Biomedical subjects

S Calvert

Publications and source records attributed to S Calvert.

At least 19 recordsLinked to original sources

PubMed2006

Respiratory function of very prematurely born infants at follow up: influence of sex.

OBJECTIVE: To test the hypothesis that male compared with female prematurely born infants would have worse lung function at follow up. DESIGN: Prospective follow up study. SETTING: Tertiary neonatal intensive care units PATIENTS: Seventy six infants, mean (SD) gestational age 26.4 (1.5) weeks, from the United Kingdom oscillation study. INTERVENTIONS: Lung function measurements at a corrected age of 1 year. MAIN OUTCOME MEASURES: Airways resistance (Raw) and functional residual capacity (FRC(pleth)) measured by whole body plethysmography, specific conductance (sGaw) calculated from Raw and FRC(pleth), and FRC measured by a helium gas dilution technique (FRC(He)). RESULTS: The 42 male infants differed significantly from the 34 female infants in having a lower birth weight for gestation, requiring more days of ventilation, and a greater proportion being oxygen dependent at 36 weeks postmenstrual age and discharge. Furthermore, mean Raw and FRC(pleth) were significantly higher and mean sGaw significantly lower. After adjustment for birth and current size differences, the sex differences in FRC(pleth) and sGaw were 15% and 26% respectively and remained significant. CONCLUSION: Lung function at follow up of prematurely born infants is influenced by sex.

Airway Resistance↗

PubMed2005

Plethysmograph and interrupter resistance measurements in prematurely born young children.

BACKGROUND: Airways obstruction in premature infants is often assessed by plethysmography, which requires sedation. The interrupter (Rint) technique does not require sedation, but has rarely been examined in children under 2 years of age. OBJECTIVE: To compare Rint results with plethysmographic measurements of airway resistance (Raw) in prematurely born, young children. DESIGN: Prospective study. SETTING: Infant and Paediatric Lung Function Laboratories. PATIENTS: Thirty children with a median gestational age of 25-29 weeks and median postnatal age of 13 months. INTERVENTIONS AND MAIN OUTCOME MEASURES: The infants were sedated, airway resistance was measured by total body plethysmography (Raw), and Rint measurements were made using a MicroRint device. Further Raw and Rint measurements were made after salbutamol administration if the children remained asleep. RESULTS: Baseline measurements of Raw and Rint were obtained from 30 and 26 respectively of the children. Mean baseline Rint values were higher than mean baseline Raw results (3.45 v 2.84 kPa/l/s, p = 0.006). Limits of agreement for the mean difference between Rint and Raw were -1.52 to 2.74 kPa/l/s. Ten infants received salbutamol, after which the mean Rint result was 3.6 kPa/l/s and mean Raw was 3.1 kPa/l/s (limits of agreement -0.28 to 1.44 kPa/l/s). CONCLUSION: The poor agreement between Rint and Raw results suggests that Rint measurements cannot substitute for plethysmographic measurements in sedated prematurely born infants.

Airway Obstruction↗

PubMed2005

Risk factors for respiratory morbidity in infancy after very premature birth.

OBJECTIVES: To determine the occurrence of respiratory morbidity during infancy after very premature birth and to identify risk factors. DESIGN: Prospective follow up study. SETTING: The United Kingdom oscillation study. PATIENTS: 492 infants, all born before 29 weeks gestation. INTERVENTIONS: Structured questionnaires were completed by local paediatricians when the infants were seen in outpatients at 6 and 12 months of age corrected for prematurity. MAIN OUTCOME MEASURES: Cough, wheeze, and treatment requirements and the composite measure of respiratory morbidity (cough, frequent cough, cough without infection, wheeze, frequent wheeze, wheeze without infection, and use of chest medicine) and their relation to 13 possible explanatory variables. RESULTS: At 6 and 12 months of corrected age, 27% of the infants coughed and 6% had frequent (more than once a week) cough, and 20% and 3% respectively had wheeze or frequent wheeze. At 6 and 12 months, 14% of infants had taken bronchodilators and 8% inhaled steroids. After adjustment for multiple outcome testing, four factors were associated with increased respiratory morbidity: male sex, oxygen dependency at 36 weeks postmenstrual age, having older siblings aged less than 5 years, and living in rented accommodation. CONCLUSIONS: Male infants are particularly vulnerable to respiratory morbidity in infancy after very premature birth. It is important to identify a safe and effective strategy to prevent chronic oxygen dependency.

