A sensor may be placed on a distal portion of a patient's finger or toe to obtain pulse oximetry measurements. The distal portion of a digit contains few if any large vascular structures that could adversely affect pulse oximetry measurements, but the distal portion does contain microvasculature that carries arterial blood that facilitates pulse oximetry measurements. The sensor may include an emitter and a detector that are spaced apart by an appropriate distance so that they may be located on the distal portion of a patient's digit during pulse oximetry measurements.