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Biomedical subjects

P Burton

Publications and source records attributed to P Burton.

At least 37 records · Page 2Linked to original sources
PubMed1996

Differing patterns of mechanical response to direct fetal hormone treatment.

A single combined intramuscular dose of betamethasone and l-thyroxine (T4) or placebo was injected into the shoulder of fetal lambs 48 hours prior to delivery at days 121 (n = 14), 128 (n = 25) or 135 (n = 20) of gestation. Respiratory mechanics were calculated using multiple linear regression analysis. Both respiratory system resistance (RRS) and elastance (ERS) decreased approximately 4 fold between gestational days 121 (D121) and 135 (D135). Both variables were also reduced by hormone treatment. Reduction in ERS was due to a reduction in both lung (EL) and chest wall (EW) components. In absolute terms EW decreased with gestational age; however, EW as a proportion of total elastance (% EW) increased. Inclusion of a volume-dependent elastance term in the multiple linear regression model enabled us to separate total elastance into volume-independent (E1) and volume-dependent (E2V) components. E1 decreased almost 8-fold compared with only a 2.5-fold fall in E2V between D121 and D135. %E2, the proportion of ERS which is volume-dependent and which provides an index of overventilation, doubled over this time period. Hormone treatment affected E1 and E2V components equally hence %E2 was not altered. Both excised lung volume and end expiratory alveolar volume increased with gestational age and with treatment. The response to treatment was qualitatively similar at each of the gestational ages examined, however, for all mechanics variables, except resistance and E1, the magnitude of response to treatment was significantly smaller in D135 animals compared with other age groups.

Airway Resistance↗
PubMed1996

A case-control study of childhood pedestrian injuries in Perth, Western Australia.

STUDY OBJECTIVES: To identify the determinants of childhood pedestrian injuries, taking the child's exposure to the road environment into account. DESIGN: This was a case-control study. SETTING AND PARTICIPANTS: The study was conducted in Perth, Western Australia between 1991 and 1993. Altogether 100 injured and 400 uninjured child pedestrians aged 1 to 14 years were studied. Aspects of the child's social and physical environments, measures of his or her behaviour, cognitive skills, and "habitual" exposure to the road environment, as well as his or her knowledge of road safety, were recorded. MAIN RESULTS: The likelihood of injury increased by 12% with each 10,000 vehicles per day increase in the volume of traffic (odds ratio (OR) 1.12, 95% confidence interval (CI) = 1.05, 1.19) on roads most frequently crossed. In addition, the presence of visual obstacles on the verge of the child's street of residence increased the likelihood of injury by more than 2.6 times (OR 2.68, 95% CI = 1.42, 5.02). In contrast, the absence of footpaths was associated with a 52% reduction in the likelihood of injury compared with the presence of footpaths on the child's street of residence (OR 0.48, 95% CI = 0.27, 0.87). CONCLUSION: The amount of exposure to the road environment and the nature of the road environment to which the child pedestrian was exposed partly influenced the likelihood of injury in children from low socioeconomic areas, male children, and children aged 13 to 14 years. Until now, the excess incidence of childhood pedestrian injuries in these subgroups of the population had not been explained because the child's exposure per se had not been examined.

Accidents, Traffic↗
PubMed1995

Antenatal antecedents of moderate and severe cerebral palsy.

Aetiological relationships between cerebral palsy, preterm birth, small-for-gestational-age (SGA) birth and selected feto-maternal factors were investigated in a case-control study of all moderate and severe cerebral palsy cases born in Western Australia between 1980 and 1986 (n = 215). Cases were individually matched to three controls of the same gender and plurality born in the same year. Two of the controls were matched to the index cases for gestational age, one of which was also matched for birthweight. Pre-eclampsia and urinary tract infections were not significantly associated with cerebral palsy. The significant association of antepartum haemorrhage with cerebral palsy was accounted for by its associations with preterm birth. Congenital malformations and non-cerebral palsy neurological disorder were significantly associated with cerebral palsy; these associations were only partially accounted for by adjusting for preterm birth and small-for-gestational-age birth. This study shows that some of the risk of cerebral palsy associated with the antenatal antecedents of some common feto-maternal factors is mediated through preterm birth, confirming the importance of interrelationships between antenatal antecedents in the aetiology of some cerebral palsy. Perinatal and post-neonatal causes now account for only around 20% of all cerebral palsy. Future reductions in cerebral palsy incidence may therefore depend on acquiring greater knowledge of inter-relationships between antenatal antecedents.