Bronchodilator Agents↗

PubMed2003

Frequent wheeze at follow up of very preterm infants: which factors are predictive?

OBJECTIVE: To determine if chest radiograph appearance at 28 days or 36 weeks postmenstrual age (PMA) can predict recurrent wheeze or cough at follow up in prematurely born infants more effectively than readily available clinical data. DESIGN: Chest radiographs of infants entered into the UKOS trial, who had had a chest radiograph at 28 days and 36 weeks PMA and completed six months of follow up, were assessed for the presence of fibrosis, interstitial shadows, cystic elements, and hyperinflation. At 6 months of corrected age, the occurrence and frequency of wheeze and cough since discharge were determined using a symptom questionnaire. PATIENTS: A total of 185 infants with a median gestational age of 26 (range 23-28) weeks. RESULTS: Thirty seven infants wheezed more than once a week, compared with the rest of the cohort. These infants had significantly higher chest radiograph scores at 28 days (p = 0.020) and 36 weeks PMA (p = 0.005), with significantly higher scores at 28 days for fibrosis (p = 0.017) and at 36 weeks PMA for fibrosis (p = 0.001) and cystic elements (p = 0.0007). They had also been ventilated for longer (p = 0.013). Forty four infants coughed more than once a week; they did not differ significantly from the rest of the cohort. An abnormal chest radiograph score at 36 weeks PMA had the largest area under the receiver operator characteristic curve with regard to prediction of frequent wheeze. CONCLUSION: An abnormal chest radiograph appearance at 36 weeks PMA predicts frequent wheeze at follow up and appears to be a better predictor than readily available clinical data.

Age Factors↗

PubMed2002

Airway resistance estimation by best fit analysis in very premature infants.

Plethysmographic measurement of airway resistance (R(aw)) has been determined by single-point analysis, usually at 50% of maximum inspiratory flow (MIF). Computer-assisted (best fit) analysis, however, allows R(aw) to be calculated by applying a regression line to any portion of the plethysmograph pressure-flow loop. We determined whether the results of best fit analysis using a computer program, sampling at 200 Hz, were influenced by the portion of the inspiratory loop analysed and if best fit or single-point analysis gave more reproducible results. Twenty infants of median gestational age 26 (range 24-28) weeks, were studied at a median age of 12 (12-14) months corrected for prematurity. R(aw) was calculated by best fit analysis between 0 and 33% MIF, 0 and 50% MIF and 0 and 67% MIF and single-point analysis at 50% of MIF. Similar mean R(aw) values were obtained by best fit analysis between 0 and 33% MIF (2.79 kPa/(l/s)) and 0 and 50% MIF (3.01 kPa/(l/s)) and single-point analysis at 50% MIF (2.86 kPa/(l/s)), but best fit analysis between 0 and 67% gave higher results (3.60 kPa/(l/s)), p < 0.0001. Within the linear portion of the inspiratory loop, the mean intrasubject coefficient of variation was lowest for best fit analysis between 0 and 50% MIF. Best fit computerized analysis between 0 and 50% MIF is recommended as the analysis of choice.

Airway Resistance↗

PubMed2002

Prophylactic high-frequency oscillatory ventilation in preterm infants.

