early diagnosis of a variety of complications that can occur in patients with head injury such as vasospasm, elevated intracranial pressure and disordered cerebral autoregulation. Careful performance of the test and experienced interpretation can identify TCD waveforms indicative of cerebral circulatory arrest, an ancillary finding used for the diagnosis of brain death. TCD is likely to play a larger role in evaluation of the patient in the future because of its safety, portability and ability to define moment-to-moment changes in cerebral blood flow velocities and cerebral blood flow.

Blood Flow Velocity↗
PubMed1997

Comparative study of 18 gauge and 20 gauge intravenous catheters during transcranial Doppler ultrasonography with saline solution contrast.

A formal technical protocol has not been established for transcranial Doppler ultrasonography in the detection of venous to arterial shunts; techniques have been adapted from contrast echocardiography. We evaluated the effect of different diameter indwelling intravenous catheters on the detection of right-to-left shunts by transcranial Doppler ultrasonography. Fifteen patients underwent transcranial Doppler sonographic evaluation with saline solution contrast using both 18 gauge and 20 gauge indwelling intravenous catheters. The larger bore intravenous catheter delivered a greater number of signals in a shorter time to the insonated middle cerebral artery. We recommend that a standardized method for transcranial Doppler sonographic contrast studies include an 18 gauge intravenous catheter.

Adult↗
PubMed2007

Role of transcranial Doppler ultrasonography in evaluation of patients with cerebrovascular disease.

Transcranial Doppler ultrasonography (TCD) is the only noninvasive examination method that enables the reliable evaluation of blood flow from the basal intracerebral vessels, adding physiologic information to the anatomic images. TCD is relatively inexpensive, can be performed at bedside, and allows monitoring in acute emergency settings and for prolonged periods with a high temporal resolution, making it ideal for studying dynamic cerebrovascular responses. In acute stroke, TCD is capable of providing rapid information about the hemodynamic status of the cerebral circulation and monitoring recanalization in real-time, with a potential for enhancing tissue plasminogen activator-induced thrombolysis. Extended applications such as emboli monitoring, right-to-left shunt detection, and vasomotor reactivity make TCD an important and valuable tool for evaluating stroke mechanisms, planning and monitoring treatment, and determining prognosis.

Cerebrovascular Disorders↗
PubMed1994

[Value of transcranial Doppler ultrasonography in the management of severe head injuries].

Transcranial doppler ultrasonography (TCD) is a non invasive technique for the assessment of cerebral blood flow (CBF). The aim of this prospective study was to evaluate the benefit of TCD for the monitoring of major head trauma patients. Therefore 10 of such patients, aged 17 to 37 years, had a TCD at admission and subsequently at least twice a day. Following data were measured simultaneously at the site of the right and the left middle cerebral arteries: the systolic (SV), diastolic (DV) and mean (MV) blood velocity, the resistance index (RI) of Pourcelot (RI = SV-DV/SV) and the pulsatility index (PI) of Gosling (PI = SV-DV/MV). Simultaneously, the mean intracranial pressure (ICP) obtained with a subarachnoid probe, the PaCO2 and the mean arterial pressure (Pa) were measured. The cerebral perfusion pressure (CPP) was calculated with the formula: CPP = Pa-ICP. A total of 132 measures were analysed. There was a linear relation between RI and CPP (r = 0.566; p < 0.001), between RI and ICP (r = 0.822; p < 0.001), as well as between PI and CPP (r = 0.563; p < 0.001) and between PI and ICP (r = 0.837; p < 0.001). In the opposite there was no statistically significant relation between ICP and MV (r = 0.18) nor between CPP and MV (r = 0.23). However, a MV over 100 cm.s-1 was regularly associated with a ICP over 60 mmHg. The close correlation between RI, PI and ICP allows to use RI or PI to estimate ICP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2003

[An transcranial Doppler ultrasonography and X-ray study of cervical vertigo patients treated by manipulation in supine position].

