Doppler Peak Systolic Velocity Research Articles

Anti-E Alloimmunization: A Rare Cause of Severe Fetal Hemolytic Disease Resulting in Pregnancy Loss

We report a case of severe intrauterine hemolysis caused by sole anti-E alloimmunization. A 36-year-old multipara woman presented with hydrops fetalis at 27 weeks of gestation. She had a history of previous neonatal death. In this pregnancy, she was found to have very high titer of anti-E antibody. Ultrasonography detected marked skin edema, cardiomegaly, hepatosplenomegaly, pleural effusion, ascites, placentomegaly, and polyhydramnios. The Doppler peak systolic velocity in the middle cerebral artery was 0.8 m/s, indicating severe fetal anemia. Multiple intrauterine transfusions for the anemic fetus were administered. However, persistent severe fetal anemia and placentomegaly caused poor neonatal death and mirror syndrome in the mother. Uncommon red blood cell alloimmunization has to be watched for early in any population, especially in a woman with a history of unexplained perinatal loss.

Influence of Fetal Anemia on Fetal Splenic Artery Doppler in Rh-Alloimmunized Pregnancies

Objective: To verify the correlation between fetal splenic artery Doppler velocimetry and fetal hemoglobin (Hb) levels in Rh alloimmunization. Methods: Splenic artery Doppler peak systolic velocity (PSV) and pulsatility index (PI) were obtained before cordocentesis in rhesus-alloimmunized fetuses. Doppler was performed before 80 cordocentesis in 36 patients between 20 and 35 weeks of gestation. Mild, moderate and severe anemia were defined as a Hb deficit of ≥2, ≥5 and ≥7 g/dl respectively. Results: Anemia was noted in 64% of the fetuses and moderate and severe anemia in 18 and 21%. Splenic artery PSV was higher in groups with moderate (p = 0.001) and severe (p < 0.000) anemia but not in the group with mild anemia (p = 0.189) when compared to non-anemic fetuses. Splenic artery PI was higher only in the severely anemic group (p = 0.001). Conclusions: The splenic artery PI and PSV are higher in fetuses with severe anemia.

Results using a self-expanding stent alone in the treatment of severe symptomatic carotid bifurcation stenosis

Conventional endovascular therapy for carotid stenosis involves placement of an embolic protection device followed by stent insertion and angioplasty. A simpler approach may be placement of a stent alone. The authors determined how often this approach could be used to treat patients with carotid stenosis, and assessed which factors would preclude this approach. Over a period of 6 years, 97 patients with symptomatic carotid stenosis were treated with the intention of using a "stent-only" approach. Arteries in 77 patients (79%) were treated with stents alone, 13 required preinsertion balloon dilation, 6 postinsertion dilation, and 1 both pre- and postinsertion dilation. The mean stenosis according to North American Symptomatic Carotid Endarterectomy Trial criteria was reduced from 82 to 40% in the stent-only group and from 89 to 37% in the stent and balloon angioplasty group. The 30-day stroke and death rate was 7.2%. Patients were followed for a mean of 15 months. In the stent-alone group, the mean preoperative Doppler peak systolic velocity (PSV) was 409 cm/second, with an internal carotid artery/common carotid artery (ICA/CCA) ratio of 7.2. At follow-up review, the PSV decreased to 153 cm/second and the ICA/CCA ratio to 2.1. In the angioplasty group the mean preoperative PSV was 496 cm/second and the ICA/CCA ratio was 9.2, decreasing to 163 cm/second and 2, respectfully, at follow-up evaluation. Restenosis occurred in 12.8% of patients at 6 months and in 15.9% at 1 year. One stroke occurred during the follow-up period in each group. Using multivariable analysis, factors precluding the "stent-only" approach were as follows: severity of stenosis, circumferential calcification, and no history of hyperlipidemia. Balloons may not be required to treat all patients with carotid stenosis. A stent alone was feasible in 79% of patients, and 79% of patients were alive and free from ipsilateral stroke or restenosis at 1 year. Restenosis rates with this approach are higher than with conventional angioplasty and stent insertion. Carotid arteries with very severe stenoses (> 90%) and circumferential calcification may be more successfully treated with angioplasty combined with stent placement.

