Aortic coarctation diagnosed in a hypertensive child undergoing Doppler sonography for suspected renal artery stenosis

A 5-year-old girl presented with hypertension, with no perceived blood pressure differential between the lower and upper extremities. Doppler ultrasound revealed a tardus-parvus pattern with diminished systolic acceleration and peak systolic velocities in the abdominal aorta and both main renal arteries. Doppler interrogation of the suprasternal aorta showed a normal waveform, suggesting a partial obstruction distally. Echocardiography and aortography confirmed severe discrete aortic coarctation with transverse arch hypoplasia. Because classic findings of aortic coarctation may not be present, especially in the older child, the radiologist must be aware that a tardus-parvus Doppler waveform in the abdominal aorta and bilateral renal arteries is suggestive of proximal aortic stenosis, which may be localized by spectral Doppler of the aortic arch.     

Color-coded Doppler sonography of the kidney blood vessels in childhood. II. Pathological findings

Pathologic flow profiles in renal arteries can be found in cardiovascular and renovascular disease. Obstructions of the left hart (aortic stenosis, hypoplastic left heart syndrome, coarctation of the aorta) cause diminished flow with low peak systolic velocities. In renal arteries of infants with leakage of the aortic "Windkessel" (persistent ductus arteriosus, truncus arteriosus communis etc.) a low diastolic amplitude can be found. Significant left-to-right shunts can lead to a diminished or even retrograde diastolic flow. In renal artery stenosis a high velocity jet with spectral broadening can be found in the region of the stenosis. Distal to the stenosis low blood flow velocities can be shown. In renal vein thrombosis the obstruction of the peripheral vessels cause a missing or even negative diastolic flow in the renal arteries, whereas venous blood flow is diminished or even missing. Kidney diseases with swelling of the organ (acute rejection of a transplanted kidney) can cause diminished, missing or even retrograde diastolic flow in the renal arteries dependent on the severity of the edema. These alterations can be used for the early diagnosis of acute rejection which offers the opportunity for early and efficient therapeutic management.     

Transient stenoses and occlusions of main cerebral arteries in children —diagnosis and control of therapy by transcranial Doppler sonography

Flow disturbances in main cerebral arteries may cause severe neurological symptoms. Using transcranial Doppler sonography (TCD) the blood flow velocities in the basal cerebral arteries (BCA) can be recorded at any age. Transient stenoses or occlusions of main cerebral arteries were detected in 11 children by this method and confirmed by other techniques. Vasospasm produced a marked increase in flow velocities in the affected arteries which was reduced by nimodipine, the calcium channel blocker. Vasospasm also occurred in severe bacterial meningitis. In acute hemiplegia due to cerebral arterial obstruction no flow velocities could be recorded at the corresponding site. If distal branches were obstructed reduced flow velocities were found proximally. Increased flow velocities or reversed flow in anastomoses indicated the collateralization. The transient nature of the occlusions was shown by repcated recordings. TCD is a reliable, noninvasive and rapidly available technique for diagnosing or excluding transient flow disturbances in the main cerebral arteries as the cause of neurological symptoms in children. It indicates the necessity and most advantageous stage for therapy.Abbreviations ACA anterior cerebral artery - BCA basal cerebral artery (-ies) - CT computed tomography - ICA internal carotid artery - MCA middle cerebral artery - MFV mean peak flow velocity - PCA posterior cerebral artery - TCD transcranial Doppler sonography     

Cerebral blood flow during vasovagal syncope induced by active standing or head up tilt.

BACKGROUND: Vasovagal syncope is usually associated with a sudden drop of blood pressure and/or heart rate. However, occasionally the symptoms of syncope induced by orthostatic stress testing are not associated with obvious haemodynamic changes. The mechanisms of syncope in these patients are not clear. AIM: To evaluate changes in cerebral blood flow velocities during orthostatic stress testing in children and adolescents with vasovagal syncope. METHODS: Electrocardiogram, instantaneous arterial blood pressure, and right middle cerebral artery blood flow velocity were recorded at rest, during active standing, and 80 degrees head up tilt. 32 children and adolescents aged between 7 and 18 years with a history of repeated vasovagal syncope and 23 healthy control subjects were studied. RESULTS: Presyncope occurred in 10 patients during standing, and 13 patients during head up tilt. None of the controls had symptoms during the test. The transcranial Doppler study showed that the symptoms were associated with significant decreases of diastolic cerebral blood flow velocity and an increase of pulsatility. There was no significant change of the systolic cerebral blood flow velocity. The changes of cerebral blood flow velocities occurred in all episodes of presyncope, including those not associated with severe drop of blood pressure or heart rate. CONCLUSIONS: Diastolic cerebral blood flow velocity decreased significantly during episodes of presyncope induced by orthostatic stress. Impairment of autoregulation of cerebral blood flow might play an important role in the pathophysiology of syncope.     

