Forced Expiratory Maneuvers Research Articles

Exhaled breath analysis in adult patients with cystic fibrosis by real-time proton mass spectrometry

BackgroundProton-transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) is a promising tool for a rapid online determination of exhaled volatile organic compounds (eVOCs) profiles in patients with cystic fibrosis (CF). ObjectiveTo detect VOC breath signatures specific to adult patients with CF compared with controls using PTR-TOF-MS. Methods102 CF patients (54 M/48, mean age 25.6 ± 7.8 yrs) and 97 healthy controls (56 M/41F, mean age 25.8 ± 6.0 yrs) were examined. Samples from normal quiet breathing and forced expiratory maneuvers were analyzed with PTR-TOF-MS (Ionicon, Austria) to obtain VOC profiles listed as ions at various mass-to-charge ratios (m/z). ResultsPTR-TOF-MS analysis was able to detect 167 features in exhaled breath from CF patients and healthy controls. According to cluster analysis and LASSO regression, patients with CF and controls were separated. The most significant VOCs for CF were indole, phenol, dimethyl sulfide, and not indicated: m/z = 297.0720 ([C12H13N2O7 and C17H13O5]H + ), m/z = 281.0534 ([C19H7NO2, C12H11NO7 and C16H9O5]H + ) during five-fold cross-validation both in forced expiratory maneuver and in normal quiet breathing. ConclusionPTR-TOF-MS is a promising method for determining the molecular composition of exhaled air specific to CF.

Beyond forced exhalation: impulse oscillometry as a promising tool for bronchial hyperresponsiveness evaluation

Introduction: The multiple forced expiratory maneuvers that must be performed during methacholine test require a high degree of collaboration and can lead to fatigue. However, impulse oscillometry (IOS) is a noninvasive test, quick and easy to perform, that does not require effort-dependent maneuvers. Objectives: The primary endpoint was to evaluate the relationship between IOS and spirometry during the methacholine test. The secondary endpoint was to study the predictive value of baseline IOS in the development of bronchial hyperreactivity. Methods: Observational, prospective, cross-sectional study, with recruitment of consecutive patients from the pulmonology department with clinical suspicion of bronchial asthma with negative bronchodilator test and normal FeNO. Results: Twenty-five patients were included, with a mean age of 49 ± 18 years. Thirteen patients (52%) had a positive methacholine test. The correlation between IOS indices and FEV1 was significant (p < 0.05) in all cases. The indices with the highest predictive power were R5-20 and AX. The optimal cutoff points were an increase of greater than 32.96% in R5, greater than 120.83% for X5, an increase of 30.30 [kPa l-1s-1] in R5-20, and an increase of 1.01 [kPa l−1] for AX. Baseline oscillometry demonstrated a strong predictive value in the development of bronchial hyperreactivity, with a sensitivity of 61.5% and a specificity of 91.7%, using the cut-off point of 160.0% for R5. Conclusions: IOS may be a valuable alternative to forced spirometry in detecting bronchial hyperreactivity during the methacholine test, showing a good correlation between both tests.

Oscillometry of the respiratory system in Parkinson's disease: physiological changes and diagnostic use

BackgroundLung function analysis in Parkinson's disease (PD) is often difficult due to the demand for adequate forced expiratory maneuvers. Respiratory oscillometry exams require onlyquiet tidal breathing and provide a detailed analysis of respiratory mechanics. We hypothesized that oscillometry would simplify the diagnosis of respiratory abnormalitiesin PD and improve our knowledge about the pathophysiological changes in these patients.Materials and methodsThis observational study includes 20 controls and 47 individuals with PD divided into three groups (Hoehn and Yahr Scale 1–1.5; H&Y scale 2–3 and PD smokers).The diagnostic accuracy was evaluated by investigating the area under the receiver operating characteristic curve (AUC).ResultsInitial stages are related to increased peripheral resistance (Rp; p = 0.001). In more advanced stages, a restrictive pattern is added, reflected by reductions in dynamic compliance (p < 0.05) and increase in resonance frequency (Fr; p < 0.001). Smoking PD patients presented increased Rp (p < 0.001) and Fr (p < 0.01). PD does not introduce changes in the central airways. Oscillometric changes were correlated with respiratory muscle weakness (R = 0.37, p = 0.02). Rp showed adequate accuracy in the detection of early respiratory abnormalities (AUC = 0.858), while in more advanced stages, Fr showed high diagnostic accuracy (AUC = 0.948). The best parameter to identify changes in smoking patients was Rp (AUC = 0.896).ConclusionThe initial stages of PD are related to a reduction in ventilation homogeneity associated with changes in peripheral airways. More advanced stages also include a restrictive ventilatory pattern. These changes were correlated with respiratory muscle weakness and were observed in mild and moderate stages of PD in smokers and non-smokers. Oscillometry may adequately identify respiratory changes in the early stages of PD and obtain high diagnostic accuracy in more advanced stages of the disease.

