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Biomedical subjects

S F Evans

Publications and source records attributed to S F Evans.

At least 37 records · Page 2Linked to original sources
PubMed2000

Reference ranges for blood pressure in preschool Australians, obtained by oscillometry.

OBJECTIVE: To derive reference centiles for blood pressure in children aged 1-6 years which seek to address shortcomings in available reference ranges. METHODS: Prospective cohort study of 2876 children in Perth, Western Australia, commenced in 1989 with serial blood pressure measurements through early childhood obtained by oscillometry under standardized conditions. RESULTS: Gender-specific reference centile charts for systolic and diastolic blood pressure, (i) across ages 1-6 years and (ii) across the range of corrected Body Mass Index values at ages 1, 3 and 6 years, were generated by fitting linear models with both fixed and random effects. CONCLUSIONS: Reference values for blood pressure for young children are of clinical use and may be of long-term predictive value.

Blood Pressure↗
PubMed2000

Postoperative intraspinal opioid analgesia after caesarean section; a randomised comparison of subarachnoid morphine and epidural pethidine.

A randomised, blinded clinical trial was performed to evaluate intraspinal opioid analgesic techniques after caesarean section. Healthy term parturients having elective caesarean section under combined spinal-epidural anaesthesia were allocated to one of three groups. Postoperative analgesia, including non-steroidal anti-inflammatory drugs, was provided using either pethidine patient-controlled epidural analgesia (group PCEA) or subarachnoid morphine 200 microg, the latter supplemented as required with patient-controlled intravenous pethidine (group SMPCIA) or oral paracetamol and codeine (group SMO). Maternal analgesia, side effects, recovery and satisfaction were assessed for 48 h. Of 144 parturients enrolled, 137 completed the study (PCEA n = 44, SMPCIA n = 45, SMO n = 48). The groups were demographically similar. All participants experienced good pain relief, including median visual analogue pain scores (0-100) with movement <40 between 0-24 h. However, pain scores were significantly lower at 8 and 12 h in those receiving subarachnoid morphine (P< 0.05). Women in groups receiving subarachnoid morphine experienced more severe pruritus (P<0.001), nausea (P< 0.001) and drowsiness (P< 0.05). Postoperative recovery of bowel function and ambulation occurred earlier in those using PCEA, although this did not appear to be of clinical significance. Patient satisfaction was similar, although women in group SMO were least likely to choose this approach again (P<0.05). We concluded that all three techniques provided effective analgesia for a prolonged period postoperatively. Better pain relief, but more opioid-related side effects, resulted from subarachnoid morphine 200 microg, and re-evaluation of reduced doses of subarachnoid morphine may be warranted.

Clinical Trial↗
PubMed2000

Obstetric and perinatal outcomes from the australian and new zealand twin-twin transfusion syndrome registry.

OBJECTIVE: Our purpose was to investigate the antepartum characteristics and perinatal outcomes of twin-twin transfusion syndrome cases from a multicenter national registry. STUDY DESIGN: Perinatal centers in Australia and New Zealand voluntarily notified a central evaluation registry with information on identified pregnancies with twin-twin transfusion syndrome during 1995 through 1998. RESULTS: One hundred twelve cases of twin-twin transfusion syndrome were registered. The median gestation at diagnosis was 21.5 weeks (range, 14.4-34.6 weeks). Oligohydramnios-polyhydramnios sequence was the most common presentation, with 84% of cases involving "stuck" twinning. Therapeutic amnioreduction was used in 92 cases (82.1%), with the median number of procedures per case being 2 (range, 1-23). The median gestation at delivery was 29 weeks (range, 18-38 weeks). The overall perinatal survival rate was 62.5%. Abnormal findings on cranial ultrasonography were present in 27.3% of live neonates, and periventricular leukomalacia was reported in 10.8%. Increased gestational age at delivery, the presence of umbilical artery diastolic flow, and a prolonged interval from final amnioreduction to delivery were positively associated with the delivery of live fetuses without complications. CONCLUSION: The majority of antenatally identified cases of twin-twin transfusion syndrome are managed with serial amnioreduction. Despite contemporary obstetric and neonatal management strategies, perinatal mortality and morbidity rates are high.

Australia↗
PubMed2000

Adjustment for current weight and the relationship between birth weight and blood pressure in childhood.

