Biomedical subjects

R W Martin

Publications and source records attributed to R W Martin.

At least 37 records · Page 2Linked to original sources

PubMed2000

Increasing maternal weight: a risk factor for preeclampsia/eclampsia but apparently not for HELLP syndrome.

BACKGROUND: Maternal obesity is a risk factor for severe preeclampsia. We sought to ascertain whether a similar relationship exists between maternal weight and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets) as an atypical form of severe preeclampsia. METHODS: In this retrospective investigation, 434 patients with HELLP syndrome were assigned to one of four study groups according to maternal weight and were analyzed in relation to selected maternal and perinatal data reflective of disease severity. RESULTS: We found no significant associations between maternal weight and parameters of HELLP syndrome severity, race, delivery mode, gestational age, or perinatal outcome. Significantly associated with increasing maternal weight were maternal age, parity, admission mean arterial pressure, peak peripartum systolic blood pressures, concurrent essential hypertension, and the interval between admission and delivery. Inversely associated were eclampsia and the interval between delivery and discharge. CONCLUSIONS: Severity and complications attendant with HELLP syndrome appear unrelated to maternal weight. Paradoxically, eclampsia occurs most commonly in the lighter gravida with HELLP syndrome.

Adult↗

PubMed1999

Influence of echocardiographic scan plane location and number on the accuracy of three-dimensional left ventricular volume and shape determination.

Quantitative 3-dimensional (3-D) echocardiography provides accurate assessment of left ventricular (LV) volume, shape, and function, but depends on manual endocardial border tracing. This study determined the minimal number of borders that need to be traced to obtain an accurate analysis of not only the volume of the left ventricle but also its shape, using the integrated methods for quantitative 3-D echocardiography developed by our laboratory. Transthoracic 3-D echocardiographic studies were obtained in 9 normal subjects and 6 patients with heart disease by freehand scanning. The LV endocardium was manually traced in 17 +/- 5 imaging planes and reconstructed in 3 dimensions. The volume and shape of each reconstruction were compared with values measured from surfaces reconstructed from 8 subsets containing 2 to 7 borders; each subset was acquired from different combinations of spatially distributed parasternal and apical views. Accurate measurements were obtained from data sets having > or = 5 borders, regardless of whether the image planes were predominantly apical or parasternal views. In conclusion, the LV border should be traced in > or = 5 imaging planes to obtain accurate measurements of volume and shape. The piece-wise smooth reconstruction method and freehand scanning using a magnetic field tracing system allow the borders to be acquired from whatever combination of acoustic windows and views provides optimal image quality.

Adult↗

PubMed1999

High-dose versus low-dose D-penicillamine in early diffuse systemic sclerosis: analysis of a two-year, double-blind, randomized, controlled clinical trial.

OBJECTIVE: To test the hypothesis that systemic sclerosis (SSc) patients taking high-dose D-penicillamine (D-Pen) would have greater softening of skin, lower frequency of renal crisis, and better survival than patients taking low-dose D-Pen. METHODS: Seventeen centers enrolled 134 SSc patients with early (< or =18 months) diffuse cutaneous scleroderma into a 2-year, double-blind, randomized comparison of high-dose D-Pen (750-1,000 mg/day) versus low-dose D-Pen (125 mg every other day). All 134 patients were followed up for a mean+/-SD of 4.0+/-1.1 years to assess the frequencies of new-onset scleroderma renal crisis (SRC) and mortality. RESULTS: Sixty-eight patients completed 24 months of drug treatment. The course of the modified Rodnan skin thickness score in the 32 high-dose and the 36 low-dose D-Pen completers was not different at 24 months: the skin score dropped 4.8+/-10.3 (mean+/-SD) units in the high-dose group and 6.9+/-8.4 units in the low-dose group (P = 0.384 by t-test; favoring low-dose D-Pen) from 20.4+/-10.3 in the high-dose and 19.9+/-6.6 in the low-dose D-Pen group at study entry. The incidences of SRC and mortality were not different (P > 0.38 by Cox proportional hazards and by chi-square test) in the 66 high-dose patients (8 developed SRC and 8 died) compared with the 68 low-dose patients (10 developed SRC and 12 died). Of the 20 adverse event-related withdrawals, 80% occurred in the high-dose D-Pen group. CONCLUSION: The course of the skin score and the frequencies of SRC and mortality in the high-dose D-Pen group were not different from those in the low-dose D-Pen group. Eighty percent of the adverse event-related withdrawals occurred in the high-dose D-Pen patients. Although this study cannot answer the question of whether low-dose D-Pen is effective, it does suggest that there is no advantage to using D-Pen in doses higher than 125 every other day.

