Prediction of hemispheric blood flow from carotid velocity measurements. A study with the Doppler and 133Xe inhalation techniques

What Is the Role of the Maternal Ophthalmic and Cervical Internal Carotid Arteries in Predicting Maternal Adverse Outcomes in Preeclampsia?

OBJECTIVES

We aimed to investigate the efficacy of maternal ophthalmic artery (OA) and cervical internal carotid artery (CICA) in predicting adverse maternal outcomes and gestational age at birth in preeclampsia (PE).

METHODS

The study was performed at the Zeynep Kamil Women and Children's Diseases Training and Research Hospital. Measurements were made in 2 groups consisting of 50 pregnant women with PE and 50 healthy pregnant women. The peak systolic velocity (PSV), end-diastolic velocity, PI, RI, first diastolic peak velocity, systolic/diastolic (S/D) ratio, and peak ratio of the maternal OA were measured by a transorbital Doppler ultrasound (US) scan. The PSV, end-diastolic velocity, PI, RI, and S/D ratio of the CICA were measured. The differences of Doppler indices between groups with P < .05 were considered statistically significant. Cutoff values were calculated, which could be used to predict adverse maternal outcomes and gestational age at birth.

RESULTS

The RI and PI values of the OA were lower, and the first diastolic peak velocity, PSV, and peak ratio values were higher among the PE group. The RI and S/D values of the CICA were significantly lower in the PE group compared to the healthy group. The OA RI was determined to be the strongest US variable in predicting adverse maternal outcomes and gestational age at birth, with a cutoff value of 0.72, 76% sensitivity, and 76% specificity.

CONCLUSIONS

Maternal OA Doppler indices can be used as US markers to predict adverse maternal outcomes.

Cerebrovascular reactivity to carbon dioxide is preserved during hypocapnia in children anesthetized with 1.0 MAC, but not with 1.5 MAC desflurane

PURPOSE

Maintenance of cerebrovascular reactivity to CO(2) (CCO(2)R) is important during neurosurgical anesthesia. This study was designed to determine the effect of different desflurane concentrations on CCO(2)R in children.

METHODS

Children undergoing urological surgery were enrolled. Anesthesia was induced with sevoflurane in air/oxygen. After intubation, sevoflurane was switched to desflurane. Analgesia was provided with an epidural neuraxial block. Mechanical ventilation was adjusted to an initial EtCO(2) of 30 mmHg. Exogenous CO(2) was used to achieve an EtCO(2) of 40 and 50 mmHg. Patients were randomized to the sequence of desflurane concentration (1.0 and 1.5 MAC) and the EtCO(2). Transcranial Doppler was used to measure middle cerebral artery blood flow velocity (Vmca). Five minutes were allowed to reach steady state after each change in EtCO(2) and 15 min after changing the desflurane concentration.

RESULTS

Sixteen patients were studied. The mean age and weight were 3.5 +/- 1.5 yr and 14.4 +/- 3.1 kg, respectively. Mean arterial pressure remained stable throughout the study, while at an EtCO(2) of 50 mmHg, heart rate decreased at both desflurane concentrations (P < 0.05). At 1.0 MAC, Vmca increased from 30 to 40 mmHg (P < 0.05), but not from 40 to 50 mmHg EtCO(2). At 1.5 MAC, Vmca increased between 30 and 50 mmHg (P < 0.05).

CONCLUSION

CCO(2)R is preserved during hypocapnia in children anesthetized with 1.0 MAC, but not with 1.5 MAC desflurane. The lack of further increase in Vmca at higher EtCO(2) concentrations implies that desflurane may cause significant cerebral vasodilatation in children. This may have important implications in children with reduced intracranial compliance.

