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Biomedical subjects

P Doubilet

Publications and source records attributed to P Doubilet.

At least 19 recordsLinked to original sources
PubMed2001

Topography of cerebral white-matter disease of prematurity studied prospectively in 1607 very-low-birthweight infants.

The objective of this study was to evaluate to what extent (1) the characteristics of localization, distribution, and size of echodense and echolucent abnormalities enable individuals to be designated as having either periventricular hemorrhagic infarction or periventricular leukomalacia and (2) the characteristics of periventricular hemorrhagic infarction and periventricular leukomalacia are independent occurrences. The population for this study consisted of 1607 infants with birthweights of 500 to 1500 g, born between January 1991 and December 1993, who had at least one cranial ultrasound scan read independently by at least two ultrasonographers. The ultrasound data collection form diagrammed six standard coronal views. The cerebrum was divided into 17 zones in each hemisphere. All abnormalities were described as being echodense or echolucent and were classified on the basis of their size, laterality, location, and evolution. Eight percent (134/1607) of infants had at least one white-matter abnormality. The prevalence of white-matter disease decreased with increasing gestational age. Most abnormalities were small or medium sized and unilateral; only large echodensities tended to be bilateral and asymmetric. Large abnormalities, whether echodense or echolucent, were more likely than smaller abnormalities to be widespread, and the extent of cerebral involvement was independent of whether abnormalities were unilateral or bilateral. Large abnormalities were relatively more likely than small abnormalities to involve anterior planes. Small abnormalities, whether echodense or echolucent, or whether unilateral or bilateral, preferentially occurred near the trigone. Using the characteristics of location, size, and laterality/symmetry, we were able to allocate only 53% of infants with white-matter abnormalities to periventricular hemorrhagic infarction or periventricular leukomalacia. Assuming that periventricular leukomalacia and periventricular hemorrhagic infarction are independent and do not share risk factors, and that each occurs in approximately 5% of infants, we would have expected 0.25%, or about 4 individuals, to have abnormalities with characteristics of both periventricular leukomalacia and periventricular hemorrhagic infarction, whereas we found 63 such infants. Most infants with white-matter disease could not be clearly designated as having periventricular hemorrhagic infarction or periventricular leukomalacia only. Periventricular hemorrhagic infarction contributes to the risk of periventricular leukomalacia occurrence, or the two sorts of abnormalities share common risk antecedent factors. The descriptive term echodense or echolucent and the generic term white-matter disease of prematurity should be used instead of periventricular leukomalacia or periventricular hemorrhagic infarction when referring to sonographically defined white-matter abnormalities.

Brain Mapping↗
PubMed1999

White matter disorders of prematurity: association with intraventricular hemorrhage and ventriculomegaly. The Developmental Epidemiology Network.

OBJECTIVES: Because intraventricular hemorrhage (IVH) often precedes the development of sonographically defined white matter damage (WMD) in very preterm infants, we sought to identify the IVH characteristics that predict WMD. HYPOTHESES: We evaluated variations on the null hypothesis that infants with IVH are no more likely than infants without IVH to have WMD. These variations dealt with characteristics of the IVH (presence or absence of ventriculomegaly) or characteristics of the WMD (size, localization, and laterality). METHODS: A total of 1605 infants weighing 500 to 1500 g at birth between January 1991 and December 1993 underwent standardized cranial ultrasound studies with 6 standard coronal and 5 sagittal views at postnatal days 1 to 3, 7 to 10, and at 3 to 8 weeks. RESULTS: A total of 129 (8%) infants had WMD, either an echodensity alone (n = 59), an echolucency alone (n = 18), or both (n = 52). In analyses that controlled for gestational age, IVH was associated with a fivefold to ninefold increased risk of WMD regardless of size, laterality, or extent of lesions (P </=.0005). Compared with infants with neither IVH nor ventriculomegaly, infants with both were at 18- to 29-fold greater risk of WMD (P </=.0005). CONCLUSIONS: In this study IVH and ventriculomegaly were powerful predictors of WMD occurrence, whether small or large, unilateral or bilateral, localized or diffuse.