OBJECTIVE: To determine the role of current weight in mediating the relationship between birth weight and blood pressure within the context of the 'fetal origins' hypothesis. DESIGN: Prospective cohort study of 2507 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia between 1989 and 1992. The study commenced at 16 weeks gestation with serial weight and blood pressure measurements recorded through early childhood. RESULTS: Inverse associations were found between birth weight and systolic blood pressure at ages 1, 3 and 6. The effect of birth weight on systolic blood pressure at age 6 reached statistical significance and was increased fourfold in magnitude to -2.3 mmHg [95% confidence interval = (-3.3 to -1.3), P < 0.01] after adjustment for current weight. The interaction term for birth weight and current weight was not statistically significant. Including intermediate weights did not produce a statistically significantly better model but did increase the magnitude of the estimated regression coefficient of birth weight on blood pressure, and only the birth weight and current weight terms were significant CONCLUSIONS: Adjustment for current weight serves to highlight the relationship between birth weight and blood pressure in childhood. Nevertheless, birth weight, rather than birth weight adjusted for current weight, is still the relevant predictor of later blood pressure within the context of the 'fetal origins' hypothesis.

Adult↗
PubMed2000

Vertebral fractures and bone mineral density in idiopathic, secondary and corticosteroid associated osteoporosis in men.

OBJECTIVE: To investigate bone mineral density (BMD) in men with symptomatic osteoporosis and compare BMD in patients with idiopathic, secondary and corticosteroid associated osteoporosis. METHODS: Age, number of vertebral fractures at presentation and BMD were investigated in men presenting to a bone metabolism clinic with idiopathic (n=105; group 1), secondary (n=67; group 2) and corticosteroid osteoporosis (n=48; group 3). BMD was measured in 176 healthy men (controls). Osteoporosis was diagnosed if there was >/=20% vertebral deformity. RESULTS: Age at peak BMD in controls was 20-29 years at spine (LS-BMD) and femoral neck (FN-BMD). LS-BMD did not change with age but FN-BMD decreased in controls and groups 1 and 2. Mean (SD) age was similar in groups 1 (62.8 (11.5) years, 2 (60.2 (11.0)) years and 3 (62.7 (10.4) years with 45%, 51% and 40% of patients respectively presenting before 60 years. Back pain, present for up to 12 months, was the commonest cause of referral. Vertebral fractures at presentation averaged mean (SD) 2.51 (1.9) in group 1, 2.76 (2.2) in group 2 and 2.48 (1.8) in group 3. LS-BMD Z scores and T scores were more negative in group 1 patients with </=3 vertebral fractures compared with FN-BMD suggesting a greater trabecular bone deficit. LS-BMD Z score in group 1 is -1.71, lower than in population studies. LS T score associated with fracture was about -2.4 in all groups. T8, T12 and L1 were the most frequent levels for fracture. CONCLUSIONS: Men with symptomatic osteoporosis present in middle age, have low BMD with similar T scores irrespective of aetiology and sustain >/= 1 fracture.

Adult↗
PubMed2000

Fetal sciatic nerve growth is delayed following repeated maternal injections of corticosteroid in sheep.

AIMS: A single course of prenatal corticosteroid reduces the mortality and morbidity of preterm birth. Repeated courses of prenatal corticosteroids are widely prescribed despite a lack of safety data. Repeated corticosteroids delay myelination in the ovine central nervous system at the time of preterm delivery but with catch-up at term. We aimed to evaluate their effect in the peripheral nervous system. METHODS: Thirty date-mated ewes were administered either saline, a single injection of betamethasone, or four injections of betamethasone between 104 and 124 days' gestation, with delivery on day 125 or 145 (term = 150 days). Sciatic nerves were dissected and fixed in modified Karnovsky's fixative and prepared for light and electron microscopy to determine the proportion of myelinated axons and mean axon diameter. RESULTS: Repeated, but not single, corticosteroid administration resulted in significant decreases in the total cross-sectional and fascicle-containing areas of the sciatic nerve, and in the mean diameter of myelinated and unmyelinated axons. Deficits persisted at term. The proportion of myelinated axons was unaffected. CONCLUSION: Repeated prenatal corticosteroids have the capacity to affect the growth of peripheral nerve axons in sheep. Documentation of their effects in human pregnancy await randomized trials.

Adrenal Cortex Hormones↗
PubMed1999

Repeated antenatal corticosteroids: size at birth and subsequent development.