UNLABELLED: The role of high-frequency oscillatory ventilation (HFOV) for the treatment of respiratory disease in preterm infants remains uncertain. Several randomized trials, comparing HFOV and conventional ventilation (CV) have been performed and their results suggest that HFOV may reduce the incidence of chronic lung disease (CLD) in preterm infants. However, the trials have several limitations and it remains unclear whether HFOV might increase intracranial pathology in very prematurely born infants. UKOS, a large, UK-based, multicentre trial was conducted to establish conclusively the role of prophylactic HFOV for the prevention of CLD in infants born prior to 29 wk of gestational age. CONCLUSION: There is still a need to fully evaluate prophylactic HFOV with particular emphasis on both short and long term respiratory and neurological outcomes.

Animals↗

PubMed2001

Levels of physical activity of a sample of 10-13 year old New Zealand children.

AIMS: To determine what proportion of a sample of 10 to 13 year old New Zealand children attained the Ministry of Health's physical activity guidelines. These guidelines recommend that children accumulate a minimum of 30 minutes of moderate intensity physical activity on most, preferably all, days of the week. METHODS: The heart rates of sixty 10-13 year olds were monitored at one minute intervals, for twelve hours on three week days and one weekend day. For each day, the number of minutes when the subject's heart rate exceeded 139 beats per minutes (bpm) was determined. The proportion of subjects who accumulated at least 30 minutes of heart rates > 139 bpm on three of the four recording days was determined. These subjects were deemed to have met the physical activity guidelines. RESULTS: 53% of subjects met the minimum physical acivity guidelines. Boys spent significantly more of their time with their heart rates elevated above 139 bpm than girls. There was no significant difference between the number of children achieving the recommended guidelines and their school's decile ranking. CONCLUSION: There are indications that children's lives are becoming more sedentary due in part to the popularity of passive forms of leisure and the reduced incidence of active forms of transportation like walking or cycling to school. The low proportion of New Zealand children meeting the minimum physical activity guidelines is a cause for great concern.

Adolescent↗

PubMed2000

Diversity of behaviour during novel object tests is reduced in pigs housed in substrate-impoverished conditions.

Modern intensive farming conditions lack the diversity of substrates present in more natural environments and offer young animals fewer opportunities for interaction. Evidence exists that this may affect the organization of interactive patterns of behaviour, but shifts in behavioural diversity have not been measured directly. We investigated the effect of the substrate in the home pen on the diversity of behaviour in young growing pigs, Sus scrofa. Over 5 months, 26 pigs were housed singly in either substrate-impoverished (SI) or substrate-enriched (SE) conditions. Once every month we recorded the behaviour of these pigs in detail both in the home pens and in two novel object tests. In addition, we calculated the diversity of behaviour shown by SI and SE pigs in the home pen and in the novel object tests, using a relative behavioural diversity index. In the two novel object tests, SI pigs were less mobile than SE pigs and focused their behaviour on particular substrates. In addition, SI pigs showed less diverse behaviour than SE pigs. Our results show that the less diverse behaviour of SI pigs previously recorded in their home pens persists under novel conditions, supporting the hypothesis that substrate-impoverished housing conditions structurally affect the organization of behaviour in young growing pigs. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed2000

Brief report: vocabulary acquisition for children with autism: teacher or computer instruction.

This study examined the impact of computers on the vocabulary acquisition of young children with autism. Children's attention, motivation, and learning of words was compared in a behavioral program and an educational software program. The educational software program was designed to parallel the behavioral program, but it added perceptually salient qualities such as interesting sounds and object movement. Children with autism were more attentive, more motivated, and learned more vocabulary in the computer than in the behavioral program. Implications are considered for the development of computer software to teach vocabulary to children who have autism.

Attention↗

PubMed2000

Minimizing postpartum pain: a review of research pertaining to perineal care in childbearing women.

