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Indian Journal of Endocrinology and... 2023Obesity is known to induce lung function impairment. Previous studies of decline in lung function associated with obesity are well established.
BACKGROUND
Obesity is known to induce lung function impairment. Previous studies of decline in lung function associated with obesity are well established.
MATERIALS AND METHODS
In this cross-sectional study, to evaluate the effects of different obesity indices on lung mechanics, healthy subjects (males-23 and females-22) were recruited. Anthropometric parameters like body mass index (BMI), waist circumference (WC), hip circumference (HC) and neck circumference (NC) were measured and waist-hip ratio (WHR) was derived. Spirometry, impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) measurements were performed to assess lung function. Subgroups were divided and analysed.
RESULTS
In males, increased WHR is associated with increased total airway resistance (R). BMI correlates positively with R, R% predicted, resistance at 20 Hz (R) and R% predicted; likewise, WHR shows a positive correlation with R. In females, increased WHR has significantly higher R, R% predicted, R, R% predicted, area of reactance (Ax), resonant frequency (Fres) and decreased reactance at 5 Hz (X), reactance at 20 Hz (X), X% predicted. The female group with higher WC shows significantly increased R, R% predicted, R, R% predicted, Ax, Fres and lower fixed ratio of forced expiratory volume in 1 s (FEV)/forced vital capacity (FVC), X, X, X% predicted. The group with higher NC has a lower FEV/FVC ratio. WHR positively correlated with R% predicted and Fres while WC correlated positively with R, R% predicted, Ax and Fres; same way, NC with X% predicted.
CONCLUSION
Obesity/overweight causes significant changes in lung volumes, capacity and airway mechanics, Higher WC and WHR are associated with significant changes in lung mechanics, which are more prominent in females than in males. NC is not associated with changes in lung mechanics.
PubMed: 37292068
DOI: 10.4103/ijem.ijem_363_22 -
Tanaffos 2016Input impedance of the respiratory system is measured by forced oscillation technique (FOT). Multiple prior studies have attempted to match the electromechanical models... (Review)
Review
Input impedance of the respiratory system is measured by forced oscillation technique (FOT). Multiple prior studies have attempted to match the electromechanical models of the respiratory system to impedance data. Since the mechanical behavior of airways and the respiratory system as a whole are similar to an electrical circuit in a combination of series and parallel formats some theories were introduced according to this issue. It should be noted that, the number of elements used in these models might be less than those required due to the complexity of the pulmonary-chest wall anatomy. Various respiratory models have been proposed based on this idea in order to demonstrate and assess the different parts of respiratory system related to children and adults data. With regard to our knowledge, some of famous respiratory models in related to obstructive, restrictive diseases and also Acute Respiratory Distress Syndrome (ARDS) are reviewed in this article.
PubMed: 27904536
DOI: No ID Found -
Neurology Aug 2016Plexiform neurofibromas (PNs) are complex, benign nerve sheath tumors that occur in approximately 25%-50% of individuals with neurofibromatosis type 1 (NF1). PNs that...
OBJECTIVE
Plexiform neurofibromas (PNs) are complex, benign nerve sheath tumors that occur in approximately 25%-50% of individuals with neurofibromatosis type 1 (NF1). PNs that cause airway compromise or pulmonary dysfunction are uncommon but clinically important. Because improvement in sleep quality or airway function represents direct clinical benefit, measures of sleep and pulmonary function may be more meaningful than tumor size as endpoints in therapeutic clinical trials targeting airway PN.
METHODS
The Response Evaluation in Neurofibromatosis and Schwannomatosis functional outcomes group reviewed currently available endpoints for sleep and pulmonary outcomes and developed consensus recommendations for response evaluation in NF clinical trials.
