Input respiratory impedance measured by head generator in preschool children.

The upper airway wall motion represents a serious problem when measuring the input impedance of the respiratory system (Zrs) by the forced oscillation technique, particularly in young children. To minimize this error, it has been proposed to vary transrespiratory pressure around the head rather than directly at the mouth, using the head generator technique (HGT). The aim of this study was to collect normative data in preschool children in whom the technique may prove most useful. Zrs was measured using HGT and 4-32-Hz pseudorandom noise input in 127 healthy children. Age ranged from 2. 8 to 7.4 years and height (H) from 0.89 to 1.29 m. The fast Fourier transforms of pressure and flow allowed us to calculate respiratory system resistance (Rrs(f)) and reactance (Xrs(f)) at each frequency (f). Resonant frequency (fn), respiratory system inertance (Irs), and compliance (Crs) were derived from the Xrs(f) data. The technique was accepted by more than 95% of the children. A coherence function

[Predictive values of peak expiratory flow measured with mechanical meters for Polish children and adolescents between 7-19 years of age]. / Wartosci nalezne szczytowego przeplywu wydechowego mierzonego miernikami mechanicznymi dla polskiej populacji dzieci i mlodziezy w wieku 7-19 LAT.

The aim of this study was to evaluate the predicted values of pack expiratory flow for the Polish children and youth by means of measures Mini Wright and Personal Best. The accounts were based on a group of 86 boys and 110 girls. It was established that it was necessary to state different predicted values for different measures and that an optimum model of regression for counting of predicted values of PEFR in relation to body height for the Polish children and youth was an exponential model. Model indices for both measures were set up separately for boys and girls.

Forced oscillation technique (FOT): a new tool for epidemiology of occupational lung diseases?

The aim of this study was to evaluate the usefulness of the forced oscillation technique (FOT) in the assessment of occupation-related airway changes. The forced oscillation technique and conventional lung function tests were applied in 80 underground coalface workers, aged 35-48 yrs, with chest roentgenogram films classified 0/1 or 1/0 according to the International Labour Office (ILO) classification (G group), and two control groups matched for age and smoking habits. The first control group, was made up of face-workers having normal chest radiographs, whilst the second comprised underground non-face-workers with normal chest radiographs. Spirometric, plethysmographic and transfer factor of the lungs for carbon monoxide single-breath (TL,CO,sb) indices revealed no significant differences between the three groups. As regards the forced oscillation technique, a higher value of resistance/frequency slope (Pa.L-1.s2) was found in the G group compared with the control groups; 2.11 vs 1.06 in the face-workers, and 1.58 in the underground workers. In all three groups, the forced oscillation technique indices (mean resistance (R), resistance at zero frequency (RO), resistance/frequency slope (S), and resonant frequency (fo)) were found to be higher in subjects having a decreased forced expiratory volume in one second (FEV1) (< or = 90% predicted) or a mildly obstructive pattern of ventilatory function, even though this did not reach statistical significance in each of the groups. These findings together with the feasibility and acceptability of the forced oscillation technique would suggest that it may be a suitable tool for epidemiological studies of occupational respiratory diseases.

[Forced oscillation technique in respiratory system studies. III. Compliance and airway resistance in children with lung fibrosis]. / Technika oscylacji wymuszonych (FOT) w badaniu ukladu oddechowego. III. Podatnosc i opór ukladu oddechowego u dzieci ze zwlóknieniem pluc.

In patient with lung fibrosis we need to monitor lung compliance to evaluate the progress of the illness or efficacy of the treatment. This examination is not well tolerated and difficult to perform, especially in children. We compared classic measurements of static compliance of the lung and airway resistance with parameters derived from forced oscillations measurements--compliance and resistance of respiratory system. Correlation coefficients were respectively 0.85 for compliance and 0.70 for resistance. We conclude that it is possible to supplement classic measurements, especially in evaluating the dynamics of illness.

[Evaluation of the bronchodilatory activity of berodual and its components: fenoterol and ipratropium bromide in children with bronchial asthma]. / Ocena skutecznosci dzialania rozszerzajacego oskrzela leku zlozonego i jego skladowych: fenoterolu i bromku ipratropium u dzieci chorych na astme oskrzelowa.

The bronchodilatory activity of Berodual in comparison to Fenoterol and Ipratropium Bromide was investigated in a group of 59 children aged 8-15 years, suffering from mild bronchial asthma in a symptoms-free period. The relaxing activity was monitored dynamically by means of the analysis of flow-volume curve measurements. We have found that the bronchodilatory activity of Berodual was faster, stronger and longer in comparison to Fenoterol and Ipratropium Bromide.

[Values of the flow-volume curve in healthy children from Cracow]. / Wartosc krzywej przeplyw-objetosc u dzieci zdrowych z krakowa.

Basing on results of spirometric tests performed in 180 healthy children from Cracow (age range 8-16 years) the following parameters of the flow-volume curve were calculated: FVC, FEV1, FEV1/FVC, PEF, FEF25-75%, FEF50%, FEF75%. Due to statistically significant differences in the above mentioned indices related to sx, normograms were calculated for boys and girls. It was found that the exponential function characterises the best relation between volume and height, and the multinomial function flow values and height.

Analysis of expiratory pattern for monitoring bronchial obstruction in school-age children.

This study was designed to assess the validity of the percent of volume expired at tidal peak flow (dV/Vt) as an indicator of bronchial obstruction in school-age children. We analyzed 126 dV/Vt ratios and compared them with spirometric and plethysmographic results measured in 24 healthy (14 males) and 60 asthmatic (41 males) children; 42 of them underwent measurements before and after bronchial challenge with histamine. The two groups differed in resistance, forced expiratory volume in 1 sec (FEV1), and forced expiratory flows, as percents of predicted (FEV1: 94.6 +/- 2.4% in controls vs 86.7 +/- 1.6% in asthmatics; P less than 0.001). They did not differ in peak expiratory flow (PEF), forced vital capacity, functional residual capacity, measured by body plethysmography, and in dV/Vt. The dV/Vt was found to correlate with FEV1 (r = 0.58, P less than 0.001), PEF (r = 0.57, P less than 0.001), and other lung function parameters. Forty-two of the asthmatic children performed a bronchoprovocation histamine test. The fall of dV/Vt after histamine was significantly correlated (r = 0.61, P less than 0.001) with the variation in FEV1 and other lung function parameters. We conclude that dV/Vt is a good indicator of bronchial obstruction, as useful in school-age children as in adults and infants, with no need for the subject's cooperation.

[Computer-assisted calibration of inductive plethysmography]. / Komputerowo wspomagana kalibracja pletyzmografu indukcyjnego.

A software program was written assisting calibration and measurement of the inductive plethysmography RESPITRACE. In 6 subjects calibration was carried out using both methods and a confirmation was found in the 20% area of dispersion. The use of only one measuring tape enables a very precise measurement of ventilation.

A correction formula for computing specific airway resistance from a single-step measurement.

Specific airway resistance (SRaw) is conventionally determined by multiplying the plethysmographically measured values of airway resistance and functional residual capacity (FRC). An alternative single-step method, which avoids the need for airway occlusion during determination of FRC, has been described by Dab and Alexander. The single-step method provides no correction for resistance or dead space of the apparatus and, as a result, systematically overestimates SRaw. Using 1,000 paired measurements, it was possible to compute a formula for correcting the single-step measurement. This correction formula can be adjusted and applied to measurements made in any laboratory. The unlimited applicability of the proposed correction has been demonstrated by 234 plethysmographic measurements made in the Pediatric Clinic in Rome.