PEAK EXPIRATORY FLOW RATE (PEFR) VALUES OBTAINED WITH WRIGHT'S PEAK FLOW METER AND DIGITAL SPIROMETER IN OBSTRUCTIVE AIRWAY DISEASE (OAD) PATIENTS – A COMPARATIVE STUDY

Introduction: Peak expiratory ow rate (PEFR) is the highest ow achieved from a maximum forced expiratory maneuver and is a good modality in diagnosing and monitoring Br.asthma; in COPD it gives a rough estimate of the severity of obstruction.Normal values in males and females range between 320-550L/min. PEFR values can be obtained by a Peak Flow Meter or by standard Spirometer. To compare PEFR values obtained Aims And Objectives: by Wright's Peak Flow meter and those obtained by a Digital Spirometer and to understand Whether PEFR values are reliable in the diagnosis and monitoring of Obstructive Airway Disease. 75 Consecutive patients who pr Materials And Methods: esented with a history of COPD, Br.asthma or Bronchiectasis to the Respiratory Medicine OP, Govt General Hospital, Nellore, AP were recruited to the studyand PEFR values were recorded by both Peakowmeter and Spirometer. The rang Results: e of PEFR values obtained was between 120-480 L/min .and the difference was in the range of 9-164 L/min. In the present study the Conclusion: difference in values is not very signicant andhence PEFR can be used as a diagnostic &amp; monitoring tool in OAD.

Understanding the fundamentals of oscillometry from a strip of lung tissue.

Metrics used in spirometry caught on in respiratory medicine not only because they provide information of clinical importance but also because of a keen understanding of what is being measured. The forced expiratory volume in 1 s (FEV1), for example, is the maximal volume of air that can be expelled during the first second of a forced expiratory maneuver starting from a lung inflated to total lung capacity (TLC). Although it represents a very gross measurement of lung function, it is now used to guide the diagnosis and management of many lung disorders. Metrics used in oscillometry are not as concrete. Resistance, for example, has several connotations and its proper meaning in the context of a lung probed by an external device is not always intuitive. I think that the popularization of oscillometry and its firm implementation in respiratory guidelines starts with a keen understanding of what exactly is being measured. This review is an attempt to clearly explain the basic metrics of oscillometry. In my opinion, the fundamentals of oscillometry can be understood using a simple example of an excised strip of lung tissue subjected to a sinusoidal strain. The key notion is to divide the sinusoidal reacting force from the tissue strip into two sinusoids, one in phase with the strain and one preceding the strain by exactly a quarter of a cycle. Similar notions can then be applied to a whole lung subjected to a sinusoidal flow imposed at the mouth by an external device to understand basic metrics of oscillometry, including resistance, elastance, impedance, inertance, reactance and resonant frequency.

Acute Effect of Bronchodilator on Intrathoracic Airway Wall Compliance in COPD Patients