Concordance between M-mode, pulsed Tissue Doppler, and colour Tissue Doppler in the assessment of mitral annulus systolic excursion in normal subjects

M-mode left atrioventricular plane displacement (AVPD) correlates with Tissue Doppler (TD) peak systolic annular velocity in healthy individuals. This approach is biased by several interacting factors related to the structural complexity of mitral annulus physiology, including the different dimensional values of measures, the confounding effect of isovolumic motions, and the spectral thickness of pulsed TD envelope. We sought to analyze the effective concordance between techniques in the assessment of systolic annular excursion. In 92 healthy subjects (age 60.5 +/- 18.6, 43.5% women), systolic AVPD was measured after exclusion of isovolumic components using three techniques: (i) M-mode; (ii) temporal integration of pulsed TD systolic wave; and (iii) colour TD-derived tissue tracking. Close correlations of M-mode AVPD with pulsed TD velocity-time integral (VTI) (R = 0.90, P < 0.0001) and colour TD AVPD (R = 0.86, P < 0.0001) were found. However, M-mode AVPD underestimated pulsed TD VTI (mean error -5.1 +/- 1.7 mm) and overestimated colour TD AVPD (mean error 3.4 +/- 1.3 mm). The concordance between M-mode and pulsed TD increased after adjustment for spectral dispersion of pulsed TD instantaneous velocities (mean error 0.1 +/- 1.1 mm). Despite strict correlations exist between M-mode and TD in the assessment of mitral annulus systolic excursion, the effective concordance between techniques is sub-optimal.

Discordant Middle Cerebral Artery Peak Systolic Velocity Doppler Studies in a Fetus With RhD Alloimmunization

Doppler measurement of the fetal middle cerebral artery peak systolic velocity is a valuable tool in detecting the presence of fetal anemia in Rh-sensitized pregnancies. We present a case in which discordant left and right middle cerebral artery Dopplers complicated clinical management. An RhD-alloimmunized patient had middle cerebral artery Dopplers at 30 weeks of gestation, which showed an elevated peak systolic velocity in the left middle cerebral artery, greater than 1.55 multiples of the mean, but the right middle cerebral artery was within the normal range. The amniotic fluid change in optical density at a wavelength of 450 nm was consistent with the right middle cerebral artery Doppler. When both Dopplers were greater than or equal to 1.5 multiples of the mean, fetal blood sampling revealed a hematocrit of 28%. Postnatal cranial ultrasound examination showed normal architecture, but there was persistent discordant Dopplers in the left versus the right middle cerebral artery. Measurement of both left and right middle cerebral artery peak systolic velocities may identify patients with intrinsic variations in cranial blood vessels resulting in abnormal Doppler flows.

Modeling Severely Discordant Hematocrits and Normal Amniotic Fluids After Incomplete Laser Therapy in Twin-To-Twin Transfusion Syndrome

Our objective was to explain the clinical presentations of sustained arteriovenous anastomotic transfusion of blood after incomplete laser therapy in twin-to-twin transfusion syndrome (TTTS). We extended our mathematical model of TTTS by adding the dynamics of hematocrit, and simulated incomplete laser therapy, first, by leaving one patent opposite arteriovenous anastomosis from the recipient to the donor and, second, by leaving one patent arteriovenous anastomosis from the donor to the recipient. In both simulations we reproduced the clinical observation of severe hematocrit discordance preceding delayed amniotic fluid imbalance. In conclusion, incomplete laser therapy may cause a severe circulatory imbalance between the twins which presents predominantly as discordant hematocrits rather than discordant amniotic fluid volumes as in primary TTTS. These results imply that the anemia-polycythemia sequence is a sensitive mechanism to identify transfusion reversal after complicated laser therapy, confirming the suggested role of middle cerebral artery peak systolic velocity Doppler measurements as a useful method of follow-up.

Thyroid Color Flow Doppler Sonography: An Adjunctive Tool for Differentiating Patients with Inappropriate Thyrotropin (TSH) Secretion Due to TSH-Secreting Pituitary Adenoma or Resistance to Thyroid Hormone

