Abstract
Measurement allows us to quantify various parameters and variables in natural systems. In addition, by measuring the effect by which a perturbation of one part of the system influences the system as a whole, insights into the functional mechanisms of the system can be inferred. Clinical monitoring has a different role to that of scientific measurement. Monitoring describes measurements whose prime purpose is not to give insights into underlying mechanisms, but to provide information to 'warn' of imminent events. What is often more important is the description of trends in measured variables. In this article, we give some examples - focussed around oxygen sensors - of how new sensors can make important measurements and might in the future contribute to improved clinical management.