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Biomedical subjects

M Hibbert

Publications and source records attributed to M Hibbert.

6 recordsLinked to original sources
PubMed1995

Gender differences in lung growth.

Annual measurements of lung volumes and forced expiratory flows were made in 281 boys and girls from 8 to 12 years and in another cohort of 287 from 12 to 20 years to measure longitudinal lung growth. Gender differences in growth of lung function were documented, with girls generating greater volume-standardized maximal expiratory flows until age 18.5 years. Beyond that age boys generated higher expiratory flows in proportion to total lung capacity (TLC). There was a time lag of up to 1 year between the age of peak growth velocity in lung volume and peak growth velocity in height. Age at peak growth in flow lagged another year behind that in volume. This was noted more in boys than girls. Dysanaptic lung growth was found with differing rates of growth of maximal expiratory flow compared with TLC or vital capacity (VC).

Adolescent↗
PubMed1995

Patterns of common drug use in teenagers.

To ascertain current levels of drug use among teenagers and to examine interrelationships in use, a two-stage cluster sample of Victorian secondary school students in years 7 (aged 12 to 13 years), 9 (14 to 15 years) and 11 (16 to 17 years) were surveyed using a questionnaire on computer. Tobacco use and alcohol consumption were evaluated by self-reported frequency of use and seven-day retrospective diaries. Marijuana and coffee consumption were assessed by self-reported frequency of recent use. The questionnaire was completed by 2525, a participation rate of 83 per cent. Tobacco use rose with year, with 24 per cent of young women and 16 per cent of young men in year 11 being regular smokers. Trends across year level for heavier alcohol consumption were also observed, with just under 10 per cent of year 11 students reporting a weekly consumption higher than the current recommended guidelines for adults. Strong interrelationships in drug use were found, with a pattern of association between smoking and drinking consistent with a mutual elevation of risk. Frequent use of tobacco and alcohol had a high risk for associated marijuana use. Coffee consumption carried a significant independent association with regular smoking. Teenage substance use is common and most occurs at low level and frequency. However, for a substantial and increasing minority across the teenage years, high levels of tobacco and alcohol consumption potentially compromise health. Frequent alcohol or tobacco use rather than heavy intermittent consumption is most likely to be associated with concurrent substance use potentially damaging to health.

Adolescent↗
PubMed1985

Rib cage mobility in pectus excavatum.

Pectus excavatum is generally regarded as a cosmetic deformity; however, some children with pectus excavatum complain of chest pain and exercise limitation. Physiologic studies sometimes show mild restrictive changes and suggest an increased oxygen cost of breathing. Limitation of rib cage mobility related to the deformity may explain these findings. If rib cage mobility is limited, the ability of the actively inspiring rib cage to lower abdominal pressure would be decreased. If this were so, increased swings in abdominal pressure would be seen during the respiratory cycle, especially at times of stress such as during exercise. To test the hypothesis that pectus excavatum is associated with decreased rib cage mobility, we studied 11 patients with pectus excavatum and 11 control subjects. Four control subjects were also studied with rib cage mobility restricted by chest wall strapping sufficient to decrease vital capacity by 5, 10, and 40%. Gastric pressure was measured using balloon catheters and was used as an index of abdominal pressure. Flow at the mouth was recorded and integrated to give volume. Measurements were made at rest, immediately after exercise, and during graded voluntary inspiration to total lung capacity. Gastric pressure was related to tidal volume, and pressure-volume loops were constructed. There were no differences in abdominal pressure swings during respiration between the patients with pectus excavatum and the control subjects. Both groups showed moderate increase in gastric pressure during inspiration at rest and smaller increases or even decreases in abdominal pressure at end inspiration after exercise and at total lung capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Assessment of proximal airway obstruction in children by analysis of flow-volume loops.

The usefulness of maximal expiratory and inspiratory flow-volume (F-V) loops was assessed in ten children with clinical evidence of tracheal or laryngeal obstruction. Normal values from 514 healthy children are presented. Measurement of maximal flow, and expiratory/inspiratory flow ratios and observation of the characteristic contours of the F-V loops distinguished between proximal and peripheral airways obstruction in all cases. Most children over the age of 7 years could perform the test adequately. F-V loop analysis is a valuable technique in the assessment of the child with proximal airway obstruction. Unlike endoscopic and radiological investigation, it measures the functional rather than the anatomical degree of obstruction, and provides a simple non-invasive way of monitoring the response to treatment.

Adolescent↗
PubMed1982

Long term pulmonary consequences of oesophageal atresia with tracheo-oesophageal fistula.

Lung function was studied in 20 children, aged 8-17 years, who had successfully repaired oesophageal atresia with tracheo-oesophageal fistula. Spirometry and plethysmography showed mild restrictive lung disease. Airways obstruction was assessed using maximal expiratory and inspiratory flow-volume loops in air and after breathing a helium-oxygen mixture. Analysis of the flow-volume data demonstrated significant obstruction at the level of the trachea and little evidence of small airways disease. Bronchial hyperreactivity, as assessed by histamine challenge, was present in 22% of subjects. Respiratory and oesophageal symptoms were common, but decreased in frequency with increasing age. The mechanisms involved in the frequent respiratory symptoms these children suffer are discussed in the light of the physiological findings.

Adolescent↗