Design of a Novel Dual-Function Spacer Valve for Selective Aerosol Size Filtering and Measuring Peak Expiratory Flow Rate.

Valved holding chambers (VHCs) are accessory devices for pressurized metered dose inhalers (pMDIs). Use of a VHC may help overcome coordination issues associated with drug delivery via the pMDI alone. Previous work has established that aspects of VHC use, including the time between actuation and inhalation (inhalation delay) and inhalation flow rate, can influence the amount of drug available to inhalation. This study compared the impact of inhalation delay and flow rate on the in vitro delivery of aerosol from different VHC brands. A custom-built inhalation delay test rig, which enabled automation of controlled inhalation delays (0, 5, or 10 sec), was developed. Extraction air flow was set to 5, 15, or 30 L/min. Delivery of albuterol (ProAir HFA 90 μg) to a filter (emitted dose) was assessed using three commercially available VHC brands (one conventional, two antistatic). Emitted dose under 27 different combinations of inhalation delay, flow rate, and VHC brand was determined in order to assess the effects of inhalation delay and flow rate. Pairwise comparisons of the different VHC brands with different inhalation delay/flow rate combinations were conducted to assess in vitro equivalence. Emitted dose increased with flow rate and decreased with longer inhalation delays. Dependence on flow rate was similar for the two antistatic VHCs and more pronounced for the conventional VHC. The two antistatic VHCs showed equivalent results for the emitted dose of albuterol, across a range of flow rates and using different inhalation delays; the relation between the two antistatic VHCs fell within the ± 15% acceptance interval criteria for in vitro equivalence. The different inhalation delays and flow rates had similar effects on the delivery of drug via the three VHCs. The two antistatic VHCs were shown to be equivalent in vitro in terms of emitted dose of albuterol.

Recent asthma guidelines recommend the assessment of severity levels based on the most severe symptoms and peak expiratory flow rate (PEFR). Discrepancies are frequently encountered in the use of these variables in determining the severity levels of asthmatics. The objective of this study was to determine the difference in asthma severity levels as assessed by either symptoms alone or by PEFR alone, as compared with the assessment by the asthma guidelines. Severity levels that were determined by recent asthma guidelines for 60 asthmatic patients were reassessed, based on symptoms alone and PEFR alone. They were compared for any significant differences to the asthma guidelines. Asthmatics were aged between 15 and 70 (mean 34) years, and 63.8% were females. Severity levels by symptoms alone were different from the guidelines in 27 cases (45%). Of these, 89% showed a tendency toward higher severity levels. Severity levels by PEFR alone were different in only three cases (5%). In both comparisons, differences of severity levels were significant (P<0.0001), but assessment by symptoms alone showed more deviation (x(2) =162.1) than PEFR alone (x(2) =73.1). The study documented significant discrepancies in asthma severity assessed by symptoms alone and PEFR alone, when compared to the recent asthma guidelines. Severity assessed by symptoms alone showed lower levels, and the use of PEFR tended to categorize some asthmatics into a more severe level.

A stratified sample of 83 children living in Uniontown, Pennsylvania, reported twice daily peak expiratory flow rate (PEFR) measurements on 3,582 child-days during the summer of 1990. Upon arising and before retiring, each child recorded the time, three PEFR measurements, and the presence of cold, cough, or wheeze symptoms. Ambient air pollution, including particle-strong acidity, was measured separately during the day (8 a.m. to 8 p.m.) and at night. Each child's maximum PEFR for each session was expressed as the deviation from his or her mean PEFR over the study and adjusted to a standard of 300 liters/minute. The session-specific average deviation was then calculated across all of the children. A second-order autoregressive model for PEFR was developed, which included a separate intercept for evening measurements, trend, temperature, and 12-hour average air pollutant concentration weighted by the number of hours each child spent outdoors during the previous 12-hour period. The results are expressed in terms of the interquartile range for each pollutant. A 12-hour exposure to a 125-nmol/m3 increment in particle-strong acidity was associated with a -2.5 liters/minute deviation in the group mean PEFR (95% confidence interval (CI) -4.2 to -0.8) and with increased cough incidence (odds ratio (OR) = 1.6, 95% CI 1.1 to 2.4). A 30-ppb increment in ozone for 12 hours was associated with a similar deviation in PEFR levels (-2.8, 95% CI -67 to 1.1). The association between PEFR and particle-strong acidity was observed among the 60 children who were reported as symptomatic on the prior symptom questionnaire (-2.5, 95% CI -4.5 to -0.5). The authors conclude that summer occurrences of excessive acid aerosol and particulate pollution are associated with declines in peak expiratory flow rates in children.

