Dupuis M, et al. - Researchers herein tested their hypothesis that the measurement of cardiac output (CO) by impedance cardiography (IPc) using the PHYSIOFLOW system is as accurate as thermodilution (TD) or using the direct Fick method in patients with pulmonary hypertension (PH) in group 1 or group 4. They found that IPc afforded a reliable tool for measuring CO in PH patients, compared to the direct Fick method and TD obtained by right heart catheterisation. However, they noted that this accuracy decreased for extreme CO values.