PurposeIn patients with chronic obstructive pulmonary disease (COPD), bronchial responsiveness after acute administration of short acting bronchodilators is conventionally assessed by measuring the improvement of forced expiratory volume in the first second (FEV1) during a maximal forced expiratory maneuver. This study aimed to measure the variation of intrathoracic airway wall compliance (AWC) after acute administration of short acting beta-2 agonist in COPD patients since this might influence the final modification of airway caliber during maximal expiratory effort and the resulting bronchodilation as inferred by FEV1 changes.MethodsIn a group of 10 patients suffering from COPD, intrathoracic AWC was measured at middle (50% of Forced Vital Capacity (FVC) and low (75% of FVC) lung volumes using the interrupter method during forced expiratory maneuver in basal conditions and after acute inhalation of albuterol (salbutamol) (400 mcg by MDI). Ten healthy subjects were examined similarly as a control group.ResultsLower values of baseline intrathoracic AWC at both lung volumes were found in COPD patients (1.72 ± 0.20 ml/cmH2O and 1.08 ± 0.20 ml/cmH2O, respectively) as compared to controls (2.28 ± 0.27 ml/cmH2O and 1.44 ± 0.22 ml/cmH2O, respectively) (p < 0.001). In COPD patients, AWC increased significantly at both lung volumes after salbutamol, amounting to 1.81 ± 0.38 ml/cmH2O and 1.31 ± 0.39 ml/cmH2O, respectively (p < 0.01), but the relative change was not different from that observed in controls.ConclusionIn COPD patients, AWC is reduced compared to controls, but after bronchodilator, the intrathoracic airways become more compliant. The consequent increased collapsibility under high positive pleural pressure could limit the airway caliber improvement seen after bronchodilator, as assessed by the FEV1 changes during the forced expiratory maneuver, underestimating the effective bronchodilation achieved in these patients.

DIAPHRAGMATIC CHOREA IN A PATIENT WITH HUNTINGTON'S DISEASE: A CASE REPORT

TOPIC: Pulmonary Physiology TYPE: Fellow Case Reports INTRODUCTION: Respiratory muscle weakness is known to occur in neurodegenerative disorders, including Huntington's disease (HD), and causes 25% of deaths in this population. Though diaphragmatic dystonia has been described in some neurodegenerative diseases, it has not been in HD. In general, little published data exists on overall respiratory function and diaphragmatic movement in HD. CASE PRESENTATION: We describe a 58-year-old male with HD, presenting with progressive dyspnea over 1 year and an accompanying choking sensation upon awakening. Cardiac evaluation with echocardiogram and dobutamine stress test revealed only left ventricular hypertrophy. Family history includes HD in his mother, diagnosed at autopsy age 72;an older brother with HD onset at 53 that died at 62;a maternal aunt with onset in her 50s that died in her 70s. His maternal grandmother and 2 other family members also had involuntary movements believed to be chorea. Most died from respiratory complications. Physical exam showed adequate air entry bilaterally, with clear breath sounds and decreased chest wall expansion. No abdominal paradox or diaphragm dysfunction was appreciated in supine or seated position. On walking oximetry, he became tachypneic and dyspneic after 2 minutes of walking, prompting him to stop. His saturation on room air did not drop below 96%. Heart rate increased to 110 beats per minute. Laboratory panel revealed hemoglobin 13.8 g/dl. A venous blood gas revealed pH 7.38 and pCO2 of 49.A dynamic digital chest radiography (DDR) was performed during two tidal breaths and a forced inspiratory and expiratory maneuver. This revealed decreased bilateral lung inflation. Diaphragmatic contours were elevated bilaterally with a mildly reduced excursion. During the breathing cycle multiple independent diaphragmatic contractions were appreciated on forced inspiration and exhalation resulting in paradoxical motion and dyssynchrony. There was exaggerated use of accessory muscles in the shoulder girdle as a compensatory mechanism. Spasms in the upper airway were also noted throughout the test. Because of covid restrictions, the patient is awaiting pulmonary function tests. DISCUSSION: DDR uniquely provides the opportunity to interrogate respiratory physiology and identify diaphragmatic abnormalities, such as coordination impairments and dyssynchrony compared to static chest radiography;with lower levels of radiation as used in video fluoroscopy. As previously described1, we suggest that the understanding of dyspnea in patients with neurologic disease is enhanced using DDR. CONCLUSIONS: We report the first case of diaphragmatic chorea in a patient with HD using DDR. Future studies are needed to better understand this newly recognized phenomenon of diaphragmatic discoordination and its association with shortness of breath. REFERENCE #1: O'Sullivan M, Singh A, Prime D, Moore J, Zink S. A Whole New Chest X-Ray. ATS 2019 ePoster Viewing Site. Published May 2019. Accessed April 28, 2021. https://cslide-us.ctimeetingtech.com/ats2019_eposter/attendee/eposter/poster/6529 DISCLOSURES: No relevant relationships by Norma Braun, source=Web Response No relevant relationships by Jose Concepcion, source=Web Response No relevant relationships by Natasha Garg, source=Web Response No relevant relationships by Mary O Sullivan, source=Web Response No relevant relationships by Valeria Santibanez, source=Web Response

Imaging Dynamic Expiration: Feasibility of MRI Spirometry Using Hyperpolarized Xenon Gas.

