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Biomedical subjects

N Greene

Publications and source records attributed to N Greene.

11 recordsLinked to original sources
PubMed2002

First-trimester trisomy screening: nuchal translucency measurement training and quality assurance to correct and unify technique.

OBJECTIVE: To describe the process of training for measuring nuchal translucency at five clinical centers in North America and to evaluate methods of quality assurance and feedback. DESIGN: Throughout a period of 18 months, the performance of sonographers in measuring fetal nuchal translucency was monitored using qualitative and quantitative methods of review. After 12 months, different approaches (written and personal feedback) were used to inform sonographers of technical aspects that needed to or could be improved. RESULTS: On initial qualitative review, discrepancies in judgment from different reviewers coincided with suboptimal magnification, failure to visualize the amniotic membrane and/or use of cross-shaped calipers. At subsequent global review, 13 (29%) images of nuchal translucency measurements were considered unacceptable. Quantitative assessment revealed that, during the first part of the study, the means from four sonographers were significantly smaller and the mean from the fifth sonographer was significantly larger than expected on the basis of findings from The Fetal Medicine Foundation (P < 0.0001). Following feedback, sonographers who underestimated nuchal translucency and who received a written report only did not change measurements overall (P = 0.9759). In contrast, those who received additional intervention showed a marked difference (P < 0.0001). CONCLUSIONS: Global qualitative review of images from one sonographer may be preferable to assessment of individual aspects of images. Results from global qualitative review correspond well with findings from quantitative analysis, indicating that the latter can be applied for ongoing audit. Observation of divergent results should prompt extensive personal feedback, rather than a written report, to prevent sonographers from settling in their own, inappropriate technique.

Allied Health Personnel↗
PubMed2000

The use of chorionic villus biopsy catheters for saline infusion sonohysterography.

BACKGROUND: Saline infusion sonohysterography is one of the recent refinements of ultrasonography that has the ability to enhance imaging of the uterine cavity in a safe, inexpensive and expedient manner. The technique can be difficult in women with a stenotic cervical os. This report describes a single-pass technique using chorionic villus sampling (CVS) catheters for saline infusion sonohysterography. METHOD: Saline infusion sonohysterography requires the transcervical passage of a catheter, through which saline is infused. The subsequent distension of the uterine cavity enhances the ability to detect intrauterine pathology with ultrasonography. In women with cervical stenosis, a catheter can be used in place of the more conventional two-pass technique, which requires the use of a uterine sound or probe followed by a conventional catheter. EXPERIENCE: We have used CVS catheters in women with cervical stenosis on 12 occasions. All have been successful and without significant discomfort to the patient. CONCLUSION: The use of CVS catheters for saline infusion sonohysterography in women with cervical stenosis can alleviate the need to remove the cervical probe prior to introduction of the catheter.

Catheterization↗
PubMed2000

Femur length and trisomy 21: impact of gestational age on screening efficiency.

OBJECTIVE: This study assesses two methods used to define relatively short femur in screening for trisomy 21 and examines changes in performance of screening with gestational age. DESIGN: Retrospective analysis of data on menstrual age, femur length (FL) and biparietal diameter (BPD) in 49 trisomy 21 pregnancies and 6069 normal controls. Reference ranges were derived for BPD/FL versus menstrual age and for FL versus BPD. Two methods of defining short femur (BPD/FL and observed-to-expected FL ratio) were examined for false-positive rates and detection rates for trisomy 21 at different gestational ages. RESULTS: In the control group the BPD/FL ratio and its standard deviation decreased with menstrual age. Trisomy 21 was associated with a significantly higher BPD/FL ratio (P < 0.001) and the deviation increased significantly with menstrual age (P < 0.05). Eleven percent of 28 fetuses examined at 15-17 weeks had a BPD/FL above the 95th centile compared with 24% of 21 fetuses examined at 18-20 weeks (P = 0.40). The median observed-to-expected FL ratio in the control group was 1.0 throughout the gestational age range but the standard deviation decreased significantly with menstrual age (P < 0.01). Trisomy 21 was associated with a significantly reduced observed-to-expected FL ratio (P < 0.001) and the deviation increased significantly with menstrual age (P < 0.05). A fixed cut-off of 0.91 for observed-to-expected FL ratio provided a false-positive rate of 12% at 15-17 weeks compared with 6% at 18-20 weeks of gestation (P < 0.001) with detection rates of 29 and 38%, respectively (P = 0.73). CONCLUSION: Irrespective of the definition used to define the condition, relatively short femur is a poor marker for trisomy 21 particularly when the assessment takes place before 18 weeks of gestation.