Monitoring peak flow.

In certain patients, such as young children or individuals with cerebral palsy or severe mental retardation, it is difficult to perform forced expiratory manoeuvres to measure expiratory flow volume. In such cases, we could evaluate obstructive lung disease through the measurement of airway resistance instead of expiratory flow volume. In this study, we evaluated the correlation of Impulse Oscillometry (IOS) parameters with spirometry values and peak expiratory flow rate (PEFR) measurements to give coherence to IOS recordings in lung function exploration. Total serum IgE levels, total eosinophil counts and specific IgE levels were measured in 48 children with asthma and 66 control subjects, aged 7-15 years of age. IOS, spirometry and PEFR measurements were performed, as well as methacholine challenge. We further analyzed the correlations in atopic asthma, atopic control, nonatopic asthma and nonatopic control groups. FEV(1) and PEFR showed a significant correlation with impedance and resistance (R) at 5, 10, 20 and 35 Hz, both in atopic asthmatic and in atopic control children. FVC also showed a correlation with impedance and R at 10, 20 and 35 Hz, both in atopic asthmatic and atopic control children. FEF(25-75%) did not show a correlation with resistances. FEV(1), FVC and PEFR were significantly correlated with IOS parameters, in both asthmatic and control subjects, especially for atopic children. IOS could be used as a suitable measure of lung function when spirometry and PEF cannot be performed.

Flow Structure and Particle Deposition Analyses for Optimization of a Pressurized Metered Dose Inhaler (pMDI) in a Model of Tracheobronchial Airway

Dry powder inhaler aerosol deposition in a model of tracheobronchial airways: Validating CFD predictions with in vitro data.

The aim of this study was to determine the cost effectiveness of 2 inhaled corticosteroids, fluticasone propionate and flunisolide, in the management of asthma from a third-party payer perspective in Germany (German Sickness Fund). Direct treatment costs were retrospectively applied to 2 prospective randomised parallel group clinical trials conducted in Germany comparing fluticasone propionate and flunisolide: one 6-week open-label study (n = 332) and one 8-week double-blind study (n = 308) in corticosteroid-naive patients with asthma of moderate severity aged between 18 and 70 years. All costs were adjusted to 1997 Deutschmarks. Efficacy parameters included changes in morning and evening peak expiratory flow rate (PEFR) measurements, the number of successfully treated patients (defined as those with a PEFR improvement of > or = 10%) and proportion of symptom-free days. The fluticasone propionate groups had higher respective proportions of successfully treated patients and symptom-free days than the flunisolide groups in both the open-label (56.8 vs 39.6% and 36.4 vs 28.5%) and double-blind (55.3 vs 44.5% and 35.1 vs 31.1%) studies. Improvements in both morning and evening PEFR measurements were also significantly (p < 0.01) greater with fluticasone propionate than with flunisolide. Although average daily treatment costs were slightly higher in the fluticasone propionate groups than in the flunisolide groups, all cost-effectiveness ratios (daily cost per successfully treated patient and daily cost per symptom-free day) favoured fluticasone propionate. Sensitivity analysis showed that these results were robust over a wide range of assumptions. In these patients, management with fluticasone propionate was more cost effective than with flunisolide in the German healthcare setting.

The purpose of this study was to determine the prevalence of exercise-induced bronchospasm (EIB) in collegiate cross-country runners using a protocol involving an intense exercise challenge conducted in the same environment in which the athletes train and compete. One-hundred eighteen collegiate cross-country runners from the Los Angeles, California, metropolitan area participated in the study. All testing took place on a track at the time and location of a normal practice session. The baseline peak expiratory flow rate (PEFR) measurements (best of three) and preexercise heart rate were recorded, after which the athletes ran 2000 m on a track at 85% of maximum heart rate. The postexercise heart rate was recorded and then PEFR measurements at 2, 5, 10, and 30 min after exercise were recorded. The athletes completed a 16-item questionnaire regarding asthma symptoms and health history. Those athletes with a history of asthma and currently taking medications for the asthma were then excluded from statistical analysis of the questionnaire responses. A decrease in PEFR of 15% was considered positive for EIB. Of the 114 athletes not currently taking medications for asthma, at least 14% (16 athletes) were EIB positive. There was a poor correlation between reported symptoms of asthma and testing positive for EIB. This study demonstrates a high prevalence of EIB in collegiate cross-country runners (at least 14%) and that reported symptoms are a poor predictor of actual EIB.