To examine the feasibility of imaging-based spirometry using high-temporal-resolution projection MRI and hyperpolarized xenon 129 (129Xe) gas. In this prospective exploratory study, five healthy participants (age range, 25-45 years; three men) underwent an MRI spirometry technique using inhaled hyperpolarized 129Xe and rapid two-dimensional projection MRI. Participants inhaled 129Xe, then performed a forced expiratory maneuver while in an MR imager. Images of the lungs during expiration were captured in time intervals as short as 250 msec. Volume-corrected images of the lungs at expiration commencement (0 second), 1 second after expiration, and 6 seconds after expiration were extracted to generate forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio pulmonary maps. For comparison, participants performed conventional spirometry in the sitting position using room air, in the supine position using room air, and in the supine position using a room air and 129Xe mixture. Paired t tests with Bonferroni corrections for multiple comparisons were used for statistical analyses. The mean MRI-derived FEV1/FVC value was lower in comparison with conventional spirometry (0.52 ± 0.03 vs 0.70 ± 0.05, P < .01), which may reflect selective 129Xe retention. A secondary finding of this study was that 1 L of inhaled 129Xe negatively impacted pulmonary function as measured by conventional spirometry (in supine position), which reduced measured FEV1 (2.70 ± 0.90 vs 3.04 ± 0.85, P < .01) and FEV1/FVC (0.70 ± 0.05 vs 0.79 ± 0.04, P < .01). A forced expiratory maneuver was successfully imaged with hyperpolarized 129Xe and high-temporal-resolution MRI. Derivation of regional lung spirometric maps was feasible.Keywords: MR-Imaging, MR-Dynamic Contrast Enhanced, MR-Functional Imaging, Pulmonary, Thorax, Diaphragm, Lung, Pleura, Physics Supplemental material is available for this article. © RSNA, 2021.

Which factors can influence the number of forced expiratory manoeuvres on spirometry in schoolchildren?

Spirometry is of great value for understanding respiratory function and management of lung diseases. Adaptations in the exam were made to meet paediatric population since the forced expiratory manoeuvres (FEM) present in the exam require effort and cooperation; therefore, its use should be reconsidered. To analyse factors that may influence the number of FEM required for successful spirometry in schoolchildren. Healthy children aged between 6 and 12years were tested. FEM were conducted according to the American Thoracic Society/European Respiratory Society guideline. The children were divided into three groups according to the number of attempts: G3M if child completed the test in three FEM; G4M if child completed in four attempts FEM; and G5/8M if child completed the test in five to eight FEM. Factors that potentially influenced the number of FEM included: age; impulse oscillometry parameters; slow vital capacity; respiratory muscle strength; orofacial motor function, school performance, physical activity level and quality of life. The Kolmogorov-Smirnov test was performed, followed by the Chi-Square, repeated measures ANOVA and Kruskal-Wallis tests; thereafter, a multinomial logistic regression was applied. One hundred and forty-nine schoolchildren (80 girls) with mean age of 9.13years (±1.98) were included, age was related to the required number of FEM (F=3.38(2), P=.03) and children with poor school performance had a 2.84-fold greater chance of completing the exam in more than five attempts. Age and school performance influenced the number of FEM required for a successful spirometry in schoolchildren.

Peak In- and Expiratory Flow Revisited: Reliability and Reference Values in Adults

