The disclosed embodiments relate to a patient monitor for evaluating a patient. The patient monitor may comprise a capnometer that is adapted to receive at least a portion of exhaled flow from the patient and to produce a first output indicative of exhaled carbon dioxide associated with the exhaled flow, an oximeter that is adapted to receive an input from the patient and to produce a second output indicative of oxygen saturation of blood of the patient, and a processor adapted to receive at least the first output and the second output and to correlate the first output with the second output.