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Respiration; International Review of... Jun 2024within-breath analysis of oscillometry parameters is a growing research area since it increases sensitivity and specificity to respiratory pathologies and conditions....
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 aims 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≤30kg/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 5-11-19Hz, 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
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.
PubMed: 38843786
DOI: 10.1159/000539532 -
Respiratory Medicine Apr 2024Impulse oscillometry (IOS) is an effective tool for assessing airway mechanics and diagnosing obstructive airway disease (OAD) in children with sickle cell disease...
BACKGROUND
Impulse oscillometry (IOS) is an effective tool for assessing airway mechanics and diagnosing obstructive airway disease (OAD) in children with sickle cell disease (C-SCD). Obesity is known to be associated with OAD, and untreated OAD often leads to hypoxia-related complications in C-SCD. Considering the increasing prevalence of obesity in C-SCD, it is important to explore the influence of body mass index (BMI) on OAD in this disease population.
METHODS
A longitudinal retrospective chart review was conducted on 55 C-SCD (161 IOS observations) and 35 non-SCD asthmatic children (C-Asthma) (58 observations), primarily to investigate the association between BMI and airway resistance in C-SCD and C-Asthma. We conducted generalized linear mixed models (GLMM), adjusted for pharmacotherapies, to demonstrate the influence of BMI on total (R), central (R), and peripheral (R) airway resistance and reactance (X, resonant frequency (Fres)). We further compared age, BMI, and IOS indices between C-SCD and C-Asthma using the Mann-Whitney test.
RESULTS
Age and BMI were not statistically different between the two groups. In C-SCD, BMI was associated with R (GLMM t-statistics:3.75, 95%CI:1.01,3.27, p-value<0.001*) and R (t-statistics:4.01, 95%CI:1.04,1.15, p-value<0.001*), but not with R or airway reactance. In asthmatics, BMI was not associated with IOS estimates except Fres (t-statistics: 3.93, 95%CI: -0.06, -0.02, p-value<0.001*). C-SCD demonstrated higher airway resistances (R and R) and reactance (Fres) compared to C-Asthma (Mann-Whitney: p-values<0.05).
CONCLUSION
BMI significantly influenced total and central airway resistance in C-SCD. While higher airway resistances reflected increased OAD in C-SCD than asthmatics, higher Fres perhaps indicated progressive pulmonary involvement in C-SCD.
Topics: Child; Humans; Airway Resistance; Body Mass Index; Retrospective Studies; Longitudinal Studies; Oscillometry; Spirometry; Lung; Asthma; Anemia, Sickle Cell; Obesity
PubMed: 38360190
DOI: 10.1016/j.rmed.2024.107564 -
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 -
Pediatric Research Dec 2023The aim of this study was to describe the trajectory of oscillatory mechanics from the first week of life to term equivalent and evaluate whether oscillatory mechanics... (Observational Study)
Observational Study
BACKGROUND
The aim of this study was to describe the trajectory of oscillatory mechanics from the first week of life to term equivalent and evaluate whether oscillatory mechanics are associated with simultaneous lung disease in infants ≤32 weeks gestation.
METHODS
In this observational, longitudinal study, we enrolled 66 infants. Forced oscillations were applied using a neonatal mechanical ventilator (Fabian HFOi) that superimposed oscillations (10 Hz, amplitude 2.5 cmHO) on a positive end-expiratory pressure (PEEP). Measurements were performed at 5-7-9 cmHO of PEEP or the clinical pressure ±2 cmHO; they were repeated at 7, 14, 28 post-natal days, and 36 and 40 weeks post-menstrual age (PMA).
RESULTS
The mean (range) gestational age of study participants was 29.2 (22.9-31.9) weeks. Nineteen infants (29%) developed bronchopulmonary dysplasia (BPD). Respiratory system reactance was significantly lower (lower compliance), and respiratory system resistance was significantly higher in infants with developing BPD from 7 post-natal days to 36 weeks PMA. All oscillatory mechanics parameters were significantly associated with the simultaneous respiratory severity score (p < 0.001 for all).
