Spirometry In Adults Research Articles

Relationship between symptoms and results on spirometry in adults seen in non-tertiary public health facilities presenting with preserved ratio impaired spirometry.

Preserved ratio impaired spirometry (PRISm), defined by reduced forced expiratory volume in 1 second (FEV1) without meeting criteria for airway obstruction, is often encountered in clinical practice. The management of this heterogeneous condition in individuals with chronic respiratory symptoms is challenging, especially under limited diagnostic resources. Since 2020, all consecutive patients referred for spirometry at our institution have been invited to participate in our registry. Other than spirometry, no other physiological lung function testing is available in this public health service. Therefore, we reviewed our databank with the aim of assessing: i) the proportion of symptomatic patients aged 18 years or older referred for spirometry presenting with PRISm; ii) the rate of inhaled medication used in this group, suggesting a referral diagnosis of obstructive airway disease (OAD); and iii) the relationship between symptoms and results on spirometry in PRISM compared to a group with obstruction matched by FEV1. To this end, the COPD Assessment Test (CAT) and the Asthma Control Test (ACT) were conjointly responded to by 1032 participants, irrespective of the clinical suspicion. We found that 22% had PRISM, of whom 200 were paired with obstruction by FEV1 (68±10% of predicted). The CAT and ACT results were well-correlated in both groups (r=-0.727 and -0,698, respectively; p<0.001) and used to measure symptoms. Participants in the final sample (n=400) were aged 62±13 years; 70% were ever smokers; and 55% reported household exposure to biomass smoke (at least 5 years). The CAT responses were in the range of moderate symptoms (17±9) and ACT borderline for uncontrolled symptoms (19±5). The main differences were higher body mass index (33±7 versus 29±7 kg/m2; p<0.001) and proportion of females (72 versus 49%; p<0.001) in PRISm compared to obstruction. This group had lower exposure to tobacco (65 versus 76% of ever-smokers) but greater exposure to biomass smoke (61 versus 49%) (p<0.05 for all). The rate of inhaled medication use was as high in PRISm as in obstruction (80%). Notwithstanding matched FEV1, we found less prominent signs of airway disease in PRISM: marginally reduced FEV1/forced vital capacity (FVC) ratio (94±8% of predicted); higher expiratory flow between 25% and 75% of vital capacity, despite presumed lower lung volumes (lower FVC); and lower rate of bronchial hyperresponsiveness. In an identical multivariate model, FEV1 predicted symptoms of obstruction only. In conclusion, these data raise suspicion of a substantial rate of misclassification of individuals with PRISM as having OAD in healthcare facilities with constraints on diagnostic resources.

WS06.01 Outcome measures for assessment of lung function – cross-sectional analysis of relationships between impulse oscillometry, electrical impedance tomography, multiple breath washout and spirometry

Objectives: Lung function assessment is key in CF care, but traditional outcome measures (OMs) such as FEV1 may not be sensitive enough in the CFTR modulator era. LCI2.5 from the multiple breath washout (MBW) is a sensitive measure of small airway disease but can be lengthy in advanced lung disease. Emerging OMs include impulse oscillometry (IOS) & electrical impedance tomography (EIT). Here we report results of cross-sectional analysis of relationships between IOS, EIT, MBW & spirometry in adults with CF.

