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Respiratory Research Jan 2024Lung recruitment and continuous distending pressure (CDP) titration are critical for assuring the efficacy of high-frequency ventilation (HFOV) in preterm infants. The... (Observational Study)
Observational Study
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, SpO) 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 SpO-driven CDP optimization.
METHODS
In this prospective observational study, extremely preterm infants born before 28 weeks of gestation undergoing SpO-guided lung recruitment maneuvers were included in the study. SpO and Xrs were recorded at each CDP step. The optimal CDP identified by oxygenation (CDP) was compared to the CDP providing maximal Xrs on the deflation limb of the recruitment maneuver (CDP).
RESULTS
We studied 40 infants (gestational age at birth = 22-27 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. CDP and CDP were highly correlated (ρ = 0.71, p < 0.001) and not statistically different (median difference [range] = -1 [-3; 9] cmHO). However, CDP were equal to CDP in only 6 infants, greater than CDP in 10, and lower in 24 infants.
CONCLUSIONS
The Xrs changes described provide complementary information to oxygenation. Further investigation is warranted to refine recruitment maneuvers and CPD settings in preterm infants.
Topics: Humans; Infant, Newborn; Infant, Extremely Premature; Oscillometry; Lung; Lung Volume Measurements; High-Frequency Ventilation
PubMed: 38178216
DOI: 10.1186/s12931-023-02639-4 -
Frontiers in Medicine 2023Severe coronavirus disease 2019 (COVID-19) may require veno-venous extracorporeal membrane oxygenation (V-V ECMO). While V-V ECMO is offered in severe lung injury to...
BACKGROUND
Severe coronavirus disease 2019 (COVID-19) may require veno-venous extracorporeal membrane oxygenation (V-V ECMO). While V-V ECMO is offered in severe lung injury to COVID-19, long-term respiratory follow-up in these patients is missing. Therefore, we aimed at providing comprehensive data on the long-term respiratory effects of COVID-19 requiring V-V ECMO support during the acute phase of infection.
METHODS
In prospective observational cohort study design, patients with severe COVID-19 receiving invasive mechanical ventilation and V-V ECMO (COVID group, = 9) and healthy matched controls ( = 9) were evaluated 6 months after hospital discharge. Respiratory system resistance at 5 and 19 Hz (R, R), and the area under the reactance curve (AX) was evaluated using oscillometry characterizing total and central airway resistances, and tissue elasticity, respectively. R and R difference (R-R) reflecting small airway function was also calculated. Forced expired volume in seconds (FEV), forced expiratory vital capacity (FVC), functional residual capacity (FRC), carbon monoxide diffusion capacity (DLCO) and transfer coefficient (KCO) were measured.
RESULTS
The COVID group had a higher AX and R-R than the healthy matched control group. However, there was no significant difference in terms of R or R. The COVID group had a lower FEV and FVC on spirometry than the healthy matched control group. Further, the COVID group had a lower FRC on plethysmography than the healthy matched control group. Meanwhile, the COVID group had a lower DLCO than healthy matched control group. Nevertheless, its KCO was within the normal range.
CONCLUSION
Severe acute COVID-19 requiring V-V ECMO persistently impairs small airway function and reduces respiratory tissue elasticity, primarily attributed to lung restriction. These findings also suggest that even severe pulmonary pathologies of acute COVID-19 can manifest in a moderate but still persistent lung function impairment 6 months after hospital discharge.
TRIAL REGISTRATION
NCT05812196.
PubMed: 38173937
DOI: 10.3389/fmed.2023.1288679 -
BMC Pulmonary Medicine Jan 2024Idiopathic pulmonary fibrosis (IPF) is a progressive disease with a poor prognosis. Pulmonary function tests (PFTs) aid in evaluating the disease status of IPF. The...
BACKGROUND
Idiopathic pulmonary fibrosis (IPF) is a progressive disease with a poor prognosis. Pulmonary function tests (PFTs) aid in evaluating the disease status of IPF. The clinical significance of oscillometry measurements in interstitial lung diseases has recently been reported. Our previous study showed that respiratory reactance (Xrs) measured by oscillometry reflected disease severity and predicted subsequent lung capacity decline in patients with IPF. However, the direct impact of Xrs on survival needs to be determined, and there are currently no reference values in oscillometry to predict prognosis. Therefore, this study aimed to investigate the association between oscillometry measurements, particularly Xrs, and survival in patients with IPF and to determine the cutoff values of Xrs that predict 3-year survival.