Using doppler signal power to detect changes in vessel size: a feasibility study using a wall-less flow phantom

The power of a Doppler signal is theoretically proportional to the volume of blood within the sample volume of an ultrasound (US) beam and, hence, may provide a means of detecting in vivo changes in the cross-sectional area of cerebral vessels, such as the middle cerebral artery. The purpose of this study was to examine the relationship between power and vessel size for signals recorded from a wall-less flow phantom. The results demonstrate the importance for the in vitro case of maximising the received signal power for each channel to obtain the true relationship between power and size, and show that a nonproportional relationship observed between the two parameters is primarily caused by high-pass filtering and nonuniform insonation. In addition, an investigation of the reproducibility of power values after transducer repositioning has shown that variation occurs even when extreme care is taken to maximise the received signal intensity. The implications of these results for the in vivo use of the Doppler signal power method are discussed.

Relative changes in cerebral blood flow during cardiac operations using xenon-133 clearance versus transcranial Doppler sonography

BACKGROUND

Changes in cerebral blood flow (CBF) during cardiac operations have implications in terms of postoperative neurologic and neuropsychological dysfunction. Current techniques of CBF measurement are cumbersome and invasive. Transcranial Doppler sonography offers a noninvasive means of assessing changes in CBF. The aim of this study was validation of this technique with existing methods of CBF measurement during cardiac operations.

METHODS

We compared the changes in CBF using xenon-133 clearance with changes in middle cerebral artery velocity by transcranial Doppler sonography (VMCA) using pH-stat and alpha-stat acid-base management during cardiopulmonary bypass. Measurements were taken (1) before bypass, (2) at 28 degrees C on bypass, (3) at 37 degrees C on bypass, and (4) after bypass. Relative changes in CBF and VMCA, calculated as the percent change from the prebypass baseline value normalized to 100%, were used in this analysis.

RESULTS

During the hypothermic phase of cardiopulmonary bypass, CBF and VMCA increased by 45.9% and 51.8%, respectively (p < 0.001), during pH-stat acid-base management but decreased by only 26.4% and 22.4%, respectively (p < 0.0001), during alpha-stat acid-base management. Linear regression analysis of the absolute changes in CBF (mL . 100 g-1 . min-1) and VMCA (cm/s) showed a significant correlation (r = 0.60; r2 = 0.36; p < 0.0001), but a better correlation was obtained when relative changes in CBF and VMCA were compared (r = 0.89; r2 = 0.79; p < 0.0001).

CONCLUSIONS

Measurements of VMCA, expressed as relative changes of a pre-cardiopulmonary bypass level (using the noninvasive transcranial Doppler sonographic technique), can be used to examine CBF changes during cardiopulmonary bypass.

Correlation of cerebral blood flow and MCA flow velocity measured in healthy volunteers during acetazolamide and CO2 stimulation

The assessment of the cerebrovascular reserve capacity (RC) has become a widely used tool in the management of cerebrovascular disease. Discrepancies become obvious, however, if results obtained with different methods are compared. Aim of the present study, therefore, was to compare blood velocity and cerebral perfusion data in the same group of healthy test persons. In 32 volunteers regional cerebral blood flow (rCBF) was measured with the 133Xe-inhalation method. F1 as grey matter flow and the initial slope index (ISI) were computed. Simultaneously flow velocity in the middle cerebral artery (VMCA) was assessed by transcranial Doppler sonography (TCD). Measurements were performed in the resting state, during inhalation of 7% CO2 and after 1 g acetazolamide. Baseline VMCA was 62.38 +/- 16.1 cm/s, 90.84 +/- 23.85 cm/s during hypercapnia and 84.91 +/- 24.54 cm/s after acetazolamide. There was no significant change of baseline or stimulated values with age. F1 rose from baseline 76.25 +/- 12.48 ml/100 g/min to 103.90 +/- 14.6 ml/100 g/min in hypercapnia and to 98.4 +/- 14.9 ml/100 g/min after acetazolamide. The baseline F1 values and the response to CO2 decreased with age (p = 0.01) whereas for the acetazolamide reaction an age dependency could not be proven. ISI baseline values (41.5 +/- 6.1 ml/100 g/min) as well as those found after CO2 or acetazolamide decreased significantly with age. In hypercapnia changes of F1 and ISI were not too well related with changes of VMCA (F1: r = 0.599; ISI: r = 0.473), but better during acetazolamide exposure (F1: r4 = 0.715; ISI: r = 0.522). The age dependency of resting and stimulated values has to be considered when assessing the reserve capacity. There is a correlation between changes of the perfusion and flow parameters in healthy individuals which, however, may be worse in cerebrovascular disease.