Prediction Equations for Spirometry in Adults from Northern India

Most of the Indian studies on prediction equations for spirometry in adults are several decades old and may have lost their utility as these were carried out with equipment and standardisation protocols that have since changed. Their validity is further questionable as the lung health of the population is likely to have changed over time. To develop prediction equations for spirometry in adults of north Indian origin using the 2005 American Thoracic Society/European Respiratory Society (ATS/ERS) recommendations on standardisation. Normal healthy non-smoker subjects, both males and females, aged 18 years and above underwent spirometry using a non-heated Fleisch Pneumotach spirometer calibrated daily. The dataset was randomly divided into training (70%) and test (30%) sets and the former was used to develop the equations. These were validated on the test data set. Prediction equations were developed separately for males and females for forced vital capacity (FVC), forced expiratory volume in first second (FEV1), FEV1/FVC ratio, and instantaneous expiratory flow rates using multiple linear regression procedure with different transformations of dependent and/or independent variables to achieve the best-fitting models for the data. The equations were compared with the previous ones developed in the same population in the 1960s. In all, 685 (489 males, 196 females) subjects performed spirometry that was technically acceptable and repeatable. All the spirometry parameters were significantly higher among males except the FEV1/FVC ratio that was significantly higher in females. Overall, age had a negative relationship with the spirometry parameters while height was positively correlated with each, except for the FEV1/FVC ratio that was related only to age. Weight was included in the models for FVC, forced expiratory flow (FEF75) and FEV1/FVC ratio in males, but its contribution was very small. Standard errors of estimate were provided to enable calculation of the lower limits of normal and standardised residuals for these parameters. The equations were found to be valid on the test dataset, and therefore, may be extended to general population. Comparison with the 1960s equations revealed lack of good agreement, and substantially higher predicted FVC with the current equations, especially in the forty-years-plus age group, in both males and females. Even in the age group upto 40 years, the level of agreement was clinically not acceptable. Validated prediction equations have been developed for spirometry variables in adults of north Indian origin using the current ATS/ERS spirometry standardisation recommendations. The equations suggest an improvement in the lung health of the population over time in the middle-aged and the elderly. These equations should address a long-felt unmet need and enable a more appropriate evaluation of spirometry data in different chest diseases in Indian subjects.

Intra-Rater Reliability of Desktop Spirometry in Adults with Type 2 Diabetes Mellitus

Objective: To evaluate the inter-rater reliability of desktop spirometry in adult patients with type 2 diabetes mellitus (T2DM) attending public sector hospital in Panchkula, India. Methods: Thirty eligible participants with T2DM completed study at government hospital, Panchkula from February 2019 to August 2019. The study was having co-relational design. Pulmonary function test (PFT) was performed twice by each participant through desktop spirometer. T2DM patients aged between 40-64 years with diabetes duration ≥ 1 year were included into the study. Statistical analysis was done using SPSS version 21 and Microsoft excel.Results: Of 30 participants, the mean age of the participants was 51.537.5 ± years. There were 19 (63.33%) females and 11 (36.7%) males. Mean difference between test-retest came out to be 0.08, 0.035, and -0.93 for Forced Vital Capacity (FVC), Forced expiratory volume in 1st second (FEV1) and % FEV1/FVC respectively. The difference was not significant for FEV1 and % FEV1/FVC with p-value=0.270 &amp; 0.340 respectively. However, it was significant for FVC with p-value=0.030. Intraclass correlation was 0.959, 0.94, and 0.89 for FVC, FEV1 and % FEV1/FVC respectively. Minimal detectable change was 0.3, 0.3, and 8 for FVC, FEV1, FEV1/FVC respectively. Conclusion: This can be concluded from the results that desktop spirometer has good absolute and relative reliability. Therefore, it can be used at the primary health care setting for the evaluation of pulmonary functions of adult patients with T2DM.

Use of Incentive Spirometry in Adults following Cardiac, Thoracic, and Upper Abdominal Surgery to Prevent Post-Operative Pulmonary Complications: A Systematic Review and Meta-Analysis

Background: Currently, consensus on the effectiveness of incentive spirometry (IS) following cardiac, thoracic, and upper abdominal surgery has been based on randomized controlled trials (RCTs) and systematic reviews of lower methodological quality. To improve the quality of the research and to account for the effects of IS following thoracic surgery, in addition to cardiac and upper abdominal surgery, we performed a meta-analysis with thorough application of the Grading of Recommendations Assessment, Development and Evaluation scoring system and extensive reference to the Cochrane Handbook for Systematic Reviews of Interventions. Objective: The objective of this study was to determine, with rigorous methodology, whether IS for adult patients (18 years of age or older) undergoing cardiac, thoracic, or upper abdominal surgery significantly reduces30-day post-operative pulmonary complications (PPCs), 30-day mortality, and length of hospital stay (LHS) when compared to other rehabilitation strategies. Methods: The literature was searched using Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, and Web of Science for RCTs between the databases’ inception and March 2019. A random-effect model was selected to calculate risk ratios (RRs) with 95% confidence intervals (CIs). Results: Thirty-one RCTs involving 3,776 adults undergoing cardiac, thoracic, or upper abdominal surgery were included. By comparing the use of IS to other chest rehabilitation strategies, we found that IS alone did not significantly reduce 30-day PPCs (RR = 1.00, 95% CI: 0.88–1.13) or 30-day mortality (RR = 0.73, 95% CI: 0.42–1.25). Likewise, there was no difference in LHS (mean difference = −0.17,95% CI: −0.65 to 0.30) between IS and the other rehabilitation strategies. None of the included trials significantly impacted the sensitivity analysis and publication bias was not detected. Conclusions: This meta-analysis showed that IS alone likely results in little to no reduction in the number of adult patients with PPCs, in mortality, or in the LHS, following cardiac, thoracic, and upper abdominal surgery.

