The contribution of estimated dead space fraction to mortality prediction in patients with chronic obstructive pulmonary disease-a new proposal.

Background: Mortality due to chronic obstructive pulmonary disease (COPD) is increasing. However, dead space fractions at rest (VD/VTrest) and peak exercise (VD/VTpeak) and variables affecting survival have not been evaluated. This study aimed to investigate these issues. Methods: This retrospective observational cohort study was conducted from 2010-2020. Patients with COPD who smoked, met the Global Initiatives for Chronic Lung Diseases (GOLD) criteria, had available demographic, complete lung function test (CLFT), medication, acute exacerbation of COPD (AECOPD), Charlson Comorbidity Index, and survival data were enrolled. VD/VTrest and VD/VTpeak were estimated (estVD/VTrest and estVD/VTpeak). Univariate and multivariable Cox regression with stepwise variable selection were performed to estimate hazard ratios of all-cause mortality. Results: Overall, 14,910 patients with COPD were obtained from the hospital database, and 456 were analyzed after excluding those without CLFT or meeting the lung function criteria during the follow-up period (median (IQR) 597 (331-934.5) days). Of the 456 subjects, 81% had GOLD stages 2 and 3, highly elevated dead space fractions, mild air-trapping and diffusion impairment. The hospitalized AECOPD rate was 0.60 ± 2.84/person/year. Forty-eight subjects (10.5%) died, including 30 with advanced cancer. The incidence density of death was 6.03 per 100 person-years. The crude risk factors for mortality were elevated estVD/VTrest, estVD/VTpeak, ≥2 hospitalizations for AECOPD, advanced age, body mass index (BMI) <18.5 kg/m2, and cancer (hazard ratios (95% C.I.) from 1.03 [1.00-1.06] to 5.45 [3.04-9.79]). The protective factors were high peak expiratory flow%, adjusted diffusing capacity%, alveolar volume%, and BMI 24-26.9 kg/m2. In stepwise Cox regression analysis, after adjusting for all selected factors except cancer, estVD/VTrest and BMI <18.5 kg/m2 were risk factors, whereas BMI 24-26.9 kg/m2 was protective. Cancer was the main cause of all-cause mortality in this study; however, estVD/VTrest and BMI were independent prognostic factors for COPD after excluding cancer. Conclusions: The predictive formula for dead space fraction enables the estimation of VD/VTrest, and the mortality probability formula facilitates the estimation of COPD mortality. However, the clinical implications should be approached with caution until these formulas have been validated.

The dynamics of recovery of external breathing function in patients after laparoscopic cholecystectomy in the acute period under the influence of the rehabilitation program.

OBJECTIVE: Aim: To determine the dynamics of renewal of the function of external respiration in patients after laparoscopic cholecystectomy at the acute stage of rehabilitation under the influence of a rehabilitation program. PATIENTS AND METHODS: Materials and Methods: The study is randomized, simple with blinded assessors. The forced vital capacity (FVC, l), forced expiratory volume in the first second (FEV1, l) and peak expiratory flow rate (PEFR, l/s) were assessed. Spirometry was performed 120 patients on the first day of admission of patients to the surgical department for surgical intervention, on the second day and on the day of discharge. Methods of mathematical statistics: arithmetic mean (M) and standard error of the mean (}m), Student's t-test were calculated, differences at p<0,05 were considered statistically significant. RESULTS: Results: It has been established that laparoscopic cholecystectomy leads to a statistically significant decrease in the parameters of respiratory function in all age categories. More pronounced positive dynamics of respiratory function in the group of respiratory therapy. It was established that without respiratory therapy on the day of discharge there was no restoration (р<0.05) in groups of elderly patients of group of FVC l, FEV1 l, PEFR l/s; in middle-aged patients did no restoration FEV1, l, PEFR, l/s; in younger patients there was no recovery of FEV1, l. CONCLUSION: Conclusions: The results of the study indicate the effectiveness of the introduction of diaphragmatic breathing exercises in combination with early mobilization at the acute and subacute stages of rehabilitation in patients after laparoscopic cholecystectomy in order to restore the function of the respiratory system.

