Short-Term Effects of Elastic Chest Wall Restriction on Pulmonary Function in Children with Cystic Fibrosis

Abstract

Background: Elastic chest wall restriction introduced by Chevaillier is thought to reduce existing hyperinflation and improve mucus clearance from peripheral airways. In healthy adults, restriction decreases the functional residual capacity (FRC) and forced vital capacity (FVC), while ventilation inhomogeneity (lung clearance index [LCI]) increases. Pulmonary function response to restriction is unknown in individuals with cystic fibrosis (CF). Objectives: To examine short-term effects of elastic chest wall restriction on pulmonary function in children with CF. Methods: Pulmonary function was first assessed twice 15 min apart at baseline and then again following 15 min of elastic chest wall restriction in 20 school-aged children with CF (12.3 ± 3.4 years). Primary outcomes were LCI from nitrogen multiple-breath washout, residual volume (RV), and FRC from plethysmography. Secondary outcomes were FVC and end-expiratory lung impedance (EELI) from electrical impedance tomography. Endpoints were test-retest reliability at baseline and lung function response to restriction, both on group and individual levels. Results: Test-retest reliability was excellent (intra-class correlation coefficients range 0.84–0.99). Following restriction, FRC significantly declined on average (95% CI) by –0.09 (–0.17 to –0.02) L. Similarly, FVC declined while LCI did not change. RV and EELI declined, but this did not reach statistical significance. On the individuals’ level, heterogeneous changes in pulmonary function occurred following elastic chest wall restriction. Conclusions: These findings indicate that the application of elastic chest wall restriction is safe, induces the intended decline in resting lung volume but does not systematically alter ventilation inhomogeneity in children with CF.

Do clinimetric properties of LCI change after correction of signal processing?

“…Overall, we found short-and midterm repeatability 17,18 to be similar after cross-sensitivity correction, and thus limits for intervisit changes and variability to be unaffected. Within-subject between test standard deviation remained independent of the magnitude of LCI, which preserves the property of LCI to guide individual clinical decisions.…”

“…As previously described, for short-and mid-term repeatability of LCI, MBW measurements were performed in triplicates 15 minutes and 24 hours apart respectively, with unchanged measurement conditions in schoolaged children with CF 17,18 . We used mixed-effects linear regression models to calculate the variability in LCI between measurements allowing for correlation of repeated measurements within individuals.…”

Reflex zone stimulation reduces ventilation inhomogeneity in cystic fibrosis: A randomised controlled cross‐over study

“…Poncin et al 37 showed improvements in LCI 2.5 and slow vital capacity after autogenic drainage in adults with non‐CF bronchiectasis. Other studies have shown no significant short‐term effects of established therapeutic approaches on ventilation inhomogeneity 38–40 …”

A narrative review of electrical impedance tomography in lung diseases with flow limitation and hyperinflation: methodologies and applications

“…Most EIT systems were developed to monitor spatial ventilation heterogeneity; therefore, the EIT data is usually illustrated as the global impedance-time curve (sum of ΔZ from all pixels against time) and regional impedance-time curves (sum of ΔZ from regions of interest against time) (Figure 1, right images). Endexpiratory lung impedances before and after certain maneuvers that reflect the change in end-expiratory lung volume are often compared to evaluate the effects of the maneuvers (49,55,56). Tidal variation (TV), which corresponds to tidal volume, is calculated by subtracting the end-expiratory global impedance from the endinspiratory global impedance.…”