Reduction in internal carotid arterial blood flow velocity in children during antiepileptic drug therapy with clinical dosages

We studied the effect of antiepileptic drugs (AEDs) on internal carotid artery (ICA) blood flow velocity, as an index of total cerebral blood flow (CBF). The subjects were 45 newly diagnosed children with febrile convulsion or epilepsy who were seizure-free for a period long enough not to affect the results. They had no neurologic deficit, received fixed monotherapy, and were examined by a noninvasive Doppler ultrasound method, in comparison with 13 age-matched normal volunteers with no AED. In 30 patients, the measurements were performed before and after AED administration [10 with phenobarbital (PB), 10 with carbamazepine (CBZ), and 10 with valproate (VPA)], and performed before and after AED discontinuation in the remaining 15 patients (all with PB). Normal volunteers underwent the two consecutive examinations with a mean interval equal to that of the entire patient group, and there was no difference in velocity values between the measurements. In patients receiving CBZ or VPA, a significant reduction was noted in blood flow velocity after drug administration. Although velocity values in the patients receiving PB did not change after drug administration, they were significantly increased after complete discontinuation. In the present study, a slight but significant reduction in CBF caused by AED administration at therapeutic doses in children was suggested.

A comparison of regional cerebral blood flow and middle cerebral artery blood flow velocities: simultaneous measurements in healthy subjects

Blood flow velocities were measured in both middle cerebral arteries (MCAs) of 36 healthy subjects using transcranial Doppler ultrasound. Measurements were first made using a hand-held probe. Velocities were then studied bilaterally with fixed probes under resting conditions and during simultaneous regional CBF (rCBF) measurements. A significant (p < 0.05) positive correlation was found between MCA flow velocities and rCBF in the estimated perfusion territory of this artery. The correlation coefficient was highest when the measurements were performed simultaneously (p < 0.001) or when velocities recorded with a hand-held probe were adjusted to take into account the significant velocity increase induced by the CBF study situation. The increased velocities during CBF measurements cannot be fully explained by the moderate but significant PCO2 increase. Other possible mechanisms are increased blood flow due to mental activation or MCA vasoconstriction secondary to stimulation of the sympathetic nervous system. The effect of mental activation and PCO2 differences should therefore be considered when comparing the results of repeated velocity and CBF measurements.

Vascular effects of noise

The possible vascular effects of noise were studied. A study of the carotid vessels was made with Doppler ultrasonography in two groups of subjects exposed to various intensity of noise. The following data were studied: age, blood pressure, serum cholesterol, blood glucose, smoking habits, excess weight, electrocardiographic anomalies, family history of vascular disease, connection with duration of exposure and the type of noise and with audiometric deficits, and cerebrovascular modifications after postural changes and after a stress test. The control group comprised subjects not exposed to noise. The findings confirm that noise does play a role in causing vascular modifications that can be detected early by use of Doppler ultrasonography. This technique is predictive and could be useful in screening campaigns, following the method suggested here.

Short-term prognosis of stroke due to occlusion of internal carotid artery based on transcranial Doppler ultrasonography

BACKGROUND AND PURPOSE

The clinical course of stroke due to occlusion of the internal carotid artery is influenced by amount of collateral flow. We measured mean frequency shifts in the middle cerebral artery by transcranial Doppler ultrasonography to determine its prognostic value.

