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Biomedical subjects

B A Carroll

Publications and source records attributed to B A Carroll.

At least 73 records · Page 4Linked to original sources
PubMed1990

Fetal umbilical artery Doppler response to graded maternal aerobic exercise and subsequent maternal mean arterial blood pressure: predictive value for pregnancy-induced hypertension.

Predictive tests for the identification of women at high risk of the development of preeclampsia are critical to allow the most appropriate preventive measures. Preeclampsia is a vasospastic condition of pregnancy characterized by early and enhanced vascular reactivity to endogenous pressor agents. Exercise tolerance testing with cycle ergometry to induce hemodynamic response measured with duplex Doppler A/B ratio of the umbilical artery could unmask latent vascular pressor hypersensitivity. Our prospective cohort study was designed to test the efficacy of the American College of Obstetricians and Gynecologists exercise in pregnancy guidelines for the low-risk athletic, physically active, or sedentary patient. The pattern of fetal response to material exercise testing at 28 weeks' gestation was compared with subsequent maternal mean arterial blood pressure and the development of pregnancy-induced hypertension and preeclampsia. Doppler A/B ratio during the recovery period was assessed as below baseline (18) or elevated above resting baseline values (12). Third-trimester blood pressure pattern was assessed to be elevated in 11 patients, 10 of whom had elevated recovery A/B ratios. The Fisher exact test results were (p = 0.00002) positive predictive value, 83%; negative predictive value, 94%; sensitivity, 91%; and specificity, 89%. Preeclampsia developed in four patients; all had elevated recovery A/B ratios. Fisher exact test results were (p = 0.01806) positive predictive value, 33%; negative predictive value, 100%; sensitivity, 100%; and specificity, 69%.

Blood Pressure↗
PubMed1990

Hepatic ultrasonic tissue characterization of video image data.

A study measuring in vivo three quantitative parameters of human liver was performed to assess the feasibility of measuring these parameters using standard ultrasound equipment and technique and to evaluate their potential for diagnosing diffuse liver disease. The parameters measured were: (1) d-bar, the average scatter spacing between semiperiodic scatterer; (2) r, a measure of the relative scattering strength; and (3) sigma, a measure of the variability in the relative scattering strength. Using linear discriminant and multivariate analysis, the above parameters are able to significantly separate normal livers from those with cirrhosis. This technique shows promise in the clinical identification of diffuse liver disease.

Humans↗
PubMed1990

Obstetric duplex sonography in patients with lupus anticoagulant syndrome.

The lupus anticoagulant (LAC) syndrome has recently been described as a potential cause of many cases of preeclampsia. This syndrome is associated with a maternal history of repeated first trimester abortions and second and third trimester demise in utero. Umbilical arterial duplex Doppler systolic/diastolic (S/D) ratios and uterine artery S/D ratios for 28 patients whose pregnancies were complicated by lupus anticoagulant syndrome are presented. Five of the six patients who subsequently delivered fetuses small for gestational age (SGA) demonstrated abnormal umbilical arterial S/D ratios, whereas only two of these patients demonstrated abnormally elevated uterine S/D ratios. Twenty three of 28 patients were treated with aspirin and prednisone throughout gestation; no cases of fetal demise in utero were noted.

Autoantibodies↗
PubMed1990

A real-time adaptive ultrasonic imaging system.

The performance of an experimental, adaptive, phased array imaging system in improving the quality of abdominal organ images in healthy volunteers was assessed. Trials were conducted under usual clinical imaging conditions and when phase aberrators of known shape and magnitude were introduced into the imaging system. The system, which uses local target brightness as a quality factor, was able to improve clinical image quality when aberrators introduced externally were present and had a negligible effect on image quality when they were not. On several of the volunteers, the phase aberrations were measured directly across the abdomen. The implications of these results for the future clinical application of adaptive imaging systems and the future system modifications are reported.

Adult↗
PubMed1990

Duplex Doppler systems in obstetric ultrasound.

Doppler ultrasound applications in normal and complicated pregnancies are presented in this article. Anatomy and pathophysiology of fetal placental blood flow are described. Potential pitfalls in the evaluation of fetal placental blood flow are explored. Doppler flow velocity waveform analysis combined with other clinical and physiologic information is valuable in monitoring of the high-risk pregnancy. Duplex technology may also be useful in the first trimester.

Aorta↗
PubMed1989

Duplex Doppler sonography of renal transplants: lack of sensitivity and specificity in establishing pathologic diagnosis.

