nitrogen washout
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2022 ◽  
Vol 9 ◽  
Author(s):  
Magdalena Postek ◽  
Katarzyna Walicka-Serzysko ◽  
Justyna Milczewska ◽  
Dorota Sands

IntroductionIn cystic fibrosis (CF), pathological lung changes begin early in life. The technological progress currently gives many diagnostic possibilities. However, pulmonary function testing in children remains problematic.ObjectivesOur study aimed to correlate the results of impulse oscillometry (IOS) with those of multiple breath nitrogen washout (MBNW) in our pediatric CF population. We also compared those parameters between the groups with and without spirometric features of obturation.MethodsWe collected 150 pulmonary function test sets, including spirometry, IOS, and MBNW in patients with CF aged 12.08 ± 3.85 years [6–18]. The study group was divided into two subgroups: IA (without obturation) and IB (with obturation). We also compared Sacin, Scond, and oscillometry parameters of 20 patients aged 14–18 years who reached the appropriate tidal volume (VT) during MBNW.ResultsStatistical analysis showed a negative correlation between lung clearance index (LCI) and spimoetric parameters. Comparison of subgroups IA (n = 102) and IB (n = 48) indicated a statistically significant difference in LCI (p < 0.001) and FEV1z-score (p < 0.001), FEV1% pred (p < 0.001), MEF25z-score (p < 0.001), MEF50 z-score (p < 0.001), MEF75 z-score (p < 0.001), R5% pred (p < 0.05), and R20% pred (p < 0.01). LCI higher than 7.91 was found in 75.33% of the study group, in subgroup IB—91.67%, and IA−67.6%.ConclusionsLCI derived from MBNW may be a better tool than IOS for assessing pulmonary function in patients with CF, particularly those who cannot perform spirometry.


2021 ◽  
pp. 00487-2021
Author(s):  
Blake M. Handley ◽  
Jack Bozier ◽  
Edward Jeagal ◽  
Sandra Rutting ◽  
Robin E. Schoeffel ◽  
...  

2021 ◽  
Vol 131 (4) ◽  
pp. 1286-1287
Author(s):  
Alexander Horsley ◽  
Chantal Darquenne
Keyword(s):  

2021 ◽  
Vol 7 (3) ◽  
pp. 00383-2021
Author(s):  
Jan Olofson ◽  
Björn Bake ◽  
Bengt Bergman ◽  
Lowie E.G.W. Vanfleteren ◽  
Kurt Svärdsudd

Early identification of subjects running an increased risk of contracting COPD enables focus on individual preventive measures. The slope of the alveolar plateau of the single-breath nitrogen washout test (N2-slope) is a sensitive measure of small-airway dysfunction. However, its role remains unexplored in predicting hospital admission or death related to COPD, i.e. incident COPD events, in relation to the presence of various respiratory symptoms.A random population sample of 625 men, aged 50 (n=218) or 60 years (n=407), was followed for 38 years for incident COPD events. At baseline, a questionnaire on respiratory symptoms and smoking habits was collected, spirometry and the single-breath nitrogen test were performed, and the N2-slope was determined. Proportional hazard regression (Cox regression) analysis was used for the prediction model.The N2-slope improved the prediction of COPD events significantly beyond that of respiratory symptoms weighted all together and other covariates (hazard ratio 1.63, 95% CI 1.20–2.22; p<0.005), a prediction applicable to subjects without (p=0.001) and with (p<0.05) airway obstruction. Dyspnoea and wheezing were the most predictive symptoms. The combination of the N2-slope and number of respiratory symptoms notably resulted in an effective prediction of incident COPD events even in nonobstructive subjects, as evidenced by a predicted incidence of ∼70% and ∼90% for a very steep N2-slope combined with many respiratory symptoms in subject without and with airway obstruction, respectively.The alveolar N2-slope should be considered in the critical need for further research on early diagnosis of COPD.


2021 ◽  
Vol 14 (3) ◽  
pp. e239146
Author(s):  
Thais Ferrari da Cruz ◽  
Rogério Rufino ◽  
Agnaldo Lopes ◽  
Cláudia Henrique Costa

We describe three cases of female subjects (aged 16, 44 and 41 years) with no respiratory symptoms, who have alpha-1 antitripsyn mutation (PiSZ, PiZZ and PiZZ) and who performed traditional pulmonary function tests and the single breath nitrogen washout test. They still did not have chronic obstructive pulmonary disease (COPD) or any identifiable change in traditional pulmonary function tests but already have change in nitrogen washout tests. Alpha-1 antitrypsin deficiency is a genetic disorder associated with early-onset COPD. There is evidence that although patients who have well-preserved FEV1 may already have signs of emphysema associated with symptoms. Therefore, the nitrogen washout test is considered to have more sensitive outcomes than other pulmonary function tests for early investigation of small airways disease and could allow the monitoring pulmonary function and evaluating of therapeutic decision.