Echocardiographic Evaluation of Systolic and Diastolic Function in Postoperative Coarctation Patients

Postoperative coarctation (CoA) patients are often found to have signs of persistent myocardial dysfunction. M-mode echocardiography was performed to study left ventricular (LV) size, mass, and systolic function and Doppler ultrasonography to study LV filling and flow velocity in the LV outflow tract and aorta in 28 ``healthy' postoperative CoA patients (5–21 years) and 28 age- and sex-matched controls. The early (E) and late (A) diastolic transmitral velocities were significantly higher in the patient group than in the controls (p < 0.05). Other diastolic parameters (isovolumic relaxation time, E/A ratio, and deceleration time of the early diastolic velocity) were similar in the two groups (p= NS). The left atrial diameter, LV wall average, end-diastolic diameter of the LV and LV mass were higher in the patients than controls (p < 0.05). The patients also had a higher stroke volume, cardiac output, and cardiac index than the controls (p < 0.01). The fractional shortening was similar in the two groups (p= NS). Blood flow velocities in both the LV outflow tract and aorta were higher in the patients than the controls (p < 0.0002). We found LV hypertrophy with signs of a hyperdynamic circulation (increased cardiac index and stroke volume) in our patients. An increase in A is associated with LV hypertrophy and seems to be a sensitive marker of diastolic abnormality. The rise in E is paradoxical but has been seen in other studies. The increased blood flow velocity in the LV outflow tract suggests obstruction to LV outflow and increased flow in the descending aorta is due to residual coarctation.     

Internal carotid artery blood flow velocities before, during, and after extracorporeal membrane oxygenation.

Blood flow velocities in the internal carotid arteries were studied with pulsed Doppler in 25 neonatal patients (birth weight range, 2600 to 4100 g) who had extracorporeal membrane oxygenation (ECMO). Time averaged mean systolic, mean diastolic, and mean blood flow velocities were calculated. Five infants had right common carotid artery reconstruction. Blood flow velocities measured in 15 healthy full-term infants were used as controls. Findings during ECMO included the following: (1) forward flow in the right internal carotid artery in 50% of the infants; (2) significant increase in the mean diastolic and the mean flow velocities (48% and 128%, respectively) in the left internal carotid artery when compared with pre-ECMO and control infants' values; (3) the elevation in the mean and the mean diastolic velocities was associated with changes in the PaCO2 and with an increase in the diastolic blood pressure; and (4) forward blood velocities in the right internal carotid artery were comparable with blood velocities in the left internal carotid artery and with the blood velocities of control infants. After ECMO, the mean diastolic velocity in the left internal carotid artery decreased significantly, but it remained elevated when compared with pre-ECMO values. Infants with right common carotid reconstruction had blood velocities in the right internal carotid artery comparable with the simultaneous blood velocities in the left internal carotid artery and to the blood velocities of control infants. Twenty-eight percent of the infants had major neuroanatomic lesions. Right or left preponderance was not noted. No association between blood velocity values in the internal carotid arteries or flow direction and the presence or the absence of brain lesions was noted.     

Pulsed Doppler sonographic determination of absolute flow velocities in the anterior cerebral artery in infants with hydrocephalus in comparison with a healthy patient sample