CONCLUSIONS
Serial measurements of oscillatory mechanics allow differentiating lung function trajectory in infants with and without evolving BPD. Oscillatory mechanics significantly correlate with the severity of simultaneous lung disease.
IMPACT
The results of the present study suggest that respiratory system reactance, as assessed by respiratory oscillometry, allows the longitudinal monitoring of the progression of lung disease in very premature infants. This paper describes for the first time the trajectory of oscillatory mechanics in very preterm infants with and without evolving bronchopulmonary dysplasia from the first week of life to term equivalent. Serial respiratory oscillometry measurements allow the identification of early markers of evolving bronchopulmonary dysplasia and may help personalizing the respiratory management strategy.
Topics: Infant; Humans; Infant, Newborn; Cohort Studies; Bronchopulmonary Dysplasia; Longitudinal Studies; Infant, Premature; Infant, Premature, Diseases
PubMed: 37452113
DOI: 10.1038/s41390-023-02724-w -
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 -
Pediatric Pulmonology Apr 2024Longitudinal measurements of intrabreath respiratory impedance (Zrs) in preschool-aged children may be able to distinguish abnormal lung function trajectories in...
BACKGROUND
Longitudinal measurements of intrabreath respiratory impedance (Zrs) in preschool-aged children may be able to distinguish abnormal lung function trajectories in children with a history of wheezing compared to healthy ones.
METHODS
Children from a prospective, longitudinal community-based cohort performed annual intrabreath oscillometry (IB-OSC) measurements from age 3- to 7-years. IB-OSC was performed using a single 10 Hz sinusoid while clinically asymptomatic. Linear mixed-effects models were developed to explore the effects of wheezing phenotypes, growth, and sex on seven IB-OSC outcome variables over time: resistance at end-expiration (ReE), resistance at end-inspiration (ReI), the tidal change in resistance (∆R=ReE-ReI), reactance at end-expiration (XeE), reactance at end-inspiration (XeI), the tidal change in reactance (∆X=XeE-XeI), and ∆X normalized by tidal volume (∆X/V).
RESULTS
Eighty-five children produced 374 acceptable IB-OSC measurements. Subjects were classified into one of three wheeze groups: never (n = 36), transient (n = 34), or persistent (n = 15). After adjusting for height, children with persistent wheezing, compared to those who never wheezed, had +0.814 hPa s L ReE (95% confidence interval [CI] +0.178 to +1.451, p = 0.015), -0.792 hPa s L XeE (95% CI -1.203 to -0.381, p = 0.003), -0.538 hPa s L ∆X (95% CI -0.834 to -0.242, p = 0.007) and -1.672 hPa s L ∆X/V (95% CI -2.567 to -0.777, p < 0.001). Increasing height had a significant effect on all IB-OSC resistance and reactance variables when adjusted for the effect of preschool wheezing.
CONCLUSIONS
IB-OSC is feasible for tracking lung function growth in preschool-aged children and may allow abnormal lung function to be identified early in asymptomatic preschoolers with a history of persistent wheezing.
PubMed: 38560779
DOI: 10.1002/ppul.26994 -
European Journal of Anaesthesiology Jul 2024Atelectasis has been reported in 68 to 100% of children undergoing general anaesthesia, a phenomenon that persists into the recovery period. Children receiving... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Atelectasis has been reported in 68 to 100% of children undergoing general anaesthesia, a phenomenon that persists into the recovery period. Children receiving recruitment manoeuvres have less atelectasis and fewer episodes of oxygen desaturation during emergence. The optimal type of recruitment manoeuvre is unclear and may be influenced by the airway device chosen.
OBJECTIVE
We aimed to investigate the different effects on lung mechanics as assessed by the forced oscillation technique (FOT) utilising different recruitment strategies: repeated inflations vs. one sustained inflation and different airway devices, a supraglottic airway device vs. a cuffed tracheal tube.
DESIGN
Pragmatic enrolment with randomisation to the recruitment strategy.
SETTING
We conducted this single-centre trial between February 2020 and March 2022.
