Assessment of a low-cost home monitoring spirometer for children

Electronic devices are now available to measure and store lung function parameters in the home. Before adopting a device for clinical or research use, it is important to validate it in the target patient group. The aim of this study was to assess a low-cost, portable, logging spirometer, the VM Plus (VM), against a standard laboratory Jaeger spirometer (JS) for use in children with respiratory disease. Seventy children with stable asthma or cystic fibrosis performed spirometry on the two devices, and results for peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) were compared. Comparison was made both using the two devices separately (separate method) and with the devices connected in series (series method). Reproducibility of the VM measurements was also assessed. Correlation between measurements was close (R values: separate, PEF, 0.91; FEV(1), 0.94; series, PEF, 0.97, FEV(1), 0.99), but PEF readings on the VM Plus were substantially higher than with the JS (mean difference: separate, 54.8 L/min; series, 28.2 L/min). This reflects well-reported differences in PEF measurements between the Mini-Wright PEF meter, on which the VM Plus spirometer is based, and conventional spirometers. Limits of agreement (series method) were: PEF, -13.2 to +69.6 L/min; FEV(1), -0.03 to +0.19 L. Reproducibility of VM Plus measurements was acceptable: coefficient of variation for PEF was 4%; for FEV(1), 4.3%; coefficient of reproducibility for PEF, 39 L/min; for FEV(1), 0.26 L. The VM Plus provides reasonably accurate, reproducible measurements of PEF and FEV(1), but intrinsic bias, particularly in PEF measurement, needs to be taken into account. Its potential to document longitudinal changes in lung function in children with respiratory disease at home merits further study.     

Evaluating the use of a portable spirometer in a study of pediatric asthma

STUDY OBJECTIVES: Laboratory-based spirometry is the "gold standard" for the assessment of lung function, both in clinical and research protocols. These spirometers, however, are neither practical nor affordable for home-based monitoring or studies that collect data in multiple locations. Traditionally, peak flowmeters have been used, but they have important limitations. DESIGN: Based on data from a cohort of 92 children with asthma, we evaluated the agreement between a portable spirometer and a office-based spirometer, using an in-line technique to evaluate measures from the same effort. We compared a range of pulmonary function parameters collected during office-based tests, and also evaluated whether adequate adherence and data quality could be achieved in a home-based study of children with asthma. RESULTS: The agreement between the devices for the actual values of peak expiratory flow, FEV(1), and forced expiratory flow at 25% of FVC was excellent. The portable device was programmed with customized software to grade each curve using revised American Thoracic Society acceptability and reproducibility criteria. For 74% of the curves, quality grade agreed with a grade assigned by physician review of the curve from the office-based spirometer. During 2 weeks of twice-daily monitoring at home, children completed an average of 23 of 28 possible sessions (83%). Of these, 84% had at least two acceptable and two reproducible curves. Although children >or= 8 years old were not more adherent, they were significantly more likely to achieve acceptable and reproducible curves. CONCLUSIONS: Portable spirometers can provide measurements that are highly comparable to those obtained from "gold standard" laboratory spirometers, and high-quality tracings can be achieved both at home and in the office setting. Visual inspection of the curves by experienced reviewers identified unacceptable curves that were not rejected by the quality control software. Portable spirometers are an important contribution to epidemiologic and clinical studies that require frequent measures of a more broad range of pulmonary function parameters than can be provided by peak flowmeters.     