OBJECTIVE: The objective was to study the effects of repeated antenatal corticosteroids on birth size, growth, and development in preterm infants. STUDY DESIGN: This observational study followed up for 3 years a prospective geographic cohort in the state of Western Australia of 477 singleton infants born at <33 weeks' gestation. RESULTS: Birth weight ratio decreased with increasing number of corticosteroid courses (P =.001), and multivariate analyses confirmed a reduction in birth weight of as much as 9% (P =.014) and a reduction in head circumference of as much as 4% (P =.0024). There were no additional benefits in mortality or respiratory outcomes, and there was a trend toward more severe chronic lung disease. At age 3 years growth and severe disability outcomes did not appear to be related to increasing number of corticosteroid courses. CONCLUSIONS: In this cohort study repeated corticosteroid courses were associated with adverse effects on size at birth without apparent benefits. These changes have the potential to affect later development.

Adrenal Cortex Hormones↗
PubMed1999

Effect of corticosteroids on brain growth in fetal sheep.

OBJECTIVE: To compare the effects of single and repeated courses of corticosteroids on brain growth in fetal sheep. METHODS: Pregnant sheep were given intramuscular betamethasone (0.5 mg/kg) at 104 days' gestation followed at 111, 118, and 124 days by equivalent volumes of sterile normal saline (n = 12) or betamethasone (n = 12). Controls received equivalent volumes of sterile normal saline at all four intervals (n = 12). Lambs were delivered at 125 (preterm) or 145 (term) days. After perfusion, we measured weights (grams) for whole brain, cerebrum, cerebellum, and brain stem, volumes (milliliters) for whole brain and cerebrum, and maximum cerebral anterior-posterior length, width, and depth (centimeters). RESULTS: In the single-injection group at preterm, there were no significant differences (P = .070) in whole-brain weight between the corticosteroid-treated animals (38.0 +/- 1.81 g) and controls (42.5 +/- 1.65 g). Cerebral length and depth were significantly reduced in the corticosteroid group (P < .05); other measures were not significantly different. At term, whole-brain weight was significantly lower (47.5 +/- 1.70 g; P = .022) compared with controls (53.4 +/- 1.73 g). All other measures were significantly reduced (P < .05) except cerebral and brain-stem weights and cerebral length. In the group that received repeated injections at preterm, whole-brain weight was significantly reduced (35.5 +/- 1.65 g; P = .005) compared with controls (42.5 +/- 1.65 g). All other measures were significantly reduced (P < .05) except cerebellar and brain-stem weights. At term, whole-brain weight was also significantly reduced (42.4 +/- 1.52 g; P = .001) compared with controls (53.4 +/- 1.73 g) as were all other measures (P < .05). CONCLUSION: Administration of single and repeated courses of corticosteroids to pregnant sheep retarded fetal brain growth.

Animals↗
PubMed1999

Hospital admissions in the first year of life in very preterm infants.

OBJECTIVE: To analyse hospital readmissions to 1 year in infants < 33 weeks' gestation. STUDY DESIGN: Cohort of very preterm infants born in Western Australia. METHODS: Parental social class, history of asthma, race, gestational age, birthweight, sex, severity of respiratory disease and oxygen requirement at 28 days chronic lung disease (CLD), 36 weeks and term, maternal smoking, cohabitation with siblings, breast-feeding duration and hospital readmissions were recorded prospectively. RESULTS: Data were available for 538 of 560 (96%) infants discharged. Eight died in the first year. Two hundred and twenty-five infants (42%) had 443 readmissions, of which 370 were medical and 73 surgical. Risk factors for medical readmission were Aboriginal race, male sex and CLD. Breast-feeding was protective. Risk factors for surgical admission were male sex, lower gestation, severe hyaline membrane disease, severe CLD and birthweight < 10th centile. CONCLUSIONS: Readmission is common after very preterm birth. Risk factors for medical and surgical admission differ with CLD being the only perinatal factor associated with both medical and surgical admission.

Australia↗
PubMed1998

Placental implantation at 18 weeks and migration throughout pregnancy.

BACKGROUND: We wanted to find the most frequent site of placental implantation at 18 weeks' gestation and placental migration during gestation. METHODS: Placental location was identified in 2,526 singleton pregnancies at 18 weeks' gestation and characterized into nine groups. Placental migration in 1,336 of these pregnancies was assessed by serial ultrasonography. RESULTS: At 18 weeks' gestation, posterior, high placental implantation was more common (45.1%) than anterior, high implantation (42.1%). Relocation of posterior, high placentas farther fundally (16.9%) was three times more likely than farther fundal migration of anterior, high placentas (4%). CONCLUSIONS: Posterior fundal placental implantation is more common at 18 weeks' gestation than anterior implantation. Posteriorly implanted placentas are more likely than anterior placentas to migrate farther fundally during gestation. The greater relocation of posterior placentas farther fundally suggests a greater growth of posterior versus anterior uterine wall smooth muscle.

