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Objective. To explore the effect of combined etomidate-ketamine anesthesia on perioperative electrocardiogram (ECG) and postoperative cognitive dysfunction (POCD) of elderly patients with rheumatic heart valve disease (RHVD) undergoing heart valve replacement. Methods. The data of 100 elderly RHVD patients treated in our hospital from May 2019 to May 2020 were selected for the retrospective analysis, and by adopting the double-blind method, the patients were divided into the ketamine group (n = 50) and the combined group (n = 50) according to the anesthesia methods. During the induction of anesthesia, the patients of the two groups were given a small dose of ketamine (0.5 mg/kg) at 5 μg/kg/min continuously via pump injection until the end of surgery, and on this basis, with the same anesthesia measures, those in the combined group were given etomidate (0.3 mg/kg) additionally. The patients’ perioperative ECG indicators, POCD scores, and Numeric Rating Scale (NRS) scores were compared between the two groups. Results. Compared with the ketamine group, the combined group presented significantly lower incidence of ST-T wave changes after anesthesia induction and at the time of intubation and skin incision ( P < 0.05 ), significantly lower average magnitude of ST-segment depression after anesthesia induction ( P < 0.001 ), significantly lower average magnitude of ST-segment elevation after anesthesia induction and extubation ( P < 0.001 ), significantly lower POCD incidence (6.%, P < 0.05 ), and significantly better NRS score after surgery ( P < 0.001 ). Conclusion. Combined etomidate-ketamine anesthesia can stabilize the perioperative ECG indicators of elderly RHVD patients undergoing heart valve replacement, improve their postoperative cognitive function, and reduce their pain sensation, which should be promoted and applied in practice.

The micromechanical properties of soft tissue can be used as markers for the physiological state and function of the tissue. Deep understanding of the micromechanics of soft tissue, such as the oesophagus, is of great significance to the design of artificial oesophagi, endoscope materials and coatings for medical devices. Here, the micromechanical properties of oesophageal mucosa were studied under different loading rates, deflections, and dwell time by using atomic force microscopy. The micromechanical properties of soft tissue included elastic modulus, plasticity and adhesion force. Results showed that the micromechanical properties changed with increasing loading rate, deflection and dwell time. The micromechanical properties of oesophageal mucosa were related to time-dependent behaviours, such as contact stress, energy transformation, and strain gradient plasticity. Furthermore, the heterogeneity of oesophageal mucosa affected the micromechanical properties. The force mapping mode was a reliable and effective means to study the micromechanical properties of soft tissue. The results can provide a basis and technical support for the diagnosis of oesophageal diseases from a microscale as well as a material design perspective.

Purpose: The friction characteristics at the interface between prosthetic socket and liner have an important influence on the walking function and wearing comfort of amputees. The frictional behavior at the prosthetic socket/liner interface can provide theoretical guidance for the design and selection of prosthetic materials. So it is of great significance to study the friction behavior at prosthetic socket/liner interface. Methods: The surface roughnesses of the prosthetic socket and liner materials were measured by a laser confocal microscope. The frictional behavior at the prosthetic socket/liner interface was studied on a UMT TriboLab Tribometer by simulating the reciprocating sliding contact mode. An infrared camera was used to take thermal images and then calculated the temperature increase at the socket/liner interface. Results: The coefficient of friction of the silicon rubber fabric are significantly smaller than that of the foam liner materials. The frictional energy dissipation at the liner/acrylic socket interface is the smallest, while it is greater for 3D-printed socket materials. Meanwhile, the temperature increase has a positive correlation to the coefficient of friction and frictional energy dissipation. Conclusions: The three kinds of 3D-printed materials with high surface roughness have higher interface coefficient of friction and energy dissipation than acrylic material. The stiffness and energy consumption play an important role in the interface friction characteristics of the prosthetic liner materials. The appropriate coefficient of friction at the surface between prosthetic socket and liner is essential. A type of the reinforcement fiber has influence on the friction behavior of the 3D-printed reinforced nylon.

The mucous layer on the surface of human digestive tract is a dynamically balanced protective system, mainly containing mucin, enzymes, bicarbonate, epidermal growth factor and other protective factors. It has been found that mucins can protect epithelial cells from infection, dehydration, and physical, mechanical or chemical damage. There are a variety of disturbances that affect or destroy the function of the mucous layer, including mucus dysfunction and diseases of digestive tract. In this paper, the mechanical function of mucin on the surface of esophagus was studied using the UMT Tribometer with the porcine esophagus as the experiment sample. Trypsin was used to control the mucin content on the surface of esophagus. Results showed that the trypsin can affect the function of the mucin on the surface of esophagus. The friction coefficient and the relevant energy dissipation of trypsin-treated and non-trypsin-treated samples were significantly different. Due to the reduction of mucin on the esophageal surface by trypsin treatment, the friction coefficient and energy dissipation of the esophageal surface were significantly higher than that of the samples without trypsin treatment. During the friction test, the esophagus surface was severely damaged at both macro and micro scales after trypsin treatment, which indicated that the mucin can play a lubrication role at the gastroscope device-esophagus interface. The results can provide reference for clinical endoscopic examination and medical advice for clinical practice.