Coupling exercise lung ultrasound with cardiopulmonary exercise testing (LUS-CPET): proof of concept

<bold>Introduction:</bold> Lung ultrasound (LUS) is a validated method for diagnosing interstitial syndrome by assessing B-lines. Its feasibility during exercise, particularly within the context of cardiopulmonary exercise testing (CPET), remains underexplored. This study seeks to evaluate the practicality and effectiveness of utilizing LUS in tandem with CPET. <bold>Methods:</bold> A point-of-care LUS (Venue^TM GE HealthCare_©) was done with a low frequency probe at rest and at peak exercise. All zones (Volpicelli et al. Intensive Care Med 2012; 38:577-91) were assessed for B-lines in this order: 4L, 3L, 5L, 6L, 7L, 5R, 6R, 7R, 4R, 3R, 1L, 2L, 1R and 2R. A manual B-lines count and an automated detection were done for each zone. A LUS score was also calculated. One clinician was assigned for the LUS and one for supervising the CPET. <bold>Results:</bold> Ten patients referred for CPET were included (three females; mean age: 49.1 ± 16.1 years). All tests were maximal (mean VO2max: 22.2 ± 6.4 mL/min/kg). The mean number of B-lines of all zones was 0.22 ± 0.30 at rest and 0.65 ± 0.47 at peak (Wilcoxon Signed-Rank test: W=45, p=0.004, r=1). If only considering the antero-lateral zones (1 to 4), the mean number of B-lines was 0.26 ± 0.36 at rest and 0.74 ± 0.50 at peak (Z=2.5, p=0.014, r=0.9). No patient had more than 3 B-lines in any zone at peak exercise. The mean LUS score was zero before and after exercise. The mean time taken for performing the LUS was 1.05 ± 0.23 min at rest and 1.28 ± 0.09 min at peak. <bold>Conclusion:</bold> Dynamic assessment of B-lines during CPET has been proved to be feasible. Dedicated studies exploring their clinical significance and prognostic value hold promise for advancing our understanding of them.