Comparison of Forced Oscillation Technique, Lung Volumes by Body Plethysmography, and Spirometry in Moderate Persistent Adult Asthma.

BACKGROUND: Spirometry is used extensively, but airway oscillometry is gaining acceptance for evaluating obstructive airway disorders. Moderate persistent asthma requires daily treatment with inhaled corticosteroids (ICS). MATERIALS AND METHODS: We aimed to examine the relationship between airway oscillometry and lung volumes, which are the markers of lung physiology in obstructive airway disease and spirometry in the real-world clinical setting. A total of 72 adults with moderate persistent asthma followed up in our outpatient department from November 2021 to August 2022, and their clinical details and tests of spirometry, forced oscillation technique (FOT), and lung volumes by body plethysmography (BP) performed before and after bronchodilator administration were analyzed. RESULTS: The mean age of the study population was 40 years, and the majority (57%) were females. FOT detected airflow limitation in 12 of the 31 patients with normal spirometry. BP detected abnormalities in more patients than both spirometry and FOT (91.6 vs 73.6%, p < 0.001). Respiratory resistance 5 (R5) had a negative correlation with functional residual capacity (FRC) and total lung capacity (TLC). Reactance 5 (X5) correlated positively with inspiratory capacity (IC) and TLC and negatively with reserve volume (RV)/TLC ratio. A positive correlation was found between IC/TLC% and postbronchodilator X5 and between R5 and 19 and RV/TLC. R5 had a negative and X5 had a positive correlation with forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC, and maximal mid expiratory flow rates (MMEF). ∇X5 had a negative correlation with FEV1, MMEF, and FEV1/FVC. Spirometry detected postbronchodilator responsiveness in more patients than FOT when only the R5 criterion was used and in a comparable number when the X5 criterion was added. ∇X5 and R5-R19/R5 declined significantly after bronchodilators. CONCLUSION: We concluded that there is a moderate correlation between FOT and spirometry and lung volumes by BP. FOT and spirometry should be used together to identify airflow obstruction and postbronchodilator responsiveness in asthma. Lung volumes by BP identify more abnormalities in adults with asthma than both spirometry and FOT. Thresholds to define postbronchodilator responsiveness (PBDR) for ∇X5 and R5-R19 need to be defined.

The sensitivity and specificity of the forced oscillation technique in the diagnosis of bronchoconstriction in children.

OBJECTIVE: The forced oscillation technique (FOT) is a useful diagnostic respiratory system for children. However, the final value of the FOT in the diagnosis of bronchoconstriction is still open. The aim of the study was to evaluate the sensitivity and specificity of the FOT vs. body plethysmography tests in the measure of bronchoconstriction in asthmatic children. MATERIALS AND METHODS: A total of 102 children aged 2 to 6 years diagnosed with early-onset asthma and 52 healthy controls were included in this prospective, randomized study. All asthmatic patients and healthy controls underwent a basic FOT as one measurement, according to the recommendation of the Resmon Pro FOT. Then, the reversibility test was performed 20 min after the administration of 200 mg salbutamol using the FOT and body plethysmography in all patients. RESULTS: The mean basic Rrs, Xrs and sRaw in asthmatic patients were, respectively, 11.13 ± 1.28 kPa sL-1, -4.6 ± 1.18 kPa sL-1 and 1.72 ± 0.58 kPa s. Similar parameters were significantly better in the control group (p < 0.05). A total of 73 (71.6%) asthmatic patients had a positive test using the FOT according to Calogero. In 4 (7.7%) patients in the control group, a positive test was obtained. In body plethysmography, similar results were reached, with a positive test in 76 (74.5%) study patients and 5 (9.6%) control patients. CONCLUSIONS: A bronchial reversibility test with the use of the FOT is useful for the diagnosis of bronchial asthma, especially with the use of an Rrs parameter, such as the body plethysmography test.

Noninvasive Measurement of Pulmonary Function in Experimental Mouse Models of Airway Disease.

