Recommendations for using the standardized terminology of respiratory physiology in radiation research

A succinct review of the terminology and of correlations between basic quantities in respiration physiology is given with special regard to oxygen as the gas of topical interest in radiation research and tumor pathophysiology. The role of the oxygen partial pressure gradient as the driving force of O2 diffusion is emphasized. It is generally recommended that the O2 partial pressure be considered when investigating oxygen diffusion and distribution problems. During those studies the physical boundary conditions, in particular the temperature, the barometric pressure, and the water vapor saturation, have to be considered and should be indicated. During equilibration of suspensions containing oxygen-consuming sites the impact of geometry and fluid agitation on the efficiency of gas exchange has to be taken into account. Reviews on solutions of diffusion equations, on numerical data for relevant constants to be considered, and on terminology and units in respiration physiology are included.