RESULTS
For patients with airway PNs, polysomnography, impulse oscillometry, and spirometry should be performed to identify abnormal function that will be targeted by the agent under clinical investigation. The functional group endorsed the use of the apnea hypopnea index (AHI) as the primary sleep endpoint, and pulmonary resistance at 10 Hz (R10) or forced expiratory volume in 1 or 0.75 seconds (FEV1 or FEV0.75) as primary pulmonary endpoints. The group defined minimum changes in AHI, R10, and FEV1 or FEV0.75 for response criteria. Secondary sleep outcomes include desaturation and hypercapnia during sleep and arousal index. Secondary pulmonary outcomes include pulmonary resistance and reactance measurements at 5, 10, and 20 Hz; forced vital capacity; peak expiratory flow; and forced expiratory flows.
CONCLUSIONS
These recommended sleep and pulmonary evaluations are intended to provide researchers with a standardized set of clinically meaningful endpoints for response evaluation in trials of NF1-related airway PNs.
Topics: Clinical Trials as Topic; Humans; Lung; Neurofibroma, Plexiform; Neurofibromatosis 1; Oscillometry; Polysomnography; Sleep; Spirometry; Treatment Outcome
PubMed: 27527645
DOI: 10.1212/WNL.0000000000002933 -
Sarcoidosis, Vasculitis, and Diffuse... 2021Sarcoidosis is a systemic inflammatory granulomatous disease which commonly affects intrathoracic lymph nodes, lung parenchyma and airways.
BACKGROUND
Sarcoidosis is a systemic inflammatory granulomatous disease which commonly affects intrathoracic lymph nodes, lung parenchyma and airways.
OBJECTIVES
To measure respiratory impedance using Impulse Oscillometry (IOS) in patients with pulmonary sarcoidosis and compare the parameters with healthy controls.
METHODS
Patients diagnosed with sarcoidosis (n=28); and age and gender matched healthy controls (n=17) were recruited. Lung volumes and capacities were measured by spirometry and respiratory system impedance was assessed using Impulse Oscillometry System (IOS). Measurements were performed before and 15 minutes after inhalation of a short acting bronchodilator. The IOS and spirometric parameters were compared between two groups and correlated. ROC curve analysis was also performed to identify the IOS parameters which can discriminate between sarcoidosis and healthy controls.
RESULTS
Resistance at 5 and 20 Hz (R5 and R20), small airway resistance (R5-R20), resonant frequency (F) and area of reactance (AX) were significantly higher in Sarcoidosis subjects compared with controls. Reactance at 5 and 20 Hz (X5 and X20) were significantly lower in sarcoidosis. FEV (% predicted) and FVC (% predicted) were significantly lower in patients with sarcoidosis while FEV/FVC ratio and peak expiratory flow rate (PEF) values were comparable. Post bronchodilator inhalation, there was improvement in airway resistance and reactance, but no significant changes observed in spirometric parameters. R5, X5 and R5-R20 are promising parameters to discriminate sarcoidosis from healthy controls.
CONCLUSION
Increased airway resistance is a better indicator of airway involvement than airflow limitation by spirometry in pulmonary sarcoidosis.
PubMed: 34744428
DOI: 10.36141/svdld.v38i3.8674 -
American Journal of Respiratory and... Feb 2024Respiratory resistance (Rrs) and reactance (Xrs) as measured by oscillometry and their intrabreath changes have emerged as sensitive parameters for detecting early...