Mouse models have become an indispensable tool in translational research of human airway disease and have provided much of our understanding of the pathogenesis of airway disease such as asthma. In these models the ability to assess pulmonary function and particularly airway responsiveness is critically important. Existing methods for testing pulmonary function in mice in vivo include noninvasive and invasive technologies. Noninvasive head-out body plethysmography is a well-established and widely accepted technique which has been proven as a reliable method to measure lung function on repeated occasions in intact, conscious mice. We have performed several validation studies in allergic mice to compare the parameter midexpiratory flow (EF50) as a noninvasive marker of airflow limitation with invasively measured gold standard parameters of lung mechanics. The results of these studies showed a good agreement of EF50 with the invasive assessment of lung resistance and dynamic compliance with a somewhat lower sensitivity of EF50. The measurement of EF50 together with basic respiratory parameters is particularly appropriate for simple and repeatable screening of pulmonary function in large numbers of mice or if noninvasive measurement without use of anesthesia is required. Beyond known applications, head-out body plethysmography also provides a much-needed high-throughput screening tool to gain insights into the impact and kinetics of respiratory infections such as SARS-COV-2 on lung physiology in laboratory mice.

Effect of Predicted Versus Measured Thoracic Gas Volume on Body Fat Percentage in Young Adults.

The BodPod® (COSMED, Concord, CA) uses predicted (pTGV) or measured thoracic gas volume (mTGV) during estimations of percentage body fat (%BF). In young adults, there is inconsistent evidence on the variation between pTGV and mTGV, and the effect of sex as a potential covariate on this relationship is unknown. This study examined the difference between TGV assessments and its effect on %BF and potential sex differences that may impact this relationship. A retrospective analysis of BodPod® pTGV and mTGV for 95 men and 86 women ages 18-30 years was performed. Predicted TGV was lower than mTGV for men (-0.49 ± 0.7 L; p < .0001). For men, %BF derived by pTGV was lower than that by mTGV (-1.3 ± 1.8%; p < .0001). For women, no differences were found between pTGV and mTGV (-0.08 ± 0.6 L; p > .05) or %BF (-0.03 ± 0.2%; p > .05). The two-predictor model of sex and height was able to account for 57.9% of the variance in mTGV, F(2, 178) = 122.5, p < .0001. Sex corrected for the effect of height was a significant predictor of mTGV (ß = 0.483 L, p < .0001). There is bias for pTGV to underestimate mTGV in individuals with a large mTGV, which can lead to significant underestimations of %BF in young adults; this was especially evident for men in this study. Sex is an important covariate that should be considered when deciding to use pTGV. The results indicate that TGV should be measured whenever possible for both men and women ages 18-30 years.

Correspondence between Capnovolumetric and Conventional Lung Function Parameters in the Diagnosis of Obstructive Airway Diseases.

BACKGROUND: Capnovolumetry is of interest as a method for the diagnosis of obstructive airway diseases, requiring little cooperation from the patient. OBJECTIVE: To help in the interpretation of capnovolumetric parameters, we aimed to identify their correspondence to conventional lung function indices. METHODS: We studied 978 patients from a diagnostic study with complete functional data and the clinical diagnosis of asthma, chronic obstructive pulmonary disease (COPD), or no respiratory disease. Using path analysis, four capnovolumetric parameters (slope of expiratory phase 3, ratio of slopes of phases 3 and 2, volume of phase 2, and the ratio area/volume of phase 3) previously identified as predictors of airway obstruction in terms of spirometry and body ple-thysmography, were analyzed regarding their relationship to each other and the diagnostic categories of asthma or COPD versus control, or obstruction versus no obstruction. We then identified four lung function parameters showing relationships as much as possible isomorphic to those between capnovolumetric parameters. RESULTS: The four capnovolumetric parameters were related to COPD and obstruction via both direct and indirect influences, but only two of them to asthma. Regarding the correspondence to lung function parameters, the slope of expiratory phase 3 corresponded best to the ratio of residual volume to total lung capacity, the ratio of slopes of phases 3 and 2 to forced expiratory volume in 1 s, the volume of phase 2 to forced expired flow at 50% of vital capacity, and the ratio area/volume of phase 3 to forced vital capacity. CONCLUSIONS: Our results indicated an intricate relationship of capnovolumetric parameters to each other and to airway obstruction, asthma, or COPD. The correspondence to conventional lung function measures seemed to reflect the entities lung hyperinflation, overall ventilatory impairment, bronchoconstriction, and ventilated lung volume, in that order. These findings might be helpful for clinicians in the interpretation of capnovolumetry.

Diagnostic accuracy of capnovolumetry for the identification of airway obstruction - results of a diagnostic study in ambulatory care.