Remote pulmonary function testing allows for early identification of need for non-invasive ventilation in a subset of persons with ALS.

The traditional ALS multidisciplinary clinical practice of quarterly respiratory assessment may leave some individuals in danger of developing untreated respiratory insufficiency between visits or beginning non-invasive ventilation (NIV) later than would be optimal. Remote, or home-based, pulmonary function testing (rPFT) allows patients with ALS to perform regular respiratory testing at more frequent intervals in the home. The aim of this study was to determine the clinical benefit of weekly rPFT compared to standard, quarterly in-clinic respiratory assessments: the number of individuals with earlier identification of NIV need, the magnitude of this advance notice, and the individual factors predicting benefit. Participants with ALS (n = 39) completed rPFT training via telemedicine and then completed one year of weekly self-guided assessments in the home. Over this period, 17 individuals exhibited remotely-measured FVC dropping below 50% of predicted, the value often used for recommendation of NIV initiation. In 13 individuals with clinical detection of this event, the median and range of advance notice of need for NIV was 53 (-61-294) days. Prescription of NIV occurred for 21 individuals on the study, six of whom began NIV as a result of remote testing, prior to indication of need as determined by in-person assessments. Weekly home assessments appeared to be of greatest clinical value in a subset of patients with low baseline respiratory test values and rapid respiratory decline. This has potential implications for clinical management of ALS as well as the conduct of clinical trials that rely on respiratory endpoints.

Clinical characterization and outcomes of impulse oscillometry-defined bronchodilator response: an ECOPD cohort-based study.

BACKGROUND: The clinical significance of the impulse oscillometry-defined small airway bronchodilator response (IOS-BDR) is not well-known. Accordingly, this study investigated the clinical characteristics of IOS-BDR and explored the association between lung function decline, acute respiratory exacerbations, and IOS-BDR. METHODS: Participants were recruited from an Early Chronic Obstructive Pulmonary Disease (ECOPD) cohort subset and were followed up for two years with visits at baseline, 12 months, and 24 months. Chronic obstructive pulmonary disease (COPD) was defined as a post-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio < 0.70. IOS-BDR was defined as meeting any one of the following criteria: an absolute change in respiratory system resistance at 5 Hz ≤ - 0.137 kPa/L/s, an absolute change in respiratory system reactance at 5 Hz ≥ 0.055 kPa/L/s, or an absolute change in reactance area ≤ - 0.390 kPa/L. The association between IOS-BDR and a decline in lung function was explored with linear mixed-effects model. The association between IOS-BDR and the risk of acute respiratory exacerbations at the two-year follow-up was analyzed with the logistic regression model. RESULTS: This study involved 466 participants (92 participants with IOS-BDR and 374 participants without IOS-BDR). Participants with IOS-BDR had higher COPD assessment test and modified Medical Research Council dyspnea scale scores, more severe emphysema, air trapping, and rapid decline in FVC than those without IOS-BDR over 2-year follow-up. IOS-BDR was not associated with the risk of acute respiratory exacerbations at the 2-year follow-up. CONCLUSIONS: The participants with IOS-BDR had more respiratory symptoms, radiographic structural changes, and had an increase in decline in lung function than those without IOS-BDR. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900024643. Registered on 19 July, 2019.

Lower Arginine Bioavailability, Increased FeNO Levels, and Airway Resistance on Impulse Oscillometry Are Characteristics of Asthma in Children and Young Adults with Sickle Cell Disease.