Relevance of a portable spirometer for detection of small airways obstruction

While portable spirometers are increasingly used, little attention has been paid to test their validity for measurement of flows in small airways. The aim of this study was to compare the Spirotel portable spirometer to a laboratory spirometer (Jeager PFT), with regard to accuracy in measuring forced expiratory flows, and more specifically those influenced by small airways (FEF(25-75)). Fifty-nine children (mean age, 12 years; range, 7-17), were studied at baseline and after a bronchodilator inhalation. Spirometers were tested separately in a randomly designed order. A total of 117 sessions of flow-volume curves was performed with each spirometer. We obtained at least two acceptable and reproducible curves in 88% and 76% of the sessions, with the laboratory and the portable spirometers, respectively. Unacceptable curves were easily detected by visual inspection of flow-time and flow-volume waveforms. Agreement was excellent between spirometers for the measurement of all expiratory flows, both at baseline and postbronchodilator. More specifically, agreement between spirometers was as high for measurements of FEF(25-75) (intraclass correlation coefficients 0.97) as for proximal flows. High correlations were found between baseline expiratory flows measured by each spirometer (and expressed as percent of predicted values), both in large and small airways (P < 0.001). The portable spirometer was highly sensitive for detecting small airways obstruction, as compared to the laboratory spirometer. Finally, the magnitudes of bronchodilator-related flow changes were also highly correlated, both in large and small airways (P < 0.001 and P = 0.004, respectively). We conclude that the Spirotel portable spirometer is reliable for measurement of forced expiratory flows, in large and small airways, provided that all curve waveforms can be stored and available for visual inspection.     

A comparison of a new transtelephonic portable spirometer with a laboratory spirometer.

The Spirophone is a new, portable transtelephonic spirometer which records the slow and the forced expiratory vital capacity tests. Data can be transmitted via the telephone to a remote receiving centre, where a volume-time curve and the flow-volume curve are displayed on screen in real time. The aim of this study was to compare the newly developed transtelephonic spirometer, with a laboratory spirometer according to the American Thoracic Society (ATS) testing guidelines. Spirometry indices (slow vital capacity (SVC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25, 50 and 75% of FVC (FEF25, FEF50, and FEF75, respectively)) were measured from the SVC and the FVC tests in 45 subjects (30 patients, 15 healthy volunteers) according to the ATS standards. The data obtained with the laboratory system were compared to those from the Spirophone. The Spirophone measurements of SVC, FVC, FEV1, PEF, FEF25, FEF50 and FEF75 correlated closely (r=0.91-0.98) to those from the laboratory system, whereas FEF25, FEF50, and FEF75 were significantly higher with the Spirophone. It is concluded that the Spirophone is comparable to the standard spirometry for home monitoring of slow vital capacity, forced vital capacity, forced expiratory volume in one second and peak expiratory flow. The validity of the manoeuvre can be assessed on screen in real time.     

Spirometric reference values in Tunisian children

BACKGROUND: In Tunisia, there are no normal values of pulmonary function for healthy Tunisian children. OBJECTIVES: The purpose of this study was to set reference values for spirometric lung function in Tunisian children and to compare these results with other data sets. METHODS: Spirometric values were measured with a Minato portable spirometer in 1,114 asymptomatic, nonsmoking Tunisian children (581 boys and 533 girls) 6-16 years of age. Natural logarithmic values of lung function and standing height were used in the final regression model. RESULTS: Prediction equations for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), FEV(1)/FVC x 100, maximum mid expiratory flow (MMEF 25-75%) and peak expiratory flow (PEF) for both sexes are presented with standing height as the dependent variable. Our data show a significant increase in lung function with standing height in both sexes. Comparing our results with recent data, values of FVC and FEV(1) in both sexes in the present study are close to those in European, white US and Asian children, whereas our values are higher than the Libyan ones. CONCLUSIONS: Healthy Tunisian children showed similar spirometric reference values compared to European, white US and Asian children. Thus, these standards of lung function could also be used in Tunisia.     

Assessment of a peak flow whistle in nonasthmatic children.

We tested the agreement of peak expiratory flow (PEF) measurements between an electronic spirometer and a peak flow whistle (Whistle Watch, HarMed, Capetown, South Africa). One hundred and three healthy children between ages 6-13 years and with no previous experience in lung function tests participated in the study. Sequential PEF-readings were obtained from the spirometer and the peak flow whistle; all children had an equal number of attempts using both devices. In the case of the spirometer, the highest PEF reading of three acceptable and reproducible efforts was noted as the best PEF (PEF(SPIRO)). Whistle Watch readings were taken as the highest value when the child could activate the whistle. Despite a strong correlation (r = 0.91; R2 = 83%) between the readings of the spirometer and Whistle Watch, there was a lack of agreement between the two devices. For any individual subject, the 95% probability interval ranged between +30.4 to -47 L.min(-1); 64% of the children obtained higher PEF-values on Whistle Watch, compared to the spirometer. These findings suggest that the whistle sound of the peak flow whistle was a significant incentive, which resulted in greater maximal expiratory efforts.     