Abnormal spirometry in adults with 22q11.2 microdeletion and congenital heart disease

BackgroundIn adults with congenital heart disease (CHD), pulmonary dysfunction is prevalent and associated with poor outcomes; however, underlying genetic contributors remain unexamined. We investigated whether the 22q11.2 microdeletion, an important genetic cause of CHD, was associated with abnormal spirometry in adults with CHD. MethodsWe conducted a retrospective case-control study of 207 adults with CHD (predominantly tetralogy of Fallot), and spirometry data available from cardiopulmonary exercise testing, matching 58 with a confirmed 22q11.2 microdeletion to 149 controls on age (median 26.4, 28.2 years, respectively), sex, ethnicity, and CHD severity (37.9%, 29.5% complex, respectively). We examined forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), their % predicted values, and FEV1/FVC ratio. ResultsAll respiratory parameters assessed were significantly worse in those with 22q11.2 deletion syndrome (22q11.2DS-CHD) as compared to CHD-controls. Linear regression models indicated that the 22q11.2 microdeletion was associated with worse spirometry values even when accounting for complex CHD (FVC% predicted, p < 0.0001), scoliosis (FVC% predicted, p = 0.0007), and asthma (FEV1/FVC, p < 0.0001). The 22q11.2 microdeletion effect appeared mixed: associated with both FVC% predicted ≤70%, suggestive of a restrictive defect (OR 3.82, p = 0.0020), and FEV1/FVC <70%, suggestive of an obstructive defect (OR 2.80, p = 0.015). Intellectual disability did not affect the 22q11.2DS-CHD spirometry results. ConclusionsThe findings indicate that adults with CHD and a 22q11.2 microdeletion are disproportionately represented amongst those with abnormal spirometry, supporting the potential value of early pulmonary function testing in those with 22q11.2DS and enhanced genetic testing for the 22q11.2 microdeletion in CHD.

Correlation between impulse oscillometry parameters and asthma control in an adult population.

Purpose: Impulse oscillometry (IOS) has been proposed as an alternative test to evaluate the obstruction of small airways and to detect changes in airways earlier than spirometry. In this study, we sought to determine the utility and association of IOS parameters with spirometry and asthma control in an adult population.Patients and methods: Adults 14–82 years of age with asthma were classified into uncontrolled asthma (n=48), partially controlled asthma (n=45), and controlled asthma (n=49) groups, and characterized with fractional exhaled nitric oxide (FENO), IOS, and spirometry in a transversal analysis planned as a one-visit study. The basic parameters evaluated in IOS are resistance at 5 Hz (R5), an index affected by the large and small airway; resistance at 20 Hz (R20), an index of the resistance of large airways; difference between R5 and R20 (R5–R20), indicative of the function of the small peripheral airways; reactance at 5 Hz (X5), indicative of the capacitive reactance in the small peripheral airways; resonance frequency (Fres), the intermediate frequency at which the reactance is null, and reactance area (XA), which represents the total reactance (area under the curve) at all frequencies between 5 Hz to Fres.Results: There were statistical differences between groups in standard spirometry and IOS parameters reflecting small peripheral airways (R5, R10, R5–R20, Fres, XA and X5) (P<0.001). Accuracy of IOS and/or spirometry to discriminate between controlled asthma vs partially controlled asthma and uncontrolled asthma was low (AUC=0.61). Using linear regression models, we found a good association between spirometry and IOS. In order to evaluate IOS as an alternative or supplementary method for spirometry, we designed a predictive model for spirometry from IOS applying a penalized regression model (Lasso). Then, we compared the original spirometry values with the values obtained from the predictive model using Bland–Altman plots, and the models showed an acceptable bias in the case of FEV1/FVC, FEV1%, and FVC%.Conclusion: IOS did not show a discriminative capacity to correctly classify patients according to the degree of asthma control. However, values of IOS showed good association with values of spirometry. IOS could be considered as an alternative and accurate complement to spirometry in adults. In a predictive model, spirometry values estimated from IOS tended to overestimate in low values of “real” spirometry and underestimate in high values.

