Fig. 1From: Impact of High-Intensity-NIV on the heart in stable COPD: a randomised cross-over pilot studyStudy flow chart. As the study was a randomized cross-over trial, patients used the LI-NIV for 6Â weeks followed by HI-NIV for 6Â weeks (LIHI group, green) or HI-NIV for 6Â weeks followed by LI-NIV for 6Â weeks (HILI group, purple)Back to article page