• Inert gas rebreathing
• cardiac output
• precapillary pulmonary hypertension
• asthma
• COPD mechanisms
• exercise
• emphysema
• respiratory infection
• sarcoidosis

Lee et al should be commended for showing that non-invasive haemodynamic monitoring using inert gas rebreathing (IGR) might be a valuable tool to detect treatment response in patients with precapillary pulmonary hypertension (PH).1 Even under resting conditions, haemodynamic parameters may be more sensitive than the 6-minute walk distance. This is especially interesting as it may facilitate frequent therapy monitoring. Although pulmonary blood flow (PBF) …