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Biomedical subjects

S F Evans

Publications and source records attributed to S F Evans.

At least 55 records · Page 3Linked to original sources
PubMed1997

Antenatal patterns of uterine activity in low-risk women: a longitudinal study.

There is a surprising lack of information on antenatal patterns of uterine activity in the normal obstetric population, with the majority of research having focussed on women at high-risk for preterm birth. We conducted a prospective longitudinal study to investigate patterns of uterine activity in women with singleton gestations at low-risk for preterm birth. Twenty pregnant women were recruited and their uterine activity was recorded using ambulatory tocodynamometry twice weekly throughout the latter half of pregnancy. The collected data were transmitted to a central receiving station for analysis. As gestation advanced there was a progressive increase in the median number of contractions detected per hour, peaking and stablizing at 37-40 weeks (median of 0 contractions/hour at 20-24 weeks rising to 5.4 contractions/hour at 37-40 weeks). In those women with uterine activity, contraction duration and amplitude of deflection significantly increased as gestation advanced. There was a progressive increase in the number of higher amplitude contractions throughout the third trimester. Increasing parity was not associated with increasing antenatal uterine contraction frequency. No association between normal daily physical activity and uterine contraction frequency was evident throughout gestation. In normal human pregnancy there is a steady, progressive increase in the frequency, duration and amplitude of antenatal uterine activity throughout the latter half of gestation. The uterine contractile profile alters from one of a low amplitude, low frequency pattern in the second trimester to a higher amplitude, higher frequency pattern at term.

Adult↗
PubMed1997

Factors influencing the selection of analgesia in spontaneously labouring nulliparous women at term.

We investigated the maternal characteristics, labour performance and delivery mode of 497 nulliparas entering labour spontaneously at term to identify the obstetric factors which influenced their choice of analgesia; 51.7% of these women used epidural analgesia. They were shorter (163 versus 165 cm, p = 0.002) and the mean gestation was 3 days greater than those not using epidural analgesia (40.2 versus 39.6 weeks, p = 0.0007). Median birth-weight in the epidural group was greater by 155 g (3,450 versus 3,295 gs, p = 0.0001). Analysis of the labour characteristics showed a lesser cervical dilatation on admission, significantly longer latent and active phases of labour and second stage length in the epidural cohort. The need for oxytocin augmentation was significantly greater in the epidural group, both prior to and after insertion. Oxytocin augmentation was strongly associated with an increased risk of operative intervention regardless of analgesia. Selection of intrapartum analgesia is not a random event and epidural analgesia appears to be an indicator of abnormal labour patterns. To further investigate the impact of analgesic methods on nulliparous labour we are currently conducting a prospective randomized controlled trial.

Adult↗
PubMed1996

Employment, exertion, and pregnancy outcome: assessment by kilocalories expended each day.

OBJECTIVE: Our purpose was to evaluate the influence of employment and physical exertion on pregnancy outcome as quantified by kilocalories expended each day. STUDY DESIGN: This prospective study assessed 2743 pregnant women who received prenatal care and were delivered at the major perinatal center in Western Australia between May 1989 and November 1991. All women completed an extensive questionnaire on their social, medical, psychosocial, and economic circumstances. The women were allocated to five groups on the basis of kilocalorie expenditure per day. RESULTS: The characteristics of women in each energy expenditure group were different, with those in the least-expenditure group being younger and shorter, more likely to be living in worse socioeconomic conditions, smoke cigarettes, be nulliparous, and to be of an ethnic group other than white. After confounding effects were adjusted, women in the medium energy expenditure group were delivered of babies of higher birth weight than were women in other groups. However, the differences in birth weight between the energy expenditure categories were small, and mean birth weights within each group were within the normal range. Women in the medium energy expenditure group also had fewer incidences of prelabor rupture of membranes and women in the lower energy expenditure category had increased risks of antepartum admission to the hospital and preterm birth. A variety of other differences were observed in pregnancy outcomes for women in each of the categories of energy expenditure, but most of these differences were explained by the characteristics of the women in each expenditure level rather than the exercise pattern itself. CONCLUSION: These results indicate that the effects of daily energy expenditure on pregnancy outcome are not great. Enthusiasm for counseling pregnant women of the benefits or hazards of extremes in daily activity should be tempered by the relative lack of an effect and the fact that most apparent differences are due to confounding variables rather than the exercise itself.

