Design of a respiratory function monitor based on surface physiological signals(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2023年第3期
- Page:
- 353-360
- Research Field:
- 医学信号处理与医学仪器
- Publishing date:
Info
- Title:
- Design of a respiratory function monitor based on surface physiological signals
- Author(s):
- SONG Xin1; LI Yunchi1; ZHANG Weiguang2; LI Yongqin1
- 1. Department of Biomedical Engineering and Imaging Medicine, Army Medical University, Chongqing 400038, China 2. Department of Critical Care Medicine, the First Affiliated Hospital of Army Medical University, Chongqing 400038, China
- Keywords:
- Keywords:diaphragm electromyography electrocardiography thoracic impedance respiratory function monitoring principle prototype
- PACS:
- R318.6
- DOI:
- DOI:10.3969/j.issn.1005-202X.2023.03.015
- Abstract:
- Abstract: Objective To design a principle prototype of respiratory function monitor based on surface electrocardiography (ECG) signals, diaphragm electromyography (DiEMG) signals and thoracic impedance signals that can continuously monitor the respiratory function at home, medical emergency and other occasions. Methods With the STM32F411VET6 microcontroller system as platform, a pair of Ag/AgCl electrodes was used as the output electrodes of high-frequency excitation signals, and the detection electrodes of ECG signals and thoracic impedance signals, while another pair of Ag/AgCl electrodes was adopted to detect the DiEMG signals. The simultaneous detection of ECG signals, DiEMG signals and thoracic impedance signals was realized using the two pairs of Ag/AgCl electrodes. The system hardware mainly included ECG signal detection circuit, thoracic impedance signal detection circuit, DiEMG signal detection circuit, constant current source excitation circuit and microcontroller. The system was powered by the rechargeable lithium battery of 12 V. The analog signals were digitalized by the A/D mode of MCU, and the digitalized signals were stored in SD memory card through the secure digital input and output protocol. After completing the prototype design and performance test, the signals of 13 patients in mechanical ventilation due to respiratory dysfunction and 13 healthy adults were collected, and 15 respiratory function parameters were calculated for comparing the differences between mechanically ventilated patients and healthy controls, thereby verifying the reliability of the respiratory function monitor. Results The signal-to-noise ratio and common mode rejection ratio of the signal acquired by the prototype were >10 dB and >80 dB, and the leakage current of the prototype was <30 μA. The following parameters in mechanically ventilated patients were lower than those in healthy adults: inspiratory time, expiratory time, tidal volume, peak-to-peak value of thoracic impedance signal, variation of thoracic impedance signal in 1 s, low-frequency (LF) and high-frequency (HF) power of DiEMG signal, HF to LF ratio, DiEMG discharge area and time, peak-to-peak value of DiEMG signal, and cardiopulmonary coupling values (P<0.05), but the heart rate was significantly higher in mechanically ventilated patients than in healthy adults (P<0.05). In addition, there were no significant differences between two groups in respiratory rate and inspiration to expiration ratio (P>0.05). Conclusion The designed respiratory function monitor prototype is demonstrated to be safe and reliable, and it can be used for continuously and non-invasively monitoring respiratory function in real-time.
Last Update: 2023-03-29