Objective. Despite training, many patients continue to misuse their metered dose inhaler (MDI). Research Ethics Committee approval was obtained to evaluate two different methods to help patients use a slow inhalation flow when they use their MDI. Methods. Asthmatic children (n = 17) and adults (n = 39) prescribed an MDI had their inhaler technique assessed. Those who achieved the recommended inhalation flow rate (IFR) of <90 l/min through their MDI formed the reference group (named (control—CT)). Others that had a poor inhaler technique with an IFR ≥ 90 l/min were randomized into either the verbal counseling (VC) group, who received verbal training on the correct MDI use with emphasis on using a slow IFR or into the 2ToneTrainer (2TT) group, who received the VC and a 2Tone Trainer to take home and use. 2TT is a training aid with audible feedback when the required slow inhalation flow is used. The participants were assessed on two occasions, 0 (baseline) and 6 weeks later. Results. For the asthmatic adults, the median IFR at visit 1 was 68, 200, and 240 l/min for the CT, VC, and 2TT groups, respectively. Whereas on visit 2, the median IFR was 88, 48.5 (p < .001), and 65 (p < .001) l/min for the CT, VC, and 2TT groups, respectively. Improvements in asthma quality of life were achieved in VC and 2TT groups. The asthmatic children showed a similar trend. Conclusions. Training by VC and a training aid helps patients use a slow IFR with an MDI and improves asthma-related quality of life.

Background : Portable devices for measuring peak expiratory flow(PEF) are now of proved value in the diagnosis and management of asthma and many lightweight PEF meters have become available. However, it is necessary to determine whether peak expiratory flow rate(PEFR) measurements measured with peak flowmeters is accurate and reproducible for clinical application. The aim of the present study is to define accuracy, agreement, and precision of mini-Wright peak flow meter(MPFM) against standard pneumotachygraph. Methods : The lung function tests by standard pneumotachygraph and PEFR measurement by MPFM were performed in a random order for 2 hours in 22 normal and 17 asthmatic subjects and also were performed for 3 successive days in 22 normals. Results : The PEFR measured with MPFM was significantly related to the PEFR and measured with standard pneumotachygraph in normal and asthmatics(for PEFR, r = 0.92 ; p , r = 0.78 ; p 0.05) and the coefficient of variation() of PEFR measured with MPFM was significantly lower than that() with standard pneumotachygraph in normal (p

Features of asthma include increases in both bronchial responsiveness and variability of airflow rates. We examined the relationship between bronchial responsiveness to histamine and the variation of peak expiratory flow rate (PFR) during the day and in response to salbutamol (200 μg), and the initial FEV₁ at the time of the histamine test and FEV₁ response to salbutamol. Bronchial responsiveness to histamine was expressed as the provocation concentration causing a fall in FEV₁ of 20% (PC₂₀). PC₂₀ ranged between 13·9 and 130 mg/ml in nonasthmatic subjects, between 10·5 and 59·9 mg/ml in five asymptomatic asthmatics, and between 0·03 and 20·8 mg/ml in 27 asthmatics with symptoms controlled by medication. The lower the PC₂₀ (the greater the bronchial responsiveness) the lower the morning PFR (r = 0·79), the greater the increase in PFR after salbutamol (morning r = −0·75, evening r = −0·80), and the greater the difference between the highest and lowest PFR each day (r = −0·81). Measurements of PFR were abnormal, compared with those in nonasthmatic subjects, in all subjects with a PC₂₀ less than 2 mg/ml—that is, moderate or severe increase in nonspecific bronchial responsiveness—and in none with a PC₂₀ greater than 21 mg/ml—that is, normal responsiveness; five of nine asthmatics with controlled symptoms had abnormal PFR measurements when PC₂₀ was between 2 and 21 mg/ml—that is, mild hyperresponsiveness. In contrast, FEV₁ at the time of the histamine test was greater than 80% predicted in all subjects with a PC₂₀ greater than 2 mg/ml and was not less than this in 10 of 18 subjects with a PC₂₀ less than 2 mg/ml. When improvement in FEV₁ was 20% or more after salbutamol, the PC₂₀ was usually moderately or severely increased (less than 0·4 mg/ml). The results identify a close relationship between nonspecific bronchial responsiveness to histamine and the variability in flow rates which occurs spontaneously and after bronchodilator. In addition, they raise the possibility that increased airflow obstruction in asthma may be a consequence of increased responsiveness.

