TABLE 2.

Challenges and future directions of endobronchial valve (EBV) treatment

Advanced patient selection
Clinical patient characteristics	To define the cut-offs regarding clinical patient characteristics such as degree of obstruction, static hyperinflation, diffusion capacity, blood oxygen tension, exercise capacity, pulmonary hypertension, comorbidities, etc. for procedure-related risk estimation and efficacy outcome.
Emphysema severity	To define the exact role of quantitative lobar tissue destruction scores related to outcomes.
Prediction of collateral ventilation	To define the optimal cut-off (both lower and upper limit) for the degree of fissure integrity calculated on CT.
	To establish the optimal method of measurement and interpretation of the Chartis system signal in the measurement of collateral ventilation.
Prediction of response using quantification	To further develop quantitative HRCT software analysis with accurate assessment of fissure integrity, emphysema scores, the amount of air trapping and lung perfusion, all on a lobar level.
Multidisciplinary team	To establish a solid base for an emphysema multidisciplinary team like our lung cancer and ILD multidisciplinary team meetings.
Therapeutic challenges
The positioning of LVRS versus EBV treatment	Not all patients that are good candidates for surgery are good candidates for valves and vice versa.
	To create decision making guidance for candidate patients for both techniques.
	To create a step-up treatment guidance for initial good responders to EBV treatment.
Closing the interlobar collateral channels	To develop treatments that successfully close the collateral channels which would significantly increase the patient population that could potentially benefit from EBV treatment.
Treatment decisions in patients with homogeneous disease	To identify the best treatment option for patients with real homogeneous disease. EBV treatment or coil treatment?
Granulation tissue	To identify predictors or risk factors for the development of granulation tissue after EBV treatment (and in fact after every implantable device in the human airways).
Burning questions
Long-term effects	To establish the long-term efficacy, cost-efficiency, effect on exacerbations, hospitalisations, survival and adverse events.
The interaction with pulmonary rehabilitation.	The combination of EBV treatment and pulmonary rehabilitation could strengthen the effect of the EBV treatment. The best timing of the rehabilitation programme has not been investigated to date.
A look in the crystal globe
Potential future developments	To develop new or customised valves.
	To develop an advanced Chartis device that could be helpful in target lobe selection.
	To establish the role of advanced functional imaging with patient selection
	To combine different endoscopic and/or surgical techniques.

LVRS: lung volume reduction surgery; CT: computed tomography; HRCT: high-resolution CT; ILD: interstitial lung disease.