METHODS

Patients with proven extracranial occlusion of the internal carotid artery and ipsilateral hemispheral stroke were enrolled in our study. We performed transcranial Doppler ultrasonography on 31 patients within 48 hours after the stroke onset and followed up 25 patients in 28 days. At the same time, neurological examination with quantification of neurological deficit was done. We correlated values of flow frequency shifts on the side of stroke with degree of neurological deficit at the onset and at 28 days as well as the degree of clinical improvement and the value of frequency shifts.

RESULTS

We found a negative correlation between blood flow frequency shifts in the middle cerebral artery and degree of neurological deficit at the onset (Spearman rank correlation coefficient, -0.567; p less than 0.001). We also found a positive correlation between the change of the neurological deficit during follow-up and frequency shifts at the onset (Spearman rank coefficient, 0.548; p less than 0.05).

CONCLUSIONS

Diminished blood flow velocity (mean frequency shift) in the area of stroke is a negative prognostic factor for the degree of neurological deficit at the onset and a negative prognostic factor for possible improvement. Knowledge of hemodynamic conditions in the stroke area may help to improve therapeutic decisions.

Internal carotid arterial blood flow velocity in infants

The differences in the velocity and pulsatility indexes in the internal carotid artery were evaluated in 62 normal controls, 42 infants with cerebral palsy, and 22 infants with mental retardation, all within the first year of life. In the normal controls, the average maximal blood flow velocity (A/L), and the maximal end-diastolic flow velocity increased during the first year of life. Pulsatility index decreased significantly between the ages of newborn to 2 mos and 3-5 mos, and remained constant thereafter. Compared with normal controls, the average maximal blood flow velocity and the maximal end-diastolic flow velocity values were significantly reduced in infants with cerebral palsy during the first 6 months of life, while no differences in these values were observed in infants with mental retardation. There were no differences in the pulsatility index values in the 3 subject groups throughout the first year of life. Flow velocity in the internal carotid artery could reflect the status of the cerebral circulation in infants within the first year of life.

Blood flow velocity changes in migraine attacks--a transcranial Doppler study

A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraineurs without aura (n = 27) and with aura (n = 4), both during and outside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. We suggest that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries.

Transcranial Doppler: response of cerebral blood-flow velocity to carbon dioxide in anaesthetized children

To determine the effect of carbon dioxide on the cerebral circulation in anaesthetized infants and children, 13 healthy children, ASA physical status I or II, between three months and seven years of age and scheduled for urologic surgery, were studied. Anaesthesia was induced with thiopentone and vecuronium. After tracheal intubation, anaesthesia was maintained with 70 per cent nitrous oxide in oxygen, fentanyl 2 micrograms.kg-1, vecuronium 0.05 mg.kg-1 and 0.8-1.0 per cent end-tidal isoflurane. A caudal block was performed before surgery. Systolic arterial pressure, heart rate, oxygen saturation, temperature, and end-tidal isoflurane were maintained constant. Ventilation was adjusted to achieve an end-tidal PCO2 (PETCO2) of 20 mmHg. The PETCO2 was then randomly adjusted between 20 and 80 mmHg by the addition of carbon dioxide from an exogenous source. Cerebral blood flow velocity increased logarithmically and directly with the PETCO2 (r2 = 0.56). There were no complications associated with the use of transcranial Doppler sonography. These data indicate that CO2 has a direct effect on the velocity of blood in the middle cerebral artery in infants and children anaesthetized with isoflurane.

Assessment of cerebral hemodynamics in pregnant women by internal carotid artery pulsed Doppler velocimetry

To date, no studies have been done of serial changes in maternal cerebral hemodynamics during pregnancy. We used the noninvasive method of Doppler velocimetry to assess cerebral hemodynamics in pregnant women. Velocimetry measurements of the internal carotid artery were performed in 17 normal nonpregnant women and 77 women with uncomplicated pregnancies with a 4 MHz pulsed Doppler ultrasound system. Peak systolic and mean velocities in the first and second trimesters were almost the same as those in nonpregnant women, whereas they became slower in the third trimester. Pulsatility index from 4 to 31 weeks' gestation was significantly higher than in nonpregnant women, but fell to the nonpregnant value after 32 weeks. Doppler velocimetry was found to be an extremely useful method of cerebrohemodynamic evaluation in pregnant women.