Adult↗
PubMed1996

Low and conventional dose transdermal oestradiol are equally effective at preventing bone loss in spine and femur at all post-menopausal ages.

OBJECTIVES: We wished to appraise the effectiveness of hormone replacement therapy (HRT) in early (< 67 years) and late (> 67 years) post-menopausal women referred to a metabolic outpatient clinic for assessment of their bone status. Because older women often experience side-effects with conventional HRT, a low dose preparation (Estraderm 25) was also compared with conventional HRT (Estraderm 50). DESIGN AND SETTING: Since all patients were symptomatic, the investigation was open and not placebo controlled. Patients were offered HRT and told about the two dosages. If they wished to use HRT, allocation of dosage was made randomly unless there were reasons to use a specific dose. PATIENTS: One hundred and ninety-six women were studied over 1 or 2 years with 80 reaching 3 years of treatment. Patients were divided into those under 67 years and those over 67 years at the start of treatment. Each group was further divided into those taking Estraderm 25 and those taking Estraderm 50 with norethisterone if appropriate. MEASUREMENTS: Bone mineral density (BMD) was measured (DXA, Hologic) at the lumbar spine and femoral neck at 0 year (196 patients), at 1 year (169 patients), at 2 years (139 patients) and at 3 years (80 patients). Patients losing bone were expressed as those whose 3 year BMD was lower than initial or as those whose BMD at 3 years had fallen by more than twice the coefficient of variation for that site (non-responders). RESULTS: In lumbar spine, BMD increased maximally in the first year in all groups and the gain was maintained after 3 years. The change was similar whether patients were divided by age or dosage. For those on Estraderm 25, mean change after 3 years was 8.1 +/- 6.8% and on Estraderm 50, 9.0 +/- 8.3% (combined 8.7 +/- 7.8%). Only 3.9% of patients were non-responders at the lumbar spine after 3 years. At femoral neck, changes were significant at 3 years only in the Estraderm 25 > 67 years and Estraderm 50 < 67 years groups and averaged 2.3 +/- 5.4% for all patients. At the femoral neck, 10.4% of patients were non-responders after 3 years. Percentage change of BMD over 3 years at lumbar spine correlated with that at the femoral neck (r = 0.56). Percentage change of BMD at lumbar spine over 3 years correlated with menopausal age (r = 0.295). No relation was found between dosage of Estraderm/kg body weight and response of BMD at either site. CONCLUSIONS: Transdermal oestrogen is effective at preventing bone loss in the spine at all post-menopausal ages and is capable of doing this in low dosage. Prevention of bone loss at the femoral neck is less certain and the average change in BMD over 3 years was significantly lower (P < 0.001) than in the lumbar spine. Use of Estraderm 50 is not associated with a greater response of bone mass and there was no evidence of an increasing BMD response as oestradiol dosage/kg body weight increased.

Administration, Cutaneous↗
PubMed1996

Effects of low- and conventional-dose transcutaneous HRT over 2 years on bone metabolism in younger and older postmenopausal women.