METHODS
We analyzed the relationship between the measured values of PFT and oscillometry derived from 178 patients with IPF. Univariate and multivariate Cox proportional hazards analyses were performed to investigate the relationships between clinical indices at the time of the first oscillometry and survival. We performed the time-dependent receiver operating characteristic (ROC) curve analysis to set the optimized cutoff values of Xrs for 3-year survival prediction. We examined the discriminating power of cutoff values of Xrs on survival using the Kaplan-Meier method and the log-rank test.
RESULTS
Xrs components, especially in the inspiratory phase (In), significantly correlated with the PFT values. In the multivariate analyses, Xrs (all of reactance at 5 Hz [X5], resonant frequency [Fres], and low-frequency reactance area [ALX] in the inspiratory phase) had a significant impact on survival (X5, p = 0.003; Fres, p = 0.016; ALX, p = 0.003) independent of age, sex, and other prognostic factors derived from the univariate analysis. The area under the ROC curve was 0.765, 0.759, and 0.766 for X5 In, Fres In, and ALX In, with cutoff values determined at - 0.98, 10.67, and 5.32, respectively. We found significant differences in survival after dividing patients using each of the cutoff values of Xrs.
CONCLUSIONS
In patients with IPF, Xrs measured by oscillometry significantly impacted survival. We also determined the cutoff values of Xrs to discriminate patients with poor prognoses.
Topics: Humans; Airway Resistance; Oscillometry; Lung; Respiratory Function Tests; Idiopathic Pulmonary Fibrosis
PubMed: 38167026
DOI: 10.1186/s12890-023-02776-y -
Lung India : Official Organ of Indian... Jan 2024The current morphological condition of an individual is described by a somatotype, which is a three-number scale. The endomorph, mesomorph and ectomorph components are...
BACKGROUND
The current morphological condition of an individual is described by a somatotype, which is a three-number scale. The endomorph, mesomorph and ectomorph components are presented in the same sequence, and each number corresponds to one of the three basic components of body composition.
METHODS
We recruited 50 healthy male subjects with a mean age of 24.10 ± 4.55 yrs. Somatotype was determined by the Heath and Carter method. Impulse oscillometry was performed followed by spirometry according to the European Respiratory Society (ERS) or American Thoracic Society (ATS) guidelines. Resistance at 5 Hz (R5) %pred, R20%pred, R5-R20, X5%pred, X20, area of reactance (Ax) and resonant frequency (Fres) were obtained by doing impulse oscillometry. Slow vital capacity (SVC), forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC ratio and maximum mid-expiratory flow (MMEF) were assessed by doing spirometry.
RESULTS
Endomorphs (0.05 (0.00-0.09) vs 0.01 (0.00-0.04); P < 0.0001) and mesomorphs (0.04 (0.000.09) vs 0.01 (0.00-0.04); P = 0.002) had significantly higher R5-R20 than ectomorphs. Similarly, endomorphs (0.32 (0.07-0.82) vs 0.15 (0.08-0.35); P = 0.001) and mesomorphs (0.28 (0.17-0.64) vs 0.15 (0.08-0.35); P = 0.015) also showed significantly higher Ax than ectomorphs, Fres of endomorphs (15.37 (8.43-21.85) vs 10.08 (8.94-14.30); P < 0.0001) and mesomorphs (14.32 (10.24-20.86) vs 10.08 (8.94-14.30); P < 0.0001) were significantly high than ectomorphs. Moreover, spirometric measures reveal significant variation in which mesomorphs had significantly higher values of % predicted of FVC than ectomorphs (92.49 ± 7.211 vs 83.86 ± 7.861; P = 0.042) and the ratio of FEV1 to FVC was significantly higher in ectomorphs than in endomorphs (89.00 ± 5.80 vs 85.04 ± 5.73; P = 0.03).