Anterior cerebral artery velocity changes in disease of the middle cerebral artery stem

Transcranial Doppler ultrasonography can map the changes in blood velocity that result from stenosis or occlusion of the middle cerebral artery. To evaluate patterns of collateral blood flow in disease of the middle cerebral artery stem, we used both cerebral angiography and transcranial Doppler ultrasonography to study the systolic blood velocities in both anterior cerebral arteries in 10 consecutive patients with middle cerebral artery stenosis or occlusion. Five patients had no evidence of hemodynamically significant carotid disease and good-quality measurements of systolic velocity in each anterior cerebral artery. Two of the five patients had middle cerebral artery stem stenosis and the other three had occlusion. The ratios of mean blood velocity in the normal compared with the abnormal side for the five patients (mean 1.34 +/- 0.23, range 1.15-1.74) were significantly higher than ratios for 10 controls (mean 1.04 +/- 0.12, range 0.76 +/- 1.19) using an unpaired t test (t = 3.492, 0.0005 less than p less than 0.005). Our results suggest that transcranial Doppler ultrasound measurements of anterior cerebral artery blood velocity may be a useful index of collateral blood flow from the anterior cerebral artery territory into the middle cerebral artery territory. Changes in mean velocity ratio may document the evolution and adequacy of collateral blood flow over the cerebral convexity in middle cerebral artery stem disease. In addition, the changes in anterior cerebral artery blood velocity appear to be an important corroborative finding for middle cerebral artery stem occlusion.

Blood velocity and regional blood flow in defined cerebral artery systems

Cerebral artery blood velocity and regional blood flow (rCBF) were investigated in 17 normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler ultrasound in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using 133Xe inhalation and a rapidly rotating single photon emission computer tomograph. Concomitant capnograph recordings showed that the end-expiratory pCO2 was higher during the rCBF than during the blood velocity examinations. This differences was highly significant. While there was no significant correlation between blood velocity and rCBF when these clear differences in pCO2 were disregarded, we did find significant positive correlations when the data were normalized to a standard pCO2 (5.3 kPa) using accepted formulas. The best correlation was found for the MCA (r = 0.630, p less than 0.001) and the PCA (r = 0.73, p less than 0.001), with a lower correlation in the ACA (r = 0.49, p less than 0.01) and the ICA (r = 0.41, p less than 0.05). The estimated blood velocity (V) given rCBF = 0 was not significantly different from 0. The results support the validity of expressing the relationship between blood velocity (V) and rCBF in defined cerebral artery systems as: V = 1/60 (rCBF) T (A)-1, where A represents the area of the lumen of the vessel segment where the velocity is being measured, and T denotes the size of the brain region being perfused from this artery.

Cerebral blood flow during ACTH therapy: especially diurnal changes within the first week of therapy

Changes in cerebral blood flow (CBF) were evaluated in children with epilepsy treated with adrenocorticotrophic hormone (ACTH) by the Doppler ultrasound method. The average maximal blood velocity (A/L) and maximal end-diastolic blood velocity (d) of the internal carotid artery, as indices of CBF, significantly decreased during ACTH therapy. These values had already decreased at 30 minutes after the first injection of ACTH and were hardly restored 24 hours later just before the next injection. Such changes repeatedly occurred for the first four days of therapy so that the reductions in the A/L and d values proceeded in a stepwise manner. These values became minimum at around one week after initiation of the therapy and then gradually increased, returning to the original levels by the 8th week of therapy. Investigation of the changes in cerebral metabolism seemed to be the next step for elucidation of the mechanism underlying the CBF reduction during ACTH therapy.