Thyrotropin (TSH)-secreting pituitary adenoma (TSHoma) and resistance to thyroid hormone (RTH) are two forms of inappropriate TSH secretion. Thyroid blood flow is largely TSH dependent. To assess whether thyroid blood flow may help to differentiate TSHoma and RTH. Intrathyroidal color flow Doppler sonography (CFDS) pattern and peak systolic velocity (PSV) were assessed at baseline and during T(3) suppression test on eight consecutive patients with TSHoma and 10 with RTH. All controls had CFDS pattern 0. Three RTH patients had pattern I and seven had pattern II. Two TSHoma patients had pattern I, five had pattern II, and one had pattern III. PSV at baseline was 3.8 +/- 1.3 cm/s in controls, 8.8 +/- 2.5 cm/s in RTH, 11.1 +/- 2.7 cm/s in TSHoma (p < 0.0003 vs. controls, p = 0.087 RTH vs. TSHoma). After T3 suppression test, PSV values were lower in RTH than in TSHoma (4.6 +/- 1.8 vs. 7.7 +/- 2.6 cm/s, p = 0.008). PSV values and CFDS pattern normalized in nine and eight RTH patients, respectively, after T(3) suppression test; conversely, only one TSHoma patient had a normalization of PSV values, and none had a normalization of CFDS pattern (p < 0.003 vs. RTH). Both RTH and TSHoma have increased CFDS pattern and PSV values; however, after T(3) both parameters normalized in most patients with RTH but not in those with TSHoma. Accordingly, CFDS pattern and PSV are adjunctive tools to differentiate these two forms of inappropriate TSH secretion.

P06.02: Use of the 95th centile MCA PSV for the prediction of fetal anemia

Objective: To evaluate the positive predictive value of the middle cerebral artery (MCA) Doppler peak systolic velocity (PSV) measurement >95th centile for the detection of fetal anemia in pregnancies complicated by red cell alloimmunization. Methods: A retrospective analysis of 41 patients over a 3 year period. In 47 cases an intrauterine fetal transfusion was undertaken between 21 and 35 weeks gestation because of suspected fetal anemia. Deviation of MCA PSV and hemoglobin from the mean/median were expressed as either Z-scores (SDs) or multiples of the median (MoM), respectively. The sensitivity of the 95th centile (>2SD) of MCA PSV for mild (<0.85 MoM) and moderate/severe (<0.65 MoM) anemia were calculated. Results: The sensitivity of the 95th centile of MCA PSV for mild and moderate/severe anemia was 97% and 100%, respectively. There were only 3 false positive MCA PSV tests, two of which were related to the presence of a coincidental fetoplacental vascular tumor causing a hyperdynamic circulation. Conclusions: The 95th centile of the MCA PSV appears to have an equal sensitivity with a low false positive rate for the detection of fetal anemia compared to the 66th centile (1.5MoM), which is the currently recommended standard. Use of the 95th centile would reduce the number of invasive tests required in the management of red blood cell isoimmunised pregnancies.

Diltiazem Reverses Tissue Doppler Velocity Abnormalities in Pre-Clinical Hypertrophic Cardiomyopathy

Background. Abnormalities in systolic and diastolic function shown by tissue Doppler imaging have been shown to be present in patients with hypertrophic cardiomyopathy who do not yet show clinical or echocardiographic evidence of the disease. These become more marked as left ventricular hypertrophy develops. We attempted to show that these abnormalities could be reversed by treatment with diltiazem. Methods and Results. Six adults, who were carriers of a mutation involving the cardiac myosin binding, protein-C gene and who did not show clinical electrocardiographic or echocardiographic evidence of the disease were given a dose of 240 mg of diltiazem daily. Tissue Doppler peak systolic and early diastolic velocities at the lateral mitral annulus were examined before treatment and at a mean of 8 weeks after starting treatment. Improvement in both parameters occurred with early diastolic velocities returning to normal and most systolic velocities also becoming normal. Conclusion. Diltiazem may have a role in helping to prevent abnormalities of function and perhaps the development of left ventricular hypertrophy in patients with pre-clinical hypertrophic cardiomyopathy.

Middle Cerebral Artery Doppler Used to Detect Fetal Anemia

Although rhesus immune globulin, also knownas Rhogam, has caused a dramatic decrease inanemic fetal demise, there are still risks. Anestimated one to six anemia cases occur per 1000births each year, but only 30% of these fetuseswill develop anemia that requires treatment.Previously, invasive techniques such ascordocentesis and amniocentesis were the only testsused to diagnosis a fetus at risk for anemia.Recently, anemia has been diagnosed by Dopplersonography of the middle cerebral arteryvelocity. The peak systolic velocities are measuredand plotted on a graph to determine anemiaseverity. These velocities are also able to diagnoseanemia in healthy fetuses by monitoring velocityincreases at a certain gestational age. Timing ofthe first and later intravenous blood transfusionscan also be determined using middle cerebralartery peak systolic velocity Doppler. Thisnoninvasive test has no known risk to the fetus andhas proven very useful in the diagnosis of fetalanemia.

