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Biomedical subjects

A Pelkonen

Publications and source records attributed to A Pelkonen.

10 recordsLinked to original sources
PubMed2006

Ultrastructure of the reticular basement membrane in asthmatic adults, children and infants.

Reticular basement membrane (RBM) thickening in asthma is considered to be the result of subepithelial fibrosis. Thus, the RBM in asthma should contain an excess of fibrils identified as interstitial collagen and the ratio of fibril to matrix should be increased above normal levels. Electron micrographs of the RBM were compared with those of interstitial collagen deeper in the bronchial wall using endobronchial biopsy specimens from adult asthmatics (aged 18-41 yrs (n = 10)), children with difficult asthma (aged 6-16 yrs (n = 10)), wheezy infants with reversible airflow limitation (aged 0.3-2 yrs (n = 10)) and age-matched nonasthmatic controls: 10 adults, nine children and nine symptomatic infants with normal lung function. Fibrils in the RBM were significantly thinner (median (range) width 39 (30-52) nm versus 59 (48-73) nm), and fewer fibrils were banded than in the interstitial collagen (ratio of banded to non-banded fibrils 0.08 (0-0.17) versus 0.22 (0-1.3)). The ratio of fibrils to matrix in the thickened RBM of asthmatics did not differ from that of their respective controls (1.34 (0.63-2.49) versus 1.18 (0.31-2.6)). The ratio of fibril to matrix in the thickened reticular basement membrane of asthmatics is normal, and, contrary to what is expected in fibrosis, the fibrils do not resemble those of interstitial collagen.

Adolescent↗
PubMed2006

Reference values for respiratory system impedance by using impulse oscillometry in children aged 2-11 years.

The forced oscillation technique makes it possible to evaluate the mechanical properties of the respiratory system with a minimum of cooperation. The method is therefore especially useful in children. Impulse oscillometry (IOS) is a commercially available version of this technique. There is, as yet, limited information on reference values for IOS in children. The aim of this study was to extend the reference values for IOS variables and to study their correlation with height, weight and age in healthy children. A sample (n = 360) of children (age 2.1-11.1 years) was measured by using impulse oscillometry (IOS; Jaeger, Würzburg, Germany). The sample was based on children attending kindergarten in Finland and children attending primary school in Sweden. Measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs) and the resonance frequency (Fr) were made. All variables were related to body height. Most of them were also weakly related to weight. Reference equations for children (height 90-160 cm) are presented.

Age Factors↗
PubMed2002

Determinants of respiratory system input impedance and bronchodilator response in healthy Finnish preschool children.

In order to study the determinants of respiratory system impedance and bronchodilator response in preschool children, a sample (n = 109) of healthy children (age 2.1-7.0 years) attending kindergarten was measured by using the impulse oscillometry. Their selection was based on a standardized questionnaire, negative skin prick test results and clinical examination, and sufficient cooperation. Triple measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs), the resonance frequency (Fr) and the frequency dependence of resistance (dRrs/df) were performed, to determine individual mean values. Measurements were repeated after inhalation of 300 microg salbutamol (n = 89) or placebo (n = 19). At the baseline, Zrs and Rrs5-20 showed negative, and Xrs5-20, Fr and dRrs/df positive correlations with age, height and weight. However, logarithmic transformed height was the best independent variable for the regression equations of all the oscillometric variables. After inhalation of placebo, none of the oscillometric variables changed significantly. In the salbutamol group, the mean (SD) change in Rrs5 was -0.187 (0.124) kPa l(-1) s(-1) and -19.2 (10.2)%, corresponding to a lower reference limit of -36.9%. Both the within-test and between-test repeatabilities for the measurement of respiratory resistance were acceptable, for Rrs5 the coefficients of variation being 6.2 and 6.1%, respectively. As the overall success rate in our sample was high (89%), the forced oscillation technique seems to be a useful method in assessing respiratory function and bronchial lability in preschool children.

Administration, Inhalation↗
PubMed2000

Lung function measured by the oscillometric method in prematurely born children with chronic lung disease.