BACKGROUND: One of the known weaknesses of spirometry is its dependence on patients' cooperation, which can only partially be alleviated by educational efforts. Therefore, procedures less dependent on cooperation might be of value in clinical practice. We investigated the diagnostic accuracy of ultrasound-based capnovolumetry for the identification of airway obstruction. METHODS: Consecutive patients from a pulmonary outpatient clinic were included in the diagnostic study. As reference standard, the presence of airway obstruction was evaluated via spirometry and bodyplethysmography. Capnovolumetry was performed as index test with an ultrasound spirometer providing a surrogate measure of exhaled carbon dioxide. Receiver operating characteristic (ROC) analysis was performed using the ratio of slopes of expiratory phases 3 and 2 (s3/s2) ≥ 0.10 as primary capnovolumetric parameter for the recognition of airway obstruction. Logistic regression was performed as secondary analysis to identify further useful capnovolumetric parameters. The diagnostic potential of capnovolumetry to identify more severe degrees of airway obstruction was evaluated additionally. RESULTS: Of 1400 patients recruited, 1287 patients were included into the analysis. Airway obstruction was present in 29% of patients. The area under the ROC-curve (AUC) of s3/s2 was 0.678 (95% CI 0.645, 0.710); sensitivity of s3/s2 ≥ 0.10 was 47.7 (95% CI 42.7, 52.8)%, specificity 79.0 (95% CI 76.3, 81.6)%. When combining this parameter with three other parameters derived from regression analysis (ratio area/volume phase 3, slope phase 3, volume phase 2), an AUC of 0.772 (95% CI 0.743, 0.801) was obtained. For severe airway obstruction (FEV1 ≤ 50% predicted) sensitivity of s3/s2 ≥ 0.10 was 75.9 (95% CI 67.1, 83.0)%, specificity 75.8 (95% CI 73.3, 78.1)%; for very severe airway obstruction (FEV1 ≤ 30% predicted) sensitivity was 86.7 (95% CI 70.3, 94.7)%, specificity 72.8 (95% CI 70.3, 75.2)%. Sensitivities increased and specificities decreased considerably when the combined capnovolumetric score was used as index test. CONCLUSIONS: Capnovolumetry by way of an ultrasound spirometer had a statistically significant albeit moderate potential for the recognition of airway obstruction in a heterogeneous population of patients typically found in clinical practice. Diagnostic accuracy of the capnovolumetric device increased with the severity of airway obstruction. TRIAL REGISTRATION: The study is registered under DRKS00013935 at German Clinical Trials Register (DRKS).

Whole-Body Plethysmography and Blood Gas Analysis in Patients with Acute Myocardial Infarction Undergoing Percutaneous Coronary Intervention.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) and coronary heart disease (CHD) often occur together. However, COPD is underdiagnosed among CHD patients. OBJECTIVES: This study investigated the prevalence of COPD and relevant pulmonary function test (PFT) impairments in patients with acute myocardial infarction (AMI). METHODS: Patients undergoing coronary angiography for AMI were prospectively included. Body plethysmography, lung diffusing capacity, blood gas analysis, and echocardiography were performed. The following patient subgroups were compared: with versus without COPD, ST elevation myocardial infarction (STEMI) versus non-STEMI (NSTEMI). The prevalence of PFT impairments was also recorded. RESULTS: A total of 100 patients (51 with NSTEMI, 49 with STEMI) were included. Twenty patients had diagnosed COPD, of whom 15 were diagnosed for the first time; 80% of all COPD patients were not receiving COPD therapy. Patients with COPD had higher maximum creatine kinase (p = 0.008) and troponin T (p = 0.054) levels than those without COPD. Hypoxaemia was more common in COPD patients (lower oxygen saturation [p = 0.008] and partial pressure of oxygen [PaO2] [p = 0.005]). PaO2 was significantly lower in STEMI compared with NSTEMI (p = 0.017). Independent of a COPD diagnosis, 65 patients had relevant PFT impairments. CONCLUSIONS: The high prevalence of undiagnosed COPD and relevant pulmonary function impairments in this cohort of patients with AMI, and the fact that pulmonary disease was untreated in the majority of COPD patients, highlight the importance of a general pulmonary workup of patients with AMI. Furthermore, patients with CHD should undergo screening for COPD, given the fact that COPD patients had larger infarction size.