In 52 infants (weight: 3174 +/- 1165 g; gestational age: 41.3 +/- 6.5 weeks) with hydrocephalus pulsed doppler recordings were obtained in the anterior cerebral arteries. For comparison 52 healthy infants (weight: 3148 +/- 1118 g; gestational age: 40.6 +/- 5.7 weeks) were investigated. In all children the maximal systolic velocity, the end-systolic velocity, the end-diastolic velocity and the pulsatility-index were measured. In the healthy control group the maximal systolic velocity was 43 +/- 14 cm x s-1, the end-systolic velocity 20 +/- 8 cm x s-1, the end-diastolic velocity 11 +/- 5 cm x s-1 and the pulsatility index was 0.75 +/- 0.10. All 9 children with minimal ventricular dilation without progression showed normal flow profiles with normal flow velocities and pulsatility-index in the anterior cerebral arteries. 17 infants with moderate, slowly progressive ventricular enlargement showed significant increase of the maximal systolic velocity (60 +/- 27 cm x s-1) and the pulsatility-index PI (0.82 +/- 0.14). There was no difference in the end-systolic and end-diastolic velocities to the healthy control group. 26 children with marked and rapid progressive hydrocephalus showed significant decrease of the end-systolic and end-diastolic velocities and an increase in the pulsatility-index. The end-systolic velocity was 15 +/- 7 cm x s-1, the end-diastolic velocity was 4 +/- 7 cm x s-1 and the pulsatility-index measured 0.91 +/- 0.18. There was no difference in the maximal systolic velocity which measured 41 +/- 17 cm x s-1. All children with increased intracranial pressure showed a pathological flow profile with a decrease of diastolic forward flow. Absent or retrograde diastolic flow in rapid progressive hydrocephalus may lead to a decrease of brain perfusion resulting in hypoxemic ischemic brain lesions. After implantation of a ventriculo-atrial shunt an increase in the end-systolic and end-diastolic velocities and a decrease of the pulsatility-index could be shown. Shunt insufficiency can be shown early by a decrease in diastolic forward flow.     

Cerebral blood flow during vasovagal syncope induced by active standing or head up tilt

BACKGROUND—Vasovagal syncope is usually associated with a sudden drop of blood pressure and/or heart rate. However, occasionally the symptoms of syncope induced by orthostatic stress testing are not associated with obvious haemodynamic changes. The mechanisms of syncope in these patients are not clear.
AIM—To evaluate changes in cerebral blood flow velocities during orthostatic stress testing in children and adolescents with vasovagal syncope.
METHODS—Electrocardiogram, instantaneous arterial blood pressure, and right middle cerebral artery blood flow velocity were recorded at rest, during active standing, and 80° head up tilt. 32 children and adolescents aged between 7 and 18 years with a history of repeated vasovagal syncope and 23 healthy control subjects were studied.
RESULTS—Presyncope occurred in 10 patients during standing, and 13 patients during head up tilt. None of the controls had symptoms during the test. The transcranial Doppler study showed that the symptoms were associated with significant decreases of diastolic cerebral blood flow velocity and an increase of pulsatility. There was no significant change of the systolic cerebral blood flow velocity. The changes of cerebral blood flow velocities occurred in all episodes of presyncope, including those not associated with severe drop of blood pressure or heart rate.
CONCLUSIONS—Diastolic cerebral blood flow velocity decreased significantly during episodes of presyncope induced by orthostatic stress. Impairment of autoregulation of cerebral blood flow might play an important role in the pathophysiology of syncope.

     

Cerebral blood flow velocity in term newborn infants: changes associated with ductal flow

The effects of ductal closure on range-gated pulsed Doppler cerebral blood flow velocity (CBFV) patterns in the internal carotid, anterior cerebral, and middle cerebral arteries were studied in 10 normal term infants (mean birth weight 3302 +/- 294 g (SD) and mean gestational age 39.6 +/- 1.3 weeks). Pulsatility was calculated from flow velocities and used as an estimate of cerebral blood flow (CBF). Ductal closure was associated with a rise in mean blood pressure from 45.0 +/- 4.2 to 51.3 +/- 6.5 mm Hg (P less than 0.05) and a significant decrease in pulsatility in all three vessels (mean = 0.77 +/- 0.07 vs 0.70 +/- 0.05 (P less than 0.02]. Changes in pulsatility were correlated with changes in mean blood pressure (P less than 0.02), providing evidence that systemic blood pressure may influence postnatal cerebral arterial pulsatility indices. We also noted significant differences in the velocity and pulsatility of individual vessels that were independent of blood pressure, suggesting that Doppler flow studies may be useful in describing regional CBF patterns. The temporal association between ductal closure and decreased pulsatility suggests that CBFV patterns reflect ductal shunting in normal term newborn infants. Diastolic runoff and reduced systemic blood pressure in the presence of ductal shunting appear to reduce diastolic flow velocity and increase CBFV pulsatility in normal term infants during the first days of life. Normal mechanisms of cerebral autoregulation compensate for decreased flow with vasodilation; therefore the increased pulsatility associated with ductal shunting may be due to diastolic runoff rather than increased cerebrovascular resistance.     