CONCLUSION
Peripheral airway dysfunction was observed in endomorphs and mesomorphs as compared to ectomorphs. Mesomorphs had a relatively higher FVC that may be due to their greater muscular strength.
PubMed: 38160452
DOI: 10.4103/lungindia.lungindia_230_23 -
Transplant International : Official... 2023Peak spirometry after single lung transplantation (SLTx) for interstitial lung disease (ILD) is lower than after double lung transplantation (DLTx), however the...
Peak spirometry after single lung transplantation (SLTx) for interstitial lung disease (ILD) is lower than after double lung transplantation (DLTx), however the pathophysiologic mechanisms are unclear. We aim to assess respiratory mechanics in SLTx and DLTx for ILD using oscillometry. Spirometry and oscillometry (tremoflo C-100) were performed in stable SLTx and DLTx recipients in a multi-center study. Resistance (R, R) and reactance (X) were compared between LTx recipient groups, matched by age and gender. A model of respiratory impedance using ILD and DLTx data was performed. In total, 45 stable LTx recipients were recruited (SLTx = 23, DLTx = 22; males: 87.0% vs. 77.3%; median age 63.0 vs. 63.0 years). Spirometry was significantly lower after SLTx compared with DLTx: %-predicted mean (SD) FEV [70.0 (14.5) vs. 93.5 (26.0)%]; FVC [70.5 (16.8) vs. 90.7 (12.8)%], . R and R were similar between groups ( and , respectively) yet X was significantly worse after SLTx: median (IQR) X [-1.88 (-2.89 to -1.39) vs. -1.22 (-1.87 to -0.86)] cmHO.s/L], . R and X measurements from the model were congruent with measurements in SLTx recipients. The similarities in resistance, yet differences in spirometry and reactance between both transplant groups suggest the important contribution of elastic properties to the pathophysiology. Oscillometry may provide further insight into the physiological changes occurring post-LTx.
Topics: Male; Humans; Middle Aged; Oscillometry; Forced Expiratory Volume; Australia; Lung; Lung Diseases, Interstitial; Allografts
PubMed: 38116170
DOI: 10.3389/ti.2023.11758 -
Physiological Reports Dec 2023Pulmonary mechanics has been traditionally viewed as determined by lung size and physical factors such as frictional forces and tissue viscoelastic properties, but few...
Pulmonary mechanics has been traditionally viewed as determined by lung size and physical factors such as frictional forces and tissue viscoelastic properties, but few information exists regarding potential influences of cytokines and hormones on lung function. Concentrations of 28 cytokines and hormones were measured in saliva from clinically healthy scholar children, purposely selected to include a wide range of body mass index (BMI). Lung function was assessed by impulse oscillometry, spirometry, and diffusing capacity for carbon monoxide, and expressed as z-score or percent predicted. Ninety-six scholar children (55.2% female) were enrolled. Bivariate analysis showed that almost all lung function variables correlated with one or more cytokine or hormone, mainly in boys, but only some of them remained statistically significant in the multiple regression analyses. Thus, after adjusting by height, age, and BMI, salivary concentrations of granulocyte-macrophage colony-stimulating factor (GM-CSF) in boys were associated with zR5-R20 and reactance parameters (zX20, zFres, and zAX), while glucagon inversely correlated with resistances (zR5 and zR20). Thus, in physiological conditions, part of the mechanics of breathing might be influenced by some cytokines and hormones, including glucagon and GM-CSF. This endogenous influence is a novel concept that warrants in-depth characterization.
Topics: Male; Child; Humans; Female; Cytokines; Granulocyte-Macrophage Colony-Stimulating Factor; Cross-Sectional Studies; Glucagon; Lung
PubMed: 38086735
DOI: 10.14814/phy2.15861 -
Respiratory Physiology & Neurobiology Feb 2024The forced oscillation technique (FOT) enables non-invasive measurement of respiratory system impedance. Limited data exists on how changes in operating lung volume...
BACKGROUND
The forced oscillation technique (FOT) enables non-invasive measurement of respiratory system impedance. Limited data exists on how changes in operating lung volume (OLV) impact FOT-derived measures of airway resistance (Rrs) and reactance (Xrs).