Effect of Thoracic Epidural Anesthesia in a Rat Model of Phrenic Motor Inhibition after Upper Abdominal Surgery.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: One important example of impaired motor function after surgery is diaphragmatic dysfunction after upper abdominal surgery. In this study, the authors directly recorded efferent phrenic nerve activity and determined the effect of the upper abdominal incision. The authors hypothesized that phrenic motor output would be decreased after the upper abdominal incision; it was also hypothesized that blocking sensory input from the incision using thoracic epidural anesthesia would diminish this incision-induced change in phrenic motor activity. METHODS: Efferent phrenic activity was recorded 1 h to 10 days after upper abdominal incision in urethane-anesthetized rats. Ventilatory parameters were measured in unanesthetized rats using whole-body plethysmography at multiple time points after incision. The authors then determined the effect of thoracic epidural anesthesia on phrenic nerve activity and ventilatory parameters after incision. RESULTS: Phrenic motor output remained reduced by approximately 40% 1 h and 1 day after incision, but was not different from the sham group by postoperative day 10. One day after incision (n = 9), compared to sham-operated animals (n = 7), there was a significant decrease in spike frequency area-under-the-curve (median [interquartile range]: 54.0 [48.7 to 84.4] vs. 97.8 [88.7 to 130.3]; P = 0.0184), central respiratory rate (0.71 [0.63 to 0.79] vs. 0.86 [0.82 to 0.93]/s; P = 0.0460), and inspiratory-to-expiratory duration ratio (0.46 [0.44 to 0.55] vs. 0.78 [0.72 to 0.93]; P = 0.0023). Unlike humans, a decrease, not an increase, in breathing frequency has been observed after the abdominal incision in whole-body plethysmography. Thoracic epidural anesthesia attenuated the incision-induced changes in phrenic motor output and ventilatory parameters. CONCLUSIONS: Upper abdominal incision decreased phrenic motor output and ventilatory parameters, and this incision-induced impairment was attenuated by thoracic epidural anesthesia. The authors' results provide direct evidence that afferent inputs from the upper abdominal incision induce reflex inhibition of phrenic motor activity.

Indacaterol and glycopyrronium versus indacaterol on body plethysmography measurements in COPD-a randomised controlled study.

BACKGROUND: Dual bronchodilator therapy is recommended for symptomatic patients with chronic obstructive pulmonary disease (COPD). There are limited data on effects of a combination of two long-acting bronchodilators on lung function including body plethysmography. METHODS: This multicentre, randomised, double-blind, single-dose, cross-over, placebo-controlled study evaluated efficacy and safety of the free combination of indacaterol maleate (IND) and glycopyrronium bromide (GLY) versus IND alone on spirometric and body plethysmography parameters, including inspiratory capacity (IC), forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), total lung capacity (TLC) and airway resistance (Raw) in moderate-to-severe COPD patients. RESULTS: Seventy-eight patients with FEV1 % pred. (mean ± SD) 56 ± 13% were randomised. The combination of IND + GLY versus IND presented a numerically higher peak-IC (Δ = 0.076 L, 95% confidence interval [CI]: -0.010 - 0.161 L; p = 0.083), with a statistically significant difference in mean IC over 4 h (Δ = 0.054 L, 95%CI 0.022 - 0.086 L; p = 0.001). FEV1, FVC and Raw, but not TLC, were consistently significantly improved by IND + GLY compared to IND alone. Safety profiles of both treatments were comparable. CONCLUSION: The free combination of IND + GLY improved lung function parameters as evaluated by spirometry and body plethysmography, with a similar safety profile compared to IND alone. TRIAL REGISTRATION: NCT01699685.

Assessment of gas compression and lung volume during air stacking maneuver.

PURPOSE: We reasoned that the application of positive pressure through air stacking (AS) technique could cause gas compression and the absolute lung volumes could be estimated. The aim of this study was to estimate the amount of gas compression (ΔV comp) during AS in healthy subjects positioned at 45° trunk inclination and verify if the simultaneous measurements of chest wall volume changes (ΔV CW), by optoelectronic plethysmography, and changes in lung volume (ΔV ao), by pneumotachograph, combined with pressure variation at the airways opening (ΔP ao) during AS are able to provide reliable data on absolute lung volumes. METHODS: Twenty healthy subjects (mean age 23.5 ± 3.8 years) were studied during a protocol that included slow vital capacity and AS maneuvers. V comp was calculated by subtracting ΔV ao and ΔV CW occurring during AS and total lung capacity (TLC) was estimated by applying Boyle-Mariote's law using V comp and ΔP ao. RESULTS: During AS, 0.140 ± 0.050 L of gas was compressed with an average ΔP ao of 21.78 ± 6.18 cmH2O. No significant differences between the estimated TLC (-0.03 ± 3.0% difference, p = 0.6020), estimated FRC (-2.0 ± 12.4% difference, p = 0.5172), measured IC (1.2 ± 11.2% difference, p = 0.7627) and predicted values were found. CONCLUSION: During AS, a significant gas compression occurs and absolute lung volumes can be estimated by simultaneous measurements of ΔV CW, ΔV ao and ΔP ao.