Adult↗

PubMed1999

Planned cesarean hysterectomy: A preferred alternative to separate operations.

OBJECTIVE: The aim of this study was to evaluate our institutional experience with planned cesarean hysterectomy. STUDY DESIGN: In this retrospective case-control investigation of a 16-year experience, 100 pregnant women who underwent planned cesarean hysterectomy were compared with 37 patients who underwent cesarean delivery followed by a hysterectomy performed within 6 months. RESULTS: Women undergoing planned cesarean hysterectomy did not have any demonstrable increase in intraoperative or postoperative complications when compared with the cesarean delivery plus later hysterectomy group. Primarily as a result of significantly reduced hospital stay and shorter total operative time, there was a significant financial advantage associated with a single planned cesarean hysterectomy with respect to separate operations. CONCLUSIONS: A policy to undertake planned cesarean hysterectomy for carefully selected patients appeared to produce advantages without increasing risks for these patients. Secondarily, it provided resident physicians the opportunity to learn the operation with supervision and under controlled circumstances.

Adult↗

PubMed1999

Second-trimester uterine evacuation: A comparison of intra-amniotic (15S)-15-methyl-prostaglandin F2alpha and intravaginal misoprostol.

OBJECTIVE: Our purpose was to compare the efficacy, safety, and adverse effects of intra-amniotically administered (15S)-15-methyl-prostaglandin F(2alpha) and intravaginally administered misoprostol for second-trimester uterine evacuation. STUDY DESIGN: Fifty-one patients were randomly assigned to receive either a single 2.5-mg intra-amniotic injection of (15S)-15-methyl-prostaglandin F(2)(alpha) (n = 26) or two 200-microg intravaginal doses of misoprostol (n = 25) at 12-hour intervals. The primary outcome measured was evacuation of the uterus within 24 hours. RESULTS: The mean time from initiation of termination to uterine evacuation was less in the prostaglandin group than in the misoprostol group (17.5 +/- 8.6 hours vs 22.3 +/- 12.5 hours), but this was not statistically significant (P >.05). The rate of successful fetal evacuation at 24 hours was significantly higher in the prostaglandin group than in the misoprostol group (88% vs 60%, P =.02). The complete-abortion rate and the incidence of adverse effects were similar in both groups. CONCLUSION: The use of an intra-amniotic injection of (15S)-15-methyl-prostaglandin F(2alpha) for midtrimester pregnancy termination is safe and is associated with a greater number of successful uterine evacuations within 24 hours, without an increase in adverse effects, than intravaginal administration of misoprostol.

Abortifacient Agents, Nonsteroidal↗

PubMed1999

Maternal mortality associated with HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome.

OBJECTIVE: The aim of this study was to determine factors contributing to deaths among women with HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome. STUDY DESIGN: Information from multiple sources was scrutinized to distinguish and profile maternal deaths associated with HELLP syndrome. RESULTS: Information was available regarding 54 maternal deaths. According to HELLP syndrome classification 60.0% had class 1 disease, 35.6% had class 2 disease, and 4.4% had class 3 disease. Events associated with maternal deaths included cerebral hemorrhage (45%), cardiopulmonary arrest (40%), disseminated intravascular coagulopathy (39%), adult respiratory distress syndrome (28%), renal failure (28%), sepsis (23%), hepatic hemorrhage (20%), and hypoxic ischemic encephalopathy (16%). Delay in diagnosis of HELLP syndrome was implicated in 22 of 43 patients' deaths (51.1%). CONCLUSIONS: It appears that (1) most maternal deaths occurred among women with class 1 HELLP syndrome, (2) delay in diagnosis was associated with mortal consequences, and (3) hemorrhage in the hepatic or central nervous system or vascular insult to the cardiopulmonary or renal system were associated with increased mortality risk.

Adult↗

PubMed1999

Hemostasis of punctured vessels using Doppler-guided high-intensity ultrasound.

The use of Doppler ultrasound was investigated to determine if it would aid in guiding the application of high-intensity focused ultrasound (HIFU) to stop bleeding from punctured vessels. Major vessels (abdominal aorta, illiac, carotid, common femoral and superficial femoral arteries and the jugular vein) were surgically exposed, punctured and treated in anesthetized pigs. Treatment was applied when the Doppler sounds indicated the focus coincided with the bleeding site. In 89 treatment trials, the average time to achieve major hemostasis (a point where bleeding was reduced to a level of only oozing) was 8 s, and for complete hemostasis was 13 s. These times were significantly shorter than those of an identical former study in which only visual guidance was used. In that study, the average times for major and complete hemostasis were 40 and 62 s, respectively. The advantage of Doppler guidance in applying HIFU in treating bleeding vessels was demonstrated.

