Determining the venous oxygen reservoir: A novel, hypothetical approach to titration of supplemental oxygen in preterm newborns.

While normal oxygen saturation is commonly thought to be a marker of normal oxygenation, cutaneous saturation does not account for the sufficiency of oxygen within each cell or that of the system overall. Rather, cutaneous oximetry simply defines the saturation of haemoglobin (Hb) with oxygen in a pulsatile vessel. Assessment of sufficiency is best determined by measurement of the amount of oxygen left over following aerobic respiration. This left over oxygen is 'stored' on Hb in the venous compartment and can be calculated as the venous oxygen content. We hypothesize that the development of a venous oxygen content or saturation reference range in a group of well, uninjured very preterm newborns and subsequent application, in a randomised trial, with a structural, functional and molecular outcome will resolve the method for assessment of oxygen sufficiency in preterms by demonstrating both clinical safety and effectiveness. This method could be subsequently used for titration of supplemental oxygen.