Influence of stenotic valve geometry on measured pressure gradients and ventricular work: The relationship between morphology and flow

The physiologic impact of aortic valve stenosis is most directly reflected by an increased workload placed on the ventricle. In the pediatric population the morphology of aortic stenosis varies considerably. Fluid dynamic principles suggest that different morphologies may require the ventricle to accelerate blood to different maximal velocities for constant cardiac outputs and valve areas, resulting in different ventricular workloads. This study examined this important concept in in vitro models designed to isolate the effect of valve geometry on distal velocity, pressure gradients, and proximal work. Four stenotic valve morphologies were examined using a variable-voltage pump system. For constant orifice areas and flows, markedly different workloads were required by the pump, and this difference was reflected in direct measurements of pressure gradient and Doppler predictions of gradient. These fundamental fluid dynamic studies isolate the relationship between flow, work, and stenotic valve morphology. Different orifice geometries affect the value of the coefficient of contraction, which is reflected in different maximum velocity values for stenosis with constant anatomic areas and flows. The proximal pumping chamber must generate different levels of force to achieve these different velocities, and this variability is reflected in the clinically measured pressure gradient.     

Abnormal blood flow patterns in renal arteries of small preterm infants with patent ductus arteriosus detected by Doppler ultrasonography

Blood flow velocities and pulsatory indices in both renal arteries (RAs) and in the internal carotid artery (CAI) were measured by pulsed Doppler ultrasonography in ten preterm infants with patent ductus arteriosus (PDA), before and after surgical ligation. The results obtained in the RAs were compared to those found in a reference group of 22 stable preterm infants. In the RAs the diastolic steal volume of the PDA led to a marked decrease in diastolic blood flow velocity (range 3 to-23 cm/s). Seven infants showed retrograde diastolic flow, whereas only three infants had these flow patterns in the CAI. In the RAs, the peak systolic blood flow velocities (range 56 to 135 cm/s) exceeded the values found in the reference group by 85% on average. The pulsatility indices reached values of above 1,00. In spite of the increase in systolic flow velocities before surgery, the time mean of maximum velocities was significantly lower than those measured after surgery and in the reference group. After PDA ligation, blood flow velocities normalized. The present study shows that a large PDA may induce abnormal flow patterns even in the RAs. These flow patterns may predispose to renal hypoperfusion and subsequent impairment of renal function.Abbreviations CAI internal carotid artery - NFC necrotizing enterocolitis - PDA patent ductus arteriosus - PI pulsatility index - RA renal artery - Vd end-diastolic velocity - V_max time mean of maximum velocity - Vs peak systolic velocity     

Increased cerebral blood flow velocity in infants of mothers who abuse cocaine

The pharmacologic effects of cocaine are considered to be secondary to an enhancement of the effects of circulating catecholamines. The effect of intrauterine cocaine exposure on the cerebral blood flow velocity was studied in 20 full-term newborn infants whose urine screens were positive for cocaine and in 18 nonexposed healthy full-term newborn infants whose urine screens were negative for cocaine metabolites. On the first day of life, peak systolic, end diastolic, and mean flow velocities in the pericallosal, internal carotid, and basilar arteries and mean arterial blood pressures were significantly greater in infants who had been exposed to cocaine. On day 2, cerebral blood flow velocities and mean arterial blood pressures were similar in exposed and nonexposed infants. The increase in mean arterial blood pressure and in cerebral blood flow velocity on the first day of life indicates a hemodynamic effect of cocaine that may put the infant exposed to cocaine at a greater risk of intracranial hemorrhage.     

Holodiastolic Flow Reversal at the Descending Aorta on Cardiac Magnetic Resonance is Neither Sensitive Nor Specific for Significant Aortic Regurgitation in Patients with Congenital Heart Disease