Pulmonary function electronic monitoring devices: a randomized agreement study

STUDY OBJECTIVES: To compare in a clinical setting the within-session reproducibility of two pulmonary function electronic monitoring devices (PiKo-1; Ferraris Respiratory Europe; Hereford, UK; and Spirotel; MIR; Rome, Italy) with one mechanical device (Mini-Wright Peak-Flow Meter; Clement-Clarke International; Harlow, Essex, UK), and to evaluate the accuracy of these devices using as reference an office pneumotachograph. DESIGN, SETTING, AND PARTICIPANTS: After detailed instructions, adults without airways diseases and patients with stable asthma attending an outpatient clinic performed four sets of expiratory maneuvers, one set for each device, in a strictly random order. Each set comprised three maneuvers with 2 to 3 min of rest between them. MEASUREMENTS: Reproducibility of FEV1 and peak expiratory flow (PEF) was assessed by a coefficient of variation (CV) and intraclass correlation coefficient (ICC), and accuracy was assessed by ICC and limits of agreement. RESULTS: Of the 38 participants evaluated, 71% were women and 61% had asthma. Ages ranged from 18 to 58 years, and FEV1 ranged from 1.2 to 4.8 L. In all monitoring devices, CV was < 6% and ICC was > 0.94 for the reproducibility of both FEV1 and PEF measurements. The accuracy of the PiKo-1 device was better for FEV1 (ICC = 0.98) than for PEF (ICC = 0.90). The Spirotel device had similar results for FEV1 and PEF (ICC = 0.95). The Mini-Wright device had the lowest accuracy (ICC = 0.87), particularly for PEF values < 500 L/min. CONCLUSIONS: These low-cost and easy-to-use electronic monitoring devices showed a very good reproducibility and were in agreement with the pneumotachograph. Therefore, the PiKo-1 and Spirotel devices seem adequate for both screening and monitoring. However, prospective studies are still needed to assess their long-term reproducibility and usability and, particularly, the effects on the improvement of respiratory care.     

A comparison of the Jones and Stead-Wells spirometers

A comparison was made between the noncounterweighted Jones and Stead-Wells spirometers, and "conversion factors" were determined for the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC). A cross-sectional study produced a high correlation between the instruments for these two measurements, yielding quadratic and linear regression equations ("conversion factors") for FEV1 and FVC, respectively. Standard deviations of measurements were similar for both spirometers. Results from a longitudinal study agreed with the "conversion factors" predicted from the cross-sectional study; however, significant day-to-day variability was observed by both spirometers. Neither spirometer met all of the technical recommendations proposed by the Committees on Environmental Health and Respiratory Physiology of the American College of Chest Physicians; however, the Stead-Wells water-sealed spirometer complied more often than the Jones waterless spirometer (Pulmonor). In addition, the open-circuit procedure used for the Jones spirometer required more corrdination in the subject than did the closed-circuit procedure employed in this study for the Stead-Wells spirometer; however, with application of the "conversion factors," both instruments, yield comparable data and prove adequate for spirometric studies.     

Clinical comparison of two electronic spirometers with a water-sealed spirometer.

Two electronic spirometers which use a hot-wire anemometer to measure air flow were clinically compared with a water-sealed spirometer. The forced vital capacity (FVC), the forced expiratory volume in one second (FEV1), the FEV1/FVC%, the mean forced expiratory flow between 200 and 1,200 ml of the FVC, the mean forced expiratory flow during the middle half of the FVC, the mean forced expiratory flow between 75 and 85 percent of the FVC, and the maximum voluntary ventilation were determined for a group of 67 subjects. Techniques are described for connecting the spirometers in series to permit evaluation by human subjects or by syringe injection. High correlation coefficients generally were obtained when comparing the electronic spirometers with the water-sealed spirometer, but the actual range of percent difference was greater than 11 percent in all spirometric tests. The results indicate the need for systematic evaluation of electronic spirometers to characterize their deviation from accented standards. Frequent calibration is necessary to maintain consistent performance.     