Background: While peak in- and expiratory flow rates offer valuable information for diagnosis and monitoring in respiratory disease, these indices are usually considered too variable to be routinely used for quantification in clinical practice. Objectives: The aim of the study was to obtain reproducible measurements of maximal inspiratory flow rates and to construct reference equations for peak in- and expiratory flows (PIF and PEF). Method: With coaching for maximal effort, 187 healthy Caucasian subjects (20–80 years) performed at least 3 combined forced inspiratory and expiratory manoeuvres, until at least 2 peak inspiratory flow measurements were within 10% of each other. The effect on PIF preceded by a slow expiration instead of a forced expiration and PIF repeatability over 3 different days was also investigated in subgroups. Reference values and limits of normal for PIF, mid-inspiratory flow, and PEF were obtained according to the Lambda-Mu-Sigma statistical method. Results: A valid PIF could be obtained within 3.3 ± 0.6(SD) attempts, resulting in an overall within-test PIF variability of 4.6 ± 3.2(SD)%. A slow instead of a forced expiration prior to forced inspiration resulted in a significant (p < 0.001) but small PIF increase (2.5% on average). Intraclass correlation coefficient for between-day PIF was 0.981 (95% CI: 0.960–0.992). Over the entire age range, inter-subject PIF variability was smaller than in previous reports, and PIF could be predicted based on its determinants gender, age, and height (r² = 0.53). Conclusions: When adhering to similar criteria for the measurement of effort-dependent portions of inspiratory and expiratory flow-volume curves, performed according to current ATS/ERS standards, it is possible to obtain reproducible PIF and PEF values for use in routine clinical practice.

Effect of Non-Newtonian Dynamics on the Clearance of Mucus From Bifurcating Lung Airway Models.

Mucus hypersecretion is a common pathophysiological manifestation of several obstructive airway diseases in which the mucociliary clearance is impaired, and the airflow generated by a cough or a forced expiratory maneuver called the huff is primarily responsible for clearing mucus. This airflow driven clearance of mucus is a complex process that is affected by the mucus rheology, airflow rate, airway geometry, and gravity. This study examines the role of mucus rheology in the transport and distribution of mucus in idealized 3D airway geometries. The complex air-mucus interface was tracked by the volume-of-fluid (VOF) model, and the turbulence in the core airflow was modeled using the k-ω shear stress transport (SST) model. Mucus was modeled as a shear-thinning liquid by using a power-law model. The computational model was validated using in vitro experimental data available in the literature. Gravity-dominated eccentric core-annular flow was observed with the core biased toward the outer wall in the inclined daughter branches of the bifurcation models, which transitions into concentric core-annular flow in the trachea. The increase in tangential shear at the interface due to the secondary flow structures developed in the flow divider location resulted in a region of enhanced mucus clearance with reduced mucus layer thickness. Secondary flow developed due to the curvature in the airway geometry resulted in a local redistribution of mucus that reduced the eccentricity. The accumulation of mucus around the carinal ridges and the regions with reduced clearance are sites with the potential for microbial growth.

The Effect of Combination Pranayama Yoga and Endurance Training Exercise on Peak Expiratory Flow (PEF) in Adult Asthmatic Patients

Pranayama Yoga can help improve breathing, and improve calm and also relieve stress. Endurance training can increase lung capacity, improve fitness, and relax the body. However, the combination of pranayama yoga and endurance exercises has never been done in asthma patients. The purpose of this study was to analyze the combination of pranayama yoga exercises and endurance exercises for Increased Peak Forced Expiration Flow. The design of this study was Quasy Experiment with a pretest-posttest control group design, the location of the study was in the pulmonary clinic of Universitas Airlangga Hospital and Haji General Hospital in Surabaya, East java. Respondents were selected by purposive sampling techniques in accordance with inclusion criteria with a total of 72 respondents. Peak Expiration Flow is measured from forced vital capacity or The peak expiratory flow (PEF) is the maximum flow obtained within the first 200 milliseconds of a forced expiratory maneuver after inhalation to total lung capacity (TLC). The intervention group was given a combination exercise by doing pranayama yoga and endurance exercise for 6 weeks, 2x per week, 51 minutes for each training session. Pranayama yoga combination exercises and endurance exercise using trainer instructors and modules. FPEF and asthma control were measured every week for 6 weeks. The results showed a significant difference in the level of FPEF and asthma control before and after 6 weeks of interventions combination of pranayama yoga and endurance exercise in the intervention group obtained significance values (p &lt;0.05) with p = 0.000 and asthma control in the intervention group (p &lt;0, 05) with p = 0.000 the results of the research shows that by practicing pranayama yoga and endurance exercise can improve FPEF and asthma control. Pranayama yoga and endurance exercise can be used as an complementary therapy in supporting pharmacological therapy to improve FPEF and control asthma.

