Using the phase III slope of exhaled methane during a single breath DLCO test to assess ventilation heterogeneity.

BACKGROUND: The Phase III slope from a single breath nitrogen washout test provides information about ventilation heterogeneity (VH) in the lungs. PURPOSE: To determine if the Phase III slope from the exhaled tracer gas concentration during a standard, single breath DLCO test using rapid gas analysis provides similar information about VH. BASIC PROCEDURES: Retrospective analysis of clinical pulmonary function laboratory data including spirometry, lung volumes, and DLCO. The normalized Phase III slope from the exhaled CH4 concentration (SnCH4) was compared among different patterns of physiologic abnormality and with VA/TLC as an indicator of VH. MAIN FINDINGS: SnCH4 was the steepest in the group with "Obstruction and Low DLCO", with significant differences between this group and the "Normal", "Obstruction with Normal DLCO", "Mixed Obstruction and Restriction" and "Isolated Low DLCO" groups. SnCH4 was steeper in current and former smokers compared to non-smokers. Among the entire study sample, SnCH4 correlated with VA/TLC (Spearman rho = -0.56, p < 0.01) and remained a significant determinant of VA/TLC by regression modeling. PRINCIPAL CONCLUSIONS: The SnCH4 derived from a standard, single breath DLCO test using rapid gas analysis varied among distinct patterns of physiologic abnormalities and was associated with VA/TLC as a measure of VH.

Improving spirometry testing by understanding patient preferences.

The American Thoracic Society and European Respiratory Society commissioned a task force to update the technical standards for spirometry testing with the aim of increasing the accuracy, precision and quality of spirometry measurements and improving the patient experience. To inform the task force with patient experiences, the European Lung Foundation, in collaboration with the task force, conducted an online survey in 10 languages between August and September 2018. There were 1760 respondents from 52 countries. The majority were adults (97.1%); the most common reasons for spirometry referral were diagnosis (35.0%) and management of an ongoing condition (60.1%). 53.2% reported regularly using inhalers. Respondents were very experienced with spirometry: 89.9% completed more than one test; 48% completed 10 or more tests. However, most reported not knowing what forced expiratory volume in 1 s (FEV1) means (59.4%) and only 39.6% knew their most recent FEV1; the exception was respondents with cystic fibrosis who reported much greater knowledge. Respondents rated as moderately or seriously problematic: being told to keep blowing when they felt nothing is coming out (31.4%), coughing (30.4%), tiredness (26.3%) and concern about shortness of breath (20.1%). Overall, respondents found spirometry to be acceptable; however, an important minority (17%) found it difficult. Patients want clear information before, during and after the test, including information on stopping medications. Operators have an important role in increasing the ease of patients and changes to the testing environment can increase patient comfort. Patients want access to their results and want to understand how they relate to their individual health.

Respiratory Duty Cycles in Individuals With and Without Airway Hyperresponsiveness.

BACKGROUND: The respiratory duty cycle (Ti/Ttot) can influence bronchoprovocation test results and nebulized drug delivery. The Ti/Ttot has not yet been examined in individuals with airway hyperresponsiveness (AHR) in typical bronchoprovocation test conditions. This study investigated the mean Ti/Ttot in participants with and without AHR and whether the Ti/Ttot changes with increasing bronchoconstriction. METHODS: Fifteen participants with AHR and fifteen participants without AHR completed this randomized crossover study. An ultrasonic spirometer was used for continuous measurement of the Ti/Ttot as participants inhaled room air or aerosolized solution. Each participant completed two methacholine challenges, one using a continuous-output vibrating mesh nebulizer/ultrasonic spirometer and one with the nebulizer only. Prior to each methacholine challenge, participants inhaled room air and aerosolized saline through the nebulizer/spirometer setup to record baseline Ti/Ttot data. RESULTS: The mean Ti/Ttot findings [95% CIs] during room air inhalation were 0.392 [0.378-0.406] and 0.447 [0.426-0.468] in participants with and without AHR, respectively (P < .001). The mean Ti/Ttot during saline inhalation were 0.389 [0.373-0.405] and 0.424 [0.398-0.450] in participants with and without AHR (P = .040). The Ti/Ttot showed a nonsignificant downward trend with progressive methacholine-induced bronchoconstriction. CONCLUSIONS: The mean Ti/Ttot in participants with AHR closely resembles the assumed Ti/Ttot of 0.40 recommended for standard use when calculating methacholine challenge results. Since the Ti/Ttot did not change significantly over the course of a methacholine challenge, the same Ti/Ttot can be used to calculate the dose of methacholine inhaled, regardless of the level of bronchoconstriction. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03505489; URL: www.clinicaltrials.gov.

Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement.