Accuracy of an electronic spirometer--a field trial

Biological calibration of the Hewlett-Packard electronic spirometer against a Stead-Wells 13.5-litre spirometer shows a good concordance for forced vital capacity (FVC; systematic error 0% in women, 1% in men, probable error 4% in both sexes). However, the electronic device underestimates both 1-second forced expiratory volume (FEV1.0) and maximum mid-expiratory flow rate (MMEF) by 8-10%. This bias is unlikely to reflect technical problems of calibration, voltage drift, condensation of moisture or an inappropriate BTPS calibration; possible causes are a non-linearity in the pneumotachograph response characteristics, a lower resistance to expiration in the electronic device, and greater feedback to the subject and observer with the traditional spirometer. Given reports that similar discrepancies arise with other electronic spirometers, care should be taken in overinterpreting data obtained by such devices.     

Volume calibration alone may be misleading.

The use of spirometry is becoming more and more widespread in non-laboratory situations such as general practice or occupational medicine. In these non-laboratory situations, volume calibration with a 3000 ml syringe is often the only feasible method to ensure that the spirometer produces valid and reproducible data. Sophisticated equipment to calibrate forced manoeuvres with standard waveforms are not present. In this study, we assessed whether volumetric calibration is a guarantee for valid and comparable spirometric results. Two portable spirometers were tested. On 8 consecutive test days, both spirometers were calibrated with a 3000 ml syringe in accordance with the American Thoracic Society (ATS) guidelines. The comparability of the spirometric results (forced expiratory volume in 1 S, FEV1) was tested in two ways. Firstly, the spirometers were compared to each other using the results from 43 volunteers on the same 8 test days. The spirometers were presented in a randomized order and volunteers were asked to perform a series of reproducible manoeuvres in both spirometers. Paired observations were analysed, using Bland and Altman plots. Secondly, the spirometers were compared to a 'gold standard', a computer-driven syringe (CDS). Calibration with the 3000 ml syringe showed that both spirometers complied with the ATS criteria for volume calibration for diagnostic spirometry. However, paired FEV1 data obtained in subjects showed a systematic, volume-dependent difference between the two spirometers (mean difference: 289 ml, P < 0.001, systematic difference: 8.6%, P < 0.0001). This systematic difference was confirmed by the comparisons with the CDS. Volume calibration may be misleading. The results from volume calibration may meet the ATS criteria, but this is no guarantee that data from forced manoeuvres are accurate. If CDS equipment to simulate standard wave forms is not available, it is recommended that biological calibration is performed regularly and, if possible, that paired data from two (or more) different spirometers are compared.     

Effect of inhaled budesonide therapy on lung function in schoolchildren born preterm.

We investigated the effect of inhaled glucocorticoid (GC) on bronchial obstruction and on bronchial lability in schoolchildren born preterm. Twenty-one children with bronchial obstruction, increased responsiveness to a beta2-agonist, and/or increased diurnal variation in peak expiratory flow (PEF) were selected for an open longitudinal study of the value of inhaled GC. None of these children had an earlier diagnosis of asthma or current GC treatment. Eighteen children with median (range) birth weight 1025 (640-1600) g and gestational age 28 (24-35) weeks, age at study 10.1 (7.7-13) years, were treated with inhaled budesonide in initially high (0.8 mg m(-2) day(-1) for 1 month) and subsequently lower dose (0.4 mg m(-2) day(-1) for 3 months). Daily symptom scores were recorded. Spirometric values were measured in the clinic at the beginning and end of each treatment period. At home, children used a data storage spirometer. After treatment with budesonide for 4 months, spirometric values in the clinic did not significantly change. The median forced expiratory volume in 1 sec (FEV1) was 74% of predicted both at entry and after budesonide treatment. However, the median number of > or = 20% diurnal change in PEF values at home decreased during treatment. According to the present study, inhaled budesonide for 4 months had no significant effect on basic lung function but may decrease bronchial lability in schoolchildren born preterm.     

