Peak inspiratory flow generated through different analogue dry powder inhalers in Shenzhen healthy preschool children / 中华儿科杂志

<p><b>OBJECTIVE</b>Dry powder inhalers (DPIs) are increasingly being used to deliver drugs for the treatment of asthma. It is known that DPIs require a crucial minimal inspiratory flow. Previous studies have demonstrated that the peak inspiratory flow (PIF, L/min) through a DPI is dependent on the type of device, the age of the patient, and the level of bronchial obstruction. However, the peak inspiratory flow of healthy preschool children in China remains scant in the literature. The present study aimed to analyze the ability of inspiring flow through the resistance state of ordinary use inhaler in Shenzhen healthy preschool children by measuring the peak inspiratory flow through the different analogue dry powder inhalers and go further into the relationship between it and the age, weight and forced expiratory volume of the children.</p><p><b>METHOD</b>A survey in 370 healthy preschool children aged 3 to 6 years (75 children aged 3 years, 104 children aged 4 years, 100 children aged 5 years and 91 children aged 6 years) was carried out in Shenzhen. Peak inspiratory flow (PIF) was measured without and with resistances, which mimicked the internal resistances of several inhalers, Diskus, Turbuhaler, Autohaler, Surehaler by PIF meter (In-check DIAL) and then data PIF-N, PIF-D, PIF-T, PIF-A and PIF-S were obtained. Peak expiratory flow (PEF) was measured by PEF meter (MicroPeak, USA). These two measurements were made in a well-controlled setting, and at least three attempts were recorded to establish maximum achievement. Six spirometry parameters forced vital capacity (FVC), forced expiratory volume at 0.5 second (FEV 0.5), forced expiratory volume at 0.75 second (FEV 0.75), forced expiratory volume at one second (FEV1), maximal mid expiratory flow rate (FEF 25 - 75, PEF were measured by using COSMED spirometry of Italy and the FVC measurements should be around the quality control for spirometry in preschool children which we suggested and published in 2005. All data were expressed as mean +/- SD and analyzed with the statistical software SPSS 12.0 for Windows. Pearson's test was used for calculation of the significances of the correlation coefficients. Variance analysis was used for analysing the variability of inspiratory flows through the inhalers.</p><p><b>RESULTS</b>Results were obtained from 295 children aged 3 - 6 years who successfully finished the tests. The PIF-N, PIF-D, PIF-T, PIF-A and PIF-S were significantly different among the groups aged 3 yrs, 4 yrs, 5 yrs and 6 yrs. The peak inspiratory flow significantly increased with age. The PIF-N, PIF-D, PIF-T, PIF-A and PIF-S in the children of 110 cm height and above were significantly higher than those in the children below 110 cm height, so were the parameters between the children of 120 cm height and above and the children below 120 cm. PIF correlated significantly with age, height and weight and the Pearson coefficient was 0.3 - 0.5. The PIFs in different inhalers varied because of the different inner resistances. The minimum and optimum PIFs in resistances of Diskus, Autohaler and Surehaler could be achieved in almost all subjects, but those in resistances of Turbuhaler could be achieved in only 87.5% subjects, most of whom aged 3 yrs or below 100 cm height. There were good correlations between the PIFs in different resistances and main parameters of ventilation function (FVC, FEV 0.5, FEV 0.75, FEV1, FEF 25 - 75, PEF), PEF was the best among them (Pearson correlative coefficient was 0.6).</p><p><b>CONCLUSION</b>The inspiratory ability of the children can be predicted and assessed by using routine measurement of lung function of normal pre-school children. As to the pre-school children of varying ages, the variety of inspiratory ability should be considered completely in the selection of inhaler used during the treatment. The best inhaler suitable for them should be selected properly in order to obtain the best efficacy of treatment individually.</p>

Feasibility and predicted equations of spirometry in Shenzhen preschool children / 中华儿科杂志

<p><b>UNLABELLED</b>Morbidity of chronic lung disease in young children is relatively high, and could increase in the future. Pulmonary function testing is used for clinical assessment of patients with suspected or obvious pulmonary disease to assess the severity of dysfunction and to evaluate therapeutic effectiveness. In the recent few years, forced expiratory parameters assessing lung function have been measured in older children. In order to assess abnormalities of lung function in preschool patients with respiratory disorders based on changes of forced expiratory parameters, adequate reference values are needed. However, such data in healthy preschool children remain scant in the literature.</p><p><b>OBJECTIVE</b>The aim of this study was to characterize the spirometry of preschool children and establish the normal lung function prediction equations for Chinese preschool children.</p><p><b>METHODS</b>A survey in 343 healthy preschool children (184 boys and 159 girls) aged 3 to 6 years (73 children aged 3 years, 96 children aged 4 years, 91 children aged 5 years and 83 children aged 6 years) was carried out in Shenzhen in 2004. Eleven flow volume tests parameters, i.e., forced vital capacity (FVC), forced expiratory volume at 0.5 second (FEV(0.5)), forced expiratory volume at 0.75 second (FEV(0.75)), forced expiratory volume at one second (FEV(1)), maximal mid expiratory flow rate (FEF(25%-75%)), peak expiratory flow (PEF), forced expiratory time (FET100%) were measured by using COSMED spirometry produced in Italy. Stepwise multiple regressions and non-linear regressions were carried out with the statistical software SPSS10.0 for Windows to identify the best predictors of lung function parameters using standing height, weight, age and gender as potential determinants.</p><p><b>RESULTS</b>Spirometric tests could be successfully carried out by using imagery methods in the following percentages of children: 69.9% of 3 to 4 years old, 70.8% of 4 to 5 years old, 92.3% of 5 to 6 years old and 91.6% of 6 to 7 years old children, 77.7% of the selected population (217/279) of children performed at least two acceptable tests respectively. The average forced expiratory time (FET) was 1.61 +/- 0.52 sec (x +/- s), the 5th percentile value was 0.9 sec, 18 of 279 (6.5%) children produced a FET less than 1 second. Forced expiratory volume in 0.50 and 0.75 sec (FEV(0.5), FEV(0.75)) were thus measured necessary in preschool children. All lung volumes and flow rates increased with age, height as well as weight growth in both gender groups. The correlation among most lung function parameters was higher in height than in age and weight in boys. Whereas the correlation among most lung function parameters was higher in age than in height and weight in girls. The regression equations of lung function were established. By comparison with the equations derived from this study and from studies by Nystad, it was found that there was a difference between the predicted values.</p><p><b>CONCLUSION</b>Spirometric testing is feasible in preschool children by using imagery methods and may be useful for both clinical practice and research. The correlation among most lung function parameters was higher in height than in age and weight in boys. Whereas the correlation among most lung function parameters was higher in age than in height and weight in girls.</p>