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We determined lung function at age 10 years in very low birthweight (VLBW

Dry powder inhalers (DPIs) are increasingly being used to deliver drugs for the treatment of asthma. Both the aerosolization and delivery of the drug from a DPI to the lung are dependent on an adequate inspiratory effort from the patient, and it is well-known that the air flow achieved early in the inspiratory profile is important in determining particle size distribution from the inhaler. The present study assessed the peak inspiratory flow (PIF) generated through the Clickhaler® DPI, and the early inspiratory flow at 150 mL of inspired volume (IF150), in asthmatic children. These measurements were made in a well-controlled setting, and two attempts were recorded to establish maximum achievement. Results were obtained from 57 children aged 6–17 years, showing a (mean ± SD) best PIF of 60.5 ± 18.7 L/min (range, 26.8–97.0). The mean PIF overall was 54.2 ± 20.8 L/min (7.9–97.0). For children aged 6–8 years, the mean best PIF was 46.5 ± 14.6 L/min (26.8–71.1); for those aged 9 years or more, it was >65 L/min (30.3–97.0). PIF values were unrelated to % predicted FEV1 measurements. Best IF150 (mean ± SD) was 42.9 ± 13.6 L/min (23.1–66.6) in children aged 6–8 years, and >55 L/min (28.0–86.4) for the older children, showing that high flow rates were achieved early in the inspiratory profile. These data indicate that children with stable asthma can generate adequate inspiratory flow rates to operate the Clickhaler® effectively. Pediatr Pulmonol. 2003; 35:220–226. © 2003 Wiley-Liss, Inc.

The free running test is a useful method for evaluation of exercise-induced bronchospasm in children. In young children this test simulates real-life circumstances and can be done more easily than histamine or methacholine challenges. The interrupter technique is a noninvasive method for measuring airflow resistance during tidal breathing. This approach requires minimal cooperation, and is therefore promising for use in young children. Fifty children aged 5-15 years with asthma symptoms were tested by exercise challenge consisting of free outdoor running for 8 min at 85% of maximal predicted heart rate for age. Pulmonary function was measured by using the interrupter technique (IR), with a Wright's peak flow meter (WPEF), and by flow-volume spirometry (FVS). The measurements were done before and 10 min after exercise. In addition, WPEF was measured at 5, 15, and 20 min after exercise. A fall of 15% or more in WPEF associated with wheezing or cough symptoms was considered a positive test. The exercise challenge was positive in 16 (32%) of the 50 children. Measurements at 10 min by WPEF identified 9 positive cases. At the same time point the IR identified 10 positive cases; a rise in resistance of 15% or more was considered positive, giving it 80% sensitivity and 93% specificity. The repeatability coefficient (CoR) for the interrupter technique was 0.06 kPa x L(-1) x s (13%) before and 0.07 kPa x L(-1) x s (14%) after exercise. The IR provides a useful alternative for estimation of airway obstruction in children following exercise challenge. The results were comparable with the current reference methods of forced expiratory volume in 1 s and peak flow measurements.

The purpose of this study was to investigate the relative effectiveness of 0.25 mg, 0.5 mg, and 1.0 mg of terbutaline, administered via Turbuhaler®, in children with mild to moderate asthma, and to register peak inspiratory flow rates through Turbuhaler® (PIFTBH). Thirty-seven children in Portugal (one center) and 45 children in Sweden (one center) aged 3–10 years participated in two separate, double-blind, placebo-controlled, crossover, and randomized studies of the same design. Because of differences in other therapies for asthma and climate, combination of the two studies into one metanalysis did not appear appropriate. The children inhaled 0.25 mg, 0.5 mg, and 1.0 mg terbutaline sulfate and placebo t.i.d. for consecutive 2-week periods without washout periods. Peak expiratory flow rates (PEF) were measured at home before and 15 minutes after each inhalation in the morning, afternoon, and evening. PIFTBH was measured twice at each of four clinic visits. At the Portuguese center the increases in mean morning PEF from before to after inhalation were 32 L/min after 0.25 mg, 35 L/min after 0.5 mg, and 40 L/min after 1.0 mg. The corresponding figures in Sweden were 26 L/min, 31 L/min, and 29 L/min after 0.25 mg, 0.5 mg, and 1.0 mg, respectively. For children 3–6 years, mean values for PIFTBH were 60 L/min in Portugal (n = 15), and 58 L/min in Sweden (n = 23). In the 7–10 year group the mean PIFTBH was 72 L/min (n = 22) in Portugal, and 68 L/min (n = 22) in Sweden. We conclude that inhalation of terbutaline sulfate via Turbuhaler® at a small dose of 0.25 mg resulted in good bronchodilation and was comparable to inhalations of 0.5 mg and 1.0 mg in children aged 3–10 years with mild to moderate asthma. PIFTBH were comparable to values previously recorded in healthy 6-year-old and older children and in adult asthmatic patients. Pediatr Pulmonol. 1996; 22:106–110. © 1996 Wiley-Liss, Inc.