Respiratory resistance (Rrs) and reactance (Xrs) as measured by oscillometry and their intrabreath changes have emerged as sensitive parameters for detecting early pathological impairments during tidal breathing. This study evaluates the prevalence and association of abnormal oscillometry parameters with respiratory symptoms and respiratory diseases in a general adult population. A total of 7,560 subjects in the Austrian LEAD (Lung, hEart, sociAl, boDy) Study with oscillometry measurements (computed with the Resmon Pro FULL; Restech Srl) were included in this study. The presence of respiratory symptoms and doctor-diagnosed respiratory diseases was assessed using an interview-based questionnaire. Rrs and Xrs at 5 Hz, their inspiratory and expiratory components, the area above the Xrs curve, and the presence of tidal expiratory flow limitation were analyzed. Normality ranges for oscillometry parameters were defined. The overall prevalence of abnormal oscillometry parameters was 20%. The incidence of abnormal oscillometry increased in the presence of symptoms or diagnoses: 17% (16-18%) versus 27% (25-29%), < 0.0001. All abnormal oscillometry parameters except Rrs at 5 Hz were significantly associated with respiratory symptoms/diseases. Significant associations were found, even in subjects with normal spirometry, with abnormal oscillometry incidence rates increasing by 6% (4-8%; < 0.0001) in subjects with symptoms or diagnoses. Abnormal oscillometry parameters are present in one-fifth of this adult population and are significantly associated with respiratory symptoms and disease. Our findings underscore the potential of oscillometry as a tool for detecting and evaluating respiratory impairments, even in individuals with normal spirometry.
Topics: Adult; Humans; Oscillometry; Lung; Respiration; Exhalation; Respiratory Tract Diseases; Spirometry; Forced Expiratory Volume; Airway Resistance
PubMed: 37972230
DOI: 10.1164/rccm.202306-0975OC -
Allergology International : Official... Sep 2012Most infants and preschool children are not able to voluntarily perform the physiological maneuvers required to complete the pulmonary function tests that are used in... (Review)
Review
Most infants and preschool children are not able to voluntarily perform the physiological maneuvers required to complete the pulmonary function tests that are used in adults and older children. Recently, commercial devices using forced oscillation technique (FOT) suitable for young children have become available. In devices with FOT, an oscillation pressure wave is generated by a loud speaker, is applied to the respiratory system, usually at the mouth, and the resulting pressure-flow relationship is analyzed in terms of impedance (Zrs). Zrs encompasses both resistance (Rrs) and reactance (Xrs). Rrs is calculated from pressure and flow signals, and is a measure of central and peripheral airway caliber. Xrs is derived from the pressure in the phase with volume and is related to compliance (Crs) and inertance (Irs). These parameters individually indicate the condition of the small and large airways in each patient and indirectly suggest the presence of airway inflammation. It is agreed that the clinical diagnostic capacity of FOT is comparable to that of spirometry. One of the advantages of FOT is that minimal cooperation of the patient is needed and no respiratory maneuvers are required. The use of FOT should be considered in patients in whom spirometry or other pulmonary function tests cannot be performed or in cases where the results of other tests appear to be unreliable. In addition, this approach is effective in assessing bronchial hyperresponsiveness. Considering these qualities, FOT is a useful method to study pulmonary function in preschool children with asthma.
Topics: Asthma; Child; Child, Preschool; Humans; Oscillometry; Positive-Pressure Respiration; Respiratory Function Tests
PubMed: 22722816
DOI: 10.2332/allergolint.12-RAI-0440 -
Respiratory Care Jan 2012Spirometry is considered the primary method to detect the air flow limitation associated with obstructive lung disease. However, air flow limitation is the end-result of... (Review)
Review
Spirometry is considered the primary method to detect the air flow limitation associated with obstructive lung disease. However, air flow limitation is the end-result of many factors that contribute to obstructive lung disease. One of these factors is increased airway resistance. Airway resistance is traditionally measured by relating air flow and driving pressure using body plethysmography, thus deriving airway resistance (R(aw)), specific airway resistance (sR(aw)), and specific airway conductance (sG(aw)). Other methods to measure airway resistance include the forced oscillation technique (FOT), which allows calculation of respiratory system resistance (R(RS)) and reactance (X(RS)), and the interrupter technique, which allows calculation of interrupter resistance (R(int)). An advantage of these other methods is that they may be easier to perform than spirometry, making them particularly suited to patients who cannot perform spirometry, such as young children, patients with neuromuscular disorders, or patients on mechanical ventilation. Since spirometry also requires a deep inhalation, which can alter airway resistance, these alternative methods may provide more sensitive measures of airway resistance. Furthermore, the FOT provides unique information about lung mechanics that is not available from analysis using spirometry, body plethysmography, or the interrupter technique. However, it is unclear whether any of these measures of airway resistance contribute clinically important information to the traditional measures derived from spirometry (FEV(1), FVC, and FEV(1)/FVC). The purpose of this paper is to review the physiology and methodology of these measures of airway resistance, and then focus on their clinical utility in relation to each other and to spirometry.