[ACOS: Clinical and functional features The Russian formulation mesalazine (kansalazine) in the therapy of ulcerative colitis]. / ACOS-sindrom: kliniko-funktsional'nye osobennosti.

AIM: To investigate the clinical and functional parameters in patients with asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS) versus those with chronic obstructive pulmonary disease (COPD) and asthma. SUBJECTS AND METHODS: A total of 129 people were examined. 51 patients with ACOS were followed up in Group 1; Group 2 included 38 patients with severe asthma; Group 3 consisted of 40 patients with severe COPD. All the patients underwent clinical examination: history data collection, physical examination, evaluation of disease symptoms, and study of respiratory function (spirometry, body plethysmography). RESULTS: ACOS is clinically characterized by considerable demands for emergency drugs and by more frequent asthmatic fits and exacerbations, which require hospitalization. The parameters of bronchial resistance in ACOS were established to be increased throughout the follow-up period and to be comparable with those in patients with COPD. In the patients with ACOS, the severity of pulmonary hyperinflation was associated with increased demands for emergency drugs (r=0.59; p=0.015). Fixed bronchial obstruction in ACOS can be caused by smoking intensity and duration associated with increased bronchial resistance in expiration (r=0.51; p=0.003) and intrathoracic volume (r=0.71; p=0.0001); as well as increased body mass index (p<0.001) and disease duration, which were interrelated with a reduction in the forced expiratory volume in one second/forced vital capacity ratio (r=-0.63; p=0.001 and r=-0.71; p=0.0034, respectively). CONCLUSION: Patients with ACOS show more severe clinical manifestations and a substantial increase in functional residual capacity and intrathoracic volume throughout the follow-up period, suggesting that the distal bronchi are impaired and pulmonary hyperinflation develops.

Spirometry or Body Plethysmography for the Assessment of Bronchial Hyperresponsiveness?

Methacholine testing is one of the standard tools for the diagnosis of mild asthma, but there is little information about optimal outcome measures. In this study a total of 395 college students were tested by the ATS dosimeter protocol for methacholine testing, with minor modification. Body plethysmography and spirometry were measured after each inhalation step. The end-of-test-criteria were (i) decrease in forced expiratory volume in 1 s (FEV1) of ≥ 20 % and (ii) doubling of specific airway resistance and its increase to ≥ 2.0 kPa∙s. The results were expressed by receiver operating characteristic (ROC) plots using questionnaire answers as a reference. The areas under the ROC curves were iteratively calculated for a wide range of thresholds for both measures. We found that ROC plots showed maximal sensitivities of about 0.5-0.6 for FEV1 and about 0.7 for specific airway conductance (sGt), with similar specificities of about 0.7-0.8 taking questions with the known high specificity as references. Accordingly, larger maximal areas under the ROC curve were observed for body plethysmography, but the differences were small. A decrease in FEV1 of about 15 % and a decrease of sGt of about 60 % showed the largest areas under the ROC curves. In conclusion, body plethysmography yielded better sensitivity than spirometry, with similar specificity. However, replacing the common spirometric criterium for a positive test (20 % decrease in FEV1 from baseline) by the optimal body plethysmographic criterium would result in an increase of false positive tests from about 4 to 8 % in healthy young adults.

Methods of airway resistance assessment.

Airway resistance is the ratio of driving pressure to the rate of the airflow in the airways. The most frequent methods used to measure airway resistance are whole-body plethysmography, the interrupter technique and the forced oscillation technique. All these methods allow to measure resistance during respiration at the level close to tidal volume, they do not require forced breathing manoeuvres or deep breathing during measurement. The most popular method for measuring airway resistance is whole-body plethysmography. The results of plethysmography include among others the following parameters: airway resistance (Raw), airway conductance (Gaw), specific airway resistance (sRaw) and specific airway conductance (sGaw). The interrupter technique is based on the assumption that at the moment of airway occlusion, air pressure in the mouth is equal to the alveolar pressure . In the forced oscillation technique (FOT), airway resistance is calculated basing on the changes in pressure and flow caused by air vibration. The methods for measurement of airway resistance that are described in the present paper seem to be a useful alternative to the most common lung function test - spirometry. The target group in which these methods may be widely used are particularly the patients who are unable to perform spirometry.

