Impulse oscillometry and spirometry measurements relative to personal best values at the time of acute exacerbations of cystic fibrosis in adults

Abstract

Background Diagnosis of acute exacerbation (AE) of cystic fibrosis (CF) must be precise because both under‐ and over‐prescription of antibiotics may be detrimental. How lung function tests contribute to diagnose AE is unclear. We aimed to describe variation of spirometry and oscillometry measurements, at Stable state and at AE in adults with CF. Methods Patients were included in a retrospective single‐centre study when both spirometry (FEV1, FVC) and oscillometry (X5, R5, R5−R20 and AX) data were available for at least one Stable and one AE visit between December 2016 and July 2019. For each visit, we calculated variation (Δ) in spirometry and oscillometry indices in comparison with personal best values. Measurements were expressed as % of predicted values and Z‐scores when applicable. Areas under ROC curves (AUC) were computed. Results Forty‐two patients (28 ± 9 years, FEV1 64 ± 21%) were included; 80 AE and 104 Stable visits were analysed. FEV1 (L, %pred and Z‐score) and FVC (%pred and Z‐score) varied significantly between AE and Stable visits (p < .05), although differences were small (80 ml/2.7%pred for FEV1). Among oscillometry indices, X5 (kPa.s.L−1), R5–R20 (kPa.s.L−1) and AX (kPa/L) varied significantly. The AUCs for the variation in spirometry indices ranged from 0.601 (ΔFVC L) to 0.635 (ΔFEV1%pred). They were not significantly different from the AUCs for ΔX5 (0.589), ΔR5−R20 (0.649) and ΔAX (0.598). Conclusions Performance of both spirometry and oscillometry to discriminate AE from Stable state was poor. Variation of oscillometry indices (X5, R5−R20, AX) may be helpful when spirometry is unreliable or uncomfortable.

Oscillometry to Assess Respiratory Function in Adult Cystic Fibrosis

“…Annual Data Report as well as the United Kingdom Cystic Fibrosis Registry Annual Data Report 2019 (18,185). The average FEV1 in our study was 63% predicted, which was also very similar to reported values in 3 of the recent publications that examined oscillometry in adult CF (141,143,144).…”

“…With respect to oscillometry, both resistance and reactance parameters were abnormal compared to population-based reference values (84). The average R5 and R5-20 values were generally comparable to those recently obtained in adults with CF by other investigators where these parameters were in fact measured (see Table 11) (141)(142)(143)(144). The average X5 was close to that reported by Lima et al (141) and Wallaert et al (142), while the average AX and Fres were very similar to that observed by Lima et al (141).…”

“…They concluded that both oscillometry and spirometry have a limited ability to identify the development of an acute CF exacerbation (144). This was a retrospective study, however.…”

“…Moreover, the utility of these data is limited because of the use of a non-commercial device, inclusion of non-standard parameters, omission of standard parameters, small patient numbers, and/or absence of population-based reference values. In addition, quality control methods were not clearly identified, suggesting that current quality control guidelines were likely not followed (141)(142)(143)(144). With all this in mind, the need for a comprehensive study to reliably characterize oscillometry findings in adult CF remains.…”

Potentiality of impulse oscillometry to evaluate bronchodilator reversibility in untreated adult patients with newly diagnosed asthma

“…IOS may provide objective information that is beneficial to patients whose spirometry is either normal or could not be performed; thus, the comparisons of spirometric and IOS data in the same patients with several types of lung diseases have received growing interest. [25][26][27] R5-R20, X5, Fres, and Ax in the patients were measured in the current study; these conventional IOS parameters have been suggested to detect airway obstruction. 9,10 For example, R5-R20 is a measure of the peripheral airway resistance that is determined mainly by airway caliber.…”