Clinical effectiveness of a pneumatic compression device combined with low-molecular-weight heparin for the prevention of deep vein thrombosis in trauma patients:A single-center retrospective cohort study

BACKGROUND:To investigate the clinical effectiveness of a pneumatic compression device(PCD)combined with low-molecular-weight heparin(LMWH)for the prevention and treatment of deep vein thrombosis(DVT)in trauma patients.METHODS:This study retrospectively analyzed 286 patients with mild craniocerebral injury and clavicular fractures admitted to our department from January 2016 to February 2020.Patients treated with only LMWH served as the control group,and patients treated with a PCD combined with LMWH as the observation group.The incidence of DVT,postoperative changes in the visual analogue scale(VAS)score,and coagulation function were observed and compared between the two groups.Excluding the influence of other single factors,binary logistic regression analysis was used to evaluate the use of a PCD in the patient’s postoperative coagulation function.RESULTS:After excluding 34 patients who did not meet the inclusion criteria,252 patients were were included.The incidence of DVT in the observation group was significantly lower than that in the control group(5.6%vs.15.1%,χ^(2)=4.605,P<0.05).The postoperative VAS scores of the two groups were lower than those before surgery(P<0.05).The coagulation function of the observation group was significantly higher than that of the control group,with a better combined anticoagulant effect(P<0.05).There were no significant differences between the two groups in preoperative or postoperative Glasgow Coma Scale scores,intraoperative blood loss,postoperative infection rate,or length of hospital stay(P>0.05).According to logistic regression analysis,the postoperative risk of DVT in patients who received LMWH alone was 1.764 times that of patients who received LMWH+PCD(P<0.05).The area under the receiver operating characteristic(AUROC)curve of partial thromboplastin time(APTT)and platelet(PLT)were greater than 0.5,indicating that they were the influence indicators of adding PCD to prevent DVT.Excluding the influence of other variables,LMWH+PCD effectively improved the coagulation function of patients.CONCLUSIONS:Compared with LMWH alone,LMWH+PCD could improve blood rheology and coagulation function in patients with traumatic brain injury and clavicular fracture,reduce the incidence of DVT,shorten the length of hospital stay,and improve the clinical effectiveness of treatment.

Jinan Huaneng Pneumatic Components and Devices Company

The Jinan Huaneng Pneumatic Components and Devices Company (Jinan Pneumatic Components Factory) is a large Class-Ⅱ enterprise, with the multiple functions of scientific research and development, production and processing, operation and sales, technical service, import and export, and personnel training. Following the renovation of its key technology in the Seventh

Simulation analysis and match experiment on negative and positive pressures of pneumatic precision metering device for rapeseed

Positive and negative pressures determine the performance of pneumatic precision metering device for rapeseed.In order to investigate the relationship between positive and negative pressures of nozzles,fluid models of chamber were developed to simulate the airflow,and the k-εturbulence model was conducted to capture the pressure and velocity of nozzles.Through these efforts linear models were achieved.Meanwhile,the three-factor factorial split-split experiment was designed with negative pressure,positive pressure and the rotating speeds varying from-1000 to-4500 Pa,50 to 250 Pa and 10 to 45 r/min,respectively.The mathematical models were developed through employing the stepwise regression method.The sequence of influential factors on the quality of feed index was positive pressure,negative pressure and rotating speed.To obtain the match regulation of negative and positive pressures with“good”performance,the ratio coefficient K of negative and positive pressures was introduced to build mathematical models.Models relating ratio coefficient K with positive pressure were fitted in different rotating speeds.The results showed that the ratio coefficient was matchedГ∈[f1(x),f2(x)]from the fitting equations with the rotating speed of 10-30 r/min;while the rotating speed has greater influence when it was 35-40 r/min and the setsΛ∈[g1(x),g2(x)]were achieved,where x∈[100,250].This study could be conducted to adjust the rotating speed of the pneumatic system to optimize the ideal performance of the seeder.

Design and indoor simulated experiment of pneumatic rice seed metering device

In order to meet the agronomy demand for hybrid rice direct seeding,a novel precise pneumatic rice seed metering device was designed with groups of sucking holes plate,by which 3-4 seeds could be synchronously sucked and synchronously dropped into the paddy field.The plate was divided into five sections:seed sucking,seed clearing,seed carrying,seed dropping,and blank sections.The seeds were sucked in sucking section by the vacuum,carried and rotated to the dropping section with the plate,blown away in dropping section by the positive pressure air,and thrown into the dropping tube.The influences of the hole diameter,vacuum degree,and clear-up equipment on precision of metering device were discussed.Experiments were conducted to investigate the seeding precision and simulate the field emergence rates on the indoor seeding test-bed.The subjects were pregnant Indic hybrid Peizataifeng under two kinds of moisture content(23.43%and 26.07%).Other experiment conditions included the vacuum degree of 2.60 kPa,the rotation speed of seed sucking plate of 30 r/min,three sucking holes with a diameter of 1.6 mm,and the seed layer thickness of 25 mm.The seeding results showed that,in condition of no more than two seeds per hill,the emergence probabilities under the two moisture contents were 11.82%and 11.95%,respectively,and in condition of 3-4 seeds per hill,the results were 64.81%and 65.84%,respectively.With 2-5 seeds per hill,the results were 92.08%and 92.60%,respectively.If the emergence probability was 80%,under the two moisture contents,the no seed per hill probabilities were 1.33%and 0.80%respectively;the probabilities with 3-4 seeds per hill were 56.13%and 56.40%respectively;the probabilities with 5 or more seeds per hill were 10.67%and 10.13%respectively;the probabilities with 2-5 seeds per hill were 87.60%and 88.13%respectively.The results showed the simulated experiment was an efficient and economic method to assess the capability of pneumatic rice seed drilling metering device,and the precise pneumatic rice seed drilling metering device had a good prospect in practical application.