Background and Objectives: Data on characteristics of asthma in children with sickle cell disease (SCD) is conflicting. Recently, the L-arginine pathway has gained attention in the pathogenesis of asthma and SCD. This study aimed to determine the distinctive clinical and laboratory features and the role of arginine metabolism in asthmatic children with SCD. Materials and Methods: A total of 52 children and adolescents with SCD, including 24 with asthma (SCD-A) and 28 without asthma (SCD-NA), and 40 healthy controls were included. A questionnaire, atopy tests, fractional exhaled nitric oxide (FeNO), and lung function tests were employed. Serum metabolites of the arginine pathway were measured. The results of the three groups were compared. Results: The demographic characteristics and atopy markers of the three groups were similar. FEV1%, FEV1/FVC, MMEF%, and total lung capacity (TLC%) values of SCD-A patients were not significantly different from the SCD-NA group, but they were significantly lower than the values measured in the controls. FeNO values greater than 35 ppb were present only in the SCD-A group. In impulse oscillometry, median resistance values at 5 Hz (R5)% were higher in both SCD subgroups than in healthy controls (p = 0.001). The (R5-20/R5)% values were higher in the SCD-A group (p = 0.028). Serum arginine levels and arginine bioavailability indices were significantly lower in the SCD-A group than in the SCD-NA group and healthy controls (p = 0.003 and p < 0.001). Conclusions: Asthma in children with SCD was not associated with atopy or low FEV1/FVC levels. However, lower arginine bioavailability and higher FeNO levels differentiated asthma in patients with SCD. High R5% and (R5-20/R5)% values indicated increased airway resistance in SCD, with a predominance of small airway disease in asthmatics.

Cardiopulmonary exercise testing on adaptive equipment in children and adults with Friedreich ataxia.

INTRODUCTION/AIMS: Traditional exercise is often difficult for individuals with Friedreich ataxia (FRDA), and evidence is limited regarding how to measure exercise performance in this population. We evaluated the feasibility, reliability, and natural history of adaptive cardiopulmonary exercise test (CPET) performance in children and adults with FRDA. METHODS: Participants underwent CPET on either an arm cycle ergometer (ACE) or recumbent leg cycle ergometer (RLCE) at up to four visits (baseline, 2 weeks, 4 weeks, and 1 year). Maximum work, oxygen consumption (peak VO2), oxygen (O2) pulse, and anaerobic threshold (AT) were measured in those who reached maximal volition. Test-retest reliability was assessed with intraclass coefficients, and longitudinal change was assessed using regression analysis. RESULTS: In our cohort (N = 23), median age was 18 years (interquartile range [IQR], 14-23), median age of FRDA onset was 8 years (IQR 6-13), median Friedreich Ataxia Rating Scale score was 58 (IQR 54-62), and GAA repeat length on the shorter FXN allele (GAA1) was 766 (IQR, 650-900). Twenty-one (91%) completed a maximal CPET (n = 8, ACE and n = 13, RLCE). Age, sex, and GAA1 repeat length were each associated with peak VO2. Preliminary estimates demonstrated reasonable agreement between visits 2 and 3 for peak work by both ACE and RLCE, and for peak VO2, O2 pulse, and AT by RLCE. We did not detect significant performance changes over 1 year. DISCUSSION: Adaptive CPET is feasible in FRDA, a relevant clinical trial outcome for interventions that impact exercise performance and will increase access to participation as well as generalizability of findings.

Relationship Between Diaphragm Thickness, Thickening Fraction, Dome Excursion, and Respiratory Pressures in Healthy Subjects: An Ultrasound Study.

PURPOSE: Diaphragm ultrasonography is used to identify causes of diaphragm dysfunction. However, its correlation with pulmonary function tests, including maximal inspiratory (MIP) and expiratory pressures (MEP), remains unclear. This study investigated this relationship by measuring diaphragm thickness, thickening fraction (TF), and excursion (DE) using ultrasonography, and their relationship to MIP and MEP. It also examined the influence of age, sex, height, and BMI on these measures. METHODS: We recruited healthy Japanese volunteers and conducted pulmonary function tests and diaphragm ultrasonography in a seated position. Diaphragm ultrasonography was performed during quiet breathing (QB) and deep breathing (DB) to measure the diaphragm thickness, TF, and DE. A multivariate analysis was conducted, adjusting for age, sex, height, and BMI. RESULTS: Between March 2022 and January 2023, 109 individuals (56 males) were included from three facilities. The mean (standard deviation) MIP and MEP [cmH2O] were 72.2 (24.6) and 96.9 (35.8), respectively. Thickness [mm] at the end of expiration was 1.7 (0.4), TF [%] was 50.0 (25.9) during QB and 110.7 (44.3) during DB, and DE [cm] was 1.7 (0.6) during QB and 4.4 (1.4) during DB. Multivariate analysis revealed that only DE (DB) had a statistically significant relationship with MIP and MEP (p = 0.021, p = 0.008). Sex, age, and BMI had a statistically significant influence on relationships between DE (DB) and MIP (p = 0.008, 0.048, and < 0.001, respectively). CONCLUSION: In healthy adults, DE (DB) has a relationship with MIP and MEP. Sex, age, and BMI, but not height, are influencing factors on this relationship.