The minimum dosage of transcutaneous hormone replacement therapy (HRT) able to exert protective effects on postmenopausal bone mass, especially in older women, is uncertain. This study investigates the effects of transcutaneous HRT at two different doses of oestradiol [Estraderm 25 and 50 (E25, E50)] over 2 years in 44 postmenopausal women younger than 67 years and 27 of 67 years and older. Circulating biochemical markers of bone and connective tissue turnover, collagen type I (intact PINP, PICP) and type III (PIIINP) propeptides and type I telopeptide (ICTP), osteocalcin (OC) and alkaline phosphatase (AP) were measured. The responses of the biochemical markers in all the groups were very similar, and most of the observed changes occurred within the first year of treatment. E25 had an effect on the bone markers similar to that of E50, and there was little difference in response according to the patient's age. PINP fell markedly after 1 year in all groups to about half the pretreatment level, with a smaller drop in the second year. PICP responded more variably, and mean values were little changed. There was a slight fall at the higher dose in the younger women, and also in the older women (whose baseline level was higher) on the lower dose. The correlation between PINP and PICP was 0.52 at pretreatment and 0.84 after 2 years of treatment. PIIINP showed no changes. OC and AP both fell in all groups by the first year, but less markedly than PINP. Their response was slightly less pronounced in the older women. ICTP fell marginally in the younger women, and only after 2 years, regardless of dose. Postmenopausal serum oestradiol levels increased after HRT and were associated with decreased binding globulin (SHBG) levels in all groups. After E25 patch application individual serum oestradiol levels were variable and peaked between 13 and 36 h with a median value of 83.8 pmol L-1. Our data suggest that low-dose transcutaneous HRT restores circulating oestradiol levels in postmenopausal osteopenic women of all ages as effectively as conventional-dose HRT and is associated with decreased circulating markers of bone and connective tissue turnover.

Administration, Cutaneous↗
PubMed1996

Recurrent wheezing in very preterm infants.

AIMS: To document the prevalence of, and identify risk factors for, recurrent wheezing treated with bronchodilators in the first year of life. METHODS: Parental history and neonatal data were collected prospectively in a regional cohort of very preterm infants (< 33 weeks). Data on maternal smoking, siblings at home, breast feeding, respiratory symptoms, and hospital re-admissions were documented at 12 months. RESULTS: Outcome data were available for 525/560 (95%) of survivors. The incidence of recurrent wheeze was 76/525 (14.5%) in very preterm infants and 20/657 (3%) in a cohort of term newborns. Significant risk factors for recurrent wheeze in very preterm infants were parental history of asthma, maternal smoking, siblings at home, neonatal oxygen supplementation at 28 days, 36, and 40 weeks of gestation. CONCLUSIONS: Wheezing respiratory illnesses are common in very preterm infants. The factors involved are similar to those in more mature infants, with the addition of immaturity and neonatal lung injury.

Bronchial Hyperreactivity↗
PubMed1996

Patient-controlled epidural analgesia following caesarean delivery: a comparison of pethidine and fentanyl.

Pethidine and fentanyl have both been used to provide patient-controlled epidural analgesia (PCEA) following caesarean delivery. Both have been compared with epidural morphine but these drugs have not been compared with each other. Patient-controlled epidural analgesia was used in a prospective, randomized, double-blind, cross-over trial to compare fentanyl and pethidine for postoperative epidural analgesia in women having elective caesarean deliveries. Two groups received either PCEA fentanyl or pethidine with a cross-over to the other drug after 24 hours. Results from 45 patients showed no difference in pain level outcomes, but pethidine scored better in all side-effects except for drowsiness at 48 hours. Patients were more satisfied with pethidine (P = 0.015) and overall 65% of patients preferred pethidine. We conclude that pethidine is a suitable drug for patient-controlled epidural analgesia and leads to greater patient satisfaction than does fentanyl.

Adult↗
PubMed1995

Low dose aspirin for the treatment of fetal growth restriction: a randomized controlled trial.

The purpose of this study was to investigate the hypothesis that maternal administration of 100mg aspirin each day will improve birth-weight and other measures of neonatal size when given as a treatment to pregnancies complicated by fetal growth restriction and umbilical-placental insufficiency. A randomized, double-blind, placebo controlled study design was employed; 51 pregnant women were enrolled. The entry criteria were a fetal abdominal circumference < 10th per centile together with an umbilical artery Doppler systolic/diastolic ratio > 95th per centile between 28 and 36 weeks' gestation. Compliance was assessed by serial measurement of maternal serum thromboxane B2 levels. The mean gestational age at enrolment was 32 weeks and at delivery was 36 weeks. There were no differences between the 2 groups in gestational age at birth; birth-weight or birth-weight ratio; circumferences of the head, chest or abdomen; skin fold thicknesses; or neonatal morbidity. Low dose aspirin therapy did not alter Doppler systolic/diastolic ratios. After 14 days therapy, mean thromboxane B2 levels fell more than 80% from baseline values; 10.5% of women did not demonstrate biochemical confirmation of aspirin ingestion, despite verbal confirmation of compliance. We conclude that low dose aspirin therapy is not of benefit in the treatment of pregnancies complicated by fetal growth restriction and umbilical-placental insufficiency between 28 and 36 weeks' gestation.