OBJECTIVE: To observe the transcranial Doppler ultrasonography and X-ray changes of cervical vertigo patients caused by cervical instability before and after the manipulation treatment in supine position. METHODS: Sixteen cervical vertigo patients who underwent supine manipulation treatment were reviewed retrospectively. After the treatment, the changes of transcranial Doppler ultrasonography of cervical vertebral artery and X-ray of cervical spine were observed. RESULTS: Before the treatment, the mean blood flow velocity of vertebral artery was (48.6+/-3.1) cm/s, much higher than that of the normal group (P<0.05), the means of the horizontal displacement of C3,4 and C4,5 were (3.18+/-0.42) mm and (3.46+/-0.26) mm respectively. After the treatment, the blood flow velocity and the C3,4 horizontal displacement decreased significantly (P<0.05). The effective rate of the manipulation treatment was 100%. CONCLUSION: The manipulation treatment is an effective method for cervical vertigo patients caused by cervical instability, and the effect is correlated with the improvement of the blood flow of cervical artery and the restoration of cervical stability.

Adult↗
PubMed1999

[Use of transcranial doppler ultrasonography in patients with vascular dementia].

The aim of the study was the evaluation of the clinical usefulness of transcranial Doppler ultrasonography /TDU/ in patients with vascular dementia. The study was carried out in a group of 69 patients divided into two groups: group i of 32 patients aged 45-78 years, mean age 58.4 years with two or more ischaemic foci on TDU and dementia symptoms. The cases in this group fulfilled the criteria of dementia according to DSM-IV, ICD 10, MMS scale and Hachinski ischaemic scale. In TDU the following parameters were analysed: maximal velocity /Vmax/, minimal velocity /Vd/, mean velocity /Vmean/ of blood flow in the middle cerebral arteries, pulsation index /PI/ and resistance index /RI/. In group II the patients were divided into three subgroups according to ICD-10 criteria and localization of ischaemic foci: with cortical, subcortical and mixed lesions. The following conclusion have been drawn: 1/ the parameters of TDU could serve for differentiation of patients with vascular dementia; 2/ the PI and RI parameters in TDU are most valuable for diagnosis establishing; 3/ the transcranial Doppler ultrasonography is insufficient for differential diagnosis of dementia.

Aged↗
PubMedDate not supplied

[Dynamics of cerebral circulation on the basis of transcranial Doppler ultrasonography evaluation in patients with moderate and minor head injury].

Patients with moderate and minor head injury were evaluated with transcranial Doppler ultrasonography (TCD) and the relationship was studied between traumatic vasospasm (TVSP) and hyperaemia and the patients' age, clinical state, head CT examination and long-term results of treatment. The group examined consisted of 45 patients. The results obtained in this group were compared with the results in the control group. TVSP was observed in about 20% while hyperaemia occurred in 25% of the cases. Traumatic vasospasm in transcranial Doppler ultrasonography was found to occur most often in the group of patients with subdural or intracerebral haematomas.

Adolescent↗
PubMed2002

Transcranial Doppler ultrasonography in neurologically asymptomatic children and young adults with sickle cell disease.

The purpose of the study was to evaluate transcranial Doppler ultrasonography for identifying cerebrovascular disease in neurologically asymptomatic children and young adults with sickle cell disease. A total of 47 consecutive patients with sickle cell disease (28 females, 19 males; age range 8 months to 29 years, mean age 9 years 6 months) were evaluated by transcranial color and duplex Doppler ultrasonography via transtemporal and occipital (2-MHz probe) as well as by transocular (5-MHz probe) approach. Eleven vessels (middle, posterior, anterior cerebral artery, vertebral artery, ophthalmic artery on each side and basilar artery) were analyzed in each patient. Following nine transcranial Doppler findings predictive for cerebrovascular disease, patients with one or more of those abnormal sonographic findings underwent MR imaging and MR angiography. In 8 patients with abnormal transcranial Doppler the MR angiography was normal. Thirty-one patients demonstrated normal results. In 15 of 16 patients with one or more abnormal Doppler findings (34% of all studied patients) MR imaging and MR angiography were performed. The MR angiography disclosed cerebrovascular stenosis in 7 patients (15% of all patients, 44% of those with pathological transcranial Doppler findings). In one of those patients MR imaging revealed silent peripheral ischemic infarction as well. Our findings indicate the usefulness of transcranial Doppler ultrasonography to reveal occult cerebrovascular lesions in neurologically asymptomatic patients with sickle cell disease. It should regularly be performed in all sickle cell patients in order to detect patients at risk for later stroke. Patients with homozygous disease and a high frequency of preceding sickle cell crises should be followed most closely.

Adolescent↗