Topics: Airway Resistance; Asthma; Forced Expiratory Volume; Humans; Lung; Lung Diseases, Obstructive; Plethysmography; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Spirometry
PubMed: 22222128
DOI: 10.4187/respcare.01411 -
Allergy, Asthma & Immunology Research Mar 2022There are reports concerning mucus plugs detected on high-resolution computed tomography images and airflow obstruction in asthma and chronic obstructive pulmonary...
PURPOSE
There are reports concerning mucus plugs detected on high-resolution computed tomography images and airflow obstruction in asthma and chronic obstructive pulmonary disease (COPD). However, little is known about the associations between mucus plugs and small airway dysfunction (SAD). We evaluated the relationship between mucus plugs and pulmonary function in patients with asthma, COPD, and asthma-COPD overlap (ACO), and investigated the relevance to SAD and type 2 inflammation in a retrospective study.
METHODS
Subjects included 49 asthmatic, 40 ACO, and 41 COPD patients. ACO was diagnosed based on the Japanese Respiratory Society ACO guidelines. Clinical and laboratory parameters, including blood eosinophil count, serum total IgE levels, fractional exhaled nitric oxide (FeNO), spirometry, and forced oscillation technique (FOT), were compared between patients with and without mucus plugs.
RESULTS
Mucus plugs were found in 29 (59%) asthmatic, 25 (65%) ACO, 17 (41%) COPD patients. Patients with mucus plugs had reduced spirometry and larger FOT parameters, especially in COPD patients. Mucus scores correlated positively with IgE in ACO and FeNO in asthmatic patients, but not in COPD patients. Multivariate logistic regression analysis revealed that SAD parameters, including forced vital capacity and resonant frequency, a respiratory reactance parameter, were significantly associated with the presence of mucus plugs in the whole studied population.
CONCLUSIONS
SAD, rather than large airway dysfunction, was associated with mucus plugs in asthma, ACO, and COPD patients.
PubMed: 35255537
DOI: 10.4168/aair.2022.14.2.196 -
Respiratory Medicine Jun 2018Impulse oscillometry (IOS) is the most commonly used type of forced oscillation technique in clinical practice, although relatively little is known about its application... (Review)
Review
Impulse oscillometry (IOS) is the most commonly used type of forced oscillation technique in clinical practice, although relatively little is known about its application in COPD. Resistance at 20 Hz (R20) is unrelated to COPD severity and does not improve with bronchodilatation or bronchoconstriction, inferring a lack of large airway involvement in COPD. Peripheral airway resistance expressed as frequency dependent heterogeneity between 5 Hz and 20 Hz (R5-R20), and peripheral airway compliance as area under the reactance curve (AX), are both closely related to COPD severity and exacerbations. Both R5-R20 and AX markedly improve in response to long acting bronchodilators, while AX appears to be more sensitive than R5-R20 in response to bronchoconstriction. Future studies may be directed to assess if IOS in combination with spirometry is more sensitive at predicting future exacerbations. Perhaps AX might also be useful as a screening tool in early stage disease or to monitor long term decline in COPD.
Topics: Airway Resistance; Female; Humans; Male; Oscillometry; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Severity of Illness Index
PubMed: 29857993
DOI: 10.1016/j.rmed.2018.05.004 -
Frontiers in Physiology 2022Metrics 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... (Review)
Review
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 (FEV), 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.
PubMed: 36203932
DOI: 10.3389/fphys.2022.978332