A Multiple Regression Model of Combined Duplex Criteria for Detecting Threshold Carotid Stenosis and Predicting the Exact Degree of Carotid Stenosis

Combined duplex criteria are commonly used in vascular laboratories for evaluating carotid stenosis. However, most of these combinations are empirical, and systemic validation is lacking. This study was completed using a multiple regression method to evaluate the accuracy of different combined duplex criteria for detecting threshold carotid stenosis and predicting the exact degree of carotid stenosis on angiography. Two hundred sixty-six sets of unilateral carotid duplex and angiographic data were randomly divided into 2 sets: a derivation set and a validation set. The derivation set was used to develop a multiple logistic regression model for detecting 70% threshold carotid stenosis. Age, sex, systolic blood pressure, diastolic blood pressure, Doppler peak systolic velocity (PSV), Doppler and diastolic velocity (EDV), the systolic carotid ratio (SCR), and ophthalmic artery flow direction were tested as independent variables. A multiple linear regression model was also developed for predicting the exact degree of carotid stenosis on angiogram. The validation set was then used to evaluate the accuracy of these models. According to the logistic regression strategy, the best multiple logistic regression model was as follows: probability of threshold carotid stenosis = exp(2.6 PSV - 6.2)/[1 + exp(2.6 PSV - 6.2)]. The best linear regression model was as follows: degree of carotid stenosis = 20.2 PSV - 7.4 EDV + 0.4 SCR + 8.5. Both models proved to be valid following an evaluation of the validation set. This study illustrates that Doppler parameters may be of use in predicting the exact degree of carotid stenosis and the probability of threshold carotid stenosis. This is important if duplex criteria are going to replace angiography as the only tool for selecting endarterectomy candidates.

Renal artery Doppler peak systolic velocity: strong predictor of SGA

Renal artery Doppler peak systolic velocity: strong predictor of SGA

Doppler ultrasonography of the middle cerebral artery peak systolic velocity in the fetus

Objective: Measurement of the middle cerebral artery Doppler peak systolic velocity (MCA-PSV) is a sensitive predictor of fetal anemia due to either red cell alloimmunization or parvovirus infection. The objective of this investigation was to assess if the MCA-PSV value changes when measured at different locations.

Splenic artery Doppler in the prediction of the small-for-gestational age infant.

We hypothesized that, as with other areas of the peripheral circulation, fetal splenic artery blood flow undergoes changes in small-for-gestational age (SGA) fetuses due to a redistribution of cardiac output, and that the Doppler peak systolic velocity (PSV) reflects such changes and thus may be used to predict fetuses being SGA. Splenic artery Doppler PSV, end-diastolic velocity (EDV), resistance index (RI) and umbilical artery RI were measured prospectively in fetuses at risk for being SGA at birth. Normal reference data were generated from appropriately grown fetuses delivering at > or = 37 weeks without complications, and SGA was defined as birth weight < 10th percentile. The Doppler indices were expressed as multiples of the normal median (MoM) for gestational age. Using receiver operating characteristic curves, optimal Doppler thresholds for the detection of SGA cases were determined and the areas under the curves calculated. The analysis was limited to singleton pregnancies delivered within 2 weeks of the last Doppler examination. There were 88 study patients of which 60 had SGA babies. The mean gestational age at Doppler examination was 31.4 weeks with a mean interval of 5.6 days from Doppler to delivery. The splenic artery PSV was lower in SGA, compared to normal cases: mean PSV (MoM), 0.93 vs. 1.09, respectively (P = 0.0001). The sensitivity, specificity and area under the curve were 70.0%, 72% and 0.734, respectively (P < 0.003), for the PSV in the prediction of delivery of a SGA fetus. For the splenic artery RI, values were 70%, 46% and 0.539, respectively (not significantly different), and for umbilical artery RI these were 70%, 61% and 0.689, respectively (P < 0.01). Splenic artery EDV was significantly reduced in SGA vs. normally grown fetuses (0.924 MoM vs. 1.145 MoM, P = 0.007). Fetal splenic artery PSV decreases in SGA infants, and is a strong predictor of the delivery of a SGA infant. It appears to be superior to the standard Doppler index, the RI, in predicting this outcome.

