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Biomedical subjects

P Helms

Publications and source records attributed to P Helms.

At least 73 records · Page 4Linked to original sources
PubMed1984

Changes in rib cage geometry during childhood.

Age related changes in rib cage geometry were found from measurements made on chest radiographs from 38 individuals aged from 1 month to 31 years and on computed tomography (CT) scans in another 28 individuals, aged from 3 months to 18 years. Chest radiographs were taken for minor respiratory symptoms or fever and only films showing no abnormality were used. CT scans were obtained in children undergoing staging for solid tumours in whom no intrathoracic deposits were found. In infants and very young children the ribs were found to be more horizontal and the sternal clavicular heads and diaphragmatic domes higher than in older children and young adults. Most of these changes were observed in the first two years of life, with something close to the adult pattern by the age of 2 years. Similarly cross sectional chest shape changed from the rounded infantile form to the more ovoid adult form by the same age. The configuration of the ribs observed in infancy and early childhood reduces the potential for thoracic expansion and may contribute to the frequency of respiratory problems found in the very young.

Adolescent↗
PubMed1983

Postural effects on gas exchange in infants.

In adults with unilateral lung disease, pulmonary gas exchange is better when the patients is positioned with the good lung dependent. We studied the effects of body position on gas exchange in 10 infants with unilateral lung disease by measuring transcutaneous oxygen and carbon dioxide pressures in the supine and right and left lateral positions. We also performed krypton lung scans and measured changes in thoracic gas volumes in four of the infants. Transcutaneous oxygen pressure (mean +/- S.E.) was greater with the good lung uppermost (82 +/- 7.6 mm Hg) than with the good lung dependent (73 +/- 7 mm Hg) (P less than 0.02) or in the supine position (78 +/- 7 mm Hg). There were no changes in transcutaneous carbon dioxide pressure. The proportion of ventilation to the good lung was greater with the good lung uppermost than with the good lung dependent (P less than 0.01) or in the supine position (P less than 0.02) (64 +/- 3, 46 +/- 6, and 59 +/- 7 per cent, respectively). There were no significant changes with position in functional residual capacity, tidal volume, or dynamic lung compliance. We conclude that oxygenation in infants with unilateral lung disease is best with the good lung uppermost--the reverse of what has been observed in adults.

Carbon Dioxide↗
PubMed1983

A comparative trial of choline theophyllinate and controlled release aminophylline in chronic childhood asthma.

A comparison of pharmacokinetics and therapeutic effects of a standard oral theophylline preparation (Choline Theophyllinate) and controlled release aminophylline (Phyllocontin) was made in two parallel double blind trials in 25 children with chronic asthma. Fourteen children entered a double blind cross-over trial; the remaining 11 were allocated to a parallel trial with no change of theophylline preparation throughout. Sustained plasma theophylline levels were observed with the controlled release preparation in contrast to the low morning levels obtained with Choline Theophyllinate. No significant differences were found for peak theophylline levels, morning or evening peak flow rates or required access to other bronchodilators. However nocturnal symptoms were significantly reduced and daytime activity scores improved (P less than 0.05) on the controlled release preparation. The sustained plasma theophylline levels found in children taking the controlled release aminophylline may have provided a small but useful therapeutic advantage over the standard preparation.

Adolescent↗
PubMed1983

The intake of vitamins and minerals by the elderly at home.

In 403 elderly people residing in their own homes a dietary interview was undertaken with special reference to the intakes of vitamins and minerals. The group was randomly selected. The data were compared with the Recommended Dietary Allowances, Joint Nordic Recommendations and the absolute minimal necessary amounts. Intakes of folacin was low in 100% of the interviewed, intakes of cholecalciferol was low in 62% and in 83% intakes of pyridoxine was low as compared to the recommendations. The majority had sufficient amounts of ascorbic acid, thiamine, riboflavin, retinol and cobalamin from the diet. The intake of zinc was low in 87% of the interviewed, but risk of zinc deficiency might only be present in 0.5%. The intakes of iron and calcium was judged to be sufficient. The physiological needs of the elderly may, however, vary from the standards used here and recommendations with special reference to the elderly are in request. The conclusion is that the diet of the elderly, possibly with exception of folacin, is well above their absolute minimal requirements, but the margin towards malnutrition is small. This means that elderly people should be considered a vulnerable group with respect to the intakes of vitamins and minerals.