Using the gli spirographic prediction equations to revisit the allometric relationships between lung volumes, height and age in adults.

The determination the forced vital capacity (FVC) and the forced expiratory volume in 1 second (FEV1) during spirometry studies, is at the core of the evaluation of the pulmonary function of patients with respiratory diseases. The Global Lung Function Initiative (GLI) offers the most extensive data set of normal lung functions available, which is currently used to determine the average expected/predicted FEV1 and FVC (predV), and their lower limit of normal (LLN, 5th percentile) at any given height and age for women and men. These prediction equations are currently expressed in a rather complex form: predV = exp [p+ (a x Ln (height) + (n x Ln (age)) + spline] and LLN = exp(Ln (predV) + Ln (1 - 1.645 x S x CV)/S); and are currently used to generate interpretations in commercialized spinographic system. However, as shown in this paper, these equations contain physiological and fundamental allometric information on lung volumes that become obvious when rewriting mean predicted values as a "simple" power function of height and LLN as a percentage of the mean predicted values. We therefore propose to present the equations of prediction obtained from the GLI data using simplified expressions in adults (18-95 years old) to reveal some of their physiological and allometric meaning. Indeed, when predicted FEV1 and FVC (predV) were expressed under the form predV= αx heightax b(age), the resulting exponent (a) ranges between 2 and 3, transforming the one dimension of a length (size) into a volume, akin to the third-order power (cubic) function of height historically used to predict lung volumes. Only one function, b (age), is necessary to replace all the factors related to age, including the tables of discrete data of spline functions original equations. Similarly, LLN can be expressed as LLN = c (age) xpredV to become a simple percentage of the predicted values, as a function of age. The equations with their respective new polynomial functions were validated in 52,764 consecutive spirometry tests performed in 2022 in 22,612 men and 30,152 women at the Cleveland Clinic. Using these equations, it become obvious that for both women and men, FEV1/FVC ratio decreases with the size as the exponent of the power function of height is lower for FEV1 than FVC. We conclude that rewriting the GLI predicted equations with simpler formulations restitutes to the GLI data some of their original allometric meaning, without altering the accuracy of their prediction.

Efficacy of Acupuncture in Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis.

Purpose: The effect of acupuncture as adjunctive therapy for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) was controversial. Thus, we aimed to evaluate the effects of acupuncture for treating AECOPD. Methods: Eight databases were searched from database inception to July 30, 2023. All RCTs compared acupuncture plus conventional western medicine with conventional western medicine alone were included. Outcomes were quality of life, lung function, blood oxygen condition, exercise capacity, daily symptoms, duration of hospitalization, and adverse events. The statistical analyses were conducted using Stata 17.0, and methodological quality was measured by the Cochrane bias risk assessment tool. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess the quality of evidence. Results: Twelve studies including 915 patients were included. Compared with conventional western medicine alone, acupuncture combined with conventional western therapy significantly improved quality of life (CAT: MD: -3.25; 95% CI: -3.73 to -2.78, P<0.001) and arterial blood gas (PaCO2: MD: -1.85; 95% CI: -2.74 to -0.95, P<0.001; PaO2: MD: 5.15; 95% CI: 1.22 to 9.07, P = 0.01). And for lung function, statistical benefits were found in FEV1/FVC (MD: 4.66; 95% CI: 2.21 to 7.12, P<0.001), but no difference was seen for FEV1% (MD: 1.83; 95% CI: -0.17 to 3.83, P = 0.073). There was no significant improvement in exercise capacity (6MWD: MD: 96.69; 95% CI: -0.60 to 193.98, P = 0.051), hospitalization duration (MD: -5.70; 95% CI: -11.97 to 0.58, P = 0.075), and dyspnea (mMRC: MD: -0.19; 95% CI: -0.61 to 0.63, P = 0.376) between two groups. Overall bias for CAT and mMRC was in "high" risk, FEV1%, FEV1/FVC, PaCO2, and PaO2 was in "some concern" and 1 RCT assessing hospitalization duration was in "low" risk. And the overall assessments were either moderate, low or very low certainty. Seven trials performed safety assessment of acupuncture, and no serious adverse events were reported. Conclusion: Acupuncture might have auxiliary effects on AECOPD. However, the quality of the evidence is limited, and more high-quality RCTs are needed to be performed in the future.