Case-Control Studies↗
PubMed1995

Wheeze in preschool children: who is followed-up, who is treated and who is hospitalized?

This study determined the proportions of children < or = 5 yrs of age with reported wheeze who were undergoing medical follow-up, receiving anti-asthma medication, or admitted to hospital; and investigated factors important in determining which children would receive these treatments. The symptomatic children represented a wheeze prevalence of 16% of the study sample of 1,422 children. The cumulative incidence of treatment and hospitalization and point prevalence of current medical follow-up were determined using a parent-answered postal questionnaire study of a population-based random sample of 222 children. Odds ratios (OR) were calculated for wheeze severity, environmental, social, familial and demographic factors found to affect the likelihood of these treatment end-points. Among 222 children with wheeze, 99 (35%) were under current medical review, 165 (75%) had received medication, and 48 (22%) reported being hospitalized. Current follow-up was more likely in girls (OR 2.22; 95% confidence interval (95% CI) 1.12-4.38), with more than three attacks of wheeze in the last year (OR 17.44; 95% CI 5.22-58.3), or with a household pet (cat or dog) where inhalants were wheeze precipitants (OR 13.65; 95% CI 3.16-58.94). Treatment became more likely in older children (OR 3.91; 95% CI 1.10-12.71), with inhalants as wheeze precipitants (OR 4.66; 95% CI 1.08-20.14) or with a household pet (OR 2.28; 95% CI 1.04-5.03). Hospitalization was less likely with frequent wheeze (OR 0.30; 95% CI 0.12-0.77), but more likely if shortness of breath occurred with wheeze. Medical follow-up and treatment are related to wheeze severity and exposure to inhaled precipitants, whereas hospital admission occurred in children with attacks causing shortness of breath, and with decreasing frequency of attacks per year.

Analysis of Variance↗
PubMed1994

Accuracy of mini peak flow meters in indicating changes in lung function in children with asthma.

OBJECTIVE: To assess whether mini flow meters used to measure peak expiratory flow can track changes in lung function and indicate clinically important changes. DESIGN: Comparison of measurements with a spirometer and different brands of mini flow meter; the meters were allocated to subjects haphazardly. SUBJECTS: 12 boys with asthma aged 11 to 17 attending boarding school. MAIN OUTCOME MEASURES: Peak expiratory flow measured twice daily for three months with a spirometer and at least one of four brands of mini flow meter. RESULTS: The relation between changes in lung function measured with the spirometer and those measured with the mini flow meters was generally poor. In all, 26 episodes (range 1-3 in an individual child) of clinically important deterioration in lung function were detected from the records obtained with the spirometer. One mini flow meter detected six of 19 episodes, one detected six of 15, one detected six of 18, and one detected three of 21. CONCLUSIONS: Not only are the absolute values of peak expiratory flow obtained with mini flow meters inaccurate but the clinical message may also be incorrect. These findings do not imply that home monitoring of peak expiratory flow has no place in the management of childhood asthma but that the values obtained should be interpreted cautiously.

Adolescent↗
PubMed1994

Influence of duration of occlusion time on respiratory mechanics measured with the single-breath technique in infants.

To determine the effect of the length of end-inspiratory occlusion on the values of respiratory system compliance (Crs) and resistance (Rrs) calculated from the single-breath technique, 6 infants with cystic fibrosis were studied. End-inspiratory occlusions lasted between 0.3 and 1.2 seconds, and between 8 and 32 separate occlusions were made in each infant. Examination of the individual data showed a systematic tendency for Crs to decrease as the length of the airway occlusion increased, with statistical significance reached in two subjects. Using a random effects model, it was demonstrated that there was a decrease of 0.15 mL/cmH2O in Crs for each 0.1 s increase in occlusion time. The influence of length of plateau time for Crs was similar to that of total occlusion time. No such tendency was seen for Rrs. These data reinforce the current emphasis on greater standardization in the methodologies used for infant lung function testing and for more fully reporting methodological details.