Adult↗
PubMed2000

Fetal echogenic bowel: parameters to be considered in differential diagnosis.

OBJECTIVES: To evaluate the extent that associated findings aid in the differential diagnosis and/or prognosis of fetal echogenic bowel. METHODS: Medical history, obstetric records and outcome details were examined for 131 consecutive pregnancies with fetal hyperechogenic bowel. RESULTS: In 62 (47%) cases, there were no visible anomalies other than hyperechogenic bowel and no evidence of growth restriction. This group included four (7%) pregnancies with Down syndrome, 15 (24%) with infection or a recent episode of influenza and eight (13%) with blood staining of amniotic fluid. In the remaining 69 (53%) cases, hyperechogenic bowel was accompanied by hydrops or nuchal edema (n = 16, 12.2%), growth restriction (n = 9, 6.9%), other markers for chromosome anomalies (n = 33, 25.2%) or multiple structural anomalies (n = 11, 8.4%). In this group, the prevalence of Down syndrome was 12%, infection or influenza was reported in 14 (20%) cases and there was blood staining of amniotic fluid in seven (10%). Cystic fibrosis screening was performed in 65 (50%) pregnancies; the results were negative in all cases and clinical assessment did not indicate cystic fibrosis in any of the 91 infants who were born alive. Maternal serum screening was performed in 41 (31%) pregnancies. High alpha-fetoprotein levels were associated with multiple abnormalities or severe growth restriction. CONCLUSIONS: In many pregnancies with fetal hyperechogenic bowel, there are multiple factors that may explain these findings. Thus identification of one potential underlying cause should not preclude further testing. Once chromosome defects, cystic fibrosis, structural abnormalities, infection and growth restriction have been excluded, parents can be counseled that the prognosis is good, irrespective of the presence or absence of blood stained amniotic fluid.

Adolescent↗
PubMed1999

Knowledge-based expert systems for toxicity and metabolism prediction: DEREK, StAR and METEOR.

It has long been recognised that the ability to predict the metabolic fate of a chemical substance and the potential toxicity of either the parent compound or its metabolites are important in novel drug design. The popularity of using computer models as an aid in this area has grown considerably in recent years. LHASA Limited has been developing knowledge-based expert systems for toxicity and metabolism prediction in collaboration with industry and regulatory authorities. These systems, DEREK, StAR and METEOR, use rules to describe the relationship between chemical structure and either toxicity in the case of DEREK and StAR, or metabolic fate in the case of METEOR. The rule refinement process for DEREK often involves assessing the predictions for a novel set of compounds and comparing them to their biological assay results as a measure of the system's performance. For example, 266 non-congeneric chemicals from the National Toxicology Program database have been processed through the DEREK mutagenicity knowledge base and the predictions compared to their Salmonella typhimurium mutagenicity data. Initially, 81 of 114 mutagens (71%) and 117 of 152 non-mutagens (77%) were correctly identified. Following further knowledge base development, the number of correctly identified mutagens has increased to 96 (84%). Further work on improving the predictive capabilities of DEREK, StAR and METEOR is in progress.

Computer Simulation↗
PubMed1999

Culture results in open wound treatment with muscle transfer for tibial osteomyelitis.

Fifty-three patients who underwent a two-staged protocol of debridement and muscle flap coverage for chronic osteomyelitis of the tibia between 1991 and 1996 were evaluated. All patients underwent a thorough debridement of all nonviable tissue and bone at initial debridement. Multiple cultures were taken, including aerobic, anaerobic and fungal cultures from the pus, soft tissue, bone curettings and bone. All patients were treated with open wound management and dressing changes. Between 2 to 7 days, median 4 days, all patients underwent a second debridement with a complete set of identical cultures, and immediate soft tissue muscle transfer. There were 42 free vascularized and 11 local tissue transfers. The 53 patients were classified according to the Cierny-Mader classification for chronic osteomyelitis. Twenty-four patients had Stage IVA osteomyelitis, 10 patients had Stage IIIA osteomyelitis, nine patients had Stage IIIB osteomyelitis, eight patients had Stage IVB osteomyelitis, one patient had Stage IA osteomyelitis, and one patient had Stage IIB osteomyelitis. All 53 patients had positive cultures at the time of their initial debridement, and 14 of 53 (26%) had a positive culture at the time of the second debridement. Based on the results, it seems from a bacteriologic stand-point that the second debridement allows for the opportunity for redebridement and wound sterilization of organisms that still may be present.

