Biomedical subjects

R W Martin

Publications and source records attributed to R W Martin.

At least 127 records · Page 7Linked to original sources

PubMed1990

Ventricular volume measurement from a multiplanar transesophageal ultrasonic imaging system: an in vitro study.

We have developed a system to assess the feasibility of using multiple transesophageal ultrasonic images to measure left-ventricular volume, an important variable in patient management. The system includes a special transesophageal probe with a micromanipulator for acquiring cardiac images in multiple planes with known interplanar spatial relationship and an off-line processing system to compute the volume. In vitro studies with the probe demonstrated that the distance between two targets in space can be identified within 2 mm (SD = 0.4 mm) for points in the imaging plane 3.4 mm (SD = 0.5 mm) for points not lying in the imaging plane. This gives an average accuracy of +/- 6.5% for distances greater than 4.5 cm. Comparison of ultrasonic measurements of the volume of water-filled balloons and excised hearts to the volume required to fill them, revealed a correlation coefficient of 0.992, a regression line having a slope of 1.0 and an ordinate intercept at 0.2 mL, and a standard error of the estimate of 8 mL.

Calibration↗

PubMed1990

Bacterial luminescence: a new tool for investigating the effects of acoustic energy and cavitation.

An assay utilizing luminescent bacteria, Photobacterium phosphoreum, was adapted to assess the antibacterial effects of acoustic energy. Acoustic pressures up to 67 kPa in the 100- to 800-Hz frequency range were applied to bacteria freely suspended in a liquid medium. Bacterial luminescence decreased after sonication, thus showing sensitivity to the effects of acoustic energy. This decreased luminescence was linearly related to exposure duration, appeared independent of acoustic frequency in this range, and was significantly heightened by the presence of cavitation. High-frequency components of the acoustic emission were recorded from the sonicated fluid, and it was found that the decrease in luminescence due to sonication was directly related to the logarithm of the acoustic emission. Viability studies on exposed bacteria indicated a diminution of luminescence without bacterial death. The potential use of luminescent bacteria in assessing the biological effects of acoustic energy-generating systems is discussed.

Acoustics↗

PubMed1990

Cost/health effectiveness of home uterine activity monitoring in a Medicaid population.

It has been shown that an intensive system of preterm birth prevention using home uterine activity monitoring can decrease the number of early births. Such a system was employed in 130 public assistance (Medicaid) patients who were at high risk for preterm birth. A retrospective review of the pregnancy outcome in these subjects was conducted and their data exposed to a model for projected patient care cost. The incidence of preterm labor in the at-risk group was 46%, with an average prolongation of pregnancy of 4.9 weeks. The occurrence of preterm delivery for failed tocolysis or advanced cervical dilatation was less than 10%. Based on a cost-analysis model that considered newborn charges and monitoring expenses, nearly [corrected] $3 million (an average of $21,813 [corrected] per patient) was saved using this system.

Cost-Benefit Analysis↗

PubMed1990

Multiple cutaneous granular cell tumors and neurofibromatosis in childhood. A case report and review of the literature.

Multiple cutaneous granular cell tumors have been previously reported in only 26 children or adolescents. An association of these tumors with neurofibromatosis has never been reported previously. We describe a 12-year-old black girl with multiple cutaneous granular cell tumors and neurofibromatosis. Although the histogenesis of these tumors is not completely clear, the findings of ultrastructural and immunohistochemical evaluation of our patient's tumors and the associated neurofibromatosis support a neural crest origin for granular cell tumors.

Child↗

PubMed1990

Evaluation of fetal and neonatal acid-base status.

Determination of fetal acid-base status, either at birth, intrapartum, or antepartum, is the gold standard for the diagnosis of fetal asphyxia. Indirect methods such as Apgar scores and fetal heart rate monitoring show at best only minimal correlation. It is evident that intrauterine hypoxia is a rare cause of central nervous system injury, and the finding of a normal acid-base status at birth should lead the clinician to search for other causes of central nervous system injury or birth depression. A combination of techniques including fetal acid-base assessment, electronic fetal heart rate monitoring, and thorough neonatal evaluation probably provides the best predictor of long-term outcome. Newer methods of umbilical cord sampling and acid-base determinations in the intrauterine growth retarded fetus hold some hope for the future.