Aged↗
PubMed1982

Lung function in infants with congenital pulmonary hypoplasia.

Lung volume and lung mechanics were measured in 19 infants, aged 2 to 8 weeks, with congenital pulmonary hypoplasia of various causes. These included nine infants with congenital diaphragmatic hernia, five infants with Werdnig-Hoffman disease of intrauterine onset, and five infants with isolated pulmonary hypoplasia or associated anomalies such as thoracic dystrophy and spina bifida. Infants were studied within the first two months of life in order to exclude the effects of natural adaptation and adverse influences such as lower respiratory tract infection. Lung volume and airway resistance were estimated by whole body plethysmography, total pulmonary resistance, and dynamic lung compliance with esophageal balloons and pneumotachography. Reductions in dynamic lung compliance were found in seven of the nine infants with congenital diaphragmatic hernia, probably reflecting lung overdistention after operative repair. Low airflow resistance was found in 12 infants, representing subjects from each category. The low airflow resistance may be related to reductions in airway generation number found when the disturbance of lung development occurs before 16 weeks of gestational age. This finding suggests a role for measurements of airflow resistance in characterizing the type of pulmonary hypoplasia.

Airway Resistance↗
PubMed1982

Methods and validity of dietary assessments in four Scandinavian populations.

Average intakes of nonstarch polysaccharides (dietary fiber), foods, and nutrients were measured in representative samples of 30 men aged 50-59 in 4 Scandinavian populations with a 3-4 fold difference in risk for large bowel cancer. The assessment technique, a 4-day weighed record of food consumed and duplicate collections of all food eaten, was validated by chemical analysis of the duplicates, by measuring 24-hour urine and fecal nitrogen excretion, and by comparing the constituents of the urine samples collected during the survey with similar collections 1-2 weeks later. There were good agreements between estimates of fat and protein intake obtained by food-table calculations of the 4-day weighed record and the chemically analyzed duplicates. Urinary plus fecal nitrogen excretion was equal to estimated nitrogen intake during the survey, and no discernable changes in urinary output occurred after the survey, thereby implying that dietary habits had not changed as a result of the investigative technique. It is concluded that the dietary data are indicative of current patterns of food consumption and are sufficiently valid for comparison with data on cancer risk in the 4 areas.

Colonic Neoplasms↗
PubMed1982

Dietary patterns in Them and Copenhagen, Denmark.

Four-day weighing and 24-hour recall were used to record food consumption in groups of 30 men, aged 50-59 years, in 2 areas of Denmark: Them, a rural Danish community, and Copenhagen. Fat consumption was found to be higher in Them, whereas alcohol consumption was higher in Copenhagen. The absolute daily intake of dietary fiber was higher in Them than in Copenhagen. These observations document changes due to industrialization of food production, modern distribution, and marketing methods.

Alcohol Drinking↗
PubMed1982

Nonstarch polysaccharide consumption in four Scandinavian populations.

Nonstarch polysaccharide (NSP) intake was measured in representative samples of 30 men aged 50-59 in 2 urban and 2 rural Scandinavian populations that exhibited a 3-4 fold difference in incidence of large bowel cancer. Intake was measured by chemical analysis of complete duplicate portions of all food eaten over one day by each individual. NSP intakes showed a rural-urban gradient, with 18.4 +/- 7.8 g/day in rural Finland and 18.0 +/- 6.4 g/day in rural Denmark versus 14.5 +/- 5.4 g/day in urban Finland and 13.2 +/- 4.8 g/day in urban Denmark. NSP intakes were also calculated (using food tables) from weighed food records kept over 4 days, one of which was the day on which the duplicate collection was made. Intakes were 2-2.5 g/day higher with this method than with direct chemical analysis, mainly because published tables of values have become outdated and inaccurate as a result of improved methods for measuring NSP in food. Individual variation from day to day in NSP intake was considerable. Average NSP intake and intake of some of its component sugars were inversely related to colon cancer incidence in this geographical comparison. To show a relationship at the individual level between diet and cancer risk in a prospective study would require detailed and accurate methods for the assessment of NSP consumption.