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.

The total-breath method yields higher values of DLCO and TLC than the conventional method.

BACKGROUND: The 2017 ATS/ERS technical standard for measuring the single-breath diffusing capacity (DLCO) proposed the "rapid-gas-analyzer" (RGA) or, equivalently, "total-breath" (TB) method for the determination of total lung capacity (TLC). In this study, we compared DLCO and TLC values estimated using the TB and conventional method, and how estimated TLC using these two methods compared to that determined by body plethysmography. METHOD: A total of 95 people with COPD (GOLD grades 1-4) and 23 healthy subjects were studied using the EasyOne Pro (ndd Medical Technologies, Switzerland) and Master Screen Body (Vyaire Medical, Höchberg, Germany). RESULTS: On average the TB method resulted in higher values of DLCO (mean ± SD Δ = 0.469 ± 0.267; 95%CI: 0.420; 0.517 mmol*min-1*kPa-1) and TLC (Δ = 0.495 ± 0.371; 95%CI: 0.427; 0.562 L) compared with the conventional method. In healthy subjects the ratio between TB and conventional DLCO was close to one. TLC estimated using both methods was lower than that determined by plethysmography. The difference was smaller for the TB method (Δ = 1.064 ± 0.740; 95%CI: 0.929; 1.199 L) compared with the conventional method (Δ = 1.558 ± 0.940; 95%CI: 1.387; 1.739 L). TLC from body plethysmography could be estimated as a function of TB TLC and FEV1 Z-Score with an accuracy (normalized root mean square difference) of 9.1%. CONCLUSION: The total-breath method yielded higher values of DLCO and TLC than the conventional analysis, especially in subjects with COPD. TLC from the total-breath method can also be used to estimate plethysmographic TLC with better accuracy than the conventional method. The study is registered under clinicaltrial.gov NCT04531293.

Impulse oscillometry in patients with pulmonary arterial hypertension: an exploratory study.

INTRODUCTION: Studies suggest peripheral airway abnormalities in Pulmonary Arterial Hypertension (PAH). Impulse Oscillometry (IOS) is a noninvasive and sensitive technique for assessing the small airways. It evaluates the impedance of the respiratory system ‒ Resistance (R) and reactance (X) ‒ to a pulse of sound waves sent to the lungs, in a range of frequencies (5‒20 Hz). METHOD: Resistance variables: R5, R20, R5-R20 and reactance variables: AX (reactance area) and Fres (resonance frequency). The aim is to evaluate R and X in patients with idiopathic PAH (IPAH) and to investigate whether there is a correlation between IOS and spirometry. RESULTS: Thirteen IPAH patients and 11 healthy subjects matched for sex and age underwent IOS and spirometry. IPAH patients had lower FVC and FEV1 values (p < 0.001), VEF1/CVF (p = 0.049) and FEF 25-75 (p = 0.006) than healthy patients. At IOS, IPAH patients showed lower tidal volumes and higher AX (p < 0.05) compared to healthy individuals, and 53.8 of patients had R5-R20 values ≥ 0.07 kPa/L/s. Correlation analysis: X5, AX, R5-R20 and Fres showed moderate correlation with FVC (p = 0.036 r = 0.585, p = 0.001 r = -0.687, p = 0.005 r = -0.726 and p = 0.027 r = -0.610); Fres (p = 0.012 r = -0.669) and AX (p = 0.006 r = -0.711) correlated with FEV1; [R5 and R20, (R5-R20)] also correlated with FEV1 (p < 0.001 r = -0.573, p = 0.020 r = -0.634 and p = 0.010 r = -0.683, respectively) in the IPAH group. There were also moderate correlations of FEF 25-75 % with Z5 (p = 0.041), R5 (p = 0.018), Fres (p = 0.043) and AX (p = 0.023). DISCUSSION: Patients showed changes suggestive of increased resistance and reactance in the IOS compared to healthy individuals, and the IOS findings showed a good correlation with spirometry variables.

