The Chartis System is a proprietary assessment system utilized immediately prior to the Zephyr EBV procedure to identify those patients with low or no collateral ventilation
, who are the most likely to respond to the treatment.
The IMPACT study was launched based on the promising results of a retrospective analysis of the VENT trial, which indicated that patients with homogeneous disease, where emphysema is diffusely distributed, and little or no collateral ventilation can also benefit from endobronchial lung volume reduction with the Zephyr valve.
This study uses the company's proprietary Chartis System to select patients with little or no collateral ventilation, and advanced imaging technology to select a target lobe for treatment.
Such collateral ventilation prevents atelectasis and thereby subverts the deflating effect of the devices.
Although numerous observational and randomised trials showed statistical benefits in respect of practically all functional parameters, minimal clinically important differences (MICDs) were significantly more likely to be observed in patients with advanced heterogeneous emphysema and no collateral ventilation and in those in whom unilateral valve placement achieved complete lobar collapse.
The absence of inter-alveolar and inter-bronchiolar collateral ventilation
, the high ventilation rate and strong resistance to airflow within the respiratory conducts make them more susceptible to respiratory diseases and to infections of this organ (Lekeux, 1998).
The alveoli are laced with the Pores of Kohn, intercommunications between the alveoli that allow for collateral ventilation
A collateral ventilation
system exists in the lung between bronchi (Channels of Martin), between the bronchi and alveoli (Canals of Lambert) and between the alveoli (Pores of Kohn) (see Figure 1).
The peer-reviewed clinical paper, "Radiological and Clinical Outcomes of Using Chartis to Plan Endobronchial Valve Treatment," demonstrates the ability of the bronchoscopic Chartis Pulmonary Assessment System to predict treatment response by determining the presence or absence of collateral ventilation
This is a normal physiological phenomenon in many individuals, but significant interlobar collateral ventilation
subverts the deflating effect of endobronchial blocking devices.
Using the Chartis system, 68 patients were confirmed to have no collateral ventilation
, independent of disease distribution, and were treated with the Zephyr EBV.
The flow velocity profiles of HFOV include bulk convection, Taylor dispersion, asymmetric velocity profiles (coaxial flow velocities), pendelluft phenomena, cardiogenic mixing, molecular diffusion, Brownian movement and collateral ventilation