Analysis of cerebroarterial Doppler flow velocity waveforms in newborn infants: towards an index of cerebrovascular resistance

Doppler ultrasound has been used extensively to study cerebral hemodynamics in the human newborn. This report presents a continuous recording in an infant with epileptic seizures. Heart rate, mean aortic blood pressure and mean flow velocity, obtained from the anterior cerebral artery by Doppler ultrasound, all increased markedly during the seizures. The Poucelot index was calculated from the cerebral blood flow velocity waveform and is supposed to reflect cerebrovascular resistance. This index decreased. Three mutually contradictive interpretations were possible in terms of cerebral metabolic rate, cerebral blood flow, metabolism-flow coupling and pressure-flow autoregulation. Sympathetic activation and its effects on cerebral hemodynamics is discussed. It is pointed out that the competence of the pressure-flow autoregulation may not be studied reliably during changes in blood pressure associated with altered sympathetic activity. An electrical model of the systemic arterial system is presented and used to demonstrate that the resistance index is likely to be severely affected by changes in cerebroarterial compliance, peripheral resistance, duration of systole as a fraction of heart cycle and patency of the arterial ductus. A pulsatility index ratio, which is corrected for arterial pulse pressure, is suggested to avoid some of these errors.

Cerebral blood flow and brain shrinkage seen on CT during ACTH therapy

By means of the Doppler ultrasound method, the cerebral blood flow (CBF) was assessed in 21 children with epilepsy undergoing treatment with adrenocorticotrophic hormone (ACTH). The maximum reduction in the internal carotid velocity, as an index of CBF during therapy, was about 35 percent compared with the values before therapy. Furthermore, sequential computed tomography (CT) examinations of the same subjects were performed to evaluate the change in the area of the intracranial brain parenchyma during therapy. The maximum reduction in the parenchymal area during therapy was about 10 percent. This corresponds to a 20 percent reduction in CBF according to Poiseuille's law, however, the remaining reduction in CBF demonstrated by velocity measurement cannot be explained only by that mechanical vascular factor. From these findings, it is concluded that in order to elucidate the mechanism of the CBF reduction, physiological factors such as changes in metabolism during therapy should also be evaluated in addition to the mechanical and physical causes.

The effect of ACTH on cerebral blood flow in children with intractable epilepsy

Cerebral blood flow was assessed by ultrasound in 12 children with intractable epilepsy who were treated with ACTH. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) of the internal carotid artery were measured, before, during and after ACTH therapy in each subject. The right and left mean A/L and d values were significantly decreased during ACTH therapy, and these values returned to the previous levels after the treatment. Cerebral function in children treated with ACTH may be affected by a decrease in cerebral blood flow.

Blood flow velocity in the pial arteries of cats, with particular reference to the vessel diameter

The blood flow velocity and diameter of feline pial arteries, ranging in diameter from 20 to 200 microns, were measured simultaneously using a newly developed video camera method under steady-state conditions for all other parameters. There was a linear relationship between blood flow velocity and pial artery diameter (y = 0.340x + 0.309), the correlation coefficient being 0.785 (p less than 0.001). The average values for blood flow velocity in pial arteries less than 50 microns, greater than or equal to 50 but less than 100 microns, greater than or equal to 100 but less than 150 microns, and greater than or equal to 150 microns in diameter were 12.9 +/- 1.3, 24.6 +/- 3.4, 42.1 +/- 4.7, and 59.9 +/- 5.3 mm/s, respectively. Blood flow rate was calculated as a product of the cross-sectional area and the flow velocity. The blood flow rate increased exponentially as the pial artery diameter increased (y = 2.71 X 10(-4) x2.98). The average values for blood flow rate in pial arteries less than 50 microns, greater than or equal to 50 but less than 100 microns, greater than or equal to 100 but less than 150 microns and greater than or equal to 150 microns in diameter were 12.8 +/- 1.5, 122.1 +/- 24.8, 510.2 +/- 74.8, and 1524.2 +/- 174.4 10(-3) mm3/s, respectively. Hemorheological parameters such as the wall shear rate and Reynolds' number were also calculated. The data obtained provide a useful basis for further investigations in the field of cerebral circulation.

