A patient monitor can noninvasively measure a physiological parameter using sensor data from a nose sensor configured to be secured to a nose of the patient. The nose sensor can include an emitter and a detector. The detector is configured to generate a signal when detecting light attenuated by the nose tissue of the patient. An output measurement of the physiological parameter can be determined based on the signals generated by the detector. The nose sensor can include a diffuser configured to disseminate light exiting from the emitter into or around a portion of the patients body. The nose sensor can also include a lens configured to focus light into the detector.
