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Background: Within-breath analysis of oscillometry parameters is a growing research area since it increases sensitivity and specificity to respiratory pathologies and conditions. However, reference equations for these parameters in White adults are lacking and devices using multiple sinusoids or pseudorandom forcing stimuli have been underrepresented in previous studies deriving reference equations. The current study aimed to establish reference ranges for oscillometry parameters, including also the within-breath ones in White adults using multi-sinusoidal oscillations. Methods: White adults with normal spirometry, BMI ≤30 kg/m2, without a smoking history, respiratory symptoms, pulmonary or cardiac disease, neurological or neuromuscular disorders, and respiratory tract infections in the previous 4 weeks were eligible for the study. Study subjects underwent oscillometry (multifrequency waveform at 5–11–19 Hz, Resmon PRO FULL, RESTECH Srl, Italy) in 5 centers in Europe and the USA according to international standards. The within-breath and total resistance (R) and reactance (X), the resonance frequency, the area under the X curve, the frequency dependence of R (R5–19), and within-breath changes of X (ΔX) were submitted to lambda-mu-sigma models for deriving reference equations. For each output parameter, an AIC-based stepwise input variable selection procedure was applied. Results: A total of 144 subjects (age 20.8–86.3 years; height 146–193 cm; BMI 17.42–29.98 kg/m2; 56% females) were included. We derived reference equations for 29 oscillatory parameters. Predicted values for inspiratory and expiratory parameters were similar, while differences were observed for their limits of normality. Conclusions: We derived reference equations with narrow confidence intervals for within-breath and whole-breath oscillatory parameters for White adults. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between three respiratory support approaches on lung volume recruitment during the first 2 h of postnatal life in preterm lambs. We estimated changes in lung aeration, measuring respiratory resistance and reactance by oscillometry at 5 Hz. We also measured intratracheal pressure in subsets of lambs. The first main finding is that sustained inflation (SI) applied noninvasively (Mask SI; n = 7) or invasively [endotracheal tube (ETT) SI; n = 6] led to similar rapid lung volume recruitment (∼6 min). In contrast, Mask continuous positive airway pressure (CPAP) without SI (n = 6) resuscitation took longer (∼30–45 min) to reach similar lung volume recruitment. The second main finding is that, in the first 15 min of postnatal life, the Mask CPAP without SI group closed their larynx during custom ventilator-driven expiration, leading to intratracheal positive end-expiratory pressure of ∼17 cmH2O (instead of 8 cmH2O provided by the ventilator). In contrast, the Mask SI group used the larynx to limit inspiratory pressure to ∼26 cmH2O (instead of 30 cmH2O provided by the ventilator). These different responses affected tidal volume, being larger in the Mask CPAP without SI group [8.4 mL/kg; 6.7–9.3 interquartile range (IQR)] compared to the Mask SI (5.0 mL/kg; 4.4–5.2 IQR) and ETT SI groups (3.3 mL/kg; 2.6–3.7 IQR). Distinct physiological responses suggest that spontaneous respiratory activity of the larynx of preterm lambs at birth can uncouple pressure applied by the ventilator to that applied to the lung, leading to unpredictable lung pressure and tidal volume delivery independently from the ventilator settings. NEW & NOTEWORTHY: We compared invasive and noninvasive resuscitation on lambs at birth, including or not sustained inflation (SI). Lung volume recruitment was faster in those receiving SI. During noninvasive resuscitation, larynx modulation reduced tracheal pressure from that applied to the mask in lambs receiving SI, while it led to increased auto-positive end-expiratory pressure and very large tidal volumes in lambs not receiving SI. Our results highlight the need for individualizing pressures and monitoring tidal volumes during resuscitation at birth. [ABSTRACT FROM AUTHOR]

