The present invention relates to novel nasal pulse oximeter probes that are configured to be placed across the septum of the nose. These probes are fabricated to provide signals to obtain arterial oxygen saturation and other photoplethysmographic data. The present invention also relates to a combined nasal pulse oximeter probe/nasal cannula. The present invention also relates to other devices that combine a pulse oximeter probe with a device supplying oxygen or other oxygen-containing gas to a person in need thereof, and to sampling means for exhaled carbon dioxide in combination with the novel nasal probe. 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.