Louvaris Z, et al. - Concurrent cardiac output (CO) measurements captured by impedance cardiography (IC) (PhysioFlow: CO_IC) were assessed vs the indocyanine green dye dilution method (CO_DD) in patients with COPD. Researchers concurrently obtained 50 paired CO measurements using the two methods from 10 patients (FEV₁:50.5±17.5% predicted) at rest and during cycling at 25%, 50%, 75% and 100% peak work rate. CO_IC and CO_DD were noted as having strong correlation from rest to peak exercise. Between CO_IC and CO_DD, the mean absolute and percentage differences were 1.08 liters/min (limits of agreement (LoA): 0.05 to 2.11 liters/min) and 18±2%, respectively; IC offered systematically higher values. When data were expressed as changes from rest, they consistently noted strong correlations and agreement between the two methods over the entire exercise range. In patients with COPD, impedance cardiography offers a satisfactory CO measurement from rest to peak cycling exercise.