Acid-Base Equilibrium↗

PubMed1990

Uterine activity compared with symptomatology in the detection of preterm labor.

The relative contribution of uterine activity obtained by home monitoring with a guard ring tocodynamometer compared with seven specific signs and symptoms reported during patient/nurse contact as an aid in detecting preterm labor has not been studied. In this prospective, multicenter study, patients at risk for developing early labor who were randomized to receive home uterine activity monitoring and perinatal nursing support were assessed. The initiator of provider contact (uterine activity detected on routine transmission, patient-perceived signs and symptoms of preterm labor during perinatal nurse contact, or both) resulting in a diagnosis of preterm labor was recorded. Contraction data were then analyzed for an association with preterm labor. There was a strong association of increased uterine activity (four or more contractions per hour) on a repeat monitoring strip with preterm labor (P less than .001). Among patients diagnosed with preterm labor, 31% had increased uterine activity detected on a routine transmission without patient-reported signs and symptoms, compared with 24% who were diagnosed as the result of patient-reported symptoms without increased uterine activity. Daily objective uterine activity data alone have greater incremental value over and above other signs and symptoms as an aid to the physician in diagnosing preterm labor.

Female↗

PubMed1990

The contribution of symptomatology and/or uterine activity to the incidence of unscheduled visits.

Home uterine activity monitoring and perinatal nursing support have been shown to be associated with a decrease in preterm births with no increase in the number of unscheduled patient visits. This prospective, randomized multicenter study compared the frequency of unscheduled visits in patients receiving home uterine activity monitoring and perinatal nursing support with that of patients receiving education regarding the detection and reporting of preterm labor symptomatology. The contribution of patient-reported signs and symptoms versus objective uterine activity data to unscheduled visits is assessed. The overall frequency of unscheduled visits was similar in both groups. In the home uterine activity monitoring and perinatal nursing support group, the contributions of uterine activity versus signs and symptoms to the diagnosis of preterm labor were equal, with 36% of patients diagnosed with preterm labor sent to the physician for increased uterine activity and 36% for signs and symptoms. The sensitivity for the group receiving monitoring and nursing support in detecting preterm labor was 93%. The majority of false-positive visits were associated with patient symptoms. These data show that this combination service does not lead to a clinically significant increase in unscheduled visits. Further, the visits resulting from the combination service provide a sensitive predictive method to aid physicians in detecting early labor.

Clinical Trials as Topic↗

PubMed1990

Relationship of uterine contractility to preterm labor.

An increased uterine contraction rate is associated with preterm labor. The contraction rate in individual patients, however, has not been evaluated critically as to its predictive value in forecasting early labor. In this randomized multicenter study, 105 patients at high risk for preterm delivery monitored their contraction rate at home on a daily basis. An analysis was conducted to determine the association of at least four contractions per hour on a routine strip followed by at least four contractions per hour on a repeat tracing with subsequent preterm labor. Using this threshold, 70% of the patients were correctly classified. This contraction rate resulted in a sensitivity of 57%, a specificity of 80%, a positive predictive value of 72%, and a negative predictive value of 68%. A threshold rate of at least four contractions per hour on a remonitor strip identifies a patient at increased risk for preterm labor (P = .003).

Cardiotocography↗

PubMed1990

Angiographic arterial embolization and computed tomography-directed drainage for the management of hemorrhage and infection with abdominal pregnancy.

Hemorrhage during or after surgery, pelvic abscess, bowel obstruction, and prolonged febrile morbidity can complicate the puerperal course of the gravida after removal of an extrauterine fetus with nondisturbance of the extrauterine placenta. In this report we describe the successful angiographic arterial gelfoam embolization of the placental vascular bed to control heavy postoperative hemorrhage in a mother suffering adult respiratory distress syndrome after removal of the fetal portion of her abdominal pregnancy. Six weeks later, computed tomography (CT)-directed drainage by catheter of a placental abscess was performed. Selective angiographic transcatheter embolization with gelfoam is a useful tool for the control of hemorrhage in the gravida who is an unfavorable operative candidate or who may present technical hemostasis problems peculiar to the placenta with abdominal pregnancy. Later use of CT-directed catheter drainage of the infected residual placental mass provided a nonoperative means of treatment.