Holodiastolic flow reversal in the descending aorta on echocardiogram suggests significant aortic regurgitation. The study aim was to determine whether the presence of holodiastolic flow reversal on cardiac magnetic resonance imaging (MRI) correlates with aortic valve regurgitant fraction. We retrospectively reviewed 166 cardiac MRIs (64 % male, age 14.1 ± 9.5 years) from January 2011 to May 2012 where velocity mapping was acquired at both the aortic valve and the descending aorta at the level of the diaphragm. Descending aorta velocity maps were checked for baseline offset using a static reference region. Holodiastolic flow reversal was defined as flow reversal throughout diastole both before and after baseline correction. Significant aortic regurgitation was defined as regurgitant fraction >10 %. Aortic valve regurgitant fraction was <10 % in 144 patients (Group A), 10–20 % inclusive in 7 patients (Group B), and >20 % in 15 patients (Group C). Though the aortic valve regurgitant fraction was significantly higher for patients with holodiastolic flow reversal versus those without (8.5 ± 14.2 vs. 3.8 ± 6.6 %, p = 0.02), holodiastolic flow reversal was present in 32 Group A patients (22 %). In comparison, 4 Group B patients (57 %) and 7 Group C patients (47 %) had holodiastolic flow reversal. The sensitivity (Groups B and C) was 0.5, and the specificity (Group A) was 0.78. Holodiastolic flow reversal in the descending aorta on cardiac MRI was neither sensitive nor specific for predicting significant aortic regurgitation in this study population. Holodiastolic flow reversal in the absence of significant aortic regurgitation may be a relatively common finding in patients with congenital heart disease.     

Intracranial blood flow velocities during seizures and generalized epileptic discharges

In 51 children with different types of epilepsy, blood flow velocities in the middle cerebral artery were recorded continuously by transcranial Doppler sonography during a standard electroencephalogram of 30 min duration. In 16 children 33 epileptic seizures were recorded. During tonic seizures, the mean flow velocity increased to a maximum of 133%–191% (median 160%) of the baseline values. Tonic-clonic seizures were also accompanied by a velocity increase. During absence seizures the mean flow velocity decreased to a minimum of 46%–82% (median 71%) of the baseline values. Changes in cerebral metabolism and arterial blood pressure in the presence of disturbed autoregulation are thought to be factors causing these alterations. No alteration of the flow velocities occurred in cases of petit-mal status, electrical status epilepticus and in 35 children with generalized epileptic discharges of up to 5 s duration without clinical manifestations.     

Cerebral blood flow velocities during orthostasis and physical exercise

The peak flow velocities in the middle cerebral artery were continuously recorded by transcranial Doppler sonography in 29 children. Arterial blood pressure and heart rates were measured every minute. The values observed during orthostasis and physical exercise were compared to baseline values obtained in the supine position. During orthostasis the velocities were, on average, reduced to 87%–94%, the minimal values being 75%–78% of the baseline values. The heart rate increased whereas blood pressure showed only minor alterations. Upon standing up the systolic peak flow velocity remained unchanged while the mean- and enddiastolic peak flow velocities decreased to 66% and 39% respectively. On average, the velocities increased to 103%–108% during physical exercise. Systolic blood pressure increased to the same extent, the heart rate even more. Continuous recording of cerebral blood flow velocities may be more useful than intermittent measurements of blood pressure to differentiate children with and without symptoms of orthostasis.Supported by the Swiss National foundation, grant NF 32-26178.89.     

Wall Motion Velocities of Abdominal Aorta Measured by Tissue Doppler Imaging in Normal Children

Tissue Doppler imaging (TDI) offers a new technique for assessing aortic wall expansion/contraction velocities and may provide a noninvasive approach to aortic wall mechanics. The purpose of this study was to determine the normal values of abdominal aortic wall motion velocities and the effect of age on these velocities in normal children. We examined 103 normal children. Using TDI, maximum wall expansion velocity during systole (peak S) and maximum wall contraction velocity during diastole (peak D) were measured. M-mode diameter of the abdominal aorta and systolic, diastolic, and mean arterial pressures were measured. Aortic stiffness was measured as (I(n)[BP(syst)/BP(diast)])/(D(s)-D(d)/D(d), where I(n) is the natural log, D(s) is the maximal abdominal aortic diameter during systole, and D(d) is the abdominal aortic diameter at end-diastole. In all subjects, wall motion velocities of the abdominal aorta were recorded. The mean values for peak S and peak D were 4.23, 1.14 and 2.16, 0.45 cm/sec, respectively. Both peak S and peak D were low in infants and increased significantly with age (r = 0.63, p < 0.0001 and r = 0.36, p = 0.0002, respectively), systolic blood pressure (r = 0.42 and 0.47, respectively, p < 0.0001), and diastolic blood pressure (r = 0.24, p = 0.016 and r = 0.28, p = 0.0038, respectively). Aortic stiffness index of the abdominal aorta was constant with age and did not correlate with peak S or peak D. Abdominal aortic wall motion velocities can be easily assessed by TDI. Age-related changes in the aortic wall motion velocities are observed in normal children. This study provides baseline information for further quantitative assessment of arterial stiffness in children with congenital or acquired heart disease.     