Developing countries face a huge challenge in managing obstructive lung disorders due to frequency, severity, management, and economic impact. Spirometry has been the popular choice to assess the severity and reversibility of airflow obstruction, but the success of evaluation depends on the practitioner’s skills and the patient’s cooperation. Impulse oscillometry (IOS), a variant of forced oscillation technique is preferred over spirometry since it can be performed without forced respiratory maneuvers. The objective of this review is to evaluate IOS techniques and weigh its benefits against spirometry. Publications from international electronic databases such as PubMed, Scopus, and Web of Science were searched using relevant keywords for 5 years (2018–2023). A total of 416 articles were filtered, and of these, 70 were selected which specifically discussed the principles, procedures, parameters, and interpretations of spirometry and oscillometry. From the full-text articles included, we have reflected on the history, defined, explained, compared, and contrasted spirometry and oscillometry methods to establish the versatility of oscillometry technique to identify small airway functions and its application in special clinical conditions. This review presents an easily comprehensible synthesis of oscillometry and spirometry bringing out the principles, advantages, and limitations that are suitable for a larger spectrum of healthcare and research community.

The fact that some SARS-CoV-2 pneumonia patients benefit from changing body position, and some from continuous positive airways pressure (CPAP), indicates the functional character of hypoxia. We hypothesize that such effects could be explained by the closure of small airways. To prove the hypothesis, we evaluated the patency of small airways in 30 oxygen-dependent, spontaneously breathing patients with SARS-CoV-2 pneumonia during their hospital stay using the FOT method and then compared the results with data obtained three months later. During the acute period, total resistance (R5) and peripheral resistance (R5-20) rose above the upper limit of normal (ULN) in 28% and 50% of all patients, respectively. Reactance indices X5, AX and Fres exceeded ULN in 55%, 68% and 66% of cases. Significant correlations were observed between PaO2/FiO2, the time spent in the hospital and R5, X5, AX and Fres. After 3 months, 18 patients were re-examined. During the hospital stay, 11 of them had risen above the upper limit of normal (ULN), for both resistance (R5-20) and reactance (X5, AX) values. Three months later, ULN for R5-20 was exceeded in only four individuals, but ULN for X5 and AX was exceeded in five individuals. Lung function examination revealed a combined restrictive/obstructive ventilatory failure and reduced CO transfer factor. We interpret these changes as lung tissue remodeling due to the process of fibrosis. We conclude that during acute period of SARS-CoV-2 pneumonia, dilated pulmonary blood vessels and parenchymal oedema induce functional closure of small airways, which in turn induce atelectasis with pulmonary right-to-left shunting, followed by the resulting hypoxemia. [ABSTRACT FROM AUTHOR]

Elayne Moura Teixeira,1 Caroline Oliveira Ribeiro,1 Agnaldo José Lopes,2,3 Pedro Lopes de Melo1,4 1Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, State University of Rio de Janeiro, Rio de Janeiro, Brazil; 2Pulmonary Function Laboratory, Pedro Ernesto University Hospital, Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil; 3Pulmonary Rehabilitation Laboratory, Augusto Motta University Center, Rio de Janeiro, Brazil; 4Laboratory of Clinical and Experimental Research in Vascular Biology - Biomedical Center, State University of Rio de Janeiro, Rio de Janeiro, BrazilCorrespondence: Pedro Lopes de Melo, Rua São Francisco Xavier 524, Pavilhão Haroldo Lisboa da Cunha, Sala 104, Maracanã, Rio de Janeiro, RJ, 20550-013, Brazil, Tel +55-21-2334-0705, Email plopes@uerj.brPurpose: Chronic obstructive pulmonary disease (COPD) phenotypes may introduce different characteristics that need to be known to improve treatment. Respiratory oscillometry provides a detailed analysis and may offer insight into the pathophysiology of COPD. In this paper, we used this method to evaluate the differences in respiratory mechanics of COPD phenotypes.Patients and Methods: This study investigated a sample of 83 volunteers, being divided into control group (CG = 20), emphysema (n = 23), CB (n = 20) and asthma-COPD overlap syndrome (ACOS, n = 20). These analyses were performed before and after bronchodilator (BD) use. Functional capacity was evaluated using the Glittre‑ADL test, handgrip strength and respiratory pressures.Results: Initially it was observed that oscillometry provided a detailed description of the COPD phenotypes, which was consistent with the involved pathophysiology. A correlation between oscillometry and functional capacity was observed (r=− 0.541; p = 0.0001), particularly in the emphysema phenotype (r = − 0.496, p = 0.031). BD response was different among the studied phenotypes. This resulted in an accurate discrimination of ACOS from CB [area under the receiver operating curve (AUC) = 0.84] and emphysema (AUC = 0.82).Conclusion: These results offer evidence that oscillatory indices may enhance the comprehension and identification of COPD phenotypes, thereby potentially improving the support provided to these patients.Keywords: asthma-COPD overlap, emphysema, chronic bronchitis, respiratory impedance, handgrip analysis, Glittre-ADL test, forced oscillation technique, bronchodilator response