COPD: A healthcare challenge

British Journal of Healthcare ManagementVol. 23, No. 6 Respiratory MedicineCOPD: A healthcare challengeJo RileyJo RileySearch for more papers by this authorJo RileyPublished Online:14 Jun 2017https://doi.org/10.12968/bjhc.2017.23.6.252AboutSectionsView articleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View article References All Party Parliamentary Group on Respiratory Health (2014) Report on Inquiry into Respiratory Deaths. Available at: https://www.networks.nhs.uk/nhs-networks/london-lungs/documents/appg-report-on-inquiry-into-respiratory-deaths-june-2014/ (accessed 23 May 2017) Google ScholarAssociation for Respiratory Technology and Physiology (2013) A Guide to performing Quality Assured Diagnostic Spirometry. Available at: http://www.artp.org.uk/en/professional/artp-standards/index.cfm/QADS%20Apr%202013 (accessed 23 May 2017) Google ScholarBritish Lung Foundation (2015) COPD Statistics. Available at: https://statistics.blf.org.uk/copd (accessed 23 May 2017) Google ScholarBritish Lung Foundation (2016) The Battle for Breath Report. Available at: http://tinyurl.com/m3hrckq (accessed 23 May 2017) Google ScholarBritish Thoracic Society (2013) BTS Guideline on Pulmonary Rehabilitation in Adults. Thorax 68(Suppl 2): ii1–30 Crossref, Google ScholarBritish Thoracic Society (2014) BTS Quality Standards for Pulmonary Rehabilitation in Adults. BTS, London Google ScholarBritish Thoracic Society (2016) Improving the Quality of Diagnostic Spirometry in Adults: The national Register of certified professionals and operators. Available at: https://www.brit-thoracic.org.uk/document-library/delivery-of-respiratory-care/spirometry/improving-the-quality-of-diagnostic-spirometry-(2016)/ (accessed 23 May 2017) Google ScholarD'Ancona G (2015) Inhaled Corticosteroids: Managing side effects. The Pharmaceutical Journal 7851: 294; 247–49 Google ScholarDepartment of Health (2011) An Outcomes Strategy for Chronic Obstructive Pulmonary Disease (COPD) and Asthma in England. Available at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/216139/dh_128428.pdf (accessed 23 May 2017) Google ScholarFletcher CM (1960) MRC Dyspnoea Scale. BMJ 2:1662 Google ScholarGlobal Initiative for Chronic Obstructive Lung Disease (2017) Global Initiative for Chronic Obstructive Lung Disease (GOLD). Available at: http://goldcopd.org (accessed 23 May 2017) Google ScholarHealth and Safety Executive (2017) Chronic Obstructive Pulmonary Disease (COPD). Available at: www.hse.gov.uk/statistics/causdis/copd/ (accessed 23 May 2017) Google ScholarJones PW, Harding G, Berry P et al. (2009) Development and first validation of the COPD Assessment Test. Eur Respir J 34(3): 648–54 Crossref, Google ScholarNational Institute for Health and Care Excellence (2010) Chronic Obstructive Pulmonary Disease in Over 16's: Diagnosis and management. CG101. Available at: https://www.nice.org.uk/Guidance/CG101 (accessed 23 May 2017) Google ScholarOffice of national Statistics (2015) Number of deaths where the underlying cause was chronic obstructive pulmonary disease by month of occurrence, England and Wales, deaths that occurred between 2001 and 2014. Available at: https://tinyurl.com/ybjpzvxn (accessed 23 May 2017) Google ScholarPublic Health England (2012) NHS Atlas of Variation in Healthcare for People with Respiratory Disease. Available at: http://fingertips.phe.org.uk/profile/atlas-of-variation (accessed 23 May 2017) Google ScholarRoyal College of Physicians (2015) Pulmonary Rehabilitation: Time to Breathe Better. Available at: https://www.rcplondon.ac.uk/projects/outputs/pulmonary-rehabilitation-steps-breathe-better (accessed 23 May 2017) Google ScholarScullion J (2017) Standards and Competencies to improve inhaler technique. Independent Nurse. February: 17–20 Google ScholarSuissa S, Patenaude V, Lapi F et al. (2013) Inhaled corticosteroids in Chronic Obstructive Pulmonary Disease and the risk of side effects. Thorax 68(11): 1029–36. doi: https://doi.org/10.1136/thoraxjnl-2012-202872 Crossref, Google ScholarUK Inhaler Group (2016) Inhaler Standards and Competency Document. Available at: www.respiratoryfutures.org.uk/programmes/uk-inhaler-group/ (accessed 23 May 2017) Google Scholar FiguresReferencesRelatedDetails 2 June 2017Volume 23Issue 6ISSN (print): 1358-0574ISSN (online): 1759-7382 Metrics History Published online 14 June 2017 Published in print 2 June 2017 Information© MA Healthcare LimitedPDF download