Inter-laboratory comparison of flow-volume curve measurements as quality control procedure in the framework of an international epidemiological study (PEACE project)

The aim of this work was to describe the results of a simple quality control procedure for the flow-volume curve adopted in a multicentre epidemiological study (PEACE). In 14 centres, 8-15 individuals (n = 157) performed forced vital capacity (FVC) manoeuvres following a standard protocol with both the local spirometer/pneumotachograph and a portable spirometer (i.e. the 'reference instrument' for this study). Deviances of measurements were assessed by computing the differences (delta) between the former and the latter, the ratios of such differences on portable spirometer values (delta %) and the coefficients of variation (CV). The portable spirometer yielded lower mean AFVC and deltaFEV1 (forced in 1 sec) than local instruments (except for two and four centres, respectively). In most instances, differences were statistically significant. Absolute mean A%FVC ranged from 4.9-18.2%, while delta%FEV1 ranged from 2.3-18.5%. The Bland and Altman analysis showed a good agreement between the portable and local instruments, except for two centres, where a systematic trend towards higher individual absolute deltaFVC and deltaFEV1 was observed. The overall variability, assessed by CV, was within 6.2% and 5.1% for FVC and FEV1, respectively: it was similar to other quality control studies ranging from 2.0-5.5% for FVC and 2.2-5.8% for FEV1. Our results point out the importance of performing interlaboratory comparisons as a quality control procedure in multicentre epidemiological studies on lung function, and of stimulating manufacturers to extend the accuracy and precision of the instruments.     

Lung function measurement in general practice: a comparison of the Escort spirometer with the Micromed turbine spirometer and the mini-Wright peak flow meter

It is important that new types of spirometer for widespread clinical use are pragmatically evaluated in primary care. This study compared measurements taken by a new portable Fleisch pneumotachograph spirometer (known as the Escort) with those of the commonly used mini-Wright peak flow meter and the Micromed Pocket turbine spirometer. A pragmatic study was conducted in two phases during routine surgeries at Aldermoor Health Centre, Southampton. Phase 1 compared the new spirometer with the mini-Wright peak flow meter and Phase 2 compared the new spirometer and the turbine spirometer. One hundred patients aged 5–88 years (56 patients with a history of chronic respiratory complaints and 44 patients without) entered Phase 1, and 100 patients aged 6–82 years (62 patients with a history of chronic respiratory complaints and 38 patients without) entered Phase 2. Each patient contributed only once to each phase, but some entered both phases on separate occasions. Ninety-five percent limits of agreement (mean ± 2 ) were wide for all comparisons. Graphical plots revealed trends towards higher Escort values as mean values rose compared with both mini-Wright and turbine readings for peak expiratory flow rate and forced expiratory volume in one second. Possible over-reading of peak expiratory flow rate with the mini-Wright meter at low mean values was also seen. Readings taken with these different types of meter cannot be interchanged with confidence in clinical practice. The clinical significance of the theoretically more accurate measures of lung function produced with the new meter, and indeed of spirometry itself, needs further investigation.     

Acceptability, reproducibility, and sensitivity of forced expiratory volumes and peak expiratory flow during bronchial challenge testing in asthmatic children.