Cerebral blood flow in the newborn infant: comparison of Doppler ultrasound and 133xenon clearance

Two techniques of Doppler ultrasound examination, continuous-wave and range-gated, applied to the anterior cerebral artery and to the internal carotid artery, were compared with 133xenon clearance after intravenous injection. Thirty-two sets of measurements were obtained in 16 newborn infants. The pulsatility index, the mean flow velocity, and the end-diastolic flow velocity were read from the Doppler recordings. Mean cerebral blood flow was estimated from the 133Xe clearance curves. The correlation coefficients between the Doppler and the 133Xe measurements ranged from 0.41 to 0.82. In the subset of 16 first measurements in each infant, there were no statistically significant differences between the correlation coefficients of the various Doppler ultrasound variables, but the correlation coefficients were consistently lower for the pulsatility index than for mean flow velocity or end-diastolic flow velocity, and they were consistently higher for the range-gated than for the continuous-wave Doppler technique.

Cerebral blood flow in children with intractable epilepsy

A good correlation of Doppler internal carotid blood velocity determinations with hemispheric blood flow measurements by the 133-xenon inhalation method was demonstrated in 14 epileptic patients without abnormal CT findings. The highest correlation was seen between the flow of gray matter (F1) and the internal carotid end-diastolic velocity (d) (left side r = 0.841, right side r = 0.817). As end-diastolic velocity (d) well correlated with the value obtained by the 133-xenon inhalation method, the d value was compared between 77 healthy children and 13 patients with intractable epilepsy. The mean d value of both internal carotid arteries in patients was 16.7 +/- 2.9 mm (mean +/- SD), and that of healthy children 20.9 +/- 4.3 mm, the difference being statistically significant. The low cerebral blood flow in patients might be due to multiple antiepileptic drugs administered and/or mental retardation and cerebral hypofunction related to seizures.

Clinical diagnosis by transcutaneous Doppler ultrasound

Transcutaneous Doppler ultrasound represents a convenient, reliable technique for the non-invasive diagnosis and assessment of a rapidly increasing number of diverse circulatory disorders.

Internal carotid blood flow velocity in children with cerebral palsy by Doppler Ultrasound method

Cerebral blood flow assessed noninvasively by Doppler ultrasound technique in 30 children with cerebral palsy. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) of internal carotid artery were measured before and during brief digital compression of contralateral common carotid artery. Both A/L and d values in children with cerebral palsy were significantly lower than those observed in normal healthy children. In 13 children with spastic hemiplegia, no significant difference in either A/L or d was seen between the non-affected side and affected side both before and during brief digital compression. This data suggests that mean cerebral blood flow decreases in our children with cerebral palsy, and that no lateralization of the decrease in hemispheric cerebral circulation in hemiplegic children may explain by supposing the existence of generalized bilateral brain damage in those subjects.

Carotid Doppler hemodynamics in posttraumatic intracranial hypertension

Repeated Doppler sonograms were performed on the common carotid arteries of patients with severe brain injury. The evolution of the flow-wave shape in 9 patients who developed massive intracranial hypertension and finally died with cerebral circulatory arrest demonstrated that, with increasing peripheral vascular resistance, the diastolic flow diminished while the peak systolic flow was not significantly affected. Thus, the so-called pulsatility index, a measure of the pulsatile characteristic of the sonogram, can be used as a semiquantitative measure of intracranial perfusion. Measurements on healthy control subjects provided pulsatility indexes between 1.5 and 2.0. In cases of posttraumatic brain edema, these values increased gradually. These data suggest that values higher than 3 are associated with severe intracranial hypertension and the decerebrate state. In angiographically demonstrated cerebral circulatory arrest, the pulsatility index was found to range between 6 and 8.