Investigation on forced vibration characteristics of Nitinol tracheal stent.

BACKGROUND: Tracheal stents can be placed in a narrow position in the human trachea to ensure smooth breathing. And the stent will deform during service by the influence of the physiological environment or random excitations, such as coughing. METHODS: This paper divides the vibration into periodic and random vibrations according to the different pressures. And a coupling vibration model was established by analyzing the contact relationship between the stent and the trachea tissue. And this study discusses the influence of tracheal diameter, respiratory pressure, and frequency on the stent vibration characteristics through Ansys simulation. In addition, the nonlinear equations were solved by the Matlab numerical analysis method, which could help analyze the influence of cough intensity on the stability of the tracheal stent system. RESULTS: The results showed that when tracheal stenosis occurred in the trachea's more significant grade, the trachea stent was more likely to fall off when treated with a tracheal stent. With the increase in respiratory frequency and pressure, the deformation of the tracheal stent is more considerable. Moreover, the frequency of normal cough hardly affects the stability of the stent system, while the excitation force and damping coefficient value greatly influence the system. When the excitation force of the cough exceeds the critical importance of 20 N, the tracheal stent is prone to fall off. This study comprehensively obtained the forced vibration characteristics of the stent under service conditions, which could make up for the shortage of the vibration theory of the stent. CONCLUSION: The results can provide a theoretical basis for predicting the possibility of stent loss in clinical treatment.

Chinese patent medicine Aidi injection for cancer care: An overview of systematic reviews and meta-analyses.

ETHNOPHARMACOLOGICAL RELEVANCE: Aidi injection is one of the China Food and Drug Administration approved Chinese herbal injections and the most competitive product in cancer care in China. It is composed of the extracts from Mylabris Phalerata, Astragalus Membranaceus, Panax Ginseng, and Acanthopanax Senticosus. AIM OF THE STUDY: This overview aims to map systematic reviews (SRs) of Aidi injection for cancer and provide a summarized evidence for clinical practice and decision making. MATERIALS AND METHODS: Seven databases were searched for SRs and/or meta-analyses of randomized controlled trials on Aidi injection for cancer care until December 2020. Six authors worked in pairs independently identified studies, collected data, and assessed the quality of included studies according to the revised Assessment of Multiple Systematic Reviews (AMSTAR 2) and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A narrative synthesis was used for the evidence mapping. RESULTS: Fifty-two SRs on Aidi injection as adjuvant therapy were included, involving lung cancer (20 SRs), liver cancer (10), colorectal cancer (7), gastric cancer (6), lymphoma (2), breast cancer (2), esophageal cancer (1), ovary cancer (1), and a mix of different cancers (4). Except for one SR focusing on Aidi injection used alone, other SRs evaluated Aidi injection in combination with chemotherapy (43), radiotherapy (4), or chemo/radiology/targeting therapy (4). Aidi injection showed additional beneficial effects on survival (9), objective response rate (44), quality of life (42), and the reduction of side-effects from chemo/radiotherapy (48). Using AMSTAR 2 tool, two reviews were assessed as low and the rest as critically low methodological quality mainly due to the lack of prospective registration. The reporting quality was insufficient assessed with PRISMA in the reporting of search strategy (26, 50.0%), additional analysis (19, 36.5%), and the summary of evidence (2, 3.8%). CONCLUSION: Aidi injection has been evaluated for its adjuvant beneficial effects on cancer survival, tumor responses, quality of life, and reducing the side effects of chemo/radiotherapy, mainly focusing on lung, liver and colorectal cancer. The methodological and reporting quality are weak and need to be improved in the future.

Investigation on puncture mechanical performance of tracheal tissue.

This paper investigated the mechanical behavior of the contact between the oblique tip puncture needle and the tracheal tissue during pathological examination for the diagnosis of respiratory diseases. By analyzing the force of the oblique tip puncture needle, this paper established a theoretical model of the contact mechanics between the needle and the tracheal tissue. With the material characteristics, needle diameter and puncture angle of trachea tissue as the loading conditions, the biomechanical simulation of piercing process was carried out by using the finite element simulation method, and realistic puncture experiments on isolated porcine tracheal tissue were performed by electronic universal testing machine. The results showed that the puncture needle was mainly subjected to the combined effect of cutting force, clamping force and frictional force on the needle shaft. When the needle diameter was 22G, penetrating the tracheal tissue vertically, the force on the needle was minimal. Meanwhile, it was found that the error between the experimental and theoretical values of the puncture force did not exceed 10%, thus verifying the feasibility of the hypothetical model of the puncture force in the tracheal tissue rupture stage. It provided a theoretical basis for the intervention of surgical instruments and reduced surgical risks.