PARTICIPANTS
Seventy healthy patients (53 boys) aged between 2 and 16 years undergoing general anaesthesia were included.
INTERVENTIONS
Forced oscillations (5 Hz) were superimposed on the ventilator waveform using a customised system connected to the anaesthesia machine. Pressure and flow were measured at the inlet of the airway device and used to compute respiratory system resistance and reactance. Measurements were taken before and after recruitment, and again at the end of surgery.
MAIN OUTCOME MEASURES
The primary endpoint measured is the change in respiratory reactance.
RESULTS
Statistical analysis (linear model with recruitment strategy and airway device as factors) did not show any significant difference in resistance and reactance between before and after recruitment. Baseline reactance was the strongest predictor for a change in reactance after recruitment: prerecruitment Xrs decreased by mean (standard error) of 0.25 (0.068) cmH 2 O s l -1 per 1 cmH 2 O -1 s l -1 increase in baseline Xrs ( P < 0.001). After correcting for baseline reactance, the change in reactance after recruitment was significantly lower for sustained inflation compared with repeated inflation by mean (standard error) 0.25 (0.101) cmH 2 O ( P = 0.0166).
CONCLUSION
Although there was no significant difference between airway devices, this study demonstrated more effective recruitment via repeated inflations than sustained inflation in anaesthetised children.
TRIAL REGISTRATION
Australian New Zealand Clinical Trials Registry: ACTRN12619001434189.
Topics: Humans; Anesthesia, General; Child; Male; Female; Adolescent; Child, Preschool; Respiratory Mechanics; Intubation, Intratracheal; Airway Management; Lung; Pulmonary Atelectasis; Respiration, Artificial
PubMed: 38769936
DOI: 10.1097/EJA.0000000000001999 -
Pediatric Research Mar 2024We investigated whether combining lung ultrasound scores (LUSs) and respiratory system reactance (Xrs) measured by respiratory oscillometry explains the severity of lung... (Observational Study)
Observational Study
BACKGROUND
We investigated whether combining lung ultrasound scores (LUSs) and respiratory system reactance (Xrs) measured by respiratory oscillometry explains the severity of lung disease better than individual parameters alone.
METHODS
We performed a prospective observational study in very preterm infants. Forced oscillations (10 Hz) were applied using a neonatal mechanical ventilator (Fabian HFOi, Vyaire). We used the simultaneous respiratory severity score (RSS = mean airway pressure × FIO) as a primary outcome. We built linear mixed-effect models to assess the relationship between Xrs z-score, LUS and RSS and compared nested models using the likelihood ratio test (LRT).
RESULTS
We enrolled 61 infants (median (Q1, Q3) gestational age = 30.00 (26.86, 31.00) weeks) and performed 243 measurements at a postnatal age of 26 (13, 41) days and postmenstrual age of 33.14 (30.46, 35.86) weeks. Xrs z-score and LUS were independently associated with simultaneous RSS (p < 0.001 for both). The model including Xrs and LUS explained the RSS significantly better than Xrs (p value LRT < 0.001) or LUS alone (p value LRT < 0.001).
CONCLUSIONS
Combining LUS and Xrs z-score explains the severity of lung disease better than each parameter alone and has the potential to improve the understanding of the underlying pathophysiology.
IMPACT
Combining respiratory system reactance by oscillometry and lung ultrasound score explains the respiratory support requirement (e.g., proxy of the severity of lung disease) significantly better than each parameter alone. We assessed the relationship between lung ultrasound and respiratory system reactance in very preterm infants for the first time. Combining respiratory oscillometry and lung ultrasound has the potential to improve the understanding of respiratory pathophysiology.
Topics: Humans; Infant, Newborn; Adult; Infant, Premature; Lung; Infant, Very Low Birth Weight; Infant, Premature, Diseases; Lung Diseases; Ultrasonography
PubMed: 37857847
DOI: 10.1038/s41390-023-02829-2 -
Respiratory Medicine and Research Nov 2023The forced oscillation technique (FOT) may be useful for diagnosis and follow-up of respiratory diseases. It is unclear how global or regional alterations in airway...