Effects of Isocaloric Resistance, Aerobic, and Concurrent Exercise on Excess Postexercise Oxygen Consumption in Older Adults.

ABSTRACT: Pilon, R, Matos-Santos, L, Matlez, MP, Rodrigues, G, Amorim, F, Lattari, E, Farinatti, P, and Monteiro, W. Effects of isocaloric resistance, aerobic, and concurrent exercise on excess postexercise oxygen consumption in older adults. J Strength Cond Res 38(4): 755-761, 2024-Excess postexercise oxygen consumption (EPOC) is a major determinant of exercise-related caloric expenditure and metabolic adaptations. Exercise modality may influence the EPOC, but this issue has not been investigated in older adults. This study compared the EPOC after isocaloric bouts of continuous aerobic exercise (AE), resistance exercise (RE), and concurrent exercise (CE) in older individuals. Ten subjects (5 men; 73 ± 6 years) had their cardiorespiratory data assessed during AE, RE, and CE and along 30-minute postexercise recovery. Total energy expenditure (EE) during exercise was similar (p > 0.05) in AE (126.0 ± 30.7 kcal), RE (123.9 ± 30.6 kcal), and CE (130.8 ± 32.6 kcal), with different times to achieve the targeted EE (RE: 61.4 ± 1.9 minutes > CE: 43.3 ± 5.6 minutes > AE: 26.6 ± 5.7 minutes; p < 0.001). Consistently, the relative intensity during exercise was superior (p < 0.05) in AE (74 ± 15% oxygen uptake reserve [VO2R]) vs. CE (43 ± 13% VO2R) vs. RE (24 ± 9% VO2R). Despite the isocaloric conditions, average EPOC and EE were approximately 45% greater (p < 0.001) in AE (8.0 ± 2.3 L; 40.1 ± 11.7 kcal) vs. RE (5.6 ± 1.2 L; 28.1 ± 5.8 kcal) and CE (5.4 ± 2.3 L; 26.9 ± 11.5 kcal). In conclusion, the EPOC was greater after isocaloric AE vs. RE and CE performed by older adults. Exercise intensity seemed to be a more important determinant of EPOC than volume reflected by EE during exercise bouts. Moderate-intensity continuous AE was more time-efficient than RE and CE to achieve a target EE. In older individuals, AE should be preferred over RE or CE when the purpose is to increase the daily caloric expenditure.

Advances in Respiratory Medicine-Aims and Scopes Update.

Advances in Respiratory Medicine, which has been published by MDPI since 2022, serves as a platform for hosting pneumological studies [...].

Predicting parameters of airway dynamics generated from inspiratory and expiratory plethysmographic airway loops, differentiating subtypes of chronic obstructive diseases.