Adult↗
PubMed1998

Fetal growth retardation, particularly within lymphoid organs, following repeated maternal injections of betamethasone in sheep.

OBJECTIVE: To examine the effect of single or repeated injections of maternally administered corticosteroids on fetal growth in sheep. METHODS: Forty-six date-mated singleton gestation ewes were allocated at random to one of 3 groups: a single, or repeated injections of betamethasone, or a control group which received saline. On days 125 (preterm) or 145 (term) caesarean section delivery was performed. After lambs were killed, measures of size and weight were recorded. Data were analysed using Fishers Exact test and the Student's t-test. RESULTS: Significant betamethasone dose dependent reductions in body and organ weights and biometry were found at preterm and term gestational ages (p < 0.05). There was little catch up growth in those in whom delivery was delayed until term. Thymus, spleen and liver were particularly targeted. CONCLUSION: Repeated injections of betamethasone to the pregnant ewe cause significant reductions in fetal growth with little evidence of catch up by term. The effect of repeated maternal injections of corticosteroids in human pregnancy will await the results of randomized controlled trails.

Animals↗
PubMed1998

Use of corticosteroids by Australian obstetricians--a survey of clinical practice.

All Fellows, Members and trainees of the Royal Australian College of Obstetricians and Gynaecologists resident in Australia (n= 1,281) received a questionnaire relating to their practice of prescribing antenatal corticosteroids. 833 (65%) responded. The key findings were that 97% of Australian obstetricians prescribe antenatal corticosteroids in the classical setting of uncomplicated early preterm labour and 85% prescribe repeated courses in those cases in which the risk of preterm birth persists or recurs; 50% of obstetricians prescribe this agent weekly in cases with persisting risk of preterm birth. Some of the prescribing practices were found to be related to the number of years since obtaining specialist qualification. In view of the widespread clinical use of repeated doses of corticosteroids revealed in this present survey, it is clear that further research is warranted to determine the possible benefits and hazards of repeated exposures of the developing fetus to this therapy.

Australia↗
PubMed1998

Microlaparoscopy for suspected pelvic pathology--a comparison of 2mm versus 10mm laparoscope.

This study presents an independently-assessed comparison of the laparoscopic view obtained using a 2mm versus 10mm laparoscope in women with suspected pelvic pathology. Fifteen female volunteers booked for laparoscopy with clinical evidence of pelvic abnormality according to clinical findings and/or pelvic ultrasound were recruited for this study. Sequential observations were carried out by independent observers for clinically significant differences. Although discrepancies were noted in 3 patients the view obtained with the 2mm microendoscope was considered to be comparable to that obtained with the 10mm telescope. The cases with discordant findings included mild or minimal endometriosis and distal tubal disease. The results of this study suggest that microendoscopy is likely to be entirely adequate for many routine laparoscopic procedures and sterilization.

Adult↗
PubMed1997

Prospective cohort study of factors influencing the relative weights of the placenta and the newborn infant.

OBJECTIVES: To determine the demographic, environmental, and medical factors that influence the relative weights of the newborn infant and the placenta and compare this ratio with other factors known to predispose to adult ill health. DESIGN: Prospective cohort study. SETTING: The tertiary referral centre for perinatal care in Perth, Western Australia. SUBJECTS: 2507 pregnant women who delivered a single live infant at term. MAIN OUTCOME MEASURES: Placental weight, birth weight, and the ratio of placental weight to birth weight. RESULTS: By multiple regression analysis the placental weight to birthweight ratio was significantly and positively associated with gestational age, female sex, Asian parentage, increasing maternal body mass index, increased maternal weight at booking, lower socioeconomic status, maternal anaemia, and increasing number of cigarettes smoked daily. There were no consistent relations between the placental weight to birthweight ratio and measures of newborn size. CONCLUSIONS: The ratio of placental weight to birth weight is not an accurate marker of fetal growth. In its role as a predictor of adult disease the ratio may be acting as a surrogate for other factors which are already known to influence health and may act before or after birth. Determining the role that relative growth rates of the fetus and placenta have in predisposing to adult disease requires prospective study to account for the many confounding variables which complicate this hypothesis.