EPS6.1 A feasibility study of remote monitoring of airway clearance vest use and home spirometry in adults with cystic fibrosis

EPS6.1 A feasibility study of remote monitoring of airway clearance vest use and home spirometry in adults with cystic fibrosis

The ARTP Accredited Spirometry Register: Improving the quality of diagnostic spirometry in adults, and addressing the myths and misconceptions

The proposal to create a National Register of clinicians who perform spirometry has been greeted with some trepidation. Christine Loveridge describes how the new system will work The publication in September 2016 of Improving the quality of diagnostic spirometry in adults: The National Register of certified professionals and operators ( NHSE 2016 ) has been the subject of both discussion and perhaps controversy as some see this as ‘red tape’ and hoops to jump through. This article aims to address these concerns and dispel some of the myths and misconceptions that exist around spirometry training, assessment and accreditation. It will direct those practising spirometry to the most appropriate route to accreditation. The national register document above (seen as a competence framework) will be followed in 2017 with a commissioning document which aims to overarch both the ‘how to’ guide to quality assured diagnostic spirometry ( PCC 2013 ) and the competence framework described above.

Disease Severity Prediction by Spirometry in Adults with Visceral Leishmaniasis from Minas Gerais, Brazil.

Visceral leishmaniasis (VL) is associated with interstitial pneumonitis according to histology and radiology reports. However, studies to address the functional impact on respiratory function in patients are lacking. We assessed pulmonary function using noninvasive spirometry in a cross-sectional study of hospitalized adult VL patients from Minas Gerais, Brazil, without unrelated lung conditions or acute infections. Lung conditions were graded as normal, restrictive, obstructive, or mixed patterns, according to Brazilian consensus standards for spirometry. To control for regional patterns of lung function, we compared spirometry of patients with regional paired controls. Spirometry detected abnormal lung function in most VL patients (70%, 14/20), usually showing a restrictive pattern, in contrast to regional controls and the standards for normal tests. Alterations in spirometry measurements correlated with hypoalbuminemia, the only laboratory value indicative of severity of parasitic disease. Abnormalities did not correlate with unrelated factors such as smoking or occupation. Clinical data including pulmonary symptoms and duration of therapy were also unrelated to abnormal spirometry findings. We conclude that the severity of VL is correlated with a restrictive pattern of lung function according to spirometry, suggesting that there may be interstitial lung involvement in VL. Further studies should address whether spirometry could serve as an index of disease severity in the management of VL.

Impulse Oscillometry Compared to Spirometry in Adults With a History of Bronchitis

Impulse Oscillometry Compared to Spirometry in Adults With a History of Bronchitis

Prediction equations for spirometry in adults in western India

BackgroundSpirometry is an essential investigation in pulmonology. The predicted normal spirometry values depend on various physiological parameters. This study was conducted to collect updated information on pulmonary functions in normal adults from western India. Material and methodsA prospective observational study was undertaken at a tertiary hospital in Mumbai enrolling healthy subjects, 18–75 years, with ethnic origin from western India. Spirometry measurements were carried out as per ATS/ERS-2005 guidelines using a non-heated Fleish Pneumotachograph spirometer. Data was analyzed using SPSS for Pearson's correlation analysis, multiple linear regressions and log transformations of variables to get the best prediction equations. Results310 subjects (185 males, 125 females) were included. Lung function values were higher in men as compared to women. In multivariate linear regression models, age and height were major predictor variables for all spirometry parameters. Addition of weight as a determinant variable did not make significant contribution to the models except for PEFR in males and F75 in females. Regression equations were established for FVC, FEV1, FEV1/FVC ratio, PEFR, F25–75, F50, and F75. The standard-error-of-estimate was provided to enable computation of lower limits of normal for these parameters. ConclusionWe propose regression equations for spirometry variables developed using the current standards for adult West Indian population fulfilling the long-felt need for updated equations.