Colonic Neoplasms↗
PubMed1982

Colon cancer and large bowel function in Denmark and Finland.

Stool weight and transit time through the gut were measured in 4 groups of 30 men, aged 50-59 years, randomly selected from populations in urban (Copenhagen) and rural (Them) Denmark and urban (Helsinki) and rural (Parikkala) Finland. These populations exhibited a 3-4 fold difference in risk for large bowel cancer. Mean transit time (37 +/- 1 hours, Copenhagen; 43 +/- 1 hours, Helsinki; 40 +/- 1 hours, Them; 37 +/- 1 hours, Parikkala) was not significantly different among populations, but average 24-hour stool weights (136 +/- 13 g, Copenhagen; 176 +/- 17 g, Helsinki; 169 +/- 16 g, Them; 196 +/- 15 g, Parikkala) were different and had a significant inverse relationship to total large bowel cancer incidence, with larger stool weights being found in the low-risk population. A high proportion of study subjects, especially in Finland, were found to be taking medication or to have a history of gastrointestinal illness, but neither of these variables related to bowel habit.

Colon↗
PubMed1982

Resistance to airflow through bedding materials used in infancy.

Various bedding materials used in infancy, including duvets (or continental quilts), were tested for airflow using the British Standards Institution tests for pillows or fabrics. Resistance was also measured when the items were placed on a dummy infant face. Measurements were made on washed and unwashed garments, which were tested both dry and wet. Results suggest that all the bedding materials tested are safe for use even in the newborn period. The duvets produced slightly lower resistance to breathing than conventional blankets and sheets. In view of the wide variety of infant bedding fabrics it seems desirable for standard airflow performance requirements to be introduced.

Bedding and Linens↗
PubMed1982

Investigating the small lung: which imaging procedure?

Ventilation and perfusion radionuclide lung scans, using krypton 81m and technetium-99m macroaggregates, were performed together with a variety of other imaging procedures in 18 children aged between 1 week and 13 years in whom radiology had shown a small lung. Radionuclide scans provided an assessment of regional ventilation and perfusion unobtainable by other means, and 4 main categories of disturbed function could be seen in the radiological small lung--namely, absence of ventilation and perfusion, absent perfusion with preserved ventilation, generalised or segmental decreases in ventilation, and perfusion and segmental perfusion defects in areas of decreased ventilation. The clinical history and other imaging procedures, including fluoroscopy and penetrated mediastinal views, enabled a firm diagnosis to be made in each of these 18 patients. In 3 main pulmonary arteries were absent, 2 had lung aplasia, 2 had lobar aplasia, 9 had varying degrees of pulmonary hypoplasia (two with additional sequestrated segments), 1 had lobar emphysema, and 1 had post-infective lung mal-development (MacLeod's syndrome).

Child↗
PubMed1982

Critical assessment of jacket plethysmographs for use in young children.

In infants and very young children changes in thoracic gas volume (Vtg) during tidal breathing and during intermittent positive-pressure lung inflations have been estimated from pressure changes within double-layered rubber jackets covering the thorax and abdomen. In vitro and in vivo assessments demonstrated the linearity of these jackets over the range of volume changes found in these young subjects during respiratory function tests, and the small intrajacket background pressure (2.5 cmH2O) had minimal effects on resting lung volume and lung mechanics. These jackets can be used to monitor tidal volume in quiet subjects, and if an intermittent positive-pressure inflation technique is used static compliance can be accurately measured. The hysteresis of natural rubber and the direct contact of the recording system with the subject renders it unsuitable for the measurement of lung mechanics during tidal breathing and for the estimation of Vtg during airway occlusions.

