A method and apparatus to identify the source of oxygen delivery failure to a patient. The apparatus comprises a pressure sensor to detect a patient's breathing pressure and ambient pressure, an oxygen flow analyzer to measure oxygen flow to the patient, and a processor to analyze the breathing pressure values, ambient pressure value, and oxygen flow rate values. When the oxygen flow rate value is greater than a predetermined threshold value, the processor is programmed to compare the breathing pressure values to the ambient pressure value and output an apnea alarm or an oxygen delivery device displacement alarm.