OBJECTIVES: To compare the acceptability, reproducibility, and sensitivity of spirometric outcome measures of airway caliber during challenge testing in children. DESIGN: FEV(1), forced expiratory volume in 0.75 s, forced expiratory volume in 0.5 s, and peak expiratory flow (PEF) were recorded during stepwise dosimetric histamine challenge tests. The responses were compared, and the reproducibility at baseline and from duplicate measurements at each challenge step was determined. PATIENTS: One hundred five children with newly diagnosed asthma, aged 5 to 10 years. RESULTS: Compared to PEF, FEV(1) showed better baseline reproducibility (p = 0.002) and higher sensitivity (p < 0.0001) during challenge testing, determined as the change normalized to the baseline variation, while the forced expiratory volumes were not significantly different in these respects. During challenge testing in subjects with acceptable flow-volume tracings, paired recordings of FEV(1) agreed within 0.1 L in 85% and within 0.2 L in 93% of measurements. During challenge testing, the reproducibility of FEV(1) measurements was not better than that of the other indexes. Failure to exhale long enough precluded the use of FEV(1) in 16 of the children, particularly the youngest children. CONCLUSIONS: The results demonstrated that the recently published guidelines for FEV(1) measurements during challenge tests can be applied to children. During challenge tests in asthmatic children, the advantage of the shorter fractions of forced expiratory volume was that they were more often acceptably recorded than FEV(1), while they showed as good reproducibility and were also equally sensitive in assessing changes in airway obstruction.     

Evaluation of daily home spirometry for school children with asthma: new insights

Home spirometers are useful for monitoring asthma therapy and for research, but the validity of maneuvers in children is in question. We evaluated the quality of PEF, FEV(1), and FVC data obtained from 67 children with persistent asthma who self-administered spirometry at home using the hand-held ndd EasyOne Frontline Spirometer with full expiratory curve data, electronic measurements of maneuver quality, and on-screen incentives. Half were studied in 2003 in one region, and half in 2004 in another region of Southern California. Subjects were followed at home weekly over 2 months and daily over 10 consecutive days. We retained completed spirometry sessions (9,916) consisting of three of six best maneuvers in the morning, afternoon, and evening. Percent compliance, software assessed repeatability and acceptability modified from American Thoracic Society criteria, and visually assessed quality of maneuvers, were compared across daily and weekly follow-up, study regions, and subject characteristics. Compliance was higher for daily (>90%) than for weekly follow-up (>84%), but not significantly different, and was consistent across subject characteristics. The number with two reproducible and acceptable maneuvers was significantly lower in the first than second region for daily (70 vs. 90%) and weekly follow-up (66 vs. 87%). Of 22,926 software accepted maneuvers, 1,944 (8.5%) were visually rejected (variable effort, cough, glottic closure). Maneuver quality was significantly lower for subjects age 9-12 versus 13-18 years, for subjects not taking anti-inflammatory medications, and for subjects with <80% predicted FEV(1). Longitudinal data collection is possible in children with asthma by employing repeated home training and follow-up, and using spirometers with built in quality assurance and incentive software. Region, age, and multiple indicators of persistent asthma, predict ability to perform reliable and accurate lung function maneuvers.     

Accuracy, precision and linearity of the portable flow-volume meter Microspiro HI-298

The accuracy, precision and linearity of a new portable flow-volume meter, the Microspiro HI-298 (Chest Corporation, Tokyo, Japan), was investigated using a Fleisch no. 4 pneumotachograph as a standard. After connection and calibration of the pneumotachograph and the Microspiro, a healthy subject performed 44 forced vital capacity (FVC) manoeuvres at different levels of lung inflation. The FVC of these expirations ranged from 2.5-5.1 l. Linear regression of Microspiro values (dependent variable) on Fleisch pneumotachograph values (independent variable) showed that a good linear relationship existed: Pearson correlation coefficients ranged from 0.938-0.985. Linearity of the Microspiro was good except for the peak expiratory flow rate (PEFR) and the maximal expiratory flow at 25% of the expired volume (MEF75). The random error (measure of precision) of all flow-volume (F-V) indices was lower than 5%. The systematic error (measure of accuracy) was low for the forced expiratory volume in one second (FEV1) and the FVC (1% and 4.6%, respectively) but much higher for the instantaneous expiratory flows (PEFR 11.0%; MEF75 7.0%; MEF50 8.5%; MEF25 11.4%). Only the total error in FEV1 complied with the tolerance of 4% of the European Community for Coal and Steel (ECCS). When the measured values were adjusted according to the regression equations of this study, all F-V indices were accurate and precise within 5%. It was concluded that the portable Microspiro HI-298 is a useful instrument for bedside, work-site spirometry and for use in general practice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Peak inspiratory flow through Turbuhaler in chronic obstructive airways disease.

