An adjusted and time-saving method to measure collateral ventilation with Chartis

Abstract

IntroductionBronchoscopic lung volume reduction with endobronchial valves is an important treatment option in selected patients with severe emphysema and absence of collateral ventilation (CV) in the treatment target lobe. The Chartis system provides an important physiological assessment of the presence or absence of collateral ventilation. We aimed to evaluate a new feature and determine whether low flow during a Chartis measurement is predictive for the absence of collateral ventilation, and whether this allows for a procedure to be shortened by earlier terminating the Chartis measurement. This is measured with the “Volume Trend for the previous 20 s” (VT20).MethodsWe retrospectively evaluated 249 Chartis assessments of patients scheduled for bronchoscopic lung volume reduction procedures. The VT20 was calculated, and several thresholds were compared between patients with collateral ventilation (CV positive) and without collateral ventilation (CV negative).Results100% of the CV negative patients reached a threshold of VT20 ≤6 mL, whereas all CV positive patients reached a VT20 ≥7 mL. The median “time saved” between VT20=6 mL and end of assessment was 60 s (range 5 to 354 s).ConclusionThe threshold of VT20 ≤6 mL is a reliable method to exclude the presence of collateral ventilation when air flow rates are low and can therefore reduce bronchoscopic lung volume procedure times.

Bronchoscopic Measurement of Collateral Ventilation: State of the Art

“…Newer Chartis ® consoles also show a VT20 trend (flow trend of the last 20 s). Recent studies suggest that if the VT20 reaches 6 mL, CV is not present and the Chartis ® assessment can be stopped, thereby reducing the measurement time by 60 s [38].…”

Bronchoscopic Lung Volume Reduction for Emphysema: Review and Update

“…We validated the VT20 in a recent study showing that all CV negative patients reached a threshold of VT20 ≤6 mL, whereas all CV positive patients reached a VT20 ≥7 mL. 26 In patients measured with conscious sedation, a diagnostic algorithm has been proposed including measurement time, resistance, and expired volume to help interpret the Chartis measurement easier. 27…”

“…We validated the VT20 in a recent study showing that all CV negative patients reached a threshold of VT20 6 mL, whereas all CV positive patients reached a VT20 !7 mL. 26 In patients measured with conscious sedation, a diagnostic algorithm has been proposed including measurement time, resistance, and expired volume to help interpret the Chartis measurement easier. 27 In case of homogeneous emphysema distribution, low diffusing capacity or lower emphysema destruction scores, the Chartis measurement can also be used to assess the contribution of the target lobe to the total gas-exchange.…”

VT20 method for Chartis assessment of collateral ventilation with flexible bronchoscopy under procedural sedation

“…Notable, a recent study showed that changes in ventilation mode did not affect Chartis outcome [10]. The study protocol described by Koster et al was applied and for analysis, only conclusive Chartis assessments (CV+ and CV) were included in this study [11]. Chartis assessments were recorded with the latest console and software version 6.1.1, which included the VT20 feature.…”