Fig. 5.

Benefits and risks of low and high oxygen saturation by pulse oximeter (SpO₂) targets. Preductal SpO₂ in the mid-90s (90–97% - green zone) results in lower oxidative stress, increased cerebral blood flow and better response to inhaled nitric oxide (iNO). However, in the presence of hypothermia and acidosis, low SpO₂ target may not be adequate to promote optimal pulmonary vasodilation resulting in high right ventricular afterload. High SpO₂ targets (~100%) require higher inspired (FiO₂) and alveolar (PAO2) increasing the risk of oxidative stress. Such targets may transiently improve pulmonary vasodilation especially in the presence of hypothermia or acidosis but there is a higher risk of reactive oxygen species formation leading to inactivation of inhaled nitric oxide (iNO), surfactant inactivation and inflammation. Copyright Satyan Lakshminrusimha.