Airway Resistance↗
PubMed1994

Survival of infants with neural tube defects in Western Australia 1966-1990.

To investigate the survival of infants with neural tube defects in Western Australia from 1966 to 1990, cases of neural tube defects were ascertained from multiple sources. Survival of infants with anencephaly, spina bifida, and encephalocoele was examined separately, and four birth cohorts were compared: 1966-1972 (when most surviving infants were actively treated), 1973-1979 (a period of stringent application of selection criteria for treatment), 1980-1985 (some relaxation of selection criteria), and 1986-1990 (further relaxation of selection criteria). There was an increase in terminations of pregnancies affected with anencephaly over the study period, and a fall in the proportion of both liveborn and stillborn infants with anencephaly. Most liveborn infants (76.4%) died in the first 24 hours, and none survived longer than 5 days. Most infants with encephalocoele (76.4%) were liveborn, and survival was poorest in the 1973-1979 cohort, although the difference in survival across cohorts just failed to attain a formal level of significance. For spina bifida, there was an increase in terminations of affected pregnancies over the study period. Survival of liveborn infants with spina bifida was poorest in the 1973-1979 cohort, and greatest in the most recent cohort. These improvements in survival are likely to be the result of relaxation of selection criteria for treatment, improvements in treatment and, to a lesser extent, selective termination of affected pregnancies.

Abortion, Therapeutic↗
PubMed1994

Family patterns of gestational age at delivery and growth in utero in moderate and severe cerebral palsy.

The relation of familial factors to the aetiology of cerebral palsy was assessed in a case-control study of all moderate and severe cases born in Western Australia between 1980 and 1986. The data did not suggest recurrence of cerebral palsy, congenital malformations or reproductive loss in cerebral palsy families. Preterm and small-for-gestational-age birth recurred within both case and control families. Cases and controls did not differ significantly from their siblings in measures of intra-uterine growth, but (with the exception of controls unmatched for both birthweight and gestational age) were born significantly earlier than their siblings. A family history of preterm or small-for-gestational-age birth was found to affect the risk of cerebral palsy by influencing the risk of preterm birth or growth retardation in the index pregnancy.

Adolescent↗
PubMed1994

Wheeze in preschool children and its relation with doctor diagnosed asthma.

OBJECTIVE: To describe the characteristics of wheeze and its relation with doctor diagnosed asthma in children aged 5 years and under. DESIGN: Questionnaire survey of population based random sample of children registered on Leicestershire Health Authority's child health index for immunisation; questionnaire completed by parents. SUBJECTS: 1650 white children born in 1985 to 1989 who were surveyed in 1990. MAIN OUTCOME MEASURES: Age distribution, severity, precipitants, seasonal characteristics, and diurnal variation of wheeze, family history of asthma/atopy, and their association(s) with doctor diagnosed asthma. RESULTS: There were 1422 replies (86.2%). Two hundred and twenty two (15.6%) were reported to have wheezed and of these 121 (8.6%) had formally been diagnosed as having asthma. More than 80% of the former had recurrences of wheeze and 40% (72) had three or more episodes in the preceding 12 months. Age, number of episodes per year, the severity of shortness of breath with attacks, and precipitants other than colds were the major factors determining the probability that a wheezy child will be diagnosed as having asthma. The data also suggest that despite the strong association of symptom based criteria with the label asthma, asthma was not diagnosed by these same severity criteria in one quarter of cases. CONCLUSIONS: Clinical and physiological follow up studies of children identified as asthmatic by the above criteria during the preschool years should validate or refute the predictive value of these measures of wheeze severity.

Age Distribution↗
PubMed1994

Component motion in bipolar hip arthroplasty: an evaluation of reamed and non-reamed acetabula.