Animals↗

PubMed1999

A 12-hour urine collection accurately assesses proteinuria in the hospitalized hypertensive gravida.

OBJECTIVE: To determine whether a urine collection of < 24 hours duration accurately assesses the level of proteinuria in inpatients being evaluated for preeclampsia. STUDY DESIGN: Patients admitted to the University of Mississippi between January and June of 1998 for evaluation of preeclampsia underwent two consecutive 12-hour urine collections. Each collection was analyzed for total protein, total calcium, total volume, and urine creatinine. A concurrent serum creatinine value was obtained. The protein:creatinine ratio, calcium: creatinine ratio, and creatinine clearance were calculated. Pearson's correlation, sensitivity, specificity, and positive and negative predictive values were assessed. RESULTS: A total of 25 patients (86%) were preeclamptic. Total protein, the protein: creatinine ratio, and serum creatinine were significantly correlated between the first and second urine collection. The sensitivity and specificity of the 12-hour urine collection was 96% and 100%, respectively. CONCLUSION: A 12-hour urine collection accurately depicts the amount of proteinuria in hospitalized gravidas being evaluated for preeclampsia.

Adult↗

PubMed1999

Preeclampsia-associated hepatic hemorrhage and rupture: mode of management related to maternal and perinatal outcome.

This article is a critical review of the obstetric literature concerning preeclampsia-associated hepatic hemorrhage to develop guidelines conducive to optimal maternal and perinatal outcomes. An English literature search was performed for reports of hepatic hemorrhage or hepatic rupture in pregnancy during 1960 to 1997. Data were analyzed by Statmost packages using ANOVA, Chi-square, and Fisher's exact tests. One hundred forty-one patients with hepatic rupture/hemorrhage were reported. The three most common presenting findings were epigastric pain, hypertension, and shock. With rare exception, patients had evidence of preeclampsia. Diagnosis was elusive and most frequently accomplished at laparotomy. When utilized, ultrasound and computed tomography (CT) were helpful diagnostic modalities. Maternal survival was highest in the arterial embolization treatment group. Maternal and perinatal survival improved considerably during the study interval. Route of delivery did not seem to impact survival rates. It was concluded that the application of ultrasound and CT for diagnosis and the use of hepatic artery embolization for treatment of hepatic hemorrhage/rupture seem to be beneficial management options for this rare event.

Antibodies, Monoclonal↗

PubMed1999

Detection of high-intensity focused ultrasound liver lesions using dynamic elastometry.

A novel ultrasound technique was developed for detecting the distribution of stiffness in biological tissue. The method, which we call 'dynamic elastometry,' involves applying a low-frequency vibration (< or = 5 Hz) to the tissue and measuring the resulting velocity pattern within the sample using Doppler spectral analysis. Based upon the velocity differences, an elastically stiff region can be differentiated from surrounding soft tissue. Dynamic elastometry was used to both detect and quantify lesions produced by high-intensity focused ultrasound (HIFU) in porcine livers. Measurements of the lesion position and length agreed well with independent geometric measurements. The mean and standard deviation of the differences between the two types of measurement were -0.01 cm and 0.10 cm for lesion position, and -0.05 cm and 0.12 cm for lesion length, respectively. The relative stiffness between lesions and normal liver tissue was estimated by the velocity gradient ratio. Results were compared with the Young's modulus ratios between lesion and normal liver tissue obtained from mechanical measurement. The dynamic elastometric estimates had a strong linear correlation with the mechanical measurements (r = 0.93) but were smaller than the latter by 26%.

Animals↗

PubMed1999

Sonographic detection of acute parenchymal injury in an experimental porcine model of renal hemorrhage: gray-scale imaging using a sonographic contrast agent.