Adult↗
PubMed1997

Postoperative epidural infusion: a randomized, double-blind, dose-finding trial of clonidine in combination with bupivacaine and fentanyl.

The aim of this randomized, double-blind trial of postoperative thoracic epidural analgesic infusions was to determine whether clonidine at 10 microg/h (group C10, n = 22), 15 microg/h (Group C15, n = 24), or 20 microg/h (Group C20, n = 24) improved postoperative analgesia in patients undergoing abdominal gynecologic surgery, without side effects or hemodynamic changes, when added to a 5-mL/h infusion of 0.125% bupivacaine and fentanyl 2 microg/mL (Group CO, n = 22). The 24-h study infusion was supplemented, as required, by patient-controlled epidural fentanyl. Groups were similar for age, weight, duration, and type of surgery. Clonidine produced a dose-dependent improvement in analgesia at rest. Only 20 microg/h significantly increased the percentage of patients who experienced no pain with coughing (relative risk 1.44, 95% confidence interval 1.24-1.94), reduced pain scores with coughing (P < 0.05), and significantly lowered supplementary fentanyl requirements (P < 0.05). Groups were similar for sedation, pruritus, nausea, time to ambulation, and satisfaction with analgesia. Clonidine produced a dose-dependent decrease in blood pressure and pulse rate and an increase in vasopressor requirement (P < 0.01). Epidural clonidine infused at 20 microg/h improves analgesia during coughing when combined with epidural bupivacaine-fentanyl in patients undergoing lower abdominal surgery but is associated with hemodynamic changes and increased vasopressor requirement.

Adrenergic alpha-Agonists↗
PubMed1997

Maternal experience during epidural or combined spinal-epidural anesthesia for cesarean section: a prospective, randomized trial.

UNLABELLED: Epidural anesthesia (EA) and combined spinal-epidural anesthesia (CSEA) are popular anesthetic techniques for elective cesarean section. A randomized, blind study was conducted to compare maternal experiences during these regional anesthetics. EA was established using alkalinized 2% lidocaine with epinephrine and fentanyl, whereas spinal anesthesia was performed using 2.5 mL hyperbaric 0.5% bupivacaine and fentanyl via a single-space CSEA approach. Both patients and observers were blinded to the anesthetic technique allocation. One hundred twenty patients were enrolled; 6 were withdrawn (Group EA, n = 55; Group CSEA, n = 59). Of the two techniques, CSEA was associated with earlier onset times (P < 0.001), more intense motor block (P < 0.05), and greater ephedrine use (P < 0.01). Anxiety was significantly lower (P < 0.05) and satisfaction was higher (P < 0.05) before starting surgery with CSEA. Pain scores were lower pre- and intraoperatively with CSEA, a difference that became significant during block placement and at delivery (P < 0.05). There were no differences between groups in the incidence or severity of hypotension and nausea or analgesic supplementation rate; or for postoperative assessments of intraoperative pain, anxiety and satisfaction, and postpartum backache and headache. We conclude that maternal conditions and experience were good with both methods, although CSEA conferred several minor advantages. IMPLICATIONS: Epidural and combined spinal-epidural anesthesia are often used for elective cesarean sections. Although the combined spinal-epidural anesthetic technique conferred minor advantages, both techniques were associated with low anesthetic failure rates, good operative conditions, and high maternal satisfaction levels.

Adult↗
PubMed1997

A validation study of home uterine activity monitoring technology in Western Australia.

Home uterine activity monitoring has been developed as an 'early warning' device to detect premature uterine activity, thereby encouraging earlier referral and tocolysis of women at risk of preterm delivery. This ambulatory monitoring system, utilizing a ring-guard tocodynamometer, was piloted in Western Australia to determine if it can reliably record and transmit antenatal uterine activity data in an Australian environment. Pregnant women were readily able to correctly apply and use the ambulatory monitoring device. The information collected was able to be transmitted using standard Australian telecommunications systems within our hospital environment. Validation studies with the ambulatory monitor and current external tocodynamometry hardware were performed. The ring-guard tocodynamometer detected more uterine activity at gestations less than 32 weeks compared with conventional external tocodynamometers. As term approached, however, the sensitivity of the ring-guard tocodynamometer decreased. A cross-sectional profile of antenatal uterine activity was developed for women at low risk of delivering preterm. A gradual increase in the number, duration and amplitude of uterine contractions as pregnancy advanced was observed.

Female↗