Exhaled nitric oxide as biomarker of acute lung injury: an unfulfilled promise?

The discovery of nitric oxide (NO) as a signalling and regulatory molecule and its subsequent detection in the exhaled breath has not only yielded new mechanistic insights but also diagnostic opportunities and therapeutic targets in several important medical conditions. In diseases involving chronic pulmonary inflammation such as asthma that affects millions worldwide, exhaled NO has achieved spectacular successes with patients currently owning handheld devices and monitoring inflammatory aspects of their conditions in their own homes.