2021 ◽  
Vol 31 (1) ◽  
pp. 30-36
Author(s):  
E. V. Kryukov ◽  
O. I. Savushkina ◽  
A. V. Chernyak ◽  
I. C. Kulagina

The aim was to evaluate the ventilation inhomogeneity (VIH) by the multiple-breath nitrogen washout test (MBNW) after COVID-19 and to identify the relationship of the lung clearance index (LCI) with other functional parameters of the respiratory system. Methods. The cross-sectional study included 35 patients (97% men); the median age was 44 years. Spirometry, body plethysmography, diffusing capacity of the lung for carbon monoxide (DLco), MBNW test, and impulse oscillometry were performed. Dyspnea was evaluated by mMRC scale. MBNW test was performed using the Easy-one Pro, MBW Module (ndd Medizintechnik AG, Switzerland). Results. The patients were divided into 2 groups. Group 1 included 21 (60%) patients who were not diagnosed with VIH. Group 2 included 14 (40%) patients with VIH. The median testing period was 72 (47 - 109) days from the onset of COVID-19. The median of the maximum volume of lung damage determined by high-resolution computed tomography (CTmax) was 50% in the acute period of the disease and 12% during the study. The medians of all analyzed parameters remained normal in the study cohort as well as in groups 1 and 2, except the resonance frequency (fres) in group 2. Statistically significant differences were found between groups 1 and 2 in the absolute frequency dependence of resistance (R5 - R20), reactance area (AX), fres. Significant differences were also found in pathological changes of vital capacity, forced expiratory volume in the first second (FEV1), (R5 - R20). The abnormalities were more common in group 2. A significant correlation was shown between LCI with the ratio of residual lung volume to total lung capacity, (R5 - R20), AX, fres, relative frequency dependence of resistance, CTmax, FEV1 and trasfer-factor (DLco). Conclusion. Seventy-two days after the onset of CoVID-19, the ventilation inhomogeneity was detected in 40% of the patients, decreased DLco - in 23%, airway obstruction - in 11.4%, and restrictive ventilatory defect - in 8.6%. Correlations were found between LCI and DLco, spirometry parameters, body plethysmography, impulse oscillometry, and CTmax.


Author(s):  
Chiara Veneroni ◽  
Alain Van Muylem ◽  
Andrei Malinovschi ◽  
Alain Michils ◽  
Raffaele L. Dellaca'

Closing volume (CV) is commonly measured by single-breath nitrogen washout (CVSBW). A method based on the forced oscillation technique was recently introduced to detect a surrogate CV (CVFOT). As the two approaches are based on different physiological mechanisms, we aim to investigate CVFOT and CVSBW relationship at different degrees and patterns of airway obstruction. A mathematical model was developed to evaluate the CVSBW and CVFOT sensitivity to different patterns of airway obstruction, either located in a specific lung region or equally distributed throughout the lung. The two CVs were also assessed during slow vital capacity (VC) maneuvers in triplicate in 13 healthy subjects and pre and post-methacholine challenge (Mch) in 12 mild-moderate asthmatics. Model simulations suggest that CVSBW is more sensitive than CVFOT to the presence of few flow-limited or closed airways that modify the contribution of tracer-poor and tracer-rich lung regions to the overall exhaled gas. Conversely, CVFOT occurs only when at least ~65% of lung units are flow-limited or closed, regardless of their regional distribution. CVSBW did not differ between healthy subjects and asthmatics (17±9%VC vs 22±10%VC) while CVFOT did (16±5%VC vs 23±6%VC, p<0.01). In asthmatics, both CVSBW and CVFOT increased post-Mch (33±7%VC p<0.001 and 43±12%VC p<0.001, respectively). CVSBW weakly correlated with CVFOT (r=0.45, p<0.01). The closing capacities (CV+residual volume) were correlated (r=0.74, p<0.001) but the changes with Mch in both CVs and closing capacities did not correlate. CVFOT is easy to measure and provides a reproducible parameter useful for describing airway impairment in obstructive respiratory diseases.


2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Joana Berger-Estilita ◽  
Matthias Haenggi ◽  
Daniel Ott ◽  
David Berger

Abstract Background The functional residual capacity (FRC) determines the oxygenating capacity of the lung and is heavily affected in the clinical context of the acute respiratory distress syndrome. Nitrogen-wash-in/wash-out methods have been used to measure FRC. These methods have rarely been validated against exactly known volumes. The aim of the study was to assess the accuracy and precision of the N2 washout/washin method in measuring FRC, by comparing it with set volumes in a lung simulator. Methods We conducted a diagnostic bench study in the Intensive Care Unit and Radiology Department of a tertiary hospital in Switzerland. Using a fully controllable high fidelity lung simulator (TestChest®), we set the functional residual capacity at 1500 ml, 2000 ml and 2500 ml and connected to the GE Carestation respirator, which includes the nitrogen washout/washin technique (INview™ tool). FRC was then set to vary by different levels of PEEP (5, 8, 12 and 15 cmH2O). The main outcome measures were bias and precision of the TestChest® when compared to the results from the washout/washin technique, according to the results of a Bland Altman Analysis. We verified our findings with volumetric computed tomography. Results One hundred and thirty-five nitrogen-wash-in/wash-out measurements were taken at three levels of FIO2 (0.4, 0.5, 0.6). The CT volumetry reproduced the set end-expiratory volumes at the Simulator with a bias of 4 ml. The nitrogen-wash-in/wash-out method had a bias of 603 ml with acceptable limits of agreement (95% CI 252 to − 953 ml). Changes were detected with a concordance rate of 97%. Conclusions We conclude that the TestChest® simulator is an accurate simulation tool, concerning the simulation of lung volumes. The nitrogen wash-in/wash out method correlated positively with FRC changes, despite a relatively large bias in absolute measurements. The reference volumes in the lung simulator verified with CT volumetry were very close to their expected values. The reason for the bias could not be determined.


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