The present invention relates to pulse oximeter probes that are configured to be placed, respectively, across the septum or nares of the nose. These probes are fabricated to provide signals to estimate arterial oxygen saturation. The present invention also relates to a combined nasal pulse oximeter probe/nasal cannula. In certain embodiments, an additional limitation of a control means to adjust the flow rate of such gas is provided, where such control is directed by the blood oxygen saturation data obtained from the pulse oximeter probe.