Caring for Miners During the Coronavirus Disease-2019 (COVID-19) Pandemic.

Caring for Miners During the Coronavirus Disease-2019 (COVID-19) Pandemic.

“Reactance inversion” at low frequencies in a child undergoing treatment of a cystic fibrosis exacerbation

IntroductionImpulse oscillometry (IOS) employs high frequency sinusoidal or impulse pressure and flow waveforms to interrogate the mechanical properties of the respiratory system. It has special applications to preschool and younger children who may have difficulty performing the repetitive forced expiratory maneuvers required for spirometry.Case presentationWe present a case illustrating improvements of respiratory system mechanics measured by IOS in a 6‐year‐old child with cystic fibrosis (CF) who demonstrated clinical and radiological improvement after a course of therapy with hospitalization and intravenous antibiotics, and initiation of a cystic fibrosis transmembrane regulator (CFTR) protein corrector/potentiator agent. We also report a new finding: observed lower than expected reactance at low compared to high frequencies (“reactance inversion”).ConclusionReactance inversion may reflect parallel pathway inhomogeneities in resistance and elastance or intrabreath airway inertance changes in young children with CF. Further study is needed in children with airway obstruction due to asthma, cystic fibrosis, and chronic lung disease of infancy to demonstrate the prevalence of this finding and whether it is specific to a measurement device.

EFFECT OF BODY MASS INDEX ON PEAK EXPIRATORY FLOW RATE

Obesity has become one of the major health issues in India. WHO defines obesity as “A condition with excessive fat accumulation in the body to the extent that the health and wellbeing are adversely affected”. Obesity results from a complex interaction of genetic, behavioral, environmental and socioeconomic factors causing an imbalance in energy production and expenditure. Peak expiratory flow rate is the maximum rate of airflow that can be generated during forced expiratory manoeuvre starting from total lung capacity. The simplicity of the method is its main advantage. It is measured by using a standard Wright Peak Flow Meter or mini Wright Meter. The aim of the study is to see the effect of body mass index on Peak Expiratory Flow Rate values in young adults. The place of a study was done tertiary health care centre, in India for the period of 6 months. Study was performed on 80 subjects age group 20 -30 years, categorised as normal weight BMI =18.5 -24.99 kg/m2 and overweight BMI =25-29.99 kg/m2. There were 40 normal weight BMI (Group A) and 40 over weight BMI (Group B). BMI affects PEFR. Increase in BMI decreases PEFR. Early identification of risk individuals prior to the onset of disease is imperative in our developing country.&#x0D; Keywords: BMI, PEFR.

Determination of reliable lung function parameters in intubated mice

BackgroundAnimal models and, in particular, mice models, are important tools to investigate the pathogenesis of respiratory diseases and to test potential new therapeutic drugs. Lung function measurement is a key step in such investigation. In mice, it is usually performed using forced oscillation technique (FOT), negative pressure-driven forced expiratory (NPFE) and pressure-volume (PV) curve maneuvers. However, these techniques require a tracheostomy, which therefore only allows end-point measurements. Orotracheal intubation has been reported to be feasible and to give reproducible lung function measurements, but the agreement between intubation and tracheostomy generated-data remains to be tested.MethodsUsing the Flexivent system, we measured lung function parameters (in particular, forced vital capacity (FVC), forced expiratory volume in the first 0.1 s (FEV0.1), compliance (Crs) of the respiratory system, compliance (C) measured using PV loop and an estimate of inspiratory capacity (A)) in healthy intubated BALB/cJ mice and C57BL/6 J mice and compared the results with similar measurements performed in the same mice subsequently tracheostomized after intubation, by means of paired comparison method, correlation and Bland-Altman analysis. The feasibility of repetitive lung function measurements by intubation was also tested.ResultsWe identified parameters that are accurately evaluated in intubated animals (i.e., FVC, FEV0.1, Crs, C and A in BALB/cJ and FVC, FEV0.1, and A in C57BL/6 J). Repetitive lung function measurements were obtained in C57BL/6 J mice.ConclusionThis subset of lung function parameters in orotracheally intubated mice is reliable, thereby allowing relevant longitudinal studies.

Spirometric indices of early airflow impairment in individuals at risk of developing COPD: Spirometry beyond FEV1/FVC.