Thyroid vascularity is increased in patients with active acromegaly.

To determine whether acromegalic patients have increased thyroidal vascularity and blood flow on colour flow Doppler sonography (CFDS). Prospective study of consecutive patients. Twenty-four acromegalic patients (11 men, 13 women, age 49 +/- 9 years); 38 patients with nontoxic goitre (NTG; 12 men, 26 women, age 50 +/- 7 years); 36 normal subjects (controls; 16 men, 20 women, age 46 +/- 9 years). Among acromegalic patients, 10 had active, untreated disease (Acro-U), seven were in remission after surgery (Acro-R), seven had active disease under treatment with somatostatin analogues (SMSa) (Acro-SA) (Sandostatin LAR, 20 mg, every 28 days). CFDS pattern and intrathyroidal peak systolic velocity (PSV) were determined by a colour Doppler system with a 7.5-MHz linear transducer. PSV measurements were made at the level of the intrathyroidal arteries (normal values 3.8 +/- 1.0 cm/s). Thyroid volume was calculated by the ellipsoidal model. Assays included measurements of serum GH, IGF-I, free T4, free T3, TSH, antithyroglobulin (anti-Tg) and antithyroperoxidase (anti-TPO) antibodies, TSH-receptor antibodies (TRAb). Serum GH (+/- SD) and IGF-I (+/- SD) levels were: Acro-U: GH 26 +/- 31 microg/l, IGF-I 783 +/- 299 microg/l; Acro-SA: GH 15 +/- 25 microg/l, IGF-I 366 +/- 212 microg/l; Acro-R: GH 1.3 +/- 1.0 microg/l, IGF-I 241 +/- 99 microg/l. To convert values for serum GH to mU/l multiply by 2.6; to convert values for serum IGF-I to nmol/l multiply by 0.13075. All controls had CFDS pattern 0 (absent vascularity or minimal spots); among NTG patients, 36 had pattern 0 and two had pattern I (parenchymal blood flow with patchy uneven distribution). Five patients with acromegaly had pattern 0, 12 had pattern I and seven pattern II (mild increase of colour flow Doppler signal with patchy distribution). Among the five acromegalic patients with pattern 0, three were Acro-R and two were Acro-SA. Among patients with pattern I, six were Acro-U, two were Acro-SA and four were Acro-R. Among patients with pattern II, four were Acro-U and three Acro-SA; two patients of the latter group had elevated serum IGF-I under SMSa treatment. Intrathyroidal PSV was 3.8 +/- 1.0 cm/s in controls, 4.0 +/- 1.1 cm/s in NTG, 7.4 +/- 0.8 cm/s in Acro-U, 4.9 +/- 1.3 cm/s in Acro-SA treatment and 4.5 +/- 1.0 in Acro-R. (Acro-U vs. Acro-SA, P = 0.0003; vs. Acro-R, Controls, or NTG, P < 0.0001). PSV values in Acro-SA were higher than those observed in NTG or controls (P = 0.05, P = 0.01, respectively); PSV values in Acro-R did not differ from those in NTG or controls. Intrathyroidal PSV values were correlated with serum IGF-I (r = 0.73, P < 0.0001) and, although less strongly, GH levels (r = 0.54, P = 0.01). Goitre was present in 19 of 24 patients; diffuse in three and nodular in 16. Thyroid function was normal in all subgroups of acromegalic patients. Anti-Tg, anti-TPO antibodies and TRAb were negative in all subjects. Patients with active acromegaly have increased intrathyroidal blood flow (colour flow Doppler sonography pattern II, increased peak systolic velocity values); this was not observed in the large majority of patients under treatment with somatostatin analogues and in any patient in remission. Accordingly, colour flow Doppler sonography and peak systolic velocity measurements may be considered an additional useful peripheral parameter for rapid assessment of the activity of acromegaly.