Relation between Blood Pressure, Left Ventricular Mass and Pulsed Doppler Parameters in Healthy School Children

We analyzed the relations between blood pressure in sitting and supine positions, left ventricular mass (LVM) and Doppler aortic, pulmonary and mitral flow velocity measurements in 163 healthy school children. Systolic blood pressure in a supine position correlated significantly with aortic acceleration (ATc) and ejection time)ETc), corrected by the square of R-R interval, pulmonary AT and peak flow velocities. Moreover, the systolic blood pressure in a sitting position correlated with pulmonary AT and LVM. LMV correlated with pulmonary ATc, the ratio of AT to ET andaverage acceleration, and aortic ETc and peak flow velocity. These data suggest the following: (1) the posture influences the relation between blood pressure and flow velocity, (2) pulmonary hemodynamics are influenced by systemic blood pressure in healthy children and (3) the development of LVM may be dependentnot only on blood pressure but also on cardiac work in childhood.     

Effect of dexamethasone therapy on cerebral and ocular blood flow velocity in premature infants studied by colour Doppler flow imaging

Although dexamethasone (DEX) is used widely in neonates with chronic, and even recently with acute respiratory disease, its potential side-effects on human cerebral and ocular haemodynamics remain unknown. The effects of DEX on cerebral and ocular blood flow velocities were assessed in preterm infants with lung disease and mechanical ventilation. Ten ventilated preterm infants received DEX (0.25 mg/kg/12 h) for ongoing chronic lung disease or extubation failure. Colour Doppler flow imaging studies of the internal carotid, anterior cerebral and ophthalmic arteries were made before and 10, 30, 60, 120 and 240 min after the 1st, 3rd, and 5th doses of DEX. Peak systolic, temporal mean, and end-diastolic flow velocities and the resistence index (RI) of Pourcelot were determined. The brain was examined by ultrasonography before and at the end of each Doppler study. All patients were continuously monitored for transcutaneous blood gases and blood pressure. All flow velocities and the RI of the internal carotid, anterior cerebral and ophthalmic arteries showed a similar trend throughout the study. The means of the values averaged for the 240 min of cerebral and ocular blood flow velocity with each dose were progressively higher and the values of the RI progressively lower up to the 5th dose. The most significant changes occurred in end-diastolic flow velocity and consisted of a percentage increase between the 1st and 5th dose of 72% in the internal carotid artery, 102% in the anterior cerebral artery and 84% in the ophthalmic artery. Changes in arterial blood pressure followed a pattern similar to that of changes in blood flow velocity. Conclusions Dexamethasone increments cerebral and ocular blood flow velocity. We speculate that this finding may be relevant to the development of brain and retinal injury. Received: 25 July 1995 / Accepted: 28 May 1996     

Effect of dexamethasone therapy on cerebral and ocular blood flow velocity in premature infants studied by colour Doppler flow imaging

Although dexamethasone (DEX) is used widely in neonates with chronic, and even recently with acute respiratory disease, its potential side-effects on human cerebral and ocular haemodynamics remain unknown. The effects of DEX on cerebral and ocular blood flow velocities were assessed in preterm infants with lung disease and mechanical ventilation. Ten ventilated preterm infants received DEX (0.25 mg/kg/12 h) for ongoing chronic lung disease or extubation failure. Colour Doppler flow imaging studies of the internal carotid, anterior cerebral and ophthalmic arteries were made before and 10, 30, 60, 120 and 240 min after the 1st, 3rd, and 5th doses of DEX. Peak systolic, temporal mean, and end-diastolic flow velocities and the resistence index (RI) of Pourcelot were determined. The brain was examined by ultrasonography before and at the end of each Doppler study. All patients were continuously monitored for transcutaneous blood gases and blood pressure. All flow velocities and the RI of the internal carotid, anterior cerebral and ophthalmic arteries showed a similar trend throughout the study. The means of the values averaged for the 240 min of cerebral and ocular blood flow velocity with each dose were progressively higher and the values of the RI progressively lower up to the 5th dose. The most significant changes occurred in end-diastolic flow velocity and consisted of a percentage increase between the 1st and 5th dose of 72% in the internal carotid artery, 102% in the anterior cerebral artery and 84% in the ophthalmic artery. Changes in arterial blood pressure followed a pattern similar to that of changes in blood flow velocity. Conclusions Dexamethasone increments cerebral and ocular blood flow velocity. We speculate that this finding may be relevant to the development of brain and retinal injury.