Baseline and post‐bronchodilator interrupter resistance and spirometry in asthmatic children

Abstract

In children unable to perform reliable spirometry, the interrupter resistance (R(int) ) technique for assessing respiratory resistance is easy to perform. However, few data are available on the possibility to use R(int) as a surrogate for spirometry. We aimed at comparing R(int) and spirometry at baseline and after bronchodilator administration in a large population of asthmatic children. We collected retrospectively R(int) and spirometry results measured in 695 children [median age 7.8 (range 4.8-13.9) years] referred to our lab for routine assessment of asthma disease. Correlations between R(int) and spirometry were studied using data expressed as z-scores. Receiver operator characteristic curves for the baseline R(int) value (z-score) and the bronchodilator effect (percentage predicted value and z-score) were generated to assess diagnostic performance. At baseline, the relationship between raw values of R(int) and FEV(1) was not linear. Despite a highly significant inverse correlation between R(int) and all of the spirometry indices (FEV(1) , FVC, FEV(1) /FVC, FEF(25-75%) ; P < 0.0001), R(int) could detect baseline obstruction (FEV(1) z-score ≤ -2) with only 42% sensitivity and 95% specificity. Post-bronchodilator changes in R(int) and FEV(1) were inversely correlated (rhô = -0.50, P < 0.0001), and R(int) (≥35% predicted value decrease) detected FEV(1) reversibility (>12% baseline increase) with 70% sensitivity and 69% specificity (AUC = 0.79). R(int) measurements fitted a one-compartment model that explained the relationship between flows and airway resistance. We found that R(int) had poor sensitivity to detect baseline obstruction, but fairly good sensitivity and specificity to detect reversibility. However, in order to implement asthma guidelines for children unable to produce reliable spirometry, bronchodilator response measured by R(int) should be systematically studied and further assessed in conjunction with clinical outcomes.

Total specific airway resistance vs spirometry in asthma evaluation in children in a large real-life population

“…The lack of importance of sRtot in other studies might be explained by its too high variability in schoolchildren or weak relation between baseline FEV 1 and sRtot, which has been reported. 14, 15 Beydon et al 12 found that the baseline relation between FEV 1 and sRtot was weak in large group of schoolchildren. The same could be true for other spirometric indices in the present study, based on previous results.…”

Challenges and Limitations of Testing Efficacy of Aerosol Device Delivery in Young Children

“…(7) The interrupter technique has good repeatability (21) and, like FOT, can detect changes in airway caliber acutely and in response to bronchodilators. (22) Again, severe bronchial obstruction and variations in upper airway compliance may result in underestimation of alveolar pressure; however, the interrupter technique has been studied in asthma, (23) CF, (24) and bronchiolitis. (25) …”

Maternal hemoglobin and hematocrit levels during pregnancy and childhood lung function and asthma. The Generation R Study

“…Prospective cohort studies that assessed the association of maternal hemoglobin or hematocrit levels with childhood lung function and asthma are scarce, 16,17 and show inconsistent results. We aimed to address all factors that explained differences in results of the previous studies into account, and now used both hemoglobin and hematocrit levels, WHO clinical cut-off definitions, lung function measured by spirometry, which is an objective and reliable 29,30 method, took gestational age at blood sampling and multiple confounders into account, and explored intermediating and effect modifying factors. We observed associations of maternal hemoglobin and hematocrit levels measured in early pregnancy with lower childhood lung function, but not with asthma at age 10 years.…”

“…We used a population-based prospective cohort design from early pregnancy onwards, with detailed information on maternal and child characteristics and on maternal red blood status. Spirometry is the preferred method to assess lung function, 29,30,38 and to date this is the first study that uses this method as asthma-related outcome with maternal hemoglobin and hematocrit levels during pregnancy and long-term pulmonary outcomes under study. However, some limitations do apply.…”