Objective:To evaluate effects of different medication forms of dexmedetomidine on perioperative cognitive function in elderly patients undergoing radical operation of gastric carcinoma, and Ramsay sedation score.Methods:A total of 150 patients aged 65 years and 75 years scheduled for elective radical operation of gastric carcinoma from December 2018 to December 2019 in Shanxi Provincial Cancer Hospital were enrolled, and they were divided into 3 groups according to random number table method: different medication forms of dexmedetomidine groups (group A, group B) and the control group (group C), 50 cases in each group. The patients in group A and group B continued to pump dexmedetomidine at a rate of 0.5 μg·kg -1·h -1 and 0.3 μg·kg -1·h -1 respectively for 15 min before induction of anesthesia. And the patients in group C were given intravenous pumping of an equal volume of 0.9% NaCl for 15 min. Subsequently, patients in group A and group B received continuous intravenous infusion of 0.3 μg·kg -1·h -1 for 30 min before the end of operation, the patients in group C received 0.9% NaCl infusion of equal volume until the end of operation. The cognitive function of the patients was measured by using the Monterey cognitive assessment scale (MoCA) the day before surgery and on day 1,3 and 7 after surgery, and the incidence of perioperative neurocognitive disorder (PND) was counted. Ramsay sedation score at 30 min, 24 h and 48 h after surgery was compared among the three groups. Results:There were 3 patients in group A and 3 patients in group C were excluded because they were transferred to ICU due to serious postoperative complications. There were significant differences in MoCA score among the three groups on day 1, 3, 7 after operation (all P < 0.01); MOCA score of group A, B and C on day 7 after operation was (26.9±0.7) scores, (26.6±1.0) scores, (26.3±1.2) scores, respectively, and the difference between group A and group C was statistically significant ( P < 0.01). The incidence of PND among the three groups on day 1, 3, 7 after surgery had statistically significant differences (all P < 0.05), and the incidence of PND in group A was lower than that in group B and C (all P < 0.05). Ramsay sedation score among the three groups at 30 min and 24 h, 48 h after operation showed statistically significant differences (all P < 0.01), and that in group C was lower than that in group A and group B, and the differences were statistically significant (all P < 0.01). Ramsay sedation score at 24 h after operation in group A was high than that in group B and group C (all P < 0.01). Conclusions:Dexmedetomidine assisted with anesthesia can reduce the incidence of PND in elderly patients undergoing radical operation of gastric carcinoma and enhance the sedative effect. What's more, the most obvious effect is the infusion of 0.5 μg·kg -1·h -1 before anesthesia induction.

Objective To investigated the effect of stenosis characteristics (vascular elasticity and plaque properties) on myocardial ischemia. Methods An ideal geometric multi-scale coronary stenosis model based on fluid-structure interaction was established, and the fractional flow reserve (FFR) was simulated to evaluate myocardial ischemia. The effects of vascular elastic wall (elastic modulus of 1 MPa) and rigid wall, plaque types (lipid-rich plaque and calcified plaque) and plaque volume on myocardial ischemia were considered separately. Results The FFRCT simulation result of vessels with elastic wall was larger than that with rigid wall under all stenosis situations. The FFRCT of vessels in lipid-rich lesions was higher than that of calcified plaque (P=0.001). The trapezoidal plaque volume was larger than the cosine plaque volume, and the FFRCT of vessels in trapezoidal plaque was smaller than that of cosine plaque (P=0.001). Conclusions Vascular elasticity is a critical factor to simulate vascular hemodynamics. In moderate stenosis, calcified plaques are more likely to induce myocardial ischemia due to the larger luminal deformation and dilation of rich lipid plaque. When the stenosis is constant, the smaller the plaque volume, the higher the FFRCT and the smaller the possibility of myocardial ischemia.