Abstract Background Intra-breath oscillometry has been proposed as a sensitive means of detecting airway obstruction in young children. We aimed to assess the impact of early life wheezing and lower respiratory tract illness on lung function, using both standard and intra-breath oscillometry in 3 year old children. Methods History of doctor-diagnosed asthma, wheezing, bronchiolitis and bronchitis and hospitalisation for respiratory problems were assessed by questionnaires in 384 population-based children. Association of respiratory history with standard and intra-breath oscillometry parameters, including resistance at 7 Hz (R7), frequency-dependence of resistance (R7 − 19), reactance at 7 Hz (X7), area of the reactance curve (AX), end-inspiratory and end-expiratory R (ReI, ReE) and X (XeI, XeE), and volume-dependence of resistance (ΔR = ReE-ReI) was estimated by linear regression adjusted on confounders. Results Among the 320 children who accepted the oscillometry test, 281 (88%) performed 3 technically acceptable and reproducible standard oscillometry measurements and 251 children also performed one intra-breath oscillometry measurement. Asthma was associated with higher ReI, ReE, ΔR and R7 and wheezing was associated with higher ΔR. Bronchiolitis was associated with higher R7 and AX and lower XeI and bronchitis with higher ReI. No statistically significant association was observed for hospitalisation. Conclusions Our findings confirm the good success rate of oscillometry in 3-year-old children and indicate an association between a history of early-life wheezing and lower respiratory tract illness and lower lung function as assessed by both standard and intra-breath oscillometry. Our study supports the relevance of using intra-breath oscillometry parameters as sensitive outcome measures in preschool children in epidemiological cohorts.

Abstract Rationale Lung recruitment and continuous distending pressure (CDP) titration are critical for assuring the efficacy of high-frequency ventilation (HFOV) in preterm infants. The limitation of oxygenation (peripheral oxygen saturation, SpO2) in optimizing CDP calls for evaluating other non-invasive bedside measurements. Respiratory reactance (Xrs) at 10 Hz measured by oscillometry reflects lung volume recruitment and tissue strain. In particular, lung volume recruitment and decreased tissue strain result in increased Xrs values. Objectives In extremely preterm infants treated with HFOV as first intention, we aimed to measure the relationship between CDP and Xrs during SpO2-driven CDP optimization. Methods In this prospective observational study, extremely preterm infants born before 28 weeks of gestation undergoing SpO2-guided lung recruitment maneuvers were included in the study. SpO2 and Xrs were recorded at each CDP step. The optimal CDP identified by oxygenation (CDPOpt_SpO2) was compared to the CDP providing maximal Xrs on the deflation limb of the recruitment maneuver (CDPXrs). Results We studied 40 infants (gestational age at birth = 22+ 6-27+ 5 wk; postnatal age = 1–23 days). Measurements were well tolerated and provided reliable results in 96% of cases. On average, Xrs decreased during the inflation limb and increased during the deflation limb. Xrs changes were heterogeneous among the infants for the amount of decrease with increasing CDP, the decrease at the lowest CDP of the deflation limb, and the hysteresis of the Xrs vs. CDP curve. In all but five infants, the hysteresis of the Xrs vs. CDP curve suggested effective lung recruitment. CDPOpt_SpO2 and CDPXrs were highly correlated (ρ = 0.71, p

