We compared respiratory events analyzed using a nasal-oral cannula/pressure sensor or thermocouple airflow sensor. Subjects numbered 29—24 men and 5 women with a mean age of 55.8±12.0 years—reporting snoring or obstructive sleep apnea and underwent all-night polysomnography. Respiratory airflow was simultaneously monitored using a nasal-oral thermocouple airflow sensor and a nasal-oral cannula connected to a pressure transducer. Respiratory events were manually analyzed from the thermal sensor, pressure sensor, and both sensors signals. The mean apnea-hypopnea index and apnea index analyzed using the pressure sensor exceeded the means analyzed using a thermal sensor at 33.6±22.8/h vs 30.5±22.8/h, 29.4±21.0/h vs 23.2±21.8/h. The mean hypopnea index analyzed using the thermal sensor was greater than the mean analyzed using the pressure sensor (7.3±10.9/h vs 4.2±7.4/h). The pressure sensor was more sensitive than the thermal sensor in detecting respiratory events, whereas the pressure sensor may have overestimated the number of apnea cases compared to the thermal sensor. The thermal sensor may overestimate the number of hypopneas compared to the pressure sensor. We therefore propose simultaneous monitoring with a nasal-oral pressure sensor and thermal sensor, which significantly improves respiratory event detection.