OBJECTIVES
This study examined the reproducibility and responsiveness of FOT-derived measures of Rrs and Xrs during simulated changes in OLV.
METHODS
Participants simulated breathing at six OLVs: total lung capacity (TLC), ∼50% of inspiratory reserve volume (IRV), ∼two-times tidal volume (VT), tidal volume (VT), ∼50% of expiratory reserve volume (ERV), and residual volume (RV), on a commercially available FOT device. Each simulated OLV manuever was performed in triplicate and in random order. Total Rrs and Xrs were recorded at 5, 11, and 19 Hz.
RESULTS
Twelve healthy participants (2 female) completed the study (weight: 76.5 ± 13.6 kg, height: 178.6 ± 9.7 cm, body mass index: 23.9 ± 3.1 kg/m). Reproducibility of Rrs and Xrs at VT, VT and IRV was good to excellent (Range: ICC: 0.89-0.98, 95% confidence interval (CI): 0.70-0.98), while reproducibility at TLC, RV, and ERV was poor to excellent (Range: ICC: 0.60-0.98, 95% CI: 0.36-0.97). Rrs and Xrs were not different between VT and VT at any frequency (P > .05). With lung hyperinflation from VT to TLC, Rrs and Xrs decreased at all three frequencies (e.g., At 5 Hz Rrs: mean difference (MD): - 0.89, 95%CI: - 0.03 to - 1.75, P = .04; Xrs: MD: - 0.56, 95%CI: - 0.25 to - 0.86, P < .01). With lung hypoinflated from VT to RV, Rrs increased, and Xrs decreased for all frequencies (e.g., MD at 5 Hz, Rrs: MD: 2.31, 95%CI: 0.94-3.67, P < .01; Xrs: MD: -2.53, 95%CI: -4.02 to -1.04, P < .01).
CONCLUSION
FOT-derived measures of airway Rrs and Xrs are reproducible across a range of OLV's, and are responsive to hyper- and hypo-inflation of the lung. To further understand the impact of lung hyper- and hypo-inflation on FOT-derived airway impedance additional study is required in individuals with pathological variations in operating lung volume.
Topics: Humans; Female; Reproducibility of Results; Electric Impedance; Respiratory Function Tests; Lung Volume Measurements; Airway Resistance; Lung
PubMed: 38036081
DOI: 10.1016/j.resp.2023.104200 -
Oscillometry in Lung Function Assessment: A Comprehensive Review of Current Insights and Challenges.Cureus Oct 2023Oscillometry, a non-invasive technique for assessing lung function, has gained significant recognition and importance in modern pulmonary medicine. This comprehensive... (Review)
Review
Oscillometry, a non-invasive technique for assessing lung function, has gained significant recognition and importance in modern pulmonary medicine. This comprehensive review thoroughly explores its principles, applications, advantages, limitations, recent innovations, and future directions. Oscillometry's primary strength lies in its ability to offer a holistic assessment of lung mechanics. Unlike traditional spirometry, oscillometry captures the natural airflow during quiet breathing, making it suitable for patients of all ages and those with severe respiratory conditions. It provides a comprehensive evaluation of airway resistance, reactance, and compliance, offering insights into lung function that were previously challenging to obtain. In clinical practice, oscillometry finds extensive application in diagnosing and managing respiratory diseases. It plays a pivotal role in asthma, chronic obstructive pulmonary disease (COPD), and interstitial lung diseases. By detecting subtle changes in lung function before symptoms manifest, oscillometry facilitates early interventions, improving disease management and patient outcomes. Oscillometry's non-invasive and patient-friendly nature is precious in pediatric care, where traditional spirometry may be challenging for young patients. It aids in diagnosing and monitoring pediatric respiratory disorders, ensuring that children receive the care they need from an early age. Despite its many advantages, oscillometry faces challenges, such as the need for standardized protocols and the complexity of data interpretation. However, ongoing efforts to establish global standards and provide education and training for healthcare professionals aim to address these issues. Looking ahead, oscillometry holds great promise in the field of personalized medicine. With its ability to tailor treatment plans based on individualized lung function data, healthcare providers can optimize therapy selection and dosing, ultimately improving patient care and quality of life. In conclusion, oscillometry is poised to play an increasingly pivotal role in modern pulmonary medicine. As standardization efforts continue and technology evolves, it is an indispensable tool in the clinician's arsenal for diagnosing, managing, and personalizing respiratory care, ultimately leading to improved patient outcomes and better respiratory health.