Guideline for office spirometry in adults, 2012

Office spirometry remains an integral part of a comprehensive respiratory evaluation and is used to categorise the nature, severity and progression of respiratory diseases and to measure response to treatment. These updated guidelines are aimed at improving the quality, standardisation and usefulness of office spirometry in South Africa. All equipment should have proof of validation regarding resolution and the system's linearity (consistency). Moreover, equipment must be calibrated daily and quality controlled. It is also important to have standard operating procedures in place, including the documentation of ambient conditions and infection control measures. Adequate spirometry relies on a competent operator, accurate equipment, standardised operating procedures, quality control and patient co-operation. The indication for spirometry in a particular patient should be unambiguous and should be documented. Subjects should be appropriately prepared for testing, and patient details must be documented. Forced vital capacity (FVC) manoeuvres (either closed or open circuit) must be performed strictly according to guidelines, and strict quality assurance methods should be in place, including acceptability criteria (for any given effort) and repeatability (between efforts). Testing should continue until at least 3 acceptable curves are produced (with 2 fulfilling repeatability criteria). Other indices are derived from these efforts. Test results must be categorised and graded according to current guidelines, taking into account the indication for the test and the appropriateness of reference values.

Associations between birth weight, early childhood weight gain and adult lung function

Background:Low birth weight is associated with lower values for spirometry in adults but it is not known if birth weight influences other measures of pulmonary function. It is also unclear...

Spirometry in 5‐year‐olds—validation of current guidelines and the relation with asthma

Spirometry is more frequently measured in younger children. Our primary aim was to validate 2005 ATS-ERS Task Force standards for spirometry in adults and older children among a population of 5-year-old children. Our secondary aim was to relate spirometry to asthma symptoms. Children were participants in a longitudinal cohort study where asthma symptoms and spirometry were assessed. Of the 827 children assessed, spirometry was obtained in 638 (85 with wheeze). A back-extrapolated volume/FVC ratio of <5% was achieved in 99% of children, the best two FVC were < or =150 ml of each other in 89% and three efforts were obtained within six attempts in 88%. The best two FVC were within 10% of each other in 82% of children. Only 13% achieved a forced expiratory time (FET) of > or =3 sec, whereas 80% had an FET of > or =1 sec. All criteria (including FET > or =1 s and FVC < or =10%) were met in 400 (65%) of the 638 children. Most spirometric indices were reduced in association with current wheeze and a history of asthma; children with current wheeze had a mean reduction of 0.65 FEV(1) z score compared to healthy children, P < 0.001. An FEV(1) z score of -1.0 had 82% sensitivity but only 50% specificity for current wheeze, the corresponding numbers for an FEF(50) z score of -1.0 being 79% and 71%. The standards for spirometry are mostly achieved in this age group but are not necessarily valid and require revision. Reliable spirometry is feasible in 5-year-old children where reduced measurements are associated with asthma symptoms and in whom FEF(50) appears to be the most discriminatory variable.

Tidal Volume Forced Expiration in Asthmatic Infants: Reproducibility and Reversibility Tests

Background: The tidal volume forced expiration technique used in infants is considered as the first practical noninvasive method of assessing airway physiology in infants. However, its role has been discussed mainly due to the high variability of the derived parameters. Objectives: The aim of the study was to assess the reproducibility of a complete measurement with the tidal volume forced expiration technique in infants as measured by the maximal flow at FRC (v̇_maxFRC). A second aim was to evaluate the bronchial reversibility test in infant asthma. Methods: Thirty infants with asthma were investigated with the tidal volume forced expiration technique twice with 10 min in between and a third time 10 min after inhalation of terbutalin 0.5 mg. Results: The mean v̇_maxFRC in the first investigation was 285 ml·s^–1 (coefficient of variation 57%), unchanged in the second investigation and significantly lower than the mean predicted value of 404 ml·s^–1. The relative difference between the 2 investigations of v̇_maxFRC was mean 10.5% (SD 8.4) of the absolute v̇_maxFRC value and independent of the size of this v̇_maxFRC value. The 95% confidence interval for individual changes would then be up to 27% (mean + 2 SD). The infants with the lowest v̇_maxFRC percent predicted decreased further in v̇_maxFRC after inhalation of the bronchodilator (p < 0.05). Conclusions: The tidal volume forced expiration technique was able to measure flow at late expiration with the same reproducibility as seen with spirometry in adults, even if the flow was low. We found the technique acceptable for clinical practice and research, but the results from reversibility tests are difficult to interpret. A significant change of v̇_maxFRC would, however, be 27% or more.