OBJECTIVE: The purpose of this study was to determine the usefulness of contrast-enhanced sonography in the detection of acute parenchymal injury. SUBJECTS AND METHODS: In a model of acute renal injury in pigs, four separate renal parenchymal bleeds were created by puncturing an interlobar artery of the upper and lower poles of the kidneys. B-mode gray-scale scans of the kidneys before and after injury, and after the administration of i.v. and intraarterial (i.a.) contrast agents were recorded on videotape for 5 min for each condition (baseline, after injury, after i.v. contrast administration, and after i.a. contrast administration). For each condition and injury, selected frames were analyzed with regions of interest of the normal renal parenchyma, the area of injury, and the perinephric space. Randomized videotape clips from each of the experimental conditions were rated by three sonologists as to the presence or absence of increased intrarenal parenchymal echogenicity, perinephric echogenicity, and confidence as to whether renal injury was present. RESULTS: Areas of renal injury were isoechoic with normal parenchyma on unenhanced scans. After both i.v. and i.a. contrast material injection, areas of injury were visible as areas of increased echogenicity. Contrast increased from 0.2 on unenhanced images to 4.0 and 4.5, respectively, after i.v. and i.a. administration of the new contrast agent. The three observers' ability to diagnose renal injury increased from 0.61, 0.64, and 0.54 to 0.71, 0.70, and 0.74 after i.v. injection and to 0.93, 0.92, and 0.97 after i.a. injection as indicated by the area under the curve in the receiver operating characteristic analysis. CONCLUSION: Transabdominal contrast-enhanced gray-scale sonography can reveal the area of acute renal hemorrhage. This procedure may be applicable in patients when sonographic contrast agents, imaging procedures, and modes of contrast administration are optimized for clinical use in trauma.

Animals↗

PubMed1998

Individually determined postpartum magnesium sulfate therapy with clinical parameters to safely and cost-effectively shorten treatment for pre-eclampsia.

OBJECTIVE: The purpose of this study was to investigate the safety of treating pre-eclampsia with magnesium sulfate, with clinical determinants used for drug discontinuation. STUDY DESIGN: One hundred sixty-eight patients were enrolled. After delivery, women with mild pre-eclampsia received a minimum of 6 hours of intravenous magnesium sulfate, whereas women with severe pre-eclampsia received a minimum of 12 hours. Magnesium sulfate was discontinued in the absence of clinical symptoms associated with spontaneous diuresis, minimal protein by urinary dipstick, and satisfaction of predetermined blood pressure criteria. RESULTS: Patients with mild pre-eclampsia required significantly less magnesium sulfate (mean 9.5 +/- 4.2 hours) than did those with severe pre-eclampsia alone (mean 16 +/- 5.9 hours); pre-eclampsia superimposed on chronic hypertension (mean 16 +/- 5.8 hours); or hemolysis, elevated liver enzyme, and low platelet count syndrome (mean 20 +/- 6.7 hours). With this protocol there was no eclampsia, and recovery room time was reduced by 50%. CONCLUSION: Individual determination of postpartum magnesium sulfate therapy for pre-eclampsia appears to be a safe approach that carries minimal risk of eclampsia.

Adolescent↗

PubMed1998

Cervical ripening: a randomized comparison between intravaginal misoprostol and an intracervical balloon catheter combined with intravaginal dinoprostone.

OBJECTIVES: Our purpose was to compare the efficacy of intravaginal misoprostol and intracervical Foley catheter/intravaginal dinoprostone for cervical ripening. STUDY DESIGN: Patients admitted for induction of labor were randomized to receive intravaginal misoprostol 25 microg every 4 hours or intracervical Foley catheter/intravaginal dinoprostone 4 mg every 4 hours. Patients not entering active labor and having ruptured membranes or arrest of dilatation received intravenous oxytocin. RESULTS: Sixty-five patients received Foley catheter/dinoprostone gel and 62 patients received misoprostol. The mean time until cervical ripening was less in the catheter/gel group (7.5 +/- 3.4 vs 12.0 +/- 5.9 hours, p < 0.01). The mean time until vaginal delivery was less in the catheter/gel group (17.4 +/- 6.9 vs 21.2 +/- 7.5 hours, p = 0.004). Among vaginal deliveries, more patients in the catheter/gel group delivered within 24 hours (90% vs 69%, p = 0.013). CONCLUSIONS: Intracervical Foley catheter/intravaginal dinoprostone was associated with more rapid cervical ripening, shorter induction to vaginal delivery interval, and greater number of vaginal deliveries within 24 hours.

Administration, Intravaginal↗

PubMed1998

Premature rupture of membranes at 34 to 37 weeks' gestation: aggressive versus conservative management.

OBJECTIVE: Our purpose was to compare induction of labor with preterm rupture of membranes between 34 and 37 weeks' gestation with expectant management. STUDY DESIGN: In this prospective investigation 120 gravid women at > or = 34 weeks 0 days and < 36 weeks 6 days of gestation were randomized to receive oxytocin induction (n = 57) or observation (n = 63). RESULTS: Estimated gestational age at rupture of membranes (34.3 +/- 1.4 weeks vs 34.5 +/- 1.4 weeks) and ultrasonographically estimated fetal weight (2230 +/- 321 gm vs 2297 +/- 365 gm) were equivalent between groups (not significant). Chorioamnionitis occurred more often (16% vs 2%, p = 0.007), and maternal hospital stay (5.2 +/- 6.8 days vs 2.6 +/- 1.6 days, p = 0.006) was significantly longer in the control group. Neonatal sepsis was also more common in the observation group (n = 3) than among induction patients (n = 0), but the difference was not statistically significant. CONCLUSION: Aggressive management of preterm premature rupture of the membranes at > or = 34 weeks 0 days of gestation by induction of labor is safe for the infant in our population and avoids maternal-neonatal infectious complications.

