Monitoring airway impedance has significant clinical value in accurately assessing and diagnosing pulmonary function diseases at an early stage. To address the issue of large oscillator size and high power consumption in current pulmonary function devices, this study adopts a new strategy of expiration-driven oscillation. A lightweight and low-power airway impedance monitoring system with integrated sensing, control circuitry, and dynamic feedback system, providing visual feedback on the system’s status, was developed. The respiratory impedance measurement experiments and statistical comparisons indicated that the system could achieve stable measurement of airway impedance at 5 Hz. The frequency spectrum curves of respiratory impedance (R and X) showed consistent trends with those obtained from the clinical pulmonary function instrument, specifically the impulse oscillometry system (IOS). The differences between them were all less than 1.1 cm H2O·s/L. Additionally, there was a significant statistical difference in the respiratory impedance R5 between the exercise and rest groups, which suggests that the system can measure the variability of airway resistance parameters during exercise. Therefore, the impedance monitoring system developed in this study supports subjects in performing handheld, continuous measurements of dynamic changes in airway impedance over an extended period of time. This research provides a foundation for further developing low-power, portable, and even wearable devices for dynamic monitoring of pulmonary function.
Objective To assess early clinical safety and efficacy of transfemoral transcatheter aortic valve replacement (TF-TAVR) for pure aortic regurgitation (PAR). Methods The clinical data of PAR patients who underwent TAVR in Wuhan Asia Heart Hospital and Wuhan Asia General Hospital from January 2018 to October 2022 were retrospectively analyzed. Patients were divided into a TF-TAVR group and a transapical transcatheter aortic valve replacement (TA-TAVR) group. The clinical data of the patients were analyzed. Results A total of 54 patients were enrolled, including 34 males and 20 females with an average age of 74.43±6.87 years. The preoperative N-terminal pro-B-type natriuretic peptide level was lower [808.50 (143.50, 2 937.00) pg/mL vs. 2 245.00 (486.30, 7 177.50) pg/mL, P=0.015], and the left ventricular end-diastolic diameter (56.00±6.92 mm vs. 63.07±10.23 mm, P=0.005) and sinus junction diameter (32.47±4.41 mm vs. 37.65±8.08 mm, P=0.007) were smaller in the TF-TAVR group. There was no death in the two groups during the hospitalization. Only 1 new death within postoperative 1 month in the TF-TAVR group (cerebral hemorrhage). A total of 2 new deaths in the TF-TAVR group (1 patient of sudden cardiac death and 1 of multiple organ failure), and there was no death in the TA-TAVR group within postoperative 3 months. There was 1 new death in the TA-TAVR group (details unknown), and there was no death in the TF-TAVR group within postoperative 6 months. There was no statistical difference between the two groups in the all-cause mortality and the cumulative survival rate during the follow-up period (P>0.05). The incidence of high atrioventricular block was 36.0% in the TF-TAVR group and 10.3% in the TA-TAVR group (P=0.024). There were no significant differences between the two groups in the perivalvular leakage (≥moderate), valve in valve, a second valve implantation, valve migration, cerebrovascular events, major vascular complications, complete left bundle branch block, new permanent pacemaker implantation or transferring to surgery (P>0.05). However, the incidence rates of complete left bundle branch block and new permanent pacemaker implantation were higher in the TF-TAVR group, accounting for 56.0% and 40.0%, respectively. Conclusion TF-TAVR is a safe and feasible treatment for PAR patients, which is comparable to TA-TAVR in the early postoperative safety and efficacy.