Change in Dynamic Hyperinflation After Bronchoscopic Lung Volume Reduction in Patients with Emphysema

[A simple method to assess dynamic hyperinflation outside a pulmonary function test laboratory: The metronome-paced tachypnea test]

Lung dynamic hyperinflation (DH) is one of the main determinants of dyspnea in chronic respiratory disease patients. Producing evidence of DH is critical during dyspnea assessment, the objectives being to explain the cause, to target treatments, and to monitor their efficacy. The gold standard method consists in repeated measurement of inspiratory capacity (IC) during cardiopulmonary exercise testing (CPET). Unfortunately, access to CPET is limited and assessment of IC during CPET can be challenging in some patients. An alternative method consists in assessment of IC during the testing known as metronome-paced tachypnea (MPT) challenge. This method is feasible, repeatable, valid (i.e. corelated with dyspnea patients' activities of daily living), and responsive to treatments. However, while its diagnostic performance is acceptable, it is lacking in specificity. Methodological standardization is detailed in the present review, as are the differences between IC changes in CPET and in MPT. As a means of assessing DH, MPT challenge is not only applicable to patients outside a pulmonary function test laboratory, but also easily affordable to any chest physician equipped with a simple spirometry device. A diagnosis threshold of 11% for IC decrease during MPT challenge can be used, albeit while bearing in mind the possibility of a false positive result. Moreover, assessment of IC variations during MPT can help to monitor a patient's overall evolution and response to treatments.

Endobronchial valve treatment improves chest-CT diaphragm configuration in COPD

This study investigated the impact of bronchoscopic lung volume reduction treatment using endobronchial valves (EBV) on diaphragm configuration. We successfully analyzed the diaphragm index using a newly developed quantitative computed tomography (QCT) tool before and after EBV treatment in forty patients with severe emphysema. We evaluated whether changes in the diaphragm index were associated with improvements in forced expiratory volume in 1 s (FEV1), residual volume (RV), Saint Georges Respiratory Questionnaire (SGRQ), and 6-min walking distance (6MWD) using Spearman's rho. The EBV treatment influenced the diaphragm configuration only on the treated side, resulting in an increased diaphragm curvature. There were significant associations of relative diaphragm index changes on the treated lung side or the entire diaphragm with improvements in FEV1 and 6MWD. These findings provide valuable insights into how EBV treatment affects the diaphragm in COPD patients.

Chronic obstructive pulmonary disease (COPD) and COPD-like phenotypes

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. Historically, two COPD phenotypes have been described: chronic bronchitis and emphysema. Although these phenotypes may provide additional characterization of the pathophysiology of the disease, they are not extensive enough to reflect the heterogeneity of COPD and do not provide granular categorization that indicates specific treatment, perhaps with the exception of adding inhaled glucocorticoids (ICS) in patients with chronic bronchitis. In this review, we describe COPD phenotypes that provide prognostication and/or indicate specific treatment. We also describe COPD-like phenotypes that do not necessarily meet the current diagnostic criteria for COPD but provide additional prognostication and may be the targets for future clinical trials.

Impact of bronchoscopic lung volume reduction with endobronchial valves on dynamic hyperinflation: Results from the PIERCE study

BACKGROUND AND OBJECTIVE

Dynamic hyperinflation (DH) is a major marker of exertional dyspnoea in severe emphysema. We hypothesized that bronchoscopic lung volume reduction (BLVR) using endobronchial valves (EBVs) decreases DH.

METHODS

In this prospective bi-centre study from both Toulouse and Limoges Hospitals, we assessed DH during an incremental cycle ergometry before and 3 months after EBVs treatment. The primary objective was to observe the change in inspiratory capacity (IC) at isotime. Target lobe volume reduction (TLVR) and changes in residual volume (RV), forced expiratory volume in one-second (FEV₁ ), mMRC, 6 minutes walking distance (6MWD), BODE and other dynamic measures like tele-expiratory volume (EELV) were also analysed.

RESULTS

Thirty-nine patients were included, of whom thirty-eight presented DH. IC and EELV at isotime significantly improved (+214 mL, p = 0.004; -713 mL, p ˂ 0.001, respectively). Mean changes were +177 mL for FEV₁ (+19%, p < 0.001), -600 mL for RV (p < 0.0001), +33 m for 6MWD (p < 0.0001), respectively. Patients who responded on RV (>430 mL decrease) and FEV₁ (>12% gain) had better improvements compared to non-responders (+368 mL vs. +2 mL; +398 mL vs. -40 mL IC isotime, respectively). On the opposite, in patients who responded on DH (>200 mL IC isotime increase), changes in TLV (-1216 mL vs. -576 mL), FEV₁ (+261 mL vs. +101 mL), FVC (+496 mL vs. +128 mL) and RV (-805 mL vs. -418 mL) were greater compared to non-responders.

CONCLUSIONS

DH decreases after EBVs treatment, and this improvement is correlated with static changes.

Comparison of Multiple Diagnostic Tests to Measure Dynamic Hyperinflation in Patients with Severe Emphysema Treated with Endobronchial Coils

Purpose

For this study, we aimed to compare dynamic hyperinflation measured by cardiopulmonary exercise testing (CPET), a six-minute walking test (6-MWT), and a manually paced tachypnea test (MPT) in patients with severe emphysema who were treated with endobronchial coils. Additionally, we investigated whether dynamic hyperinflation changed after treatment with endobronchial coils.

Methods

Dynamic hyperinflation was measured with CPET, 6-MWT, and an MPT in 29 patients before and after coil treatment.

Results

There was no significant change in dynamic hyperinflation after treatment with coils. Comparison of CPET and MPT showed a strong association (rho 0.660, p < 0.001) and a moderate agreement (BA-plot, 202 ml difference in favor of MPT). There was only a moderate association of the 6-MWT with CPET (rho 0.361, p 0.024).

Conclusion

MPT can be a suitable alternative to CPET to measure dynamic hyperinflation in severe emphysema but may overestimate dynamic hyperinflation possibly due to a higher breathing frequency.