Background: Spirometry is the most common pulmonary function test. It is widely used in the assessment of lung function to provide objective information used in the diagnosis of lung diseases and monitoring lung health. In 2005, the American Thoracic Society and the European Respiratory Society jointly adopted technical standards for conducting spirometry. Improvements in instrumentation and computational capabilities, together with new research studies and enhanced quality assurance approaches, have led to the need to update the 2005 technical standards for spirometry to take full advantage of current technical capabilities.Methods: This spirometry technical standards document was developed by an international joint task force, appointed by the American Thoracic Society and the European Respiratory Society, with expertise in conducting and analyzing pulmonary function tests, laboratory quality assurance, and developing international standards. A comprehensive review of published evidence was performed. A patient survey was developed to capture patients' experiences.Results: Revisions to the 2005 technical standards for spirometry were made, including the addition of factors that were not previously considered. Evidence to support the revisions was cited when applicable. The experience and expertise of task force members were used to develop recommended best practices.Conclusions: Standards and consensus recommendations are presented for manufacturers, clinicians, operators, and researchers with the aims of increasing the accuracy, precision, and quality of spirometric measurements and improving the patient experience. A comprehensive guide to aid in the implementation of these standards was developed as an online supplement.

Recommendations for a Standardized Pulmonary Function Report. An Official American Thoracic Society Technical Statement.

BACKGROUND: The American Thoracic Society committee on Proficiency Standards for Pulmonary Function Laboratories has recognized the need for a standardized reporting format for pulmonary function tests. Although prior documents have offered guidance on the reporting of test data, there is considerable variability in how these results are presented to end users, leading to potential confusion and miscommunication. METHODS: A project task force, consisting of the committee as a whole, was approved to develop a new Technical Standard on reporting pulmonary function test results. Three working groups addressed the presentation format, the reference data supporting interpretation of results, and a system for grading quality of test efforts. Each group reviewed relevant literature and wrote drafts that were merged into the final document. RESULTS: This document presents a reporting format in test-specific units for spirometry, lung volumes, and diffusing capacity that can be assembled into a report appropriate for a laboratory's practice. Recommended reference sources are updated with data for spirometry and diffusing capacity published since prior documents. A grading system is presented to encourage uniformity in the important function of test quality assessment. CONCLUSIONS: The committee believes that wide adoption of these formats and their underlying principles by equipment manufacturers and pulmonary function laboratories can improve the interpretation, communication, and understanding of test results.

Official ERS technical standards: Global Lung Function Initiative reference values for the carbon monoxide transfer factor for Caucasians.

There are numerous reference equations available for the single-breath transfer factor of the lung for carbon monoxide (T LCO); however, it is not always clear which reference set should be used in clinical practice. The aim of the study was to develop the Global Lung Function Initiative (GLI) all-age reference values for T LCOData from 19 centres in 14 countries were collected to define T LCO reference values. Similar to the GLI spirometry project, reference values were derived using the LMS (lambda, mu, sigma) method and the GAMLSS (generalised additive models for location, scale and shape) programme in R.12 660 T LCO measurements from asymptomatic, lifetime nonsmokers were submitted; 85% of the submitted data were from Caucasians. All data were uncorrected for haemoglobin concentration. Following adjustments for elevation above sea level, gas concentration and assumptions used for calculating the anatomic dead space volume, there was a high degree of overlap between the datasets. Reference values for Caucasians aged 5-85 years were derived for T LCO, transfer coefficient of the lung for carbon monoxide and alveolar volume.This is the largest collection of normative T LCO data, and the first global reference values available for T LCO.

The Global Lung Function Initiative (GLI) Network: bringing the world's respiratory reference values together.

The Global Lung Function Initiative (GLI) Network has become the largest resource for reference values for routine lung function testing ever assembled. This article addresses how the GLI Network came about, why it is important, and its current challenges and future directions. It is an extension of an article published in Breathe in 2013 [1], and summarises recent developments and the future of the GLI Network. KEY POINTS: The Global Lung Function Initiative (GLI) Network was established as a result of international collaboration, and altruism between researchers, clinicians and industry partners. The ongoing success of the GLI relies on network members continuing to work together to further improve how lung function is reported and interpreted across all age groups around the world.The GLI Network has produced standardised lung function reference values for spirometry and gas transfer tests.GLI reference equations should be adopted immediately for spirometry and gas transfer by clinicians and physiologists worldwide.The recently established GLI data repository will allow ongoing development and evaluation of reference values, and will offer opportunities for novel research. EDUCATIONAL AIMS: To highlight the advances made by the GLI Network during the past 5 years.To highlight the importance of using GLI reference values for routine lung function testing (e.g. spirometry and gas transfer tests).To discuss the challenges that remain for developing and improving reference values for lung function tests.