Abscess↗

PubMed1990

Successful pregnancy outcome following mid-gestational uterine rupture and repair using Gore-Tex soft tissue patch.

The first reported gestational use of the Gore-Tex soft tissue patch (expanded polytetrafluoroethylene) for uterine repair and support is presented in a pregnant woman whose partially dehisced, congenitally abnormal uterus was operated upon at 19 weeks' gestation. Use of the expanded polytetrafluoroethylene Gore-Tex soft tissue patch for assisted uterine integrity in combination with a program of uterine tocolysis and close maternal/fetal surveillance averted a pregnancy loss.

Abruptio Placentae↗

PubMed1990

Home uterine activity monitoring is associated with a reduction in preterm birth.

The value of home uterine activity monitoring plus perinatal nursing support in the prevention of preterm birth among high-risk patients has been demonstrated by several studies. Other reports with less stringent guidelines and less intensive nursing contact have questioned the contribution of home uterine activity monitoring and perinatal nursing support to a preterm birth prevention program. In this large, prospective, randomized multicenter study, patients were assigned to receive either daily monitoring and nursing contact or a preterm birth prevention program including intensive education and more frequent prenatal visits. Among the monitored patients, there was a significant increase in early detection of preterm labor (2 cm or less), successful tocolysis, and prolongation of pregnancy to term. Thirty-one percent of these diagnoses of preterm labor resulted from evaluation of increased uterine activity without associated patient-perceived symptoms. We conclude that a program of daily uterine activity monitoring and perinatal nursing support results in earlier diagnosis of preterm labor and subsequently more effective tocolysis.

Cardiotocography↗

PubMed1990

Preventing preterm birth in twin gestation: home uterine activity monitoring and perinatal nursing support.

In this investigation, 45 women with twin gestations in four centers were randomly assigned to either daily home uterine activity monitoring and perinatal nursing support (19) or an education group (26). Patients in the home uterine activity monitoring and perinatal nursing support group monitored uterine activity twice daily, transmitted the data each day, and had 24 hour-a-day access to nursing support. Education patients were counseled regarding the common signs and symptoms of preterm labor. Both groups had scheduled prenatal visits at least every 2 weeks. Sixteen (62%) of the education group and 14 (74%) of the home uterine activity monitoring and perinatal nursing support group developed preterm labor, values that were not significantly different. Of the monitored group who experienced preterm labor, all 14 were dilated 3 cm or less at diagnosis of the first preterm labor, compared with ten of 16 in the education group (P = .01; one-tailed Fisher test). The mean cervical dilatation at the first preterm labor episode in the group receiving daily monitoring and contact (1.6 cm) was significantly less (P = .01) than that in the education group (2.9 cm). Thus, fewer preterm births were recorded in the home uterine activity monitoring and perinatal nursing support group and significantly fewer patients delivered because of failed tocolysis (P = .03).

Adult↗

PubMed1990

Management of preterm labor patients at home: does daily uterine activity monitoring and nursing support make a difference?

Daily home uterine activity monitoring and perinatal nursing support were compared with standard care in managing patients with recurrent preterm labor during the current pregnancy in an effort to reduce preterm birth. Sixty-seven successfully treated preterm labor patients were randomly assigned in this multicenter study to daily home uterine activity monitoring and perinatal nursing support or to a standard-care group. Recurrent preterm labor occurred in 15 (45%) of monitored patients and 19 (56%) of standard-care patients. The risk of preterm birth (before 37 weeks) for patients with recurrent preterm labor was significantly reduced (P = .025) in the monitored group (seven, or 47%) compared with the standard-care group (16, or 84%). The relative risk of delivering because of failed tocolysis was 2.8 for the standard-care group versus the monitored group. There were no patients in the monitored group who delivered at the first recurrence of preterm labor for failed tocolysis. The data suggest that home uterine activity monitoring and perinatal nursing support are helpful in achieving term birth through earlier detection and treatment of recurrent preterm labor.

Adult↗

PubMed1990

Uterine activity among a diverse group of patients at high risk for preterm delivery.