Dynamic model for sucking process of pneumatic cutting-type safflower harvest device

This study proposed a method using negative pressure sucking the petals adhered around cones.The structural parameters of the sucking device affect the flow-field distribution in the negative-pressure air chamber.In order to improve the harvesting efficiency and quality of the pneumatic cutting-type safflower harvest device,a dynamic model was established and the safflower petals upwind area were measured.According to the test,the size parameters of the thornless Yumin safflower were as follows:the average necking diameter was 6.30 mm,the average capitulum diameter was 20.89 mm and the average petal length was 22.39 mm.The measured maximum frontal area of the safflower petal was 11-40 mm2.Secondly,the required negative pressure power that resulted in the rise of safflower petals was calculated.In general,when the suction of the negative pressure reaches 9.8 m/s,the safflower petals can be sucked successfully.The simulation of the flow field in the suction mouth indicated that the streamlined suction mouth was beneficial in reducing resistance and the test results of high-speed photography showed that the aforementioned condition could improve the efficiency of the upright safflower.And the test verified that the rate of the unshaped petals in the cylindrical air tunnel was low and the efficiency of carding and shaping under negative pressure was considerably better in wet petals than in dry ones.Results of the upright safflower petal experiment were consistent with the theoretical analysis and simulation conclusion,and indicated the precision of the dynamic model and suction flower mouth orifice-shaped simulation analysis.

Design and experiment of the pneumatic cylinder type precision metering system for wheat

The main goal of this study was to design a pneumatic cylindrical-type metering device with six-rows for wheat precision and to analyze its output under different rotating speeds and vacuum pressure values.The effect of the pressure,rotating speed and rows on seed suction,retention and dropping was shown inspected.Six levels of rotating speed(5,10,15,20,25 and 30 r/min.)combined with the applying of different vacuum pressures(1.8,2.1,2.4,2.7,3.0,and 3.3 kPa)were inspected to detect the optimum pressure which was adequate for seed sucking at each speed.In addition,to predict the vacuum pressure corresponding with each rotating speed,a regression model was developed.Based on seed mass analysis,statistical differences under the influence of velocities and negative pressure were found at 5 percent significance according to Duncan’s Test,whereas the differences were existed between and within rows.Results revealed that the highest seed mass means of 19.02 g and 22.64 g were obtained by row1while the lowest means of 18.02 g and 21.49 g were attained by row6 under the effect of the speed and vacuum pressure,respectively.The noticeable variation between row1 and row 6,particularly under high speeds(25 and 30 r/min),might be returned to the truth that row 1 was closer to vacuum inlet,and row 6 was the farthest one.Results concluded that the multiple-row pneumatic cylinder with oblong shape seed nozzle was found to be capable for single seed picking with a small rows variation but without seed damage.

Two mechanical methods for thromboembolism prophylaxis after gynaecological pelvic surgery： a prospective, randomised study

Background Venous thromboembolism is known to be an important social and health care problem because of its high incidence among patients who undergo surgery. Studies on the mechanical prophylaxis of thromboembolism after gynaecological pelvic surgery are few. The aim of our study was to evaluate the effect of mechanical thromboembolism prophylaxis after gynaecological pelvic surgery using a combination of graduated compression stockings （GCS） and intermittent pneumatic compression （IPC） or GCS alone. Methods The study was performed on 108 patients who were randomly assigned to two groups. The first group received GCS before the operation and IPC during the operation （IPC＋GCS group）, The second group received GCS before the operation （GCS group）. To analyze the effect of the preventive measures and the laboratory examination on the incidence of thrombosis and to compare the safety of these measures, the incidence of adverse reactions was assessed. Results The morbidity associated with DVT was 4.8% （5/104） in the IPC＋GCS group and 12.5% （14/112） in the GCS group. There were significant statistical differences between the two groups. There were no adverse effects in either group. Conclusions The therapeutic combination of GCS and prevention in high-risk patients undergoing gynaecological group.（No. ChiCTR-PRC-10000935）. IPC was more effective than GCS alone for thrombosis pelvic surgery, and there were no adverse effects in either