A measurement technology that provides new opportunities for modelling respiratory gas exchange
Measuring respiratory gas exchange is “old” physiology, and mathematical models of this process are some of the earliest physiological models to have been developed. In clinical medicine, apart from in cardiopulmonary exercise testing and in certain tests of lung function, measurements and models of respiratory gas exchange have nevertheless been of limited value. One possible reason is that, while mass balance is a physical principle of immense precision, our abilities to measure respiratory exchange have been too inaccurate to be able to exploit this to the full. In this seminar, the development of a new form of respiratory gas analysis will be described, based on laser absorption spectroscopy, that is capable of conducting highly-accurate gas analyses every 10 ms within the main airway. This work has been coupled with the development of a high-precision respiratory flowmeter. Traditional dynamic measures of respiratory flux are probably accurate to only 1 in 20 molecules (5%), whereas the new device is accurate to around 1 in 500 molecules (0.2%). The seminar will cover areas of medicine where this instrument may be of direct value. It will also briefly cover a new, parsimonious, model of lung inhomogeneity that is being developed, the parameters of which should be directly estimable from experiments conducted using this new technique for in-airways molecular flux sensing.