Sixty-four patients with 67 bipolar arthroplasties of the hip were reviewed for a mean follow up of 3.1 years. The study group consisted of 46 hemiarthroplasties secondary to primary osteoarthritis of the hip and 21 hemiarthroplasties secondary to displaced subcapital hip fractures. Reaming of the acetabulum was performed in 47 of the hips studied. The Harris hip scores were not significantly affected by acetabular reaming. Total motion decreased when hips were loaded in the standing position. Reaming of the acetabulum resulted in a decrease in percent outer component motion and an increase in percent inner component motion. The non-reamed acetabula had the largest percent inner motion decrease when taken from the supine to the standing position. The reamed acetabula had significantly higher average percentage of inner component motion in both standing and supine positions. There was no patient with postoperative acetabular protrusion.

Aged↗
PubMed1994

Bipolar hemiarthroplasty for primary osteoarthritis of the hip.

One hundred twenty-five bipolar hemiarthroplasties of the hip were performed at the authors' hospital. Although the procedure was performed for acute femoral neck fractures, rheumatoid arthritis, revision hemiarthroplasty, and primary osteoarthritis, only the latter is the subject of this review. A modified Harris hip score (HHS) was used to evaluate the patients both preoperatively and postoperatively. Radiographs were taken preoperatively as well as postoperatively at 2-, 4-, 6-, and 24-month intervals. A total of 68 patients underwent bipolar hemiarthroplasty for primary hip osteoarthritis. The mean preoperative HHS was 35.5 (SEM = 1.86); the mean postoperative score was 81.2 (SEM = 1.64) with an average improvement of 45.7 (SEM = 2.03). The results of this review were compared to a control group of conventional total hip arthroplasties performed at the same institution. The mean postoperative HHS for the group of conventional arthroplasties was 87.2 (SEM = 1.07). The results of this review indicate a good clinical result from bipolar hemiarthroplasty, but significantly less postoperative function when compared to conventional total hip arthroplasty.

Adult↗
PubMed1993

Evaluation of current practices in routine preoperative crossmatching for transurethral resection of the prostate.

Increasing demand for blood during elective surgery has led to attempts to rationalize routine preoperative crossmatching to those operations when there is a reasonable (greater than 30%) chance of it being required. Results of a questionnaire returned by 86% of the urology units in Great Britain show that 41% continue to crossmatch 2 units of blood before transurethral prostatectomy. A review of 301 transurethral prostatectomies performed with preoperative grouping and saving of blood showed that only 11% of the patients required transfusion. The need for transfusion was significantly associated with presentation in chronic or acute on chronic retention (p < 0.01), and the operative factors of weight of resection (p < 0.0001) and degree of hemostasis (p < 0.001). Therefore, a policy of routine preoperative blood grouping and saving is safe, and could be widely adopted, leading to financial saving and a decrease in wastage of blood that becomes too old to use.

Aged↗
PubMed1992

A combination of electrocardiographic methods represents a further step toward the noninvasive identification of patients with syndrome X.

Identification of patients with angina but normal coronary arteriograms (syndrome X) using noninvasive means would be desirable. The ability of four established exercise electrocardiographic methods to identify angina patients with and without coronary artery disease was compared with that of a method based on a combination of the above (combined method). A treadmill score, a multivariate method, the ST segment recovery loop, the ST/heart rate adjustment, and the combined method were applied to 112 patients who had typical exertional angina and positive exercise tests (greater than 1 mm ST segment depression); 90 had documented coronary artery disease and 22 had syndrome X. The combined method and the treadmill score had a significantly higher diagnostic accuracy (both 81%, as 91 of the 112 patients were correctly identified by both methods) than the multivariate (66%) and ST segment recovery loop (64%) methods (p less than 0.05). The ST/heart rate adjustment had a lower sensitivity for syndrome X than any other method (1 of 22). Thus methods that involve the assessment of both ST and non ST segment variables have greater accuracy in separating syndrome X and coronary artery disease patients than methods relying more heavily on ST segment changes.

Adrenergic beta-Antagonists↗