In this study, 98 patients with early premature rupture of membranes (PROM), postoperative recuperation, placenta previa, or blunt abdominal trauma were assessed for uterine contractions with an ambulatory uterine activity monitor. Uterine irritability manifested by low-amplitude, high-frequency contractions of 30 seconds' duration or less was prevalent in all groups but decreased as the patients were stabilized and diminished or disappeared in those who did not develop preterm labor. In the 18 women who developed preterm labor, daily uterine activity monitoring detected contractions 24-48 hours before clinical symptoms of preterm labor and/or vaginal bleeding occurred. A number of patients with early PROM and placenta previa had low-amplitude, high-frequency contractions, and the majority occurred in those who subsequently developed preterm labor.

Abdominal Injuries↗

PubMed1990

Characteristics of uterine activity in gestations less than 20 weeks.

Ambulatory tocodynamometry has been used for some time to record uterine activity during pregnancy. Most studies, however, have been performed in the third trimester (more than 24 weeks). The current study was initiated to assess uterine activity at earlier gestational ages. One hundred thirty-seven patients were studied between 14-19 weeks' gestation (inclusive). Seven patients who were being monitored were noted to have preterm labor, and six of these seven were found to have increased uterine activity before the diagnosis of preterm labor. There was no difficulty encountered in the vast majority of cases in recording objective, accurate uterine activity information even at these early gestational ages. There was an increase in the uterine activity (during the 18th and 19th weeks) in patients destined to develop preterm labor later in gestation as compared with the contraction pattern of those who labored at term. This study demonstrates that accurate uterine activity information can be gained at these early gestational ages and that when increased contraction frequency is present, it is related to preterm labor.

Adult↗

PubMed1990

Postpartum eclampsia: a recurring perinatal dilemma.

Because identification of patients at risk and preventive therapies are imperfect, eclamptic seizures continue to occur occasionally during the puerperium. During an 18-year span in a single tertiary medical center, 36 of 254 patients with eclampsia (14.2%) experienced postpartum seizures at a mean gestational age of 35.6 weeks. Early (before 48 hours) postpartum eclampsia was experienced by 72% of patients, and 28% had late (after 48 hours) postpartum eclampsia. Prospectively only 67% of patients were correctly diagnosed, and retrospectively only 83% could be considered to have had preeclampsia before seizure. Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome was present in 30% of the affected patients. Seven patients were receiving magnesium sulfate by controlled infusion when an eclamptic seizure occurred. The presence or absence of diuresis was unrelated to seizure occurrence. Preeclampsia recurred in 38.5% of subsequent gestations. It appears that HELLP syndrome may be a predisposing factor for eclampsia.

Blood Pressure↗

PubMed1989

Design characteristics for intravascular ultrasonic catheters.

Several factors are important in the design of intracoronary ultrasonic imaging catheters. The mechanical considerations are first discussed and equations are developed for calculating the forces affecting catheter passage in a blood vessel. These equations are applied to the problem of Judkins (transfemoral) coronary artery catheterization, using previously described anatomical information and catheter moduli values. The introduction force is calculated for each position along the vessel for both a high and low value of estimated catheter-wall friction (coefficient values of 0.04 and 0.2, respectively). Next, the problem of catheter or transducer rotation is analytically described. The advantages of spiral drive cables with high torsional rigidity and low bending stiffness are numerically shown. Finally, several methods and considerations are given for electrical connection to the transducer. These results and equations should facilitate the design of intracoronary ultrasound imaging devices in the future.

Angioplasty, Balloon↗

PubMed1989

Histologic correlates of gastrointestinal ultrasound images.

Endoscopic ultrasound imaging has potential for improving the diagnosis of gastrointestinal disease. However, the anatomic correlates of gastrointestinal ultrasound images have not been precisely defined. We have compared ultrasound images with the corresponding histologic sections of 81 specimens of resected and postmortem, normal and diseased gastrointestinal tissue. The five layers seen on ultrasound images of the normal gastrointestinal tract correspond to (1) superficial mucosa, (2) deep mucosa, (3) submucosa plus the acoustical interface between the submucosa and muscularis propria, (4) muscularis propria minus the acoustical interface between the submucosa and muscularis propria, and (5) serosa and subserosal fat. This interpretation takes into consideration the echoes produced by the tissue layers and the echoes produced by the interfaces between layers. Abnormal findings on ultrasound images of neoplastic and inflammatory diseases correspond to histologic tissue structure. When properly interpreted, ultrasound images of the gastrointestinal wall can provide potentially useful diagnostic information.

Digestive System↗