Incorporation of capillary microsampling into whole body plethysmography and modified Irwin safety pharmacology studies in rats.

UNLABELLED: Limited toxicokinetic data is generated during modified Irwin screen and whole body plethysmography safety pharmacology studies, due to disturbance of primary endpoints by standard blood sampling methods. We evaluated if incorporation of microsampling would impact on data quality, as providing toxicokinetic data from main test animals could reduce the need for satellite animals. METHODS: A modified Irwin screen was performed, testing oral clonidine (0, 0.03, 0.1, or 0.3 mg/kg). One cohort of rats per dose level underwent standard blood sampling (post-4 h Irwin assessment), and another cohort underwent microsampling after the 0.5, 1, 2, 4 and 24 h Irwin assessments. The respiratory effects of oral theophylline (0 or 10 mg/kg) and oral baclofen (0 or 5 mg/kg), were tested using whole body plethysmography. Groups of animals underwent standard blood sampling (at end of recording at 4 h post-dose) or microsampling at either 0.5 h or 1 h intervals (4 or 8 microsamples, respectively). RESULTS: Microsampling did not impact on the quality of the data generated. The expected effects of clonidine on behavioural parameters, and of theophylline and baclofen on changes in ventilatory parameters were observed at a similar magnitude and duration independent of sampling method. DISCUSSION: The incorporation of multiple capillary microsamples into the modified Irwin or respiratory study did not adversely affect the primary endpoints. The capillary microsampling method is a refinement in blood sampling technique which can easily be adapted into safety pharmacology studies to generate pharmacokinetic profiles within the same animal as the primary data, thus enhancing scientific robustness and reducing the satellite animals required.

[Dyspnea. Profile of the most important diagnostic tests]. / Dyspnoe. Profile der wichtigsten diagnostischen Tests.

The diagnostic pathway for the evaluation of patients with dyspnea requires a thorough history taking and physical examination. Based on the results of these basic steps a broad variety of additional diagnostic tests are available. Each test can contribute valuable information when correctly indicated and performed. Among these are electrocardiography (ECG), laboratory parameters, X-ray examination, echocardiography, spirometry and whole body plethysmography and finally spiroergometry. This article presents a focused review of what each of these diagnostic modalities can contribute to the diagnostic process for dyspnea.

[THE INFLUENCE OF SMOKING ON THE LUNG VENTILATION FUNCTION IN YOUNG SUBJECTS].

The aim of the work was to evaluate effect of smoking on the lung ventilation function in young subjects. The study included 1552 subjects (808 men and 744 women) of the mean age 31.6 ± 4.7 and 29.27 ± 5.3 years respectively divided into 3 groups: smokers (n = 568), ex-smokers (n = 103), and non-smokers (n = 881). A sample of the general population contained 36.6% smokers, 6.6% ex-smokers, and 56.8% non-smokers; it showed significant correlation of smoking habits with the gender and the education level. Functional studies revealed lower spirographic and higher whole-body plethysmographic parameters in the smokers and ex-smokers. Also, they more frequently suffered obstructive disorders. These data suggest negative effect of tobacco smoke on the respiratory system in practically healthy young subjects revealed by the studying external respiratory function with the use of spirographic and whole-body plethysmographic methods.

Whole-body MRI-based fat quantification: a comparison to air displacement plethysmography.

PURPOSE: To demonstrate the feasibility of an algorithm for MRI whole-body quantification of internal and subcutaneous fat and quantitative comparison of total adipose tissue to air displacement plethysmography (ADP). MATERIALS AND METHODS: For comparison with ADP, whole-body MR data of 11 volunteers were obtained using a continuously moving table Dixon sequence. Resulting fat images were corrected for B1 related intensity inhomogeneities before fat segmentation. RESULTS: The performed MR measurements of the whole body provided a direct comparison to ADP measurements. The segmentation of subcutaneous and internal fat in the abdomen worked reliably with an accuracy of 98%. Depending on the underlying model for fat quantification, the resultant MR fat masses represent an upper and a lower limit for the true fat masses. In comparison to ADP, the results were in good agreement with ρ ≥ 0.97, P < 0.0001. CONCLUSION: Whole-body fat quantities derived noninvasively by using a continuously moving table Dixon acquisition were directly compared with ADP. The accuracy of the method and the high reproducibility of results indicate its potential for clinical applications.