Abstract: Background: In India, obesity is rapidly growing health concern across all age groups. Obesity has significant effects on pulmonary function. The peak expiratory flow rate (PEFR) demonstrates the caliber of the airways and is widely recognized as an objective indicator of respiratory efficiency. This indicator is useful for the diagnosis and management of respiratory disorders. Aim: This study aimed to determine the relationship between BMI and immediate post-exercise changes in PEFR among medical undergraduate students. Methods:A cross-sectional study was conducted among 120 healthy undergraduate medical college students. Baseline anthropometric data, including height and weight, were collected for assessment of BMI. BMI was calculated using the Quetelet index. PEFR was measured using a Wright Peak Flow Meter. PEFR Measurements were taken before and after performing a 5-min moderate-intensity Harvard Step Test by participants. Results:The results showed that individuals with a normal BMI had the highest mean increase in PEFR (mean difference: 27.85 ± 7.97, p&lt; 0.0001), followed by the overweight group (mean difference: 15.23 ± 12.04, p &lt; 0.0001). The obese group exhibited the least improvement (mean difference: 5.49 ± 11.82, p &lt; 0.0001). The P values in all three groups for PEFR before and after exercise were low (&lt;0.0001) indicating a statistically significant difference in PEFR across BMI categories. Conclusion:This study assessed the impact of BMI on immediate post-exercise changes in PEFR among young medical students. A significant negative association was observed between BMI and PEFR. This relationship was present both before and after exercise. The study found that students with a normal BMI group demonstrated the most substantial improvement in PEFR after exercise, followed bythe overweight group. The obese group exhibited the least improvement in PEFR. These findings suggest that excess weight has a direct impact on PEFR. Further research is warranted to explore the underlying mechanisms.

Daily variations in ambient particulate air pollution are associated with variations in respiratory lung function. It has been suggested that the effects of particulate matter may be due to particles in the ultrafine (0.01-0.1 microm) size range. Because previous studies on ultrafine particles only used self-monitored peak expiratory flow rate (PEFR), we assessed the associations between particle mass and number concentrations in several size ranges measured at a central site and measured (biweekly) spirometric lung function among a group of 54 adult asthmatics (n = 495 measurements). We also compared results to daily morning, afternoon, and evening PEFR measurements done at home (n = 7,672-8,110 measurements). The median (maximum) 24 hr number concentrations were 14,500/cm(3) (46,500/cm(3)) ultrafine particles and 800/cm(3) (2,800/cm(3)) accumulation mode (0.1-1 microm) particles. The median (maximum) mass concentration of PM(2.5) (particulate matter < 2.5 microm) and PM(10) (particulate matter < 10 microm in aerodynamic diameter) were 8.4 microg/m(3) (38.3 microg/m(3)) and 13.5 microg/m(3) (73.7 microg/m(3)), respectively. The number of accumulation mode particles was consistently inversely associated with PEFR in spirometry. Inverse, but nonsignificant, associations were observed with ultrafine particles, and no associations were observed with large particles (PM(10)). Compared to the effect estimates for self-monitored PEFR, the effect estimates for spirometric PEFR tended to be larger. The standard errors were also larger, probably due to the lower number of spirometric measurements. The present results support the need to monitor the particle number and size distributions in urban air in addition to mass.

Background PRAAN, a digital peak flow meter, was developed to measure peak expiratory flow rate (PEFR) for asthma monitoring. This study aimed to compare PRAAN’s accuracy to that of spirometry and the mini-Wright peak flow meter for PEFR measurement. Methods Two cross-sectional studies were conducted in 106 healthy adult participants. Study A (n=56) compared PRAAN with spirometry, while study B (n=50) compared PRAAN with the mini-Wright peak flow meter. PEFR values were collected using crossover studies. Pearson’s correlation and Bland-Altman plots were used to report the relationship and agreement between two measurements, respectively. Results In study A, 51.8% were female, mean age was 24.3±5.6 years, and PEFR was 480.3±86.8 L/min. PEFR measured by PRAAN had very strongly positive correlation with spirometry (r=0.980, P&lt;0.001). Bland-Altman analysis showed that there was good agreement between them, with a low mean difference of -7.07 liters/minute (95% CI: -40.58 to 26.44 liters/minute) and 92.9%, which were within the limit of agreement (LOA). In study B, 54.0% were female, mean age was 23.5±2.4 years, and PEFR was 495.1±82.7 L/min. PEFR measured by PRAAN and by the mini-Wright peak flow meter showed very strongly positive correlation (r=0.971, P&lt;0.001). Bland-Altman comparison of PEFR between these two measurements showed that there was a very good agreement between them, with a low mean difference of 0.84 liters/minute (95% CI: -38.68 to 40.38 liters/minute) and 94.0%, which were within LOA. Conclusions The accuracy of PRAAN is in the agreement with spirometry and the mini-Wright peak flow meter. The clinical application of PRAAN may potentially lead to a monitoring strategy that healthcare providers can use to improve the management of asthma.