The objective of the study was to assess the feasibility of initiating daily peak flow monitoring in a research study of asthma in inner city children. We performed a descriptive study of patterns of peak flow monitoring in children randomized to receive a simple mini-Wright (SM) or an electronic recording meter (ERM). The ERM served as a "covert" meter, providing objective documentation of actual peak flow use. Sixty-five Hispanic or African-American children, ages 5-9 years, with a history of physician-diagnosed asthma participated in the study. All children resided in census tracts with 40% or more of the population living at or below the poverty level. Subjects were instructed to use a peak flow meter (the SM or ERM) at least twice daily over a 3 week period, and to record peak flow values in a paper diary. Subjects who received the ERM were not made aware that measurements were also recorded electronically. Differences in patterns of use of the SM and ERM were assessed with the Wilcoxon signed rank test and Wilcoxon sum rank test. Adherence to peak flow monitoring was evaluated by comparing the percent days with missing values in the manually completed diary with those obtained by computer record. The Friedman statistic was used to compare changes in compliance (percent of days with missing peak flow entries) over time. Accuracy of peak flow readings was assessed by comparing the manual and electronic recordings with paired and unpaired t-tests and with Pearson product moment correlations. The percent of days with missing peak flow entries on diaries increased from 1.4% to 10.6% from the first to third week of monitoring (P < 0.004). The ERMs indicated a significantly greater percent of missing data than did the manual records (P < 0.0002). The difference in the percent of missing data for the electronic and manual records was most notable during the third study week, when the ERM and the manually completed records indicated that 52% and 15% of days, respectively, were without peak flow measures. Large inter-subject variations in the relationship between manually and electronically recorded peak flow measurements were observed, suggesting that errors in reading and transcribing peak flow rates occur in a subset of asthmatics. We conclude that children and caretakers in the inner city may have considerable difficulty initiating and maintaining peak flow recordings. Data obtained by manual records may considerably overestimate actual use. Compliance with monitoring decreases markedly between the first and third week of monitoring.

We established pediatric reference values for peak expiratory flow rate (PEFR), using the Mini Wright Peak Flow Meter. The study was based on 1,566 Mediterranean white children, aged 7 to 14 years from Valencia (Spain) schools. Height was the biometric variable with the greatest correlation to PEFR in both sexes; significant differences were noted between males and females. Prediction equations and percentile tables are presented for each sex. The performance of the Mini Wright Peak Flow Meter was compared with that of a spirometer. Pediatr Pulmonal 1990; 9:86–90.

Drug delivery and lung deposition from a dry powder inhaler (DPI) are dependent on the peak inspiratory flow (PIF) through the DPI. Therefore, when prescribing a DPI, it is important to know whether a child is able to generate sufficient PIF through a particular device. Using a PIF meter (In-Check Dial) that mimics the internal resistance of DPIs, two commonly used devices (high-resistance Turbohaler (TH) and low-resistance Diskus (DK)) determined the PIF generated by asthmatic children through each of them. Two hundred and twenty-three children were studied, of whom 100 (mean age, 9.1 +/- 3.0 years; range, 3-15 years) were experienced with the use of a DPI (>1 month of regular DPI use), and 123 (mean, 5.5 +/- 1.9 years; range, 3-9 years) were inexperienced (no previous DPI use). All of the experienced patients generated more than 30 l/min through both devices, but a PIF of 60 l/min through the TH was obtained by only 68 (68%) of them. The age above which a minimal PIF of 30 l/min (for DK) or 60 l/min (for TH) could be achieved in new DPI users (inexperienced) was 4 years and 9 years, respectively. Even among experienced patients, many young children may not generate optimal PIFs through high-resistance DPIs. When DPI treatment is considered for young children, some devices may be successfully introduced at a younger age. It may thus be important to measure PIF in children who use a DPI or in whom DPI use is contemplated. This evaluation can be easily undertaken in the clinic with the In-Check Dial device.