Influence of acclimatization time on parameters of barometric whole-body plethysmography in healthy adult cats.

BACKGROUND: Pulmonary function testing by barometric whole-body plethysmography (BWBP) is a long-established and well-accepted, non-invasive investigative procedure in cats. HYPOTHESIS/OBJECTIVES: To evaluate, if different acclimatization times influence the measurement parameters of BWBP in healthy adult cats. ANIMALS: 48 healthy adult cats. METHODS: In the prospective observational study, healthy cats were placed in a measuring chamber and BWBP was performed over 30 minutes. Parameters obtained during the three measurement units of 10 minutes each (T1, T2 and T3) were compared. RESULTS: All measurement parameters except for tidal volume per body weight changed significantly (p<0.05) over the three time periods. From T1-T2, the parameters minute volume per body weight (p<0.001), peak inspiratory flow per body weight (p<0.001), peak expiratory flow per body weight (p = 0.002), pause (p = 0.03), enhanced pause (p = 0.03) and quotient of peak expiratory flow divided by expiratory flow at end expiratory volume plus 50% tidal volume (p = 0.03) changed significantly. From the time interval T2-T3, only respiratory rate (p = 0.02), inspiratory time (p = 0.02), expiratory time (p = 0.04), and relaxation time (p = 0.01) changed significantly. All measurement parameters except for tidal volume per body weight changed significantly (p<0.05) between T1 and T3. Age had a significant influence on all parameters except for peak expiratory flow per body weight and peak inspiratory flow per body weight. The parameters were not influenced by sex. CONCLUSION AND CLINICAL IMPORTANCE: All measurement parameters except tidal volume per body weight were significantly affected by acclimatization time. Controlling for age and sex, there was still a significant influence of acclimatization time on all parameters except for tidal volume per body weight. Standardization of the acclimatization time for future studies would be appropriate in order to maintain comparability.

Methods for Detecting Cough and Airway Inflammation in Mice.

Chronic cough, which lasts for more than 8 weeks, is one of the most common complaints requiring medical attention, and patients suffer from a huge socioeconomic burden and a marked decrement in quality of life. Animal models can mimic the complex pathophysiology of the cough and are important tools for cough research. The detection of cough sensitivity and airway inflammation is of great significance for studying the complex pathological mechanism of cough. This article describes the measurement of cough using a noninvasive and real-time whole-body plethysmography (WBP) system and the normative procedures for harvesting tissue samples (including blood, lung, spleen, and trachea) of mice. It introduces some methods to assess airway inflammation, including pathological changes in hematoxylin and eosin (HE)-stained lung and trachea sections, the total protein concentration, the uric acid concentration, and the lactate dehydrogenase (LDH) activity in the supernatant of bronchoalveolar lavage fluid (BALF), and the leukocytes and differential cell counts of BALF. These methods are reproducible and serve as valuable tools to study the complex pathophysiology of cough.

Adapting Real-Time Lung Function Measurements for SARS-CoV-2 Infection Studies in Syrian Hamsters.

Pulmonary function examinations are critical to assess respiratory disease severity in patients. In preclinical rodent models of viral respiratory infections, however, disease is frequently evaluated based on virological, pathological and/or surrogate clinical parameters, which are not directly associated with lung function. To bridge the gap between preclinical and clinical readouts, we aimed to apply unrestrained whole-body plethysmography (WBP) measurements in a SARS-CoV-2 Syrian hamster challenge model. While WBP measurements are frequently used for preclinical research in mice and rats, results from studies in hamsters are still limited. During unrestrained WBP measurements, we obtained highly variable breathing frequency values outside of the normal physiological range for hamsters. Importantly, we observed that animal movements were recorded as breaths during WBP measurements. By limiting animal movement through either mechanical or chemical restraint, we improved the reliability of the lung function readout and obtained breathing frequencies that correlated with clinical signs when comparing two different variants of SARS-CoV-2 post-inoculation. Simultaneously, however, new sources of experimental variation were introduced by the method of restraint, which demands further optimalization of WBP measurements in Syrian hamsters. We concluded that WBP measurements are a valuable refinement either in combination with video recordings or if average values of measurements lasting several hours are analyzed.