Rationale: 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. Objectives: This study evaluates the prevalence and association of abnormal oscillometry parameters with respiratory symptoms and respiratory diseases in a general adult population. Methods: 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. Measurements and Main Results: 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%), P < 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%; P < 0.0001) in subjects with symptoms or diagnoses. Conclusions: 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. [ABSTRACT FROM AUTHOR]

To date both the clinical management and our understanding of respiratory disease have benefitted from widely available tests like spirometry, plethysmography and gas transfer. In recent years, however, there has been a growing interest in the use of more sensitive diagnostic tools in evaluating respiratory disorders. In this context, oscillometry applied to the study of small airways is emerging, and an interesting cohort of subjects of study is represented by the high-risk population undergoing CT lung cancer screening in the RISP program. The aim of the study is to characterize, in this cohort, patients with evidence of emphysema on low- dose chest CT and investigate their clinical and functional characteristics with spirometry and oscillometry. [ABSTRACT FROM AUTHOR]

The fact that some SARS-CoV-2 pneumonia patients benefit from changing body position, and some from continuous positive airways pressure (CPAP), indicates the functional character of hypoxia. We hypothesize that such effects could be explained by the closure of small airways. To prove the hypothesis, we evaluated the patency of small airways in 30 oxygen-dependent, spontaneously breathing patients with SARS-CoV-2 pneumonia during their hospital stay using the FOT method and then compared the results with data obtained three months later. During the acute period, total resistance (R5) and peripheral resistance (R5-20) rose above the upper limit of normal (ULN) in 28% and 50% of all patients, respectively. Reactance indices X5, AX and Fres exceeded ULN in 55%, 68% and 66% of cases. Significant correlations were observed between PaO2/FiO2, the time spent in the hospital and R5, X5, AX and Fres. After 3 months, 18 patients were re-examined. During the hospital stay, 11 of them had risen above the upper limit of normal (ULN), for both resistance (R5-20) and reactance (X5, AX) values. Three months later, ULN for R5-20 was exceeded in only four individuals, but ULN for X5 and AX was exceeded in five individuals. Lung function examination revealed a combined restrictive/obstructive ventilatory failure and reduced CO transfer factor. We interpret these changes as lung tissue remodeling due to the process of fibrosis. We conclude that during acute period of SARS-CoV-2 pneumonia, dilated pulmonary blood vessels and parenchymal oedema induce functional closure of small airways, which in turn induce atelectasis with pulmonary right-to-left shunting, followed by the resulting hypoxemia.

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by defects in lysosome-related organelles. Given the high mortality rate associated with HPS pulmonary fibrosis (PF) and the significant risks tied to lung transplantation, it is essential to explore new tools for the early surveillance of PF to monitor its progression before clinical symptoms become apparent. This study evaluates the forced oscillation technique (FOT) for assessing PF in five adult patients with HPS, all homozygous for the HPS-1 (c.1472&#95;1487dup p.His497Glnfs*90) founder mutation. Using the Resmon™ Pro V3 device, the FOT measured resistance (Rrs) and reactance (Xrs) at 5, 11, and 19 Hertz (Hz). High-resolution computed tomography (HRCT) scans of the chest were reviewed for radiographic findings. The cohort ( n = 5) had a median age of 43 years. All patients exhibited HPS clinical features, including oculocutaneous albinism and respiratory symptoms such as dry cough and dyspnea. Radiographic analysis revealed PF in four patients (80%), with traction bronchiectasis, reticular patterns, honeycombing, and ground-glass opacities. The FOT detected progressive changes in pulmonary resistance and reactance correlating with fibrosis severity. These findings suggest that the FOT is a valuable non-invasive tool for monitoring PF in patients with HPS-1, potentially improving early diagnosis and management.