Adolescent↗
PubMed1999

Facilitating edema resolution with a foot pump after calcaneus fracture.

OBJECTIVES: To determine whether the use of a foot pump (intermittent pneumatic pedal compression device) in patients with excessive edema precluding surgery after acute fracture of the calcaneus leads to more rapid resolution of the edema. DESIGN: Prospective randomized setting. Standard hospital in-patient ward at a Level I trauma center. PATIENTS: Those patients with excessive edema precluding operative intervention upon admission after an intraarticular calcaneus fracture who signed an informed consent participated in the study. Twenty-eight patients were enrolled and completed the study: thirteen patients in the foot pump group and fifteen patients in the control group. INTERVENTION: In the control group, patients had a bulky compression dressing, posterior splint, and elevation while awaiting surgery. In the study group, the patients had a foot pump applied to the foot with a posterior splint and elevation while awaiting surgery. MAIN OUTCOME MEASUREMENTS: The volumetric change of the foot at twenty-four-hour intervals for up to seventy-two hours in both the control and study groups. RESULTS: All thirteen patients tolerated the foot pump. The differences in the volume between Day I (baseline) and Day 2 for the foot pump and control groups were minus forty and plus seventy-six milliliters, respectively (p = 0.02). Between Days 1 and 3, the differences were minus ninety-six milliliters for the foot pump group and plus thirty-seven milliliters for the control group (p = 0.02). CONCLUSIONS: A significant progressive decrease in the foot volume was noted during the first forty-eight hours after application of the foot pump in patients with excessive edema precluding operative fixation of a calcaneus fracture upon presentation. The pump was well tolerated by all the patients in the study group. Thus, we believe the pump serves as a useful adjunct in the preoperative edema resolution following these complicated fractures.

Ankle Injuries↗
PubMed1998

Three-dimensional ultrasonography in obstetrics and gynecology: preliminary experience.

OBJECTIVE: Technologic advances in ultrasonographic imaging have revolutionized the management of women's health care. We recently began to evaluate the clinical applications of three-dimensional ultrasonography. STUDY DESIGN: This study prospectively evaluated 161 obstetric and gynecologic patients. Both two- and three-dimensional imaging data were acquired from real-time ultrasonography. Three orthogonal planes were displayed on a monitor and were used to create the rendered three-dimensional images. RESULTS: To date, 201 three-dimensional ultrasonographic studies have been performed, 165 transabdominally and 36 transvaginally. Transabdominally, an average of eight acquisitions per patient were obtained. Of the clinically suspected abnormalities, 29 of 32 (91%) were confirmed by three-dimensional imaging. Three of 32 (9%) improved the diagnostic capabilities or changed the diagnosis. Of the 36 transvaginal studies, an average of four acquisitions per patient were done. Thirty (83%) of these patients had suspected abnormalities and all were confirmed. CONCLUSIONS: Three-dimensional ultrasonographic imaging appears to be highly promising in the clinical setting.

Computer Systems↗
PubMed1998

In vitro elution of tobramycin and vancomycin polymethylmethacrylate beads and spacers from Simplex and Palacos.

In vitro studies of antibiotic elution from polymethylmethacrylate cement comparing Simplex (Howmedica, Rutherford, NJ) with Palacos brands (Richards, Memphis, TN) have shown variable results. This study compares the elution of tobramycin and vancomycin from Simplex and Palacos beads and spacers. Six-millimeter beads and spacers were incubated in phosphate-buffered saline, and the solution was sampled and changed daily until the concentration of antibiotic fell below the minimum inhibitory concentration (MIC) for Staphylococcus aureus. In all groups, the Palacos PMMA beads and spacers showed elution at higher levels and remained above the MIC longer than did the Simplex PMMA beads. Tobramycin had superior elution to vancomycin in all groups. This in vitro study shows that Palacos PMMA has superior elution properties to Simplex PMMA in tobramycin and vancomycin beads and spacers.

Anti-Bacterial Agents↗