A device that looks similar to a nasal cannula is secured just under the patient's nose. Thermistors and thermocouples can provide information about the presence or absence of airflow based on temperature differences between inhaled and exhaled air. The devices incorporate small sensors that can be taped below the patient's nostril and next to the mouth.
Two Velcro bands, one placed around the chest under the breasts and one around the abdomen, serve to determine chest wall and abdominal movements during breathing. Each band is joined together by a piezo crystal transducer. The force of chest/abdominal expansion on the bands stretches the transducer and alters the signal to a physiological recorder. These leads, combined with the airflow sensor, are how apnea is demonstrated and categorized during the test.