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Objective To investigate the prognostic value and clinical significance of preoperative prognostic nutritional index （PNI） in patients with extensive burns. Methods Clinical data of 56 patients with extensive burns were retrospectively analyzed，and they were divided into the survival group （n=37） and death group （n=19） according to clinical outcomes. Baseline data and relevant laboratory indexes at preoperative 1 d were collected. PNI was calculated using the following equation： serum albumin level （g/L） +5×total lymphocyte count （×109/L）. Clinical data were statistically compared between two groups. The influencing factors of clinical prognosis were identified by univariate and multivariate Logistic regression analyses. The predictive value of preoperative PNI for clinical prognosis of patients with extensive burns was evaluated by the ROC curve. The area under the ROC curve （AUC） represents the accuracy of prediction. All patients were divided into the high and low PNI groups according to the optimal cut-off value of preoperative PNI. The survival curve was drawn by Kaplan Meier method to predict the differences in 90-d survival rate between two groups. Results Among 56 patients，19 （33.93%） died within postoperative 90 d. There were significant differences in burn area，lymphocyte count and preoperative PNI between the death and survival groups （all P<0.05）. In the death group，burn area was larger，lymphocyte count and preoperative PNI were lower than those in the survival group. There were no significant differences in age，sex，CRP，white blood cell count，creatinine，PLR，albumin levels and the incidence of respiratory tract injury between two groups. Univariate Logistic regression analysis showed that burn area，lymphocyte count and preoperative PNI were the risk factors of death. Multivariate Logistic regression analysis indicated that burn area and preoperative PNI were the independent risk factors for death. The optimal cut-off value of preoperative PNI to predict death in patients with extensive burns was 34.45. The 90-d survival rate of patients with PNI≤34.45 was significantly lower than that of their counterparts with PNI>34.45. Conclusions Preoperative PNI is associated with 90-d death rate in patients with extensive burns. The 90-d survival rate of patients with low PNI is lower than that of those with high PNI. These findings indicate that it is of significance to identify preoperative PNI for patients with extensive burns，which can provide reference for selecting the optimal timing for surgery，accelerate wound healing and reduce the death rate of patients with extensive burns.

Objective To analyze the sensitivity of common pathogens and common antibiotics in burn and wound repair surgery patients, aiming to provide reference for the prevention and treatment of burn and various wounds. Methods From March 2019 to March 2021, 310 bacterial culture specimens of wound secretion from burn and wound repair surgery patients with suspected wound infection were collected. VITEK 2 Compact automatic bacterial identification instrument and VITEK MS automatic rapid microbial mass spectrometry detection system were used for pathogen identification. Disk diffusion method and instrumental method were employed to detect the antimicrobial susceptibility. The drug resistance of pathogens was analyzed by WHONET 5.6 software. Results Among 310 samples, 179 positive samples were detected, with a positive rate of 57.74%, 84 cases of Gram-positive bacteria, accounting for 46.93%, 91 cases of Gram-negative bacteria, accounting for 50.84% and 4 cases of fungi, accounting for 2.23%. Among them, Gram-negative bacteria were Pseudomonas aeruginosa （PAE）, Acinetobacter baumannii （ABA）, Klebsiella pneumoniae （KPN） and Escherichia coli （ECO）. Staphylococcus aureus （SAU） was the main Gram-positive bacteria. Among the detected Gram-negative bacteria, the sensitivity rate of PAE to polymyxin B, myxin and amikacin was more than 80.40%. The sensitivity rate of ABA to myxin, polymyxin B and tegacyclin exceeded 96.70%. The sensitivity rate of KPN to tegacyclin and polymyxin B antibiotics was higher than 88.90%. The sensitivity rate of ECO to cefotetan, amikacin, piperacillin/tazobactam and carbapenem antibiotics was >92.90%. Among the detected Gram-positive bacteria, the sensitivity of SAU to linezolid, vancomycin and tetracycline was up to 100.00%, and that of Enterococcus to tetracycline, vancomycin and linezolid was also 100.00%. Conclusions Gram-negative bacteria are the main pathogens in patients with wound infection from Department of Burn and Wound Repair Surgery. Antibiotic susceptibility rate of these bacteria were different. Necessary attention should be paid to these pathogens. During the treatment of infection, clinicians should cultivate and prepare bacterial specimens for accurate examination before selecting antibiotics. According to the results of drug sensitivity, they should choose proper antibiotics, and adopt definite treatment instead of empirical medication as early as possible, aiming to inhibit the generation of drug-resistant strains and improve the effectiveness of antibiotic treatment.

In order to understand the effect of secondary perforation on screen pipe strength, the finite element models of bullet hole were established with the help of software ANSYS when the positions of secondary and original perforation were different, and then the effect of secondary perforation on the residual intensity of screen pipe was analyzed. The results show that the best position for secondary perforation is regions near the midline. With the favorable position, large oil and gas flow area can be ensured which will result in higher oil recovery efficiency. And the goals of secondary perforation can be met by enhancing residual intensity of screen pipe. At the same time, the intersection of secondary and original perforation bullet hole should be avoided, if it can't be avoided, the cross hole central angle should be more than 90 degree, because that the residual strength will grow with the increase of central angle. [ABSTRACT FROM AUTHOR]