Temperature Profile of Nasal Breathing for Respiration Monitoring in Ambulatory Settings

The nasal breathing parameters have shown promising applications in hyperventilation, Kussmaul breathing, sleep apnea, shortness of breath in COVID-19, bradypnea, sinus arrhythmia, and breathing pranayama. However, a wearable setup, which is affordable, esthetic, and accurate in real time during various physical activities, is not available currently. This article developed a novel, low-cost and wearable instrumented nasal temperature sensing (NTS) device for measuring various breathing parameters. The proposed device was tested during controlled breathing exercises in a seated position at three ambient temperature settings (18 °C, 28 °C, and 38 °C). The device was further tested for standing and walking at various speeds, including slow (1.5 km/h), medium (3.5 km/h), and fast (5.5 km/h). The NTS device is compared against a commercially available respiration belt (RB) (gold standard). The mean absolute error (MAE) (averaged across subjects and ambient temperature settings) was 0.09 ± 0.05 breaths per minute (bpm), 0.17 ± 0.10 bpm, and 0.13 ± 0.13 bpm for controlled breathing at 6, 12, and 18 bpm, respectively. The root mean square between the NTS device and RB across the subjects at the normal standing position was 1.13 ± 0.39 bpm. The results suggest that the proposed NTS device is accurate for real-time applications with the potential advantage of being robust enough to motion artifacts.