Child, Preschool↗
PubMed1982

Problems with plethysmographic estimation of lung volume in infants and young children.

In 57 infants and very young children, less than 2 yr of age and with a variety of cardiopulmonary illnesses, problems were encountered in the estimation of lung volume with the plethysmographic technique. In 19 subjects calculated thoracic gas volume (TGV) was found to be consistently larger when airway occlusions were performed at low lung volumes than when performed at higher lung volumes. In 13 infants, changes in intraesophageal pressure (Pes) during airway occlusions were found to be larger than simultaneous changes in mouth pressure. In 25 subjects in whom none of the above changes were observed, total pulmonary resistance (TPR) and airway resistance (Raw) did not differ significantly [mean TPR, 50.1 +/- 27.5 cmH2O X l-1; mean Raw, 48.1 +/- 26.5 (P greater than 0.5)]. In the 13 subjects in whom the delta Pes-to-delta Pm occlusion ratio exceeded 1.05, closest agreement with specific resistance (sRaw) and TPR derived lung volume was found when TGV was calculated with delta Pes rather than mouth pressure change (delta Pm). A similar close agreement with the sRaw TPR derived volume was obtained when TGV was calculated during airway occlusions at the higher lung volume. Two separate lung models are proposed to explain these observations, one with a segmental airway closure and the other with more a generalized airway closure. If plethysmographic techniques are to be used in these young subjects for the estimation of lung volume and airway resistance, possible errors may be reduced by performing airway occlusions at lung volumes above functional residual capacity and noting the delta Pes-to-delta Pm ratio obtained during the occlusion.

Airway Resistance↗
PubMed1982

Lung volume and lung mechanics in infancy lateral or supine posture?

In 23 infants and young children aged from 3 wk to 2 1/2 years, lung volume, by plethysmography, dynamic lung compliance and total pulmonary resistance with air-filled balloons and pneumotachography, have been measured in the supine and right lateral postures in order to observe any possible systematic differences in either body position. Fourteen subjects were studied under light sedation, the remaining nine under general anaesthesia before elective surgery. In the sedated group, no significant differences were found between the two positions for lung mechanics. In the anaesthetised group the only measurement that varied with position was dynamic lung compliance, being lower in the supine posture (P less than 0.05). In one of the sedated infants with predominantly left sided lung disease, large position dependent changes in lung volume and lung mechanics were observed suggesting that care should be taken in interpreting lung function tests in infants with unilateral lung disease. In the anaesthetised subjects, the finding of reduced ratios of esophageal to mouth pressure change during brief airway occlusions, suggests that under these conditions pleural pressure changes were unequally distributed.

Adult↗
PubMed1981

Absolute intraesophageal pressure at functional residual capacity in frequency.

Absolute intraesophageal pressure at functional residual capacity (FRC) has been estimated in 15 infants (age 1-30 wk) by the extrapolation of the esophageal pressure-volume relationships to zero balloon volume by use of air-filled balloons in their ranges of infinite compliance. The pressure-volume relationships of the esophageal balloons (length 3.5-5.0 cm, perimeter 1.7-2.5 cm, wall thickness 0.045-0.075 mm) were determined in air and in erect and horizontal positions under water, the behavior of the balloons placed horizontally under water closely approximated that of the balloons in vivo. The mean absolute intraesophageal pressure at FRC was -1.44 cmH2O in eight normal infants and -1.56 cmH2O in seven convalescent infants with a variety of cardiorespiratory disorders. The less negative absolute end-expiratory esophageal pressure in infants when compared with that in adults can be explained by changes in lung elastic recoil, chest wall recoil, or a combination of these factors during the development and growth of the respiratory system from birth to adulthood.

Esophagus↗