This paper provides a review of literature that relates to perineal pain and care. Articles evaluated include systematic reviews and research papers from the disciplines of midwifery, physiotherapy and obstetrics. The major themes to emerge from the literature and be reviewed are the need for episiotomy, suturing methods and materials, assessment of perineal trauma, treatment of perineum in the postpartum period, and postpartum recovery. Research has highlighted that many practices relating to perineal care remain un-researched and therefore the need for evaluation is urgent. Further postpartum morbidity has been seen to affect many women, but is often unrecognized by practitioners. It is also a topic that requires further evaluation through well-designed and implemented research.

Episiotomy↗

PubMed2000

The chest radiograph appearances of very premature infants at 36 weeks post-conceptional age.

The chest radiograph of very premature infants at 36 weeks post-conceptional age (PCA) was evaluated with regard to the degree of hyperinflation and cardiomegaly, and the presence of fibrosis/interstitial shadowing, cystic elements, air bronchograms and opacification. The evolution of abnormalities was assessed by comparing the radiograph appearance at 36 weeks PCA with that at 28 days post-natal age (PNA). Three scoring systems were used to determine how any abnormalities present could be best quantified to reflect disease severity as determined by chronic dependency upon supplementary oxygen status. Chest radiographs at 36 weeks PCA from 60 infants (median gestational age 26 weeks (range 24-28)) were studied. 47 infants also had radiographs at 28 days PNA. Only three infants had no chest radiograph abnormalities at 36 weeks PCA, although 24 infants were not dependent upon supplementary oxygen. The most common abnormalities were interstitial shadowing and hyperinflation, while cystic elements and cardiomegaly were rare. The radiographic appearance had deteriorated from 28 days PNA to 36 weeks PCA (p < 0.05); more infants at 36 weeks PCA were hyperinflated (p < 0.01). The chest radiograph appearances of infants who were dependent upon supplementary oxygen scored higher than those who were not (p < 0.01) using all three scoring systems. The system that assessed only the presence of interstitial shadowing, cystic elements and hyperinflation had the highest specificity in identifying oxygen dependency beyond 36 weeks PCA and had the highest area under the respective receiver operator characteristic curve. In conclusion, the majority of very immature infants have an abnormal chest radiograph appearance at 36 weeks PCA. The appearance can, however, be meaningfully scored by evaluating only three abnormalities.

Female↗

PubMed1999

A simple chest radiograph score to predict chronic lung disease in prematurely born infants.

A simple scoring system has been evaluated with regard to its ability to characterize the pre-term infant's chest radiograph appearance at 28 days and predict oxygen dependency beyond 36 weeks post-conceptional age (PCA). Chest radiographs taken at approximately 1 month of age in 42 infants (median gestational age 28 weeks) were assessed by the scoring system for the presence of fibrosis/interstitial shadows, cystic elements and degree of hyperinflation (maximum score 8). The system's results were then compared with those obtained using two previously published scoring systems. Using all three systems, there were significant differences in the scores of infants who were and were not oxygen dependent at 28 days (p < 0.001) and 36 weeks PCA (p < 0.001). For the three systems, the positive predictive values of a score of 3 or more to predict oxygen dependency at 36 weeks (PCA) were between 67% and 80% and similar receiver operating characteristic curves were obtained. We conclude that scoring only three abnormalities of the 28 day chest radiograph appearance of pre-term infants gives useful predictive information.

Chronic Disease↗

PubMed1991

6-(substituted methylene)penems, potent broad spectrum inhibitors of bacterial beta-lactamase. III. Structure-activity relationships of the 5-membered heterocyclic derivatives.

Sodium (5RS)-Z-6-(heterocyclylmethylene)penem-3-carboxylates (2) are a series of extremely potent inhibitors of bacterial beta-lactamases. A variety of 5-membered heteroaromatic derivatives have been prepared and structure-activity studies reveal a preferred substituent orientation. One of these derivatives, the 1-methyl-1,2,3-triazolyl compound (5m) is a more potent synergist of amoxycillin than clavulanic acid, sulbactam or tazobactam.

Amoxicillin↗

PubMed1986