Brain Diseases↗
PubMed1999

Maternal infection, fetal inflammatory response, and brain damage in very low birth weight infants. Developmental Epidemiology Network Investigators.

Echolucent images (EL) of cerebral white matter, seen on cranial ultrasonographic scans of very low birth weight newborns, predict motor and cognitive limitations. We tested the hypothesis that markers of maternal and feto-placental infection were associated with risks of both early (diagnosed at a median age of 7 d) and late (median age = 21 d) EL in a multi-center cohort of 1078 infants <1500 x g. Maternal infection was indicated by fever, leukocytosis, and receipt of antibiotic; fetoplacental inflammation was indicated by the presence of fetal vasculitis (i.e. of the placental chorionic plate or the umbilical cord). The effect of membrane inflammation was also assessed. All analyses were performed separately in infants born within 1 h of membrane rupture (n = 537), or after a longer interval (n = 541), to determine whether infection markers have different effects in infants who are unlikely to have experienced ascending amniotic sac infection as a consequence of membrane rupture. Placental membrane inflammation by itself was not associated with risk of EL at any time. The risks of both early and late EL were substantially increased in infants with fetal vasculitis, but the association with early EL was found only in infants born > or =1 after membrane rupture and who had membrane inflammation (adjusted OR not calculable), whereas the association of fetal vasculitis with late EL was seen only in infants born <1 h after membrane rupture (OR = 10.8; p = 0.05). Maternal receipt of antibiotic in the 24 h just before delivery was associated with late EL only if delivery occurred <1 h after membrane rupture (OR = 6.9; p = 0.01). Indicators of maternal infection and of a fetal inflammatory response are strongly and independently associated with EL, particularly late EL.

Brain Damage, Chronic↗
PubMed1994

Is fetal hyperechoic bowel on second-trimester sonogram an indication for amniocentesis?

OBJECTIVE: To determine the clinical significance of hyperechoic bowel seen sonographically in second-trimester fetuses. METHODS: Fifty fetuses (0.6%) with echogenic bowel were identified sonographically from a population of 8680 consecutive second-trimester fetuses over 21 months. The fetal bowel was considered hyperechoic if its echogenicity was similar to that of surrounding bone. Follow-up was obtained through medical record review. RESULTS: Twenty-nine of 50 fetuses (58%) were normal; eight (16%) were aneuploid, including six Down syndrome, one trisomy 13, and one Turner syndrome. All eight fetuses with aneuploidy had sonographic anomalies in addition to the echogenic bowel. Eight of 50 fetuses (16%) were growth-retarded, and five others (10%) had normal karyotypes but are still undelivered. Among the eight growth-retarded fetuses, there were five intrauterine or neonatal deaths, one elective abortion, and two survivors. In addition, the six fetuses with Down syndrome and echogenic bowel represented 12.5% of all second-trimester Down syndrome fetuses karyotyped in our laboratory during the study period. Combining results from the present study (six Down syndrome fetuses) with three studies from the literature (21 additional Down syndrome fetuses), a total of 27 fetuses with echogenic bowel and Down syndrome were identified, 11 (40.7%) of whom had no other sonographic findings. We calculate that if 1,000,000 second-trimester fetuses were scanned, 5105 would have hyperechoic bowel as the only finding, of whom 71 would have Down syndrome and 5034 would not. The risk of Down syndrome in fetuses with isolated hyperechoic bowel is, therefore, 71 in 5105 or 1.4%. CONCLUSION: The finding of isolated hyperechoic bowel in the second trimester should prompt genetic counseling and consideration of karyotypic analysis.

Amniocentesis↗
PubMed1992

Form-based clinical input from a structured vocabulary: initial application in ultrasound reporting.

Ultra-STAR (Ultrasound Structured Attribute Reporting) allows a sonographer to record reports using a hierarchic standardized vocabulary. Reports are constructed interactively by using checkboxes and radio buttons in a graphical user interface to select concepts from the vocabulary. Concepts are presented in small windows that open when needed to record further detail. Preliminary reports are printed for the referring physician. Reports are later finalized by an attending radiologist and uploaded to the hospital's information system. Clinicians involved so far prefer an outline report to a natural language format.