BACKGROUND: The plethysmographic shift volume-flow loop (sRaw-loop) measured during tidal breathing allows the determination of several lung function parameters such as the effective specific airway resistance (sReff), calculated from the ratio of the integral of the resistive aerodynamic specific work of breathing (sWOB) and the integral of the corresponding flow-volume loop. However, computing the inspiratory and expiratory areas of the sRaw-loop separately permits the determination of further parameters of airway dynamics. Therefore, we aimed to define the discriminating diagnostic power of the inspiratory and expiratory sWOB (sWOBin, sWOBex), as well as of the inspiratory and expiratory sReff (sReff IN and sReff EX), for discriminating different functional phenotypes of chronic obstructive lung diseases. METHODS: Reference equations were obtained from measurement of different databases, incorporating 194 healthy subjects (35 children and 159 adults), and applied to a collective of 294 patients with chronic lung diseases (16 children with asthma, aged 6-16 years, and 278 adults, aged 17-92 years). For all measurements, the same type of plethysmograph was used (Jaeger Würzburg, Germany). RESULTS: By multilinear modelling, reference equations of sWOBin, sWOBex, sReff IN and sReff EX were derived. Apart from anthropometric indices, additional parameters such as tidal volume (VT), the respiratory drive (P0.1), measured by means of a mouth occlusion pressure measurement 100 ms after inspiration and the mean inspiratory flow (VT/TI) were found to be informative. The statistical approach to define reference equations for parameters of airway dynamics reveals the interrelationship between covariants of the actual breathing pattern and the control of breathing. CONCLUSIONS: We discovered that sWOBin, sWOBex, sReff IN and sReff EX are new discriminating target parameters, that differentiate much better between chronic obstructive diseases and their subtypes, especially between chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap (ACO), thus strengthening the concept of precision medicine.

FEV1Q: a race-neutral approach to assessing lung function.

BACKGROUND: Forced expiratory volume in 1 s quotient (FEV1Q) is a simple approach to spirometry interpretation that compares measured lung function to a lower boundary. This study evaluated how well FEV1Q predicts survival compared with current interpretation methods and whether race impacts FEV1Q. METHODS: White and Black adults with complete spirometry and mortality data from the National Health and Nutrition Examination Survey (NHANES) III and the United Network for Organ Sharing (UNOS) database for lung transplant referrals were included. FEV1Q was calculated as FEV1 divided by 0.4 L for females or 0.5 L for males. Cumulative distributions of FEV1 were compared across races. Cox proportional hazards models tested mortality risk from FEV1Q adjusting for age, sex, height, smoking, income and among UNOS individuals, referral diagnosis. Harrell's C-statistics were compared between absolute FEV1, FEV1Q, FEV1/height2, FEV1 z-scores and FEV1 % predicted. Analyses were stratified by race. RESULTS: Among 7182 individuals from NHANES III and 7149 from UNOS, 1907 (27%) and 991 (14%), respectively, were Black. The lower boundary FEV1 values did not differ between Black and White individuals in either population (FEV1 first percentile difference ≤0.01 L; p>0.05). Decreasing FEV1Q was associated with increasing hazard ratio (HR) for mortality (NHANES III HR 1.33 (95% CI 1.28-1.39) and UNOS HR 1.18 (95% CI 1.12-1.23)). The associations were not confounded nor modified by race. Discriminative power was highest for FEV1Q compared with alternative FEV1 approaches in both Black and White individuals. CONCLUSIONS: FEV1Q is an intuitive and simple race-neutral approach to interpreting FEV1 that predicts survival better than current alternative methods.

Dynamic hyperinflation is a risk factor for mortality and severe exacerbations in COPD patients.

OBJECTIVE: To assess if dynamic hyperinflation is an independent risk factor for mortality and severe exacerbations in COPD patients. METHODS: A cohort of 141 patients with stable COPD and moderate to very severe airflow limitation, treated according to conventional guidelines, was followed for a median of 9 years. Clinical characteristics were recorded and arterial blood gases, pulmonary function tests, 6-min walk and incremental exercise test with measurement of respiratory pattern and operative lung volumes were performed. Endpoints were all-cause mortality and hospitalization for COPD exacerbation. RESULTS: 58 patients died during the follow-up period (1228 patients x year). The mortality rate was higher in patients with dynamic hyperinflation (n = 106) than in those without it (n = 35) (14.6; 95% CI, 14.5-14.8 vs. 7.2; 95% CI, 7.1-7.4 per 1000 patients-year). After adjusting for sex, age, body mass index, pack-years and treatment with inhaled corticosteroids, dynamic hyperinflation was associated with a higher mortality risk (adjusted hazard ratio [aHR], 2.725; 95% CI, 1.010-8.161), and in a multivariate model, comorbidity, peak oxygen uptake and dynamic hyperinflation were retained as independent predictors of mortality. The time until first severe exacerbation was shorter for patients with dynamic hyperinflation (aHR, 3.961; 95% CI, 1.385-11.328), and dynamic hyperinflation, FEV1 and diffusing capacity were retained as independent risk factors for severe exacerbation. Moreover, patients with dynamic hyperinflation had a higher hospitalization risk than those without it (adjusted incidence rate ratio, 1.574; 95% CI, 1.087-2.581). CONCLUSION: In stable COPD patients, dynamic hyperinflation is an independent prognostic factor for mortality and severe exacerbations.