PubMed: 38034137
DOI: 10.7759/cureus.47935 -
Open Respiratory Archives 2024The role of oscillometry in interstitial lung disease (ILD) is still unclear. The main objective of our study was to describe the parameters determined by oscillometry...
INTRODUCTION
The role of oscillometry in interstitial lung disease (ILD) is still unclear. The main objective of our study was to describe the parameters determined by oscillometry in these patients and compare them with those obtained in conventional respiratory function tests.
METHODS
This was a cross-sectional observational study. Patients with no respiratory disease and patients being followed up for ILD in the specialist unit of Hospital Universitario de Getafe, Madrid were included.
RESULTS
A total of 45 individuals were analyzed. Fifteen had no respiratory disease, 15 were ILD patients with mild functional impairment, and another 15 were ILD patients with severe impairment. None of the participants had an obstructive pattern on spirometry.Comparison between the three groups showed statistically significant differences in the values of R5-19, reactance at 5 Hz and reactance at 11 Hz. No differences were observed between the three groups in Delta Xrs. The study showed a strong correlation between total and inspiratory reactance at 5 Hz and forced vital capacity and diffusing capacity for carbon monoxide.
CONCLUSIONS
Our results suggest that the findings in ILD are characteristic of this disease and that they differ from those found in other diseases such as chronic obstructive pulmonary disease. It also seems that there are differences according to the degree of functional impairment of the patients. The results show a strong correlation with standard pulmonary function tests, so oscillometry could be a useful tool in patients with ILD who are unable to perform it, and could provide additional information.
PubMed: 38022789
DOI: 10.1016/j.opresp.2023.100278 -
American Journal of Respiratory and... Feb 2024Respiratory resistance (Rrs) and reactance (Xrs) as measured by oscillometry and their intrabreath changes have emerged as sensitive parameters for detecting early...
Respiratory resistance (Rrs) and reactance (Xrs) as measured by oscillometry and their intrabreath changes have emerged as sensitive parameters for detecting early pathological impairments during tidal breathing. This study evaluates the prevalence and association of abnormal oscillometry parameters with respiratory symptoms and respiratory diseases in a general adult population. A total of 7,560 subjects in the Austrian LEAD (Lung, hEart, sociAl, boDy) Study with oscillometry measurements (computed with the Resmon Pro FULL; Restech Srl) were included in this study. The presence of respiratory symptoms and doctor-diagnosed respiratory diseases was assessed using an interview-based questionnaire. Rrs and Xrs at 5 Hz, their inspiratory and expiratory components, the area above the Xrs curve, and the presence of tidal expiratory flow limitation were analyzed. Normality ranges for oscillometry parameters were defined. The overall prevalence of abnormal oscillometry parameters was 20%. The incidence of abnormal oscillometry increased in the presence of symptoms or diagnoses: 17% (16-18%) versus 27% (25-29%), < 0.0001. All abnormal oscillometry parameters except Rrs at 5 Hz were significantly associated with respiratory symptoms/diseases. Significant associations were found, even in subjects with normal spirometry, with abnormal oscillometry incidence rates increasing by 6% (4-8%; < 0.0001) in subjects with symptoms or diagnoses. Abnormal oscillometry parameters are present in one-fifth of this adult population and are significantly associated with respiratory symptoms and disease. Our findings underscore the potential of oscillometry as a tool for detecting and evaluating respiratory impairments, even in individuals with normal spirometry.
Topics: Adult; Humans; Oscillometry; Lung; Respiration; Exhalation; Respiratory Tract Diseases; Spirometry; Forced Expiratory Volume; Airway Resistance
PubMed: 37972230
DOI: 10.1164/rccm.202306-0975OC