Medical Records Systems, Computerized↗
PubMed1991

Relationship between placental blood flow and combined ventricular output with gestational age in normal human fetus.

STUDY OBJECTIVE: The aim was to quantify the changes in placental blood flow and combined ventricular output with gestational age in normal human fetuses to determine the percentage of total cardiac output that placental blood flow represented, and whether this changed with age. DESIGN: Two dimensional echocardiographic images of the umbilical vein, the proximal aorta and proximal main pulmonary artery were obtained, and cross sectional areas calculated from vessel diameters. Doppler velocity signals were recorded from each vessel and digitised to obtain velocity-time integrals. Placental blood volume flow and combined ventricular output were calculated as the products of flow velocity time integrals and cross sectional areas of the umbilical vein, and of the great arteries respective. SUBJECTS: Subjects were 64 normal human fetuses aged between 20 and 42 weeks gestation. MEASUREMENTS AND MAIN RESULTS: Placental flow and combined ventricular output both increased exponentially with gestational age (r = 0.79, and r = 0.84; both p less than 0.001). Placental flow correlated linearly with combined ventricular output (r = 0.69; p less than 0.01) and comprised almost one third of total cardiac output throughout the second and third trimesters. CONCLUSIONS: These data describe the relationship between placental blood flow and combined ventricular output with age in the normal human fetus and provide a substrate by which placental insufficiency and resulting intrauterine growth retardation may be recognised early.

Cardiac Output↗
PubMed1991

Assessment of right and left ventricular function in terms of force development with gestational age in the normal human fetus.

OBJECTIVE: To assess right and left ventricular systolic function in normal human fetuses by cross sectional Doppler echocardiography to calculate the force developed by myocardial shortening. DESIGN: Cross sectional echocardiographic images of the aorta and pulmonary arteries were obtained prospectively in order to measure great vessel diameters and calculate their cross sectional areas. Doppler velocity signals were recorded from the proximal aorta and the proximal pulmonary artery and digitised to obtain peak velocity, acceleration time, flow velocity time integral during acceleration, and the flow velocity time integral for the whole of ejection. Right and left ventricular force development was estimated by Newton's equation in which force is defined as the product of mass and acceleration. PATIENTS: 58 normal human fetuses at a gestational age of from 20 to 42 weeks. RESULTS: The cross sectional area of the pulmonary artery was 20% greater than that of the aorta. Aortic acceleration time was longer than that in the pulmonary artery, and peak blood flow velocity in the aorta was consistently greater than that in the pulmonary artery. Right ventricular stroke volume was significantly greater than left ventricular stroke volume. The force developed by the right and left ventricles was, however, similar throughout the gestational period studied, increasing tenfold from 20 weeks' gestation to term (r = 0.74, p less than 0.0001; r = 0.75, p less than 0.0001) respectively. CONCLUSION: The development of right and left ventricular force in the human fetus is similar in spite of the greater volume handled by the right ventricle. This index of ventricular performance does not require calculation of ventricular volume and because it varies independently of ventricular geometry and heart rate it should prove useful in assessing cardiac function in the normal human fetus and in fetuses with ventricular dysfunction.

Blood Flow Velocity↗
PubMed1990

Changes in placental blood flow in the normal human fetus with gestational age.

We assessed fetoplacental blood volume flow and placental resistance prospectively with Doppler sonography in 74 normal human fetuses of 19 to 42 wk gestation to determine the changes in placental perfusion with gestational age. Placental blood volume flow was assessed from the umbilical vein as the product of the mean flow velocity integral and the cross-sectional area of the umbilical vein. Placental resistance was assessed as the ratio of maximum systolic and minimum diastolic blood flow velocities from an umbilical artery. Umbilical vein blood volume flow increased exponentially (r = 0.86) with gestational age from 19 wk to term, and did not decrease in postdate fetuses. Umbilical vein blood volume flow increased linearly with fetal weight (r = 0.77), although volume flow per unit body weight changed little with gestational age. Umbilical artery velocity ratio decreased progressively, indicating diminishing placental resistance with gestational age, but did not correlate closely with umbilical vein blood volume flow. We submit that fetoplacental blood volume flow can be readily calculated directly from the umbilical vein with Doppler ultrasound and may provide a better index of placental perfusion than the umbilical artery velocity ratio.