BACKGROUND
The forced oscillation technique (FOT) may be useful for diagnosis and follow-up of respiratory diseases. It is unclear how global or regional alterations in airway resistance (Raw) and lung compliance (C) alter FOT measurements.
METHODS
A 2-compartment physical model of the respiratory system allowed to simulate variations in Raw, C, and their heterogeneity during tidal breathing in an adult human. Five-Hz respiratory system resistance (Rrs5) and reactance (Xrs5), area of reactance (AX), resonance frequency (Fresp) and intrabreath variation in Rrs5 and Xrs5 were measured by FOT. Frequency dependance of resistance could not be studied in this model. Relationships between model characteristics (Raw, C, and heterogeneity) and FOT measurements were explored by multiple regression.
RESULTS
Rrs5 and intrabreath variation in Rrs5 and Xrs5 strongly associated with model characteristics (R=0.753, 0.5 and 0.658). Associations of Xrs5, AX, and Fresp with model characteristics were weak (R=0.214, 0.349 and 0.076). Raw heterogeneity was the main determinant of Rrs5 (Coeff=0.594), AX (Coeff=0.566) and intrabreath variation in Rrs5 and Xrs5 (Coeff=0.586 and 0.732). Regional extremes in Raw strongly determined Rrs5 (Coeff=1.006). Xrs5 did not strongly associate with any model characteristic.
CONCLUSION
Raw heterogeneity and maximal regional Raw were the main determinants of FOT measurements, in particular Rrs5. Associations between C and FOT measurements were weak.
Topics: Adult; Humans; Asthma; Respiratory Function Tests; Lung; Airway Resistance; Respiration
PubMed: 37717385
DOI: 10.1016/j.resmer.2023.101027 -
Frontiers in Medicine 2024Sulfur mustard (SM) exposure causes acute and chronic respiratory diseases. The extent of small airway dysfunction (SAD) in individuals exposed to SM is unclear. This...
BACKGROUND
Sulfur mustard (SM) exposure causes acute and chronic respiratory diseases. The extent of small airway dysfunction (SAD) in individuals exposed to SM is unclear. This study evaluated and compared SAD in SM-exposed and SM-unexposed participants using noninvasive lung function tests assessing small airway function.
METHODS
This retrospective cohort study involved SM-exposed ( = 15, mean age: 53 ± 8 years) and SM-unexposed ( = 15, mean age: 53 ± 7 years) Kurdish-Swedish individuals in Sweden. Small airway resistance and reactance were assessed using impulse oscillometry (IOS). Nitrogen (N) multiple breath washout (MBW) was employed to assess lung ventilation heterogeneity. The gas-exchanging capacity of the lungs was assessed using the diffusing capacity of the lungs for the carbon monoxide (DLCO) test. Lung function outcomes were reported as absolute values and -scores. Group comparisons were performed using the Mann-Whitney U test.
RESULTS
No statistically significant differences in age, height, or body mass index were observed between the two groups. IOS showed significantly increased small airway resistance, while NMBW exhibited significantly increased global and acinar ventilation heterogeneity in SM-exposed individuals compared to that in unexposed individuals. SAD was identified in 14 of 15 SM-exposed individuals, defined as at least one abnormal IOS difference between resistance at 5 and 20 Hz (R5-R20) and/or area of reactance (AX) or NMBW lung's acinar zone (S), and DLCO adjusted to the alveolar volume (DLCO/VA) outcome. Of these 14 individuals, only 5 demonstrated concordant findings across the IOS and NMBW tests.
CONCLUSION
Exposure to SM was positively associated with long-term impairment of respiratory tract function in the small airways in the majority of the previously SM-exposed individuals in the present study. Furthermore, both IOS and NMBW should be employed to detect SAD in SM-exposed survivors as they provide complementary information. Identifying and characterizing the remaining pathology of the small airways in survivors of SM exposure is a first step toward improved treatment and follow-up.
PubMed: 38500955
DOI: 10.3389/fmed.2024.1251500