Adult↗
PubMed1995

Single-dose prophylaxis for postoperative nausea and vomiting after major abdominal surgery: ondansetron versus droperidol.

The new antiemetic ondansetron is effective for the prophylaxis and treatment of postoperative nausea and vomiting (PONV), but has been subject to limited comparative evaluation in surgical inpatients. Two hundred and seventy women having abdominal gynaecological surgery were investigated for 24 hours postoperatively in a randomized, double-blind, placebo-controlled study of intraoperative intravenous ondansetron 8 mg (n = 83), droperidol 2.5 mg (n = 89) or saline placebo (n = 87). Patients receiving either ondansetron or droperidol remained likely to vomit, although the incidence was significantly reduced compared with placebo (72% and 83% versus 91%, P < 0.01). Both drugs also resulted in significantly fewer vomiting episodes (P < 0.001), lower nausea scores (P < 0.05) and a lower incidence of patients requiring treatment for PONV (P < 0.01). Compared with droperidol, the risk of vomiting after ondansetron was less (odds ratio 0.5, CI 0.3-1.0). Ondansetron resulted in fewer vomiting episodes (P < 0.05) and a higher percentage of patients free of nausea after six hours postoperatively (P < 0.05). In patients with a past history of PONV, both drugs had a similar short-lived antiemetic effect, reducing the incidence of vomiting and the need for treatment while in the recovery room, but not thereafter. Droperidol was associated with significantly less headache (P < 0.05), but higher early sedation scores (P < 0.05). Although, compared to placebo, both droperidol and ondansetron administered intraoperatively reduced vomiting after major abdominal gynaecological surgery, the incidence during the first 24 postoperative hours was very high in all groups. Ondansetron reduced the risk of experiencing nausea after six hours postoperatively and the risk of vomiting, with respect to the total number of episodes, in the first 24 hours. It was no better than droperidol, however, in reducing the incidence of vomiting or the need for antiemetic treatment during the first postoperative day, whether or not patients had a past history of PONV. It was no better than droperidol, however, in reducing the incidence of vomiting or the need for antiemetic treatment during the first postoperative day, whether or not patients had a past history of PONV.

Abdomen↗
PubMed1995

Prospective clinical evaluation of two combined spinal-epidural kits.

One hundred combined spinal epidural kits (Portex, n = 51, Mallinckrodt, n = 49) were evaluated clinically by twelve anaesthetists with respect to performance of the loss-of-resistance syringe, epidural needle and spinal needle, and success in establishing single-segment combined spinal-epidural anaesthesia for caesarean section. Similar components included a plastic loss-of-resistance device, a Tuohy epidural needle, 26 or 27 gauge pencil-point spinal needle and closed end, three-lateral-eye epidural catheter. The Mallinckrodt kit incorporated a "back-eye" design for exit of the spinal needle from the epidural needle. The epidural and the subarachnoid spaces were satisfactorily identified on 98 occasions. Most anaesthetists preferred the Mallinckrodt kit packaging and the Portex loss-of-resistance syringe, although the latter may have been biased by familiarity with this device. The portex spinal needle was more likely to be felt penetrating the dura (P = 0.02) and aspiration of cerebrospinal fluid was more frequently described as easy (P = 0.01). The most common criticisms of both kits were difficulty controlling the spinal needle position after entry into the subarachnoid space and subjectively, a high degree of resistance to injection through the spinal needle.

Adult↗
PubMed1994

Catecholamine response to ultrasonographically guided percutaneous blood sampling in fetal sheep.