Peak Systolic Velocity Doppler Index Reflects Most Appropriately the Dynamic Time Course of Intact Cerebral Autoregulation

Background: Transcranial Doppler sonography measures blood flow velocity in basal cerebral vessels with high accuracy and time resolution. Dynamic blood flow tests were used to investigate functional integrity of the cerebral autoregulation (CA) mechanism. It is known from cortical activation studies that velocity indices differ in their appropriateness to measure changes in blood flow velocity. We aimed to compare the peak systolic, enddiastolic and time-averaged mean flow velocity indices for their use in measuring the effectiveness of the CA mechanism. Methods: We performed the leg cuff test to induce in 15 healthy volunteers (aged 24.8 ± 0.4 years, 9 males) CA due to a sudden arterial blood pressure decrease. Data from the middle and posterior cerebral arteries were measured continuously with transcranial Doppler ultrasound, and the arterial blood pressure with a noninvasive photoplethysmographic method. After transforming all variables to relative changes, velocity-pressure diagrams were calculated for each velocity-pressure index. Additionally, we calculated the autoregulation index. Results: The step decrease in arterial blood pressure resulted in an initial drop, which is followed by a rapid recovery of cerebral blood flow velocity. The autoregulation index was 5.5 ± 1. Efficacy of CA is illustrated more accurately by peak systolic velocity-pressure curves, which lie continuously above a passive velocity-pressure relationship assuming CA to be absent. Conclusions: Our data show peak systolic blood flow velocity index to be most accurate for measuring effectiveness of the dynamic CA mechanism. No differences in the CA were found between the vascular territory of the middle and posterior cerebral arteries.

Effects of bleeding on uteroplacental, umbilicoplacental and yolk-sac hemodynamics in early pregnancy.

To determine the influence of vaginal bleeding with or without a persisting subchorionic hematoma on uteroplacental, umbilicoplacental and yolk-sac hemodynamics in early pregnancy. Twenty-six consecutive patients with vaginal bleeding entered this longitudinal study 1-3 days after the beginning of vaginal bleeding and were re-examined every 1-2 weeks. In three cases vaginal bleeding occurred at the 5th completed gestational week, in 13 at the 7th week, in nine at the 8th week and in one case at the 10th week. A subchorionic hematoma was identified in one case at the 5th week, in nine cases at the 7th week, in nine cases at the 8th week, and in seven cases at the 10th week. Four pregnancies ended in miscarriage. Blood velocity waveforms of uterine, arcuate, radial, spiral, umbilical, chorionic and yolk-sac arteries were obtained by transvaginal pulsed Doppler ultrasound and peak systolic velocities, time-averaged maximum velocities and pulsatility indices were calculated. The results were compared with our earlier observations in normal pregnancy obtained with a similar study protocol. At the 7th week, radial artery pulsatility-index values (mean (SD)) were higher in pregnancies with vaginal bleeding (1.84 (0.59); P = 0.04) and in pregnancies with a subchorionic hematoma (1.96 (0.63); P = 0.03) than in normal pregnancies (1.40 (0.46)). The pulsatility-index values of uterine, arcuate, spiral, umbilical and chorionic arteries did not differ between the groups. Vaginal bleeding with or without a subchorionic hematoma at the 8th week did not affect any of the measured parameters. Persistence of the subchorionic hematoma until the 10th week did not affect uterine, arcuate, radial, spiral, umbilical or chorionic artery hemodynamics. Yolk-sac hemodynamic parameters did not differ between the groups. Vaginal bleeding with or without a subchorionic hematoma is associated with increased radial artery impedance at the 7th week of pregnancy. Persistence of the subchorionic hematoma does not affect utero- and umbilicoplacental circulation.

Splenic artery Doppler peak systolic velocity predicts severe fetal anemia in rhesus disease