Recent reports have suggested the value of duplex Doppler sonography in the assessment of renal transplant function. Accurate diagnosis of acute rejection and its distinction from acute tubular necrosis and cyclosporine A toxicity have been claimed. We undertook a combined retrospective and prospective analysis of duplex Doppler examinations performed over a 2-year period to assess the value of such studies in evaluating renal allograft dysfunction. Seventy-seven sonographic examinations were performed on 77 renal transplants. A mean resistive index was calculated from Doppler measurements within main, segmental, and interlobar renal arteries by using the following ratio. peak systolic blood-flow velocity--minimum end-diastolic blood-flow velocity/peak systolic blood-flow velocity Forty-eight Doppler results were correlated with transplant biopsies and 29 with clinical course. Twenty-three episodes of acute allograft rejection were confirmed. When a resistive index of greater than or equal to 0.9 was used to indicate acute rejection, sonography had a sensitivity of only 9% and a specificity of 91% for this diagnosis. In one of eight cases of cyclosporine A toxicity and in three of six examples of acute tubular necrosis, the resistive index was greater than 0.9. In all six instances of chronic rejection, the resistive index was less than 0.84. None of eight patients with evidence of infection had a resistive index greater than 0.9. The resistive index range of 12 normally functioning allografts was 0.57-0.69. Correlation between the resistive index and the severity of arterial and arteriolar changes on biopsy was poor. An increased resistive index of renal transplant blood flow, as measured by duplex Doppler sonography, usually signals pathologic changes in an allograft. However, our data indicate that this test is not as sensitive or specific in identifying the cause of transplant dysfunction as has been suggested previously.

Adolescent↗
PubMed1989

Duplex sonography in patients with hemispheric symptoms.

Many patients with hemispheric neurologic symptoms do not have operative stenoses of the extracranial carotid arteries. In order to assess the frequency of such atherosclerotic lesions, 154 patients with documented hemispheric events underwent duplex Doppler examinations of the extracranial carotid bifurcation to assess if operative stenosis (70% to 80% stenosis) was present. Seventy-two patients with transient ischemic attacks (TIA), 62 patients with cerebrovascular accidents (CVA), and 20 patients with amaurosis fugax (AF) were studied. Sixty-nine percent of patients with TIAs demonstrated a less than 50% stenosis, 52% of patients with CVAs demonstrated a less than 50% stenosis, and 65% of patients with AF demonstrated a less than 50% stenosis on duplex Doppler examination. Intra-arterial digital subtraction angiography (IADSA) was performed in 35 of 154 patients. In all of these 35 cases, ultrasound and angiographic studies agreed with respect to whether or not a greater than 50% stenosis was present. Our findings support the use of duplex Doppler sonography as a triage procedure in patients with hemispheric events in order to determine those patients who have significant carotid stenoses and who may be potential operative candidates.

Arterial Occlusive Diseases↗
PubMed1989

Nonuniformity of fetal umbilical systolic/diastolic ratios as determined with duplex Doppler sonography.

Fetal umbilical arterial systolic/diastolic (S/D) ratios are said to be uniform throughout the umbilical cord. We evaluated this phenomenon by performing duplex Dopper on 73 fetuses at three sites in the umbilical cord: near the placental origin, in the free-floating midcord, and near the fetal abdominal wall insertion. Twenty-one of 73 fetuses examined (29%) demonstrated pronounced nonuniformity of the S/D ratios with a discrepancy of 1 or greater between any two S/D measurements. Studies demonstrated the highest S/D ratios at the fetal abdominal wall and lowest S/D ratios at the placental origin. These findings suggest that umbilical arterial flow velocity waveforms (FVWs) and S/D ratios are not uniform throughout the cord in all patients. The significance of this finding is uncertain; however, this variability in umbilical cord flow velocity waveforms stresses the importance of identifying the portion of the umbilical cord from which S/D ratios are obtained.

Blood Flow Velocity↗
PubMed1986

Effects of repeated administration of the monoamine oxidase inhibitor phenelzine on the discriminability of d-lysergic acid diethylamide (LSD) and 1-(m-trifluoromethylphenyl) piperazine (TFMPP).

Rats trained to discriminate d-lysergic acid diethylamide (LSD; 0.08 mg/kg) or 1-(m-trifluoromethylphenyl) piperazine (TFMPP; 0.8 mg/kg) were treated with the monoamine oxidase inhibitor (MAOI) phenelzine (10 mg/kg/day) for 7 days. After a 24 h "washout" period, they were challenged with the training drug (and dose) or saline, during extinction test sessions. Following 0.08 mg/kg LSD, LSD-trained rats responded primarily on the saline lever (29% drug-appropriate responding) while, after TFMPP (0.8 mg/kg), TFMPP-trained animals responded on the drug lever (75% drug-appropriate responding). These preliminary data suggest that, if serotonin receptors are involved in the behavioral effects of TFMPP, these receptors differ from those involved in the effects of LSD.

Animals↗
PubMed1986

Ultrasonography in the jaundiced infant: a new approach.

Diagnostic ultrasonography plays a major role in the evaluation of jaundiced infants. Seventeen such infants were studied in both fasting and post-prandial states. The gallbladder and biliary tract were evaluated to define features most useful in distinguishing children with biliary atresia from those with other causes of jaundice. Demonstration of a decrease in gallbladder size following feeding virtually eliminates the diagnosis of biliary atresia, even in children with abnormal HIDA scans.

Bile Ducts↗
PubMed1985

Diagnostic ultrasound in pediatric oncology.

Sonography is an extremely versatile diagnostic tool for the assessment of cancer in children, offering several advantages over other imaging modalities, chief of which is its truly noninvasive nature. In view of the available comparative studies and the risk/benefit and cost/benefit ratios of the imaging procedures available, ultrasound is attractive for use as the initial study of many pediatric mass lesions. Its availability, ease of application, and lower cost also favor its use in the assessment of the child with known or suspected malignancy.

Abdomen↗