Many patients with chronic obstructive airways disease (COAD) receive therapy by the inhaled route. This study was performed to assess whether patients with severe COAD could generate sufficient peak inspiratory flow (PIF) through Turbuhaler (Astra, Sodertalje) to operate it effectively. One hundred patients (45 men, 55 women, mean age 69.1 years) with COAD (mean (SD) duration 17.7 (16.3) years) and peak expiratory flow (PEF) < or = 200 l min-1 or forced expiratory volume in 1 sec (FEV1) < or = 1 litre were studied. A series of randomly assigned inspiratory and expiratory lung function tests were contiguously performed, using portable spirometers, within 48 h of a screening visit. An empty Turbuhaler was used in the study. The patients' normal medication was not restricted. Sixty-six patients were previous smokers, eight occasional smokers, 19 habitual smokers and seven had never smoked. Mean (SD) FEV1 was 0.7 (0.2) 1 and mean PEF was 182 (68) l min-1. All patients were able to generate PIF through Turbuhaler (PIF-T) of 28 l min-1 (mean 53; range 28-78 l min-1). Eighty-three patients generated PIF-T of > or = 40 l min-1. PIF-T correlated with PIF without Turbuhaler (r = 0.35), PEF (r = 0.3), FEV1 (r = 0.2) and forced vital capacity (FVC) (r = 0.23) although the relationships were too weak to be used to predict PIF-T. The results suggest that patients with severely limited lung function caused by COAD can operate Turbuhaler effectively.     

Performance evaluation of contemporary spirometers

A comprehensive evaluation of 62 spirometers from 37 different sources was performed using a two-part protocol: calibrated syringe, and dynamic waveform testing. All testing was done with ambient air. Calibrated syringe testing examined the ability of the spirometers to accurately measure the output of a 3 L calibrating syringe under varying conditions. The accuracy, FVC volume linearity, and stability of each spirometer was determined from these data. All but five of 42 spirometers accurately measured a 3 L calibrating syringe to within +/- 3 percent. Dynamic waveform testing consisted of introducing 24 standard waveforms into the spirometer from a computer-controlled air pump. The values of FVC, FEV1, and FEF25-75% were compared to the actual values for each waveform to determine a performance rating. Only 35 (56.5 percent) of the spirometers performed acceptably when measuring the 24 standard waveforms. Nine (14.5 percent) were marginal and 18 (29.0 percent) were unacceptable. Fifty-nine (95 percent) of the 62 spirometers were computerized. Software errors were found in 25 percent of the computerized systems evaluated. Although using a 3 L syringe for quality control purposes is essential, simple testing of spirometers with a 3 L calibrating syringe for validation purposes was inadequate to assess spirometer performance when compared to dynamic waveform testing. Dynamic waveform testing is essential to accurately measure and validate acceptability of spirometer system performance.     

Spirometric values in Gypsy (Roma) children

Values of spirometry indices vary among subjects of similar age, gender and somatometrics but of different ethnic origins. Low socioeconomic status in childhood is inversely related to lung growth. The aim of this investigation was to assess spirometry values in Gypsy children and compare them to reported values for Caucasians. Gypsy students attending primary schools in Central Greece were recruited. Spirometry indices were measured using a portable spirometer. Regression analysis was applied to construct prediction equations for forced vital capacity (FVC) and other spirometric indices (FEV(1), FEF(50), FEF(25), FEF(25-75)) based on standing height. Predicted spirometric values were compared to values for Caucasians from published studies. In 152 children (ages 5-14 years; 57 girls) lung function increased linearly with height: spirometry index=intercept+[slopexheight], (r(2)=0.68 for FVC and FEV(1) in girls; r(2)=0.78 for FVC and r(2)=0.74 for FEV(1) in boys). Excluding boys-but not girls-in puberty increased fit for FVC (r(2)=0.83) and FEV(1) (r(2)=0.79). Mean predicted values were 5-10% lower than values for Caucasians. In Gypsy children, FVC and expiratory flow function increase linearly with standing height and predicted values are lower than those for Caucasians of similar height.