Female↗
PubMed1988

How to image the gallbladder in suspected cholecystitis.

As a result of important advances in medical imaging, the oral cholecystogram is no longer the primary test of gallbladder function and anatomy. Real-time ultrasonography and cholescintigraphy, both highly sensitive and specific tests, are the two major methods for assessing gallbladder pathology. Oral cholecystography, endoscopic retrograde pancreatography, and percutaneous gallbladder puncture serve as supplementary tests. Decisions about which test to use depend on the kind of gallbladder disease that is suspected as well as the estimated likelihood of the disease before the information is obtained from the procedure. Thus, ultrasonography is the test of choice for chronic cholecystitis, with oral cholecystography reserved for situations in which the diagnosis is uncertain after ultrasonography. When acute cholecystitis is suspected, ultrasonography is also the test of choice in most patients, and cholescintigraphy is used to resolve uncertainty.

Cholecystitis↗
PubMed1987

Effects of heart rate on ventricular size, stroke volume, and output in the normal human fetus: a prospective Doppler echocardiographic study.

The effect of heart rate on cardiac output in the fetal heart is controversial. We used Doppler echocardiography to investigate the effects of increasing heart rate on stroke volume and ventricular output in the normal human fetal heart. Heart rate was increased in 25 human fetuses (mean age 36 weeks) by auditory stimulation with a sound emitter placed on the mother's abdomen. Aortic or pulmonary diameters were measured at valve level from two-dimensional echocardiographic images and cross-sectional areas were calculated. Blood flow velocity spectra from the pulmonary artery or aorta were digitized to obtain flow velocity integrals before and after auditory stimulation. Stroke volume was calculated as the product of the flow velocity integral and the area of the great vessel. Prestimulation mean heart rate was 132 +/- 8 beats/min and increased after auditory stimulation to 158 +/- 9 beats/min (p less than .001). Stroke volume decreased with the increase in heart rate from 3.7 +/- 1.4 ml before stimulation to 3.0 +/- 1.1 ml after stimulation (p less than .001), but ventricular output calculated as the product of stroke volume and heart rate remained unchanged (0.48 +/- 0.18 liter/min before vs 0.48 +/- 0.17 liter/min after stimulation). The decrease in stroke volume was accompanied by a decrease in ventricular end-diastolic area, although there was no change either in end-systolic area or fractional change in area. This study demonstrates that increases in heart rate within the physiologic range in the normal human fetus result in a decrease in ventricular size and stroke volume but no change in ventricular output or ventricular shortening.

Cardiac Output↗
PubMed1986

Changes in intracardiac blood flow velocities and right and left ventricular stroke volumes with gestational age in the normal human fetus: a prospective Doppler echocardiographic study.

We used Doppler echocardiography to quantitate the changes in intracardiac blood flow velocities and right and left ventricular stroke volumes in 80 normal human fetuses from 19 to 40 weeks gestation. Blood flow velocity spectra across the aortic, pulmonary, tricuspid, and mitral valves were digitized to obtain peak velocities (m/sec) and flow velocity integrals. Aortic and pulmonary diameters were measured at valve level from two-dimensional echocardiographic images and cross-sectional area was calculated assuming a circular orifice. Ventricular stroke volume was calculated as the product of the cross-sectional area of a great vessel and the flow velocity integral through that vessel. The pulmonary arterial and aortic diameters increased linearly with gestational age (r = .82, r = .84), and pulmonary arterial diameter consistently exceeded aortic diameter. There was a positive relationship between stroke volume and gestational age: stroke volume increased exponentially from 0.7 ml at 20 weeks to 7.6 ml at 40 weeks for the right ventricle (r = .87) and from 0.7 ml at 20 weeks to 5.2 ml at 40 weeks for the left ventricle (r = .91). Similar results were obtained for right and left ventricular and combined cardiac outputs. In 44% of the fetuses it was possible to quantitate both right and left ventricular stroke volumes. There was a close correlation between right and left ventricular stroke volumes in these fetuses (r = .96) and right ventricular stroke volume exceeded left ventricular stroke volume by 28%.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1985

Excretory urography in current practice: evidence against overutilization.