Spirometry is used to monitor respiratory progress in children with Duchenne muscular dystrophy (DMD). Mucociliary clearance depends on cough strength, which can be measured by peak cough flow (PCF). It is not routinely measured in most centers. When the PCF falls below 270 l/min, mucociliary clearance is likely to be impaired during viral illnesses, and techniques to assist mucociliary clearance should be taught. There is no known association between spirometry and PCF. Our aim was to assess if PCF relates to spirometry measures, and if spirometry can be used to predict when the PCF

Dry-powder inhalers (DPIs) have been proposed for treatment of acute asthma. Different DPIs vary in their inspiratory resistance and have different recommended optimal peak inspiratory flows (PIFs). Reduced PIF during acute asthma may result in inadequate drug delivery to the lungs. Our aim was to measure the inspiratory flow in relation to inspiratory resistance during acute asthma in children presenting to the emergency room. School-age (range, 6-18 years) children were referred to the emergency room for acute asthma. PIF measurements were performed by In-Check Dial trade mark device with simulated airflow resistances equivalent to Turbuhaler, Diskus, and free flow. Percent change in PIF between remission and acute asthma (%Delta) was correlated with percent change in clinical score (CS) and percent change in spirometry in children 9 years old. Thirty-three children (21 males) participated. PIF with simulated Turbuhaler resistance was significantly lower than with simulated Diskus resistance in both acute and remission states (P < 0.0001). PIF with simulated Turbuhaler resistance increased from 62.1 +/- 15.3 (acute) to 74.4 +/- 16.5 l/min (remission, P < 0.0001), while with Diskus it rose from 72.6 +/- 20.5 to 91.1 +/- 18.9 l/min (P < 0.0001). Turbuhaler %Delta PIF correlated with %Delta FEV(1) (P = 0.01) and with %Delta CS (P = 0.0001). A lesser degree of correlation was observed while using Diskus resistance and in children above 9 years old. During acute asthmatic attacks, PIF is reduced; this reduction is particularly prominent in young children who use a high-resistance device. However, the PIF generated is generally within the values considered compatible with adequate lung deposition with both Diskus and Turbuhaler.

In order to construct reference equations, we attempted to measure forced inspiratory flows, i.e., peak inspiratory flow (PIF) and maximal inspiratory flow at 50% of FVC (MIF50%FVC) in 332 healthy schoolchildren aged 7–15 years during flow-volume loop measurements, using an electronic spirometer. In 255 children (122 boys and 133 girls), the results were satisfactory. Statistical analysis revealed that the only predictive variables were sex and height. The best fit of the data was obtained with the power model (Y = A * HB); the coefficients of correlation between flows and height ranged from 0.66–0.77, and were slightly greater for boys. Forced inspiratory flows in children increase with height, and the variability is higher than for forced expiratory flows. Reference values for forced inspiratory flows can be useful in assessing the ability of children to generate affective inspiratory flows for choosing an inhalation device, or in resolving diagnostic problems, e.g., extrathoracic obstruction. © 2004 Wiley-Liss, Inc.

Drug release from dry powder inhalers depends for a large part on a sufficiently high peak inspiratory flow (PIF). We determined the variation of PIF through two commonly prescribed dry powder inhalers in children with asthma. We analyzed the effect of inhaler device, age, and severity of asthma symptoms on variation of PIF. Fifty-eight children with asthma (4-15 years old) recorded PIF values together with asthma symptoms in a diary twice daily for 4 weeks. PIF was measured with a portable PIF-meter (In-Check) equipped with adapters to simulate flow resistance through the Accuhaler and Turbohaler inhalers. Children generated higher PIF values through an Accuhaler adapter than through a Turbohaler adapter (95% CI for difference, 25.7-31.7). Mean PIF values increased with age, independent of type of inhaler. The mean (SD) variation of PIF (low%high) was 72.3 (8.1)% for patients using the Accuhaler adapter, and 67.0 (14.5)% for patients using the Turbohaler adapter (mean difference, 5.2%; 95% CI, -0.9 to 11.4). Childrenor =7 years of age had a significantly greater variation of PIF in addition to a lower mean PIF (P = 0.0003). PIF decreased significantly when symptoms of asthma increased (mean maximal decrease 11 l/min; P0.01), but the correlation between PIF and morning and evening symptoms was weak (r = -0.18 and r = -0.16, respectively). Patients who reported moderate or severe symptoms during the study period had a significantly greater variation of PIF compared to patients who remained free of symptoms or reported mild symptoms. The majority of patients generated PIF30 l/min during the study, even when they experienced symptoms of asthma. The variation of PIF through the Accuhaler and Turbohaler adapter was significantly greater for childrenor =7 years of age and for patients experiencing moderate or severe symptoms of asthma.