OBJECTIVE: The purpose of this study was to investigate the fetal catecholamine and arterial blood gas responses to ultrasonographically guided percutaneous needle aspiration of blood from a fetal cardiac ventricle. STUDY DESIGN: A crossover trial design was used. Nine pregnant sheep of 120 to 130 days' gestation were stratified to either percutaneous fetal blood sampling or a sham experiment performed on the first day, and the alternative study on the following day. Arterial blood samples were withdrawn from chronically implanted catheters. RESULTS: Percutaneous fetal blood sampling caused small but statistically significant increases in mean plasma epinephrine and norepinephrine levels 5 seconds after the procedure. Levels thereafter were similar to baseline values. Arterial pH and PCO2 values were unaltered except in one fetus, where blood sampling was followed by bradycardia with acidosis and elevated catecholamine levels. CONCLUSIONS: Ultrasonographically guided percutaneous fetal blood sampling from a cardiac ventricle in sheep produces a rise in catecholamine levels that return to baseline values within 5 minutes. This technique provides an alternative to chronic catheterization for some experiments in which blood sampling or drug injection is required. The results also indicate that needle insertion produces only a modest and transient stress response in the fetus.

Animals↗
PubMed1994

Meperidine for patient-controlled analgesia after cesarean section. Intravenous versus epidural administration.

BACKGROUND: Although meperidine has been used for patient-controlled analgesia both intravenously (PCIA) and epidurally (PCEA), these routes have not been compared, and many studies have suggested that there is no advantage to the epidural route for administration of lipophilic opioids. METHODS: A randomized, double-blind, crossover study was conducted for 24 h after cesarean section to compare the analgesic efficacy, side effects, patient satisfaction, drug use, and plasma drug concentrations with meperidine administered either as PCIA or as PCEA. Two groups, stratified for time of cesarean section during epidural anesthesia, postoperatively received either PCEA (group 1) or PCIA (group 2) with identical variables for 12 h before crossing to the other route for an additional 12 h. RESULTS: Results from 45 patients showed a similar speed of analgesic onset but, subsequently, significantly lower pain scores both at rest and with coughing in those receiving PCEA (P = 0.0001). Nausea and pruritus scores did not differ between the groups in the first 12 h postoperatively, but sedation scores were significantly higher with PCIA (P = 0.0001). Patient satisfaction scores and preference significantly favored PCEA (P = 0.0001), with almost 90% of participants preferring the epidural route. Meperidine use was reduced approximately 50% with PCEA (P = 0.0001), and plasma meperidine and normeperidine concentrations were significantly lower (P = 0.0001). CONCLUSIONS: We conclude that after cesarean section, PCEA with meperidine produces high-quality pain relief with few side effects and has significant advantages over PCIA meperidine. With the caveat that neonatal effects in breast-feeding mothers have yet to be evaluated, it can be highly recommended in this population.

Adult↗
PubMed1994

C-reactive protein as a diagnostic tool of sepsis in very immature babies.

Three hundred and nine septic screens were performed on 123 consecutively admitted infants of < 30 weeks gestation. As part of the septic screen, serial quantitative measurements of C-reactive protein (CRP) were performed daily until discontinuation of antibiotic therapy. Complete blood counts were performed daily for the first 2 days of each septic episode. The babies had a mean birth weight of 1035.8 g s.d. 273.2 and a mean gestational age of 27 weeks s.d. 1.8. A CRP level of 10 mg/L or above was considered abnormal. Subsequently the receiver operator characteristic curve for CRP was constructed to demonstrate the ideal cut off value. Of the 309 septic screens, there were 51 instances of proven sepsis and 39 instances of deep culture negative sepsis. In the remaining 219, a diagnosis of proven or deep culture negative sepsis could not be made. On the first day of the septic episode CRP showed a sensitivity of 62.7%, specificity of 87.2% and negative predictive value of 92.2% for proven sepsis. There was a significant increase in the sensitivity (90.2%) and negative predictive value (97.7%) of CRP with a specificity of 80.6 when both day 1 and 2 estimations were combined. We conclude that when the CRP is elevated on day 1 and/or day 2, the diagnosis of sepsis is extremely likely and when the CRP is within normal limits on days 1 and 2 of the septic episode, neonatal sepsis can be confidently excluded and antibiotic therapy ceased.

C-Reactive Protein↗
PubMed1993

Effects of frequent ultrasound during pregnancy: a randomised controlled trial.