Risk factors associated with severe adverse events in patients with relapsing polychondritis undergoing flexible bronchoscopy.

BACKGROUND: Patients with relapsing polychondritis (RP) sometimes experience upper airway collapse or lower airway stenosis, and bronchoscopy may provide a valuable typical image to confirm the diagnosis. This study aimed to identify potential risk factors associated with severe adverse effects during bronchoscopy. METHODS: We performed a retrospective cohort study of 82 consecutive patients with RP hospitalized at Peking Union Medical College Hospital between January 1, 2012 and December 31, 2022. Clinical features and disease patterns were compared among patients with RP undergoing bronchoscopy with or without severe adverse effects. Binary logistic regression analysis was performed to identify the associated risk factors. RESULTS: For patients with RP undergoing bronchoscopy with severe adverse effects, the forced vital capacity (FVC), forced vital capacity percent predicted values (FVC%), and peak expiratory flow were significantly lower (P = 0.001, P = 0.001, and P = 0.021, respectively) than those in the non-severe adverse effect subgroup. Binary logistic regression analysis revealed that low FVC% (odds ratio, 0.930; 95% confidence interval, 0.880-0.982; P = 0.009) was an independent risk factor for severe adverse events in patients undergoing bronchoscopy. CONCLUSIONS: Low FVC or FVC% suggests a high risk of severe adverse effects in patients with RP undergoing bronchoscopy. Patients with such risk factors should be carefully evaluated before bronchoscopy and adequately prepared for emergency tracheal intubation or tracheostomy.

Large airway T cells in adults with former bronchopulmonary dysplasia.

BACKGROUND: Bronchopulmonary Dysplasia (BPD) in infants born prematurely is a risk factor for chronic airway obstruction later in life. The distribution of T cell subtypes in the large airways is largely unknown. OBJECTIVE: To characterize cellular and T cell profiles in the large airways of young adults with a history of BPD. METHODS: Forty-three young adults born prematurely (preterm (n = 20), BPD (n = 23)) and 45 full-term-born (asthma (n = 23), healthy (n = 22)) underwent lung function measurements, and bronchoscopy with large airway bronchial wash (BW). T-cells subsets in BW were analyzed by immunocytochemistry. RESULTS: The proportions of both lymphocytes and CD8 + T cells in BW were significantly higher in BPD (median, 6.6%, and 78.0%) when compared with asthma (3.4% and 67.8%, p = 0.002 and p = 0.040) and healthy (3.8% and 40%, p < 0.001 and p < 0.001). In all adults born prematurely (preterm and BPD), lymphocyte proportion correlated negatively with forced vital capacity (r= -0.324, p = 0.036) and CD8 + T cells correlated with forced expiratory volume in one second, FEV1 (r=-0.448, p = 0.048). Correlation-based network analysis revealed that lung function cluster and BPD-birth cluster were associated with lymphocytes and/or CD4 + and CD8 + T cells. Multivariate regression analysis showed that lymphocyte proportions and BPD severity qualified as independent factors associated with FEV1. CONCLUSIONS: The increased cytotoxic T cells in the large airways in young adults with former BPD, suggest a similar T-cell subset pattern as in the small airways, resembling features of COPD. Our findings strengthen the hypothesis that mechanisms involving adaptive and innate immune responses are involved in the development of airway disease due to preterm birth.