Background: The diagnosis of mild-moderate equine asthma (MEA) can be confirmed by airway endoscopy, bronchoalveolar lavage fluid (BALf) cytology, and lung function evaluation by indirect pleural pressure measurement. Oscillometry is a promising pulmonary function test method, but its ability to detect subclinical airway obstruction has been questioned., Objectives: To evaluate the differences in lung function measured by oscillometry between healthy and MEA-affected horses., Study Design: Prospective case-control clinical study., Methods: Thirty-seven horses were divided into healthy and MEA groups, based on history and clinical score; the diagnosis of MEA was confirmed by airway endoscopy and BALf cytology. Horses underwent oscillometry at frequencies ranging from 2 to 6 Hz. Obtained parameters included whole-breath, inspiratory, expiratory, and the difference between inspiratory and expiratory resistance (Rrs) and reactance (Xrs). Differences between oscillometry parameters at different frequencies were evaluated within and between groups by repeated-measures two-way ANOVA and post hoc tests with Bonferroni correction. Frequency dependence was compared between groups by t test. For significant parameters, a receiver operating characteristics curve was designed, cut-off values were identified and their sensitivity and specificity were calculated. Statistical significance was set at p < 0.05., Results: No significant differences in Xrs and Rrs were observed between groups. The frequency dependence of whole-breath and inspiratory Xrs significantly differed between healthy (respectively, -0.03 ± 0.02 and -0.05 ± 0.02 cmH 2 O/L/s) and MEA (-0.1 ± 0.03 and -0.2 ± 0.02 cmH 2 O/L/s) groups (p < 0.05 and p < 0.01). For inspiratory Xrs frequency dependence, a cut-off value of -0.06 cmH 2 O/L/s was identified, with 86.4% (95% CI: 66.7%-95.3%) sensitivity and 66.7% (95% CI: 41.7%-84.8%) specificity., Main Limitations: Sample size, no BALf cytology in some healthy horses., Conclusions: Oscillometry can represent a useful non-invasive tool for the diagnosis of MEA. Specifically, the evaluation of the frequency dependence of Xrs may be of special interest., (© 2024 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Background: Several factors may influence quality of life (QOL) for patients with primary ciliary dyskinesia (PCD). We aimed to evaluate the association between pulmonary functions, nasal symptoms and QOL in PCD patients., Methods: A prospective single center study. Patients performed spirometry, whole body plethysmography, forced oscillation technique (FOT), lung clearance index (LCI), 6-min walk test (6MWT), and filled two questionnaires: a specific PCD QOL questionnaire (PCD-QOL) and Sino-nasal outcome test (SNOT-22) questionnaire, assessing symptoms of chronic rhinosinusitis and health related QOL., Results: Twenty-seven patients (56% females), age 19.4 ± 10.5 years were included; their, FEV1 was 74.6 ± 22.7%, and RV/TLC was (157.3 ± 39.3% predicted). Health perception and lower respiratory symptoms domains of PCD-QOL had the lowest score (median [IQR]: 50 [33.3-64.6] and 57.1 [38.9-72.2], respectively). FOT parameters correlated with several PCD-QOL domains. R5 z-score (indicating total airway resistance) and AX z-score (indicating airway reactance) correlated negatively with physical domain (r = -0.598, p = .001, and r = -0.42, p = .03, respectively); R5 z-score also correlated negatively with hearing domain (r = -0.57, p = .002). R5-20 z-score (indicating small airway resistance) correlated negatively with role domain (r = -0.49, p = .03). SNOT-22 score correlated negatively with several PCD-QOL domains (lower respiratory symptoms r = -0.77, p < .001; physical r = -0.72, p < .001; upper respiratory symptoms r = -0.66, p < .001). No correlations were found between spirometry values, LCI, 6MWT, and PCD-QOL., Conclusions: FOT suggested small airway dysfunction, and correlated negatively with several PCD-QOL domains. Nasal symptoms had strong negative correlations with PCD-QOL. Larger longitudinal studies will further elucidate factors affecting QOL in PCD., (© 2023 The Authors. Pediatric Pulmonology published by Wiley Periodicals LLC.)