Objective: We sought to determine whether main splenic artery Doppler peak systolic velocity predicts severe anemia in the rhesus-alloimmunized fetus. Study Design: Splenic artery Doppler peak systolic velocity was obtained before cordocentesis in rhesus-alloimmunized fetuses. Normative values for mean peak systolic velocity based on gestational age were obtained cross-sectionally from a separate group of 144 normal fetuses. The peak systolic velocity values in the study group were expressed as multiples of the median for gestation, and threshold values were used as a screening test for severe anemia. The hemoglobin deficit was defined as mean hemoglobin for gestation minus measured hemoglobin. A hemoglobin deficit value of ≥5 g/dL was used to define severe anemia. We used the peak systolic velocity to screen for severe anemia in the overall study group and the subgroups with or without prior transfusions. Results: The study population consisted of 26 singleton nonhydropic fetuses in which cordocentesis and Doppler measurements were performed on a total of 55 occasions. The mean gestational age and standard deviation at cordocentesis was 29.6 ± 4.0 weeks. Severe anemia was noted in 20% of fetal cord blood specimens obtained. On the basis of a receiver operating characteristic curve, a peak systolic velocity of ≥1.4 multiples of the median had a detection rate of 100%, with a false-positive rate of 20.8% in the subgroup with no prior transfusion (relative risk, 4.8; 95% confidence interval, 2.2-10.5). For peak systolic velocity threshold of ≥1.50 multiples of the median, corresponding values in the group with one prior transfusion were 80% and 12.5%, respectively (relative risk, 2.5; 95% confidence interval, 1.2-5.3). There was no risk of severe anemia with a peak systolic velocity below the median for gestation. Conclusion: Fetal hydrops is rare, with a hemoglobin deficit of <5 g/dL. In the first such report the main splenic artery peak systolic velocity was noted to be a strong predictor of severe anemia. For the overall population, all such instances could be diagnosed while cordocentesis was performed 22.7% of the time. There is no risk of severe anemia with Doppler peak systolic velocities below the median for gestational age. The measurement is easily obtained and should be investigated as a clinical tool for minimizing the necessity for cordocentesis. (Am J Obstet Gynecol 2000;182:1222-6.)

Factors Associated with Retrobulbar Hemodynamic Measurements at Variable Intraocular Pressure

The authors determine those clinical variables that influence color Doppler measurements at spontaneous and artificially elevated intraocular pressure (IOP). Color Doppler peak systolic velocity (PSV), end diastolic velocity (EDV), and Pourcelot ratio (PR) were measured in the central retinal artery (CRA) and posterior ciliary artery (PCA) at spontaneous IOP and artificially elevated IOP of 30 mmHg, 40 mmHg, and after release of suction-induced pressure elevation in 33 eyes of 33 patients. Those with varied ocular and systemic backgrounds were enrolled to facilitate determination of relationships between these hemodynamic measures at elevated IOP and multiple patient characteristics including the degree of glaucomatous damage. Intraocular pressure elevation reduced velocity and increased Pourcelot ratio in both vessels at 30 mmHg and at 40 mmHg. On release of suction-induced IOP elevation, velocity increased above the velocity measured at spontaneous IOP (hyperemic response). Blood pressure consistently correlated with velocity and with PR in both vessels at all IOP levels tested. The change in velocity with IOP challenge decreased with age, and increased with vertical cup-to-disc ratio in the CRA, and decreased with ocular beta-blocker use in the PCA. Because blood pressure and age relate to velocity, studies comparing cohorts with respect to disease or drug effects should be matched for these variables. While it is clear that the presence of glaucoma and use of beta-blockers correlate with vascular parameters, from this study it is not possible to distinguish pathogenic factors from pathologic results of disease or drug effects.

The value of Doppler resistive index and peak systolic velocity in the evaluation of porcine renal obstruction.

We evaluated the use of Doppler resistive indexes and systolic velocities as diagnostic tools in a partially obstructed animal model. We studied 12 normal pigs by Doppler sonography, which served as control units. In 9 subjects partial ureteral obstruction was then created surgically, and 3 continued as controls. The presence or absence of obstruction was confirmed by ultrasound, antegrade nephrostography and intrapelvic pressure monitoring. Doppler parameters were measured 1 hour to 21 days postoperatively. Resistive index, and angle corrected peak and mean systolic velocities were measured bilaterally from samplings of interlobar and arcuate arteries. An average of 4 samplings per kidney was obtained at each session. Data from the control and obstruction groups were compared for statistical differences. In controls mean resistive index was 0.53, and peak and mean systolic velocities were 0.38 and 0.26 m. per second, respectively. In the subacute period after obstruction (defined as days 4 to 21) mean resistive index was 0.54, and peak and mean systolic velocities were 0.33 and 0.22 m. per second, respectively. Compared to control data there was no significant change in resistive index after obstruction (p = 0.6). However, peak and mean systolic velocities showed significant downward trends (p < 0.05). Known small sequential changes in renal blood flow after ureteral obstruction are reflected in flow velocities, as measured by duplex Doppler sonography. However, resistive indexes are not useful in assessing these changes in renal blood flow, and they do not correlate with the presence or absence of obstruction in this animal model.