Spirometry is the current gold standard for diagnosing and monitoring the progression of Chronic Obstructive Pulmonary Disease (COPD). However, many current and former smokers who do not meet established spirometric criteria for the diagnosis of this disease have symptoms and clinical courses similar to those with diagnosed COPD. Large longitudinal observational studies following individuals at risk of developing COPD offer us additional insight into spirometric patterns of disease development and progression. Analysis of forced expiratory maneuver changes over time may allow us to better understand early changes predictive of progressive disease. This review discusses the theoretical ability of spirometry to capture fine pathophysiologic changes in early airway disease, highlights the shortcomings of current diagnostic criteria, and reviews existing evidence for spirometric measures which may be used to better detect early airflow impairment.

Application of the forced oscillation technique in diagnosing and monitoring asthma in preschool children.

The measurement of lung function in preschool children for the diagnosis of asthma is not routinely used. The need to perform forced expiratory manoeuvres requires active cooperation and thus limits the use of spirometry in this age group. The forced oscillation technique (FOT) is a simple and noninvasive method of assessing the mechanical properties of the respiratory system during tidal breathing. It is used in young patients and requires minimal cooperation. It provides an objective assessment of the respiratory system in a group of patients in whom we have not yet had appropriate diagnostic tools. In recent years, due to the availability of new technical solutions, FOT has been increasingly used and has a chance to become a method used routinely in diagnosing and monitoring treatment in preschool children. This article presents the possibility of the clinical application of FOT in diagnosing and monitoring of early childhood asthma.

Reference norms for evaluating maximum expiratory flow of children and adolescents of the Maule Region in Chile.

BackgroundThe norms for evaluating the maximum expiratory flow (MEF) usually are developed according to chronological age and height. However, to date, little research has been conducted using reference values that take into account the temporal changes of biological maturation. The objectives of this study were to (a) compare the MEF with those of other international studies, (b) align the MEF values with chronological and biological age, and (c) propose reference standards for children and adolescents.MethodsThe sample studied consisted of 3,566 students of both sexes (1,933 males and 1,633 females) ranging in age from 5.0 to 17.9 years old. Weight, standing height, and sitting height were measured. Body mass index was calculated. Biological maturation was predicted by using age of peak height velocity growth (APHV). MEF (L/min) was obtained by using a forced expiratory manoeuvre. Percentiles were calculated using the LMS method.Results and DiscussionPredicted APHV was at age 14.77 ± 0.78 years for males and for females at age 12.74 ± 1.0 years. Biological age was more useful than chronological age for assessing MEF in both sexes. Based on these findings, regional percentiles were created to diagnose and monitor the risk of asthma and the general expiratory status of paediatric populations.

Measurement and estimation of human forced expiratory noise parameters using a microphone with a stethoscope head and a lapel microphone

Objective: The time signature of tracheal noise in the 200–2000 Hz frequency band recorded during a forced expiratory manoeuvre (FETa) is a promising tool for diagnosis of bronchial obstructions. FETa is typically registered using a microphone with a stethoscope head placed on the neck over the trachea (stethoscope sensor). We studied basic time and spectral parameters of forced expiratory tracheal noises with a microphone placed near the mouth (lapel microphone, outside the flow of exhaled air) and compared these with measurements via stethoscope sensor, with the aim of providing patient home monitoring via standard personal computer facilities. Approach: FETa, 200 Hz band pass times, and frequency responses of signals recorded simultaneously with both sensors were analysed in a sample of 24 healthy volunteers. Main results: Averaged real transfer function of signals from a stethoscope sensor and a lapel microphone in the frequency range 200–1800 Hz was characterized by a slope of −7.2 dB/octave. This is near the slope of −6 dB/octave predicted via theoretical models of both sensors. The lapel microphone and stethoscope sensor were not interchangeable regarding spectral characteristics of forced expiratory tracheal noises. However, FETa measurements in healthy volunteers via stethoscope sensor and lapel microphone showed no significant differences according to U-Mann–Whitney test for independent samples. Significance: The ability to measure FETa successfully with a lapel microphone placed near the mouth was experimentally demonstrated in healthy volunteers. Additional studies are needed to verify whether FETa measured near the mouth is acceptable for monitoring pulmonary status in patients with asthma or chronic obstructive pulmonary disease.