Despite widespread application of ultrasound imaging and Doppler blood flow studies, the effects of their frequent and repeated use in pregnancy have not been evaluated in controlled trials. From 2834 women with single pregnancies at 16-20 weeks gestation, 1415 were selected at random to receive ultrasound imaging and continuous-wave Doppler flow studies at 18, 24, 28, 34, and 38 weeks gestation (the intensive group) and 1419 to receive single ultrasound imaging at 18 weeks (the regular group). Outcome data was obtained from 99% of women who entered the study. The only difference between the two groups was significantly higher intrauterine growth restriction in the intensive group, when expressed both as birthweight < 10th centile (relative risk 1.35; 95% confidence interval 1.09 to 1.67; p = 0.006) and birthweight < 3rd centile (relative risk 1.65; 95% confidence intervals 1.09 to 2.49; p = 0.020). While it is possible that this finding was a chance effect, it is also plausible that frequent exposure to ultrasound may have influenced fetal growth. Repeated prenatal ultrasound imaging and Doppler flow examinations should be restricted to those women to whom the information is likely to be of clinical benefit.

Adult↗
PubMed1993

Vertebral deformity, bone mineral density, back pain and height loss in unscreened women over 50 years.

Bone mineral density (BMD) was measured in the lumbar spine using dual-energy X-ray absorptiometry in 222 unscreened women (aged 50-82 years), and information on back pain and historic loss of standing height was obtained at interview. Vertebral morphometry was performed on lateral spinal radiographs. The shape of the vertebral body was quantified using appropriate vertebral shape indices (VSIs), and vertebral deformities were identified using thresholds defined in terms of the means (M) and standard deviations (SD) of these VSIs for the whole group. Severity of deformity was defined as either grade 1 (M+2SD < VSI < M+3SD), grade 2 (M+3SD < VSI < M+4SD or grade 3 (VSI > M+4SD). Subjects with grade 1 vertebral deformities were older than subjects without such deformities, but did not have a reduced age-related Z-score of BMD. Grade 2 wedge and concave deformities were associated with a reduced age-related Z-score of BMD, suggesting that the aetiology of such deformities is closest to conventional concepts of 'osteoporotic fracture'. Grade 3 deformities were associated with neither increased age nor decreased BMD. Stature decreased in these subjects with age. Subjects reporting historic height loss had a higher mean number of wedge deformities. Subjects with back pain did not have a higher incidence of vertebral deformity than subjects without, confirming that many deformities were asymptomatic. Neither back pain nor historic loss of height were found to be associated with low spinal BMD.

Absorptiometry, Photon↗
PubMed1993

Vertebral morphometry in women aged 50-81 years.

Vertebral dimensions and vertebral shape indices (VSI) were investigated in T4-L4 in 926 females aged 50-81 years. The most consistent finding was the increase of inferior antero-posterior dimension with age. Wedging and concavity also increased with age but the changes were not significant at all vertebral levels. The value of VSIs also varied with level. Thus a particular degree of VSI, considered normal at one level or at one age, would be outside the reference range at a different level or age group. The number of subjects identified as osteoporotic by skewness (5.4%) or in excess of three standard deviations from the mean (6.5%) was much lower than in recent reports from North America. The number of subjects contributing to a skewed distribution increased with age from 0.5% at 55-59 years to 10.0% at 75-79 years. Change with age in the antero-posterior dimension could increase load-bearing area in older subjects, but the decline in bone density will be increased as a declining bone mineral content occupies a larger volume.

Aged↗
PubMed1993

A computerized technique for vertebral morphometry.

A new technique for morphometric measurement of vertebral bodies has been described, in which a computerized image analysis system was used to digitize and measure standardized lateral radiographs of the thoracic and lumbar spine. The sources of error in the radiographic system and the image analysis system were assessed using vertebral phantoms and test images. Oblique projection in the radiographic image of a vertebra did not produce a significant error in the measured area. The radiographic magnification was approximately 35%. Optical non-uniformity was detected in the image analysis system, and was ascribed to the lens optics. The maximum intra-observer and inter-observer variations in vertebral area were 3.1% and 5.3% respectively for experienced observers. The technique is applicable to clinical studies of large populations, and has value in investigating vertebral deformity in the management of metabolic bone disease.

Female↗