Excretory urography could be performed less frequently if some combinations of genitourinary signs and symptoms were found to be predictive of either a specific disease or normality. To explore this possibility, the authors conducted a prospective study involving more than 3,000 patients at three institutions (a teaching hospital, a community hospital, and a health maintenance organization). Predictive algorithms were obtained by application of a polychotomous logistic regression model but did poorly at differentiating normal from abnormal patients or arriving at a specific diagnosis. Selection of patients on the basis of the logistic model would have required testing 90% of all patients in order to detect 95% of those with abnormal urograms. These results suggest that current clinical selection criteria for excretory urography are effective, and that present frequency of utilization is appropriate.

Diagnosis, Differential↗
PubMed1985

Probabilistic sensitivity analysis using Monte Carlo simulation. A practical approach.

The data for medical decision analyses are often unreliable. Traditional sensitivity analysis--varying one or more probability or utility estimates from baseline values to see if the optimal strategy changes--is cumbersome if more than two values are allowed to vary concurrently. This paper describes a practical method for probabilistic sensitivity analysis, in which uncertainties in all values are considered simultaneously. The uncertainty in each probability and utility is assumed to possess a probability distribution. For ease of application we have used a parametric model that permits each distribution to be specified by two values: the baseline estimate and a bound (upper or lower) of the 95 percent confidence interval. Following multiple simulations of the decision tree in which each probability and utility is randomly assigned a value within its distribution, the following results are recorded: (a) the mean and standard deviation of the expected utility of each strategy; (b) the frequency with which each strategy is optimal; (c) the frequency with which each strategy "buys" or "costs" a specified amount of utility relative to the remaining strategies. As illustrated by an application to a previously published decision analysis, this technique is easy to use and can be a valuable addition to the armamentarium of the decision analyst.

Decision Making↗
PubMed1985

The decision concerning coronary angiography in patients with chest pain. A cost-effectiveness analysis.

We examined the decision whether to perform coronary angiography (followed by bypass surgery if appropriate findings are present) in middle-aged men who have chest pain and have undergone exercise tolerance testing (ETT). We developed a model of this decision that combines data from a variety of sources and selects the optimal strategy based on health outcome and, if desired, monetary cost. The analysis supports the following conclusions: for patients with nonspecific chest pain or atypical angina, the ETT provides useful information concerning the decision; furthermore, the number of millimeters of ST-segment depression above which angiography should be performed depends on coronary risk factors and pain severity. A normal ETT is insufficient evidence to exclude coronary angiography for patients with typical angina, provided that one is willing to expand resources for health benefits at levels comparable to those for other accepted medical practices. If monetary considerations are excluded, the preceding statement concerning ETT and angiography also holds for patients with atypical angina and for those with nonspecific pain and advanced risk factors. These last two conclusions suggest that ETT is not useful in guiding management decisions concerning coronary angiography in patients at high enough risk of coronary artery disease on the basis of symptoms and risk profile.

Angina Pectoris↗
PubMed1984

The cost of underutilization. Percutaneous transluminal angioplasty for peripheral vascular disease.

Despite the considerable literature on the overuse of new medical technologies, little attention has been paid to the biologic and monetary costs that may be incurred by underuse. Percutaneous transluminal angioplasty as a treatment for peripheral vascular disease is an example of an important technology that has been underused. Although angioplasty alone is less costly but also less efficacious than surgery, a strategy that combines the two procedures (angioplasty first, then surgery if angioplasty is unsuccessful or if occlusion recurs) is uniformly superior to surgery alone in patients who have lesions for which angioplasty can be considered. From a nationwide perspective, if 40 per cent of all patients with iliac or femoral disease (or both) requiring intervention were treated with the combined strategy, there would be an estimated savings (as compared with surgery alone) of 352 lives and $82 million, as well as an additional 5006 patent limbs. Despite these advantages, the use of angioplasty during the period under consideration (up to 1980) was limited, possibly because of the mechanism of patient triage and the inertial forces that operate when a therapeutic method that appears effective--even if more complex and hazardous than a newer approach--has been widely applied.

Angioplasty, Balloon↗