Adolescent↗

PubMed1998

Estimation of the human liver volume and configuration using three-dimensional ultrasonography: effect of a high-caloric liquid meal.

The aim of this study was to investigate whether or not a magnetic position sensing system for free-hand acquisition of 3-D ultrasound images could be used to estimate liver volumes, and to study the effect of a high-caloric meal on these volumes in healthy subjects. In vitro accuracy was evaluated by scanning porcine and rabbit livers. Ten healthy subjects were examined fasting and 30 min after ingesting a high-caloric liquid meal. Portal and hepatic vein blood flow were measured by 2-D duplex sonography. The 3-D system yielded a strong correlation (r = 0.99) between true and estimated volumes in vitro. No significant increase in liver volume in response to the meal was seen. However, portal and hepatic vein flow volume increased significantly. Experience in human subjects suggests that a complete 3-D study of liver volumes can be obtained from multiple acoustic windows. In healthy subjects, no significant increase in liver volume was seen in response to ingestion of a high-caloric liquid meal.

Adult↗

PubMed1998

Screening for fetal abdominal wall defects.

Failure of the lateral ventral folds to close by the third month of embryonic life results in an omphalocele. Although the abdominal wall defect is easily closed, the survival rate for infants with an omphalocele remains only 79%, largely the result of coexistent anomalies and chromosomal abnormalities. Gastroschisis is a deformation caused by disruption of the right omphalomesenteric artery and a resultant full-thickness defect in the abdominal wall. As a result, small bowel and, on occasion, even large bowel herniate into the amniotic space. Despite evidence of increased bowel irritability manifested by echogenic bowel wall thickening in fetuses with gastroschisis, the survival rate of more than 95% is largely the result of the lack of other severe anomalies associated with this defect. In addition, recent evidence suggests that the improvement in survival rate is also the result of improved perinatal care. The ability of perinatal specialists to categorize the defect along with associated anomalies and improved counseling regarding neonatal outcome have measurably increased the ability of families to assess the reproductive consequences and make informed decisions. This article outlines methods to identify patients at risk for having a fetus with an abdominal wall defect along with sonographic techniques to diagnose the majority of cases. Prompt consultation with individuals skilled in evaluating such defects ensures that appropriate perinatal care is provided.

Abdominal Muscles↗

PubMed1998

Left ventricular shape analysis from three-dimensional echocardiograms.

The objective of this study was to develop and validate a three-dimensional technique of left ventricular shape analysis. Geometric phantoms and left ventricles of excised calf hearts, normal human subjects, and one subject each with aortic stenosis and dilated cardiomyopathy were reconstructed from three-dimensional echocardiograms. The fit between the reconstructions and true surfaces of the geometric phantoms and excised ventricles was determined. To evaluate in vivo left ventricular shape, a center axis was constructed from the centroid of the mitral annulus to the furthest endocardial point. Regional shape was evaluated as the relative distances of 16 separate myocardial segments from the center axis compared with a population-derived mean value. Global shape was evaluated as the average standard deviation from the normal value over the 16 segments. The system precisely reproduced the shapes of the phantoms and excised left ventricles (root-mean-square error between true and reconstructed surface 1.0 0.2 mm and 1.2 0.8 mm, respectively). The in vivo shape analysis differentiated the pathological from normal left ventricles.

Adult↗

PubMed1998

Three-dimensional measurement of the mitral annulus by multiplane transesophageal echocardiography: in vitro validation and in vivo demonstration.

Ten phantoms were scanned with a multiplane transesophageal echocardiographic probe in a water bath to assess a new method for three-dimensional modeling of the mitral annulus. The annulus was reconstructed from manually outlined borders with Fourier series in each of the three spatial coordinates. Comparisons with direct measurements by least-squares linear regression gave coefficients of determination of 0.99 for annular height, area, and circumference. Expressed as a percentage of their true values, the mean +/- SD of the errors were -0.1% +/- 3.0% for annular height, -2.8% +/- 3.1% for area, and -0.2% +/- 1.7% for circumference. The mean residual error length for phantoms was 0.64 mm compared with 1.21 mm in nine patients studied during general anesthesia. This method gives accurate and precise measurements of the mitral annulus in vitro and should be valuable for studying its morphology and dynamics in vivo.

Adult↗