Premature birth is related to a chronic respiratory morbidity, which may persist until school-age. In these children, the forced oscillation technique would be suitable for evaluation of lung function even at preschool age, since it requires only minimal patient cooperation. In order to investigate the oscillometric findings related to premature birth, using the oscillation technique and conventional lung function methods 49 school-aged children born prematurely with (n=15) or without (n=34) chronic lung disease (CLD), and 18 healthy children born at full term were studied. Children with CLD had higher respiratory resistance (Rrs,5) and lower reactance (Xrs,5) than prematurely born children without CLD or healthy controls. Both Rrs,5 (r=-0.55, p<0.0001) and Xrs,5 (r=0.76, p<0.0001) were significantly associated with forced expiratory volume in one second (FEV1), the agreement with spirometry being better in Xrs,5 than in Rrs,5 (p=0.02). Rrs,5 was significantly related to airway resistance (Raw) measured by body plethysmography (r=0.63, p<0.0001), but underestimated resistance at high values of Raw. There was no significant relationship between the pulmonary diffusing capacity and the oscillometric findings. Compared to conventional methods, the oscillometric method yields concordant information on the severity of lung function deficit in children born prematurely, with or without chronic lung disease. In these children, the oscillometric findings are probably due to peripheral or more widespread airway obstruction. As conventional methods are not usually suitable for preschool children, oscillometry may serve as an alternative for early evaluation of chronic lung disease among children with premature birth in clinical or research settings.

Analysis of Variance↗
PubMed1999

Intraindividual variability of infant whole-body plethysmographic measurements: effects of age and disease.

The intraindividual variability of whole-body plethysmographic measurements was studied in a large series of consecutive infants (N = 144), divided into two groups: a group of infants born very prematurely (PM, N = 63), with (N = 28) or without (N = 35) a history of bronchopulmonary dysplasia (BPD), and a group of infants with persistent respiratory symptoms (PRS, N = 81), i.e., wheezing (N = 53) or cough (N = 28). The intraindividual variability was determined within each test and between tests, separated by a 10-min interval. In both study groups, the between-test variability was significantly larger than that within tests. Expressed as the median coefficient of variation (CV), the between-test repeatabilities in the PRS group were 8.0% for thoracic gas volume (TGV), 17.5% for airway resistance (Raw), and 18.4% for specific airway conductance (sGaw), and in the PM group, 8.9% for TGV, 20.4% for Raw, and 20.7% for sGaw. However, the individual range of CVs was large, ranging from 3 to 19% for TGV and from 5 to 55% for sGaw. With respect to TGV, the difference between the groups was statistically significant (P = 0.03). In infants with a history of BPD, there was also a significant negative age dependency in CVs of sGaw (r = -0.50, P = 0. 009), showing larger variation among younger individuals. The presenting symptom (wheezing or cough) in the PRS group did not influence the measurement variability significantly, and neither did the degree of bronchial obstruction. We conclude that on a group basis, the repeatability of infant body plethysmographic measurements may be satisfactory for scientific studies demonstrating pharmacodynamic effects; however, the intraindividual measurement variability should be reported for each test conditions and for infant groups in each study. Due to the large range in individual variation and the influence of age and disease processes on the variation, for an individual child there is only questionable benefit from a given measurement, unless the intrasubject, between-test variability is assessed individually before interventions, such as a bronchodilation test.

Bronchopulmonary Dysplasia↗
PubMed1999

Metered dose inhaler add-on devices: is the inhaled mass of drug dependent on the size of the infant?

Limited cooperation and low tidal volumes in infants make aerosol therapy difficult. We measured the amount of drug delivered from two baby spacer devices especially developed for use in infants. Designed as a randomized crossover study, aerolized budesonide from a pressurized metered dose inhaler (pMDI) was collected in the inspiratory filter interposed between the face mask and the spacer in 13 infants aged from 2 to 19 months old. The study was performed in connection with pulmonary function testing with a plethysmograph, and the children were sedated with cloral hydrate. Two small-volume baby spacer devices were used: a Babyhaler spacer (GlaxoWellcome, Hertfordshire, UK) made of polycarbonate with a volume of 350 mL and a built-in dead space of 40 mL and a NebuChamber spacer (AstraZeneca, Lund, Sweden) made of stainless steel with a volume of 250 mL and no dead space. Budesonide delivery from the NebuChamber was significantly higher than from the Babyhaler: 38.2% (range, 28.3%-47.5%) of the nominal dose versus 12% (range, 3.3%-21.25%) of the nominal dose of 400 micrograms of budesonide (P = 0.002). The inhaled mass of budesonide from the Babyhaler correlated significantly with skin surface area (r = 0.68, P = 0.018), weight (r = 0.66, P = 0.019), height (r = 0.69; P = 0.017), tidal volume (r = 0.82; P = 0.004), and minute volume (r = 0.67; P = 0.019). No correlations were found between these variables and the inhaled mass of budesonide from the NebuChamber. The results indicate that the design of the NebuChamber spacer affords stable drug delivery in infants and that a large variability in the inhaled mass of drug may be found when infants are inhaling from different baby spacers.

Administration, Inhalation↗