Airflow pattern complexity and airway obstruction in asthma

Veiga, Juliana; Lopes, Agnaldo José; Jansen, José Manoel; Melo, Pedro Lopes de

doi:10.1152/japplphysiol.00267.2011

Cited by 38 publications

(38 citation statements)

References 57 publications

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“…This group of infants could be in need of diagnostic evaluation, which is only possible by long-term monitoring of lung function. Recordings of longer duration also enable the calculation of more robust measures of tidal airflow profiles than the conventional TBFV parameters, as well as complex indices of flow variability [38]. By using nocturnal recordings with IP, we demonstrated that preschool children with a high risk of asthma present with an increased variation of tidal flow profile shape, and momentarily lowered chaoticity, compared to children with a lower risk of asthma [14].…”

Section: Discussionmentioning

confidence: 89%

Measurement of tidal breathing flows in infants using impedance pneumography

et al. 2016

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Tidal breathing flow volume (TBFV) profiles have been used to characterise altered lung function. Impedance pneumography (IP) is a novel option for assessing TBFV curves noninvasively. The aim of this study was to extend the application of IP for infants and to estimate the agreement between IP and direct pneumotachograph (PNT) measurements in assessing tidal airflow and flow-derived indices.Tidal flow profiles were recorded for 1 min simultaneously with PNT and uncalibrated IP at baseline in 44 symptomatic infants, and after methacholine-induced bronchoconstriction in a subgroup (n=20).The agreement expressed as the mean deviation from linearity ranged between 3.9 and 4.3% of tidal peak inspiratory flow, but was associated with specific airway conductance (p=0.002) and maximal flow at functional residual capacity () (p=0.004) at baseline. Acute bronchoconstriction induced by methacholine did not significantly affect the agreement of IP with PNT. TBFV indices derived from IP were slightly underestimated compared to PNT, but were equally well repeatable and associated with baseline (p=0.012 and p=0.013, respectively).TBFV profiles were consistent between IP and PNT in most infants, but the agreement was affected by reduced lung function. TBFV parameters were not interchangeable between IP and PNT, but had a similar association with lung function in infants.

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Section: Discussionmentioning

confidence: 89%

Measurement of tidal breathing flows in infants using impedance pneumography

et al. 2016

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“…Entropy measurements give a statistical probability that a series of points within a physiological signal will repeat themselves at a subsequent timepoint, within a given tolerance [13]. The entropy of FOT time series was recently investigated by VEIGA et al [14], who found that the entropy of airflow time series was reduced in patients with asthma compared with healthy controls, and that reduced entropy was associated with increased severity of airflow obstruction. However, the possible associations between the entropy of airway impedance measurements and other clinically important patient-centred outcomes in asthma, including asthma control and exacerbations, have not been evaluated.…”

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confidence: 99%

Airway impedance entropy and exacerbations in severe asthma

et al. 2012

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Variability of peak flow measurements has been related to clinical outcomes in asthma. We hypothesised that the entropy, or information content, of airway impedance over short time scales may predict asthma exacerbation frequency.66 patients with severe asthma and 30 healthy control subjects underwent impulse oscillometry at baseline and following bronchodilator administration. On each occasion, airway impedance parameters were measured at 0.2-s intervals for 150 s, yielding a time series that was then subjected to sample entropy (SampEn) analysis.Airway impedance and SampEn of impedance were increased in asthmatic patients compared with healthy controls. In a logistic regression model, SampEn of the resistance at 5 Hz minus the resistance at 20 Hz, a marker of the fluctuation of the heterogeneity of airway constriction over time, was the variable most strongly associated with the frequent exacerbation phenotype (OR 3.23 for every 0.1 increase in SampEn).Increased airway impedance and SampEn of impedance are associated with the frequent exacerbation phenotype. Prospective studies are required to assess their predictive value.KEYWORDS: Airflow obstruction, asthma, entropy, oscillometry A cute exacerbations of asthma account for much of the morbidity and mortality associated with this condition [1]. However, there is no currently available biomarker that can accurately predict the risk of future exacerbations. Previous studies have suggested that a geometrically self-similar airway tree may confer increased risk of asthma exacerbations and that fatal asthma is associated with a reduction in the structural complexity of the airway tree [2]. Similarly, the ventilation heterogeneity observed in asthma follows power law behaviour, which predicts catastrophic closure of small airways [3]. Therefore, characterising structural complexity may have utility in predicting asthma exacerbations.It has been speculated that the temporal variability in lung function may also exhibit self-similarity at multiple time scales [4]. This would suggest that monitoring lung function over short time scales may provide insights into lung function variability over longer time scales of weeks to months, thus providing a more practical predictive tool for exacerbations. A number of tools have been utilised to characterise time series properties of physiological signals, including those that predict scaling and power law behaviour of information over multiple time scales and those that predict the probability of information repeating itself within a time series [5,6]. Fluctuations and power law behaviour observed in a time series of lung function measurements such as peak expiratory flow (PEF) may predict poor asthma control or exacerbations [7,8]. THAMRIN et al [9] found that the degree of long-range correlation (self-similarity at different temporal length scales) in PEF measurements appeared to provide additional predictive information with respect to exacerbations in mildto-moderate asthma, but less so in severe asthma.The force...

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“…Therefore, interest in using fluctuation analysis to characterize respiratory patterns has become widespread over the past five years Veiga et al, 2011). Using these methods, Frey and colleagues (2005) investigated the use of the day-to-day fluctuations in peak expiratory flow (PEF) over 6 months in patients with chronic asthma to determine whether the future risk of exacerbation could be predicted from fluctuations in PEF.…”

Section: Contribution Of Forced Oscillation To Systems Medicine and Cmentioning

confidence: 99%