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Background/Aim. The best treatment for the occlusion of the largest artery in the thigh is a femorodistal (FD) bypass. Ankle-brachial index (ABI) and multidetector computed tomographic (MDCT) angiography are the gold standards for diagnosing peripheral arterial occlusive disease. The finite element analysis (FEA) method can help measure the quantity of blood flow and arterial pressure in the arteries in the leg. The aim of this study was to examine the possibility of using the FEA method in predicting the outcome of FD bypass surgery. Methods. The study involved 45 patients indicated for FD arterial reconstruction from December 1, 2021, to March 31, 2023. Each patient underwent pre- and postoperative MDCT angiography of the arteries of the lower extremities, on the basis of which, with the use of FEA, models were made for measuring ABI. All patients had their ABI measured pre-operatively and postoperatively using the Doppler ultrasound and sphygmomanometer. Based on the findings of the preoperative MDCT angiography, postoperative virtual surgical models were created using the FEA method, on which ABI were also measured. The values of ABI were divided into five groups: ABI measured preoperatively (ABI pre-op), ABI measured postoperatively (ABI post-op), ABI measured on FEA models based on the MDCT findings [ABI (sim) pre-op], ABI sim post-op, and ABI measured on virtual surgery model [ABI sim post-op (virtual)]. The ABI of the models were statistically compared with preoperative and postoperative measurements done on patients. Results. The values based on the virtual ABI model did not show significant differences compared to the values obtained on patients and values obtained with the FEA method using MDCT angiography (p < 0.001). A strong statistically significant correlation was shown between the virtual ABI and the values obtained by the other two methods, measured on the postoperative MDCT angiography model and virtual postoperative model (p < 0.001). Conclusion. Virtual simulation based on the MDCT angiography parameters of peripheral blood vessels can be successfully used to predict the immediate outcome of the FD bypass surgery.

Background/Aim. Although distal venous patch and cuff techniques are recommended to improve the patency of by-pass in the lower extremities, the advantage of these techniques remains unproven. Autovenous bypass graft remains the method of choice, but when there is no possibility of using the great saphenous vein, the venous cuff method may have an advantage. The aim of this study was to evaluate the results of femorodistal bypass procedures with a venous cuff in critical lower extremity ischemia. Methods. The study described the results of femorodistal bypass procedures after a follow-up period of 6 to 24 months. We followed 28 patients with distal composite anastomosis of femorodistal arterial reconstruction. Indications for surgical treatment were set on the basis of the clinical exam and morphological criteria based on multidetector computed tomographic angiography. Three types of distal graft-arterial anastomoses were applied: Miller’s cuff, Taylor’s patch, and St. Mary’s vein boot anastomosis. Results. After 6 months of surgery, all bypasses were passable; after one year, 2 (7%) patients had graft occlusion and above-knee amputation, and 8 (28%) patients died; after 24 months, 18 (64%) patients had primary bypass patency. Conclusion. Femorodistal bypass procedures using a synthetic graft and venous cuff have good long-term results. The optimal anastomosis type is St. Mary’s boot. A longer follow-up period and comparison with the autovenous bypass are necessary for a more detailed assessment of the final conclusion.

Background/Aim. An aggressive approach with radical nephrectomy and thrombectomy is the mainstay of the treatment in patients with renal tumors. The aim of this study was to present the results of such surgical procedures performed in the last 25 years at our institution. Methods. We made a retrospective analysis of radical nephrectomy and thrombectomy in patients with renal tumor and tumor thrombus (TT) extending into the inferior vena cava (IVC) operated on at our institution between January 1995 and October 2021. Results. There were 92 patients (72 males and 20 females) aged 60.5 on average who were operated on in the mentioned period. A predominance of right-sided tumors was present in 73.33% of patients. Patients with TT in the renal vein (levels 0 and I) were not included. TT levels II, III, and IV were present in 32 (34.8%), 52 (56.5%), and 8 (8.7%) patients, respectively. One patient had thrombosis of the right pulmonary artery. Four patients had liver metastases, and ten had lymph node involvement. The surgical approach by subcostal incision was achieved in 8 (8.69%) patients, by chevron incision in only 11 (11.95%) patients, while in 73 (79.34%) patients, we performed median sternotomy and subcostal/chevron incision. Intraoperatively, there was one complication which was pulmonary thromboembolism. Six patient required re-exploration after the surgery due to the IVC hemorrhage. The three-year survival in patients with renal tumors and TT levels II−IV in the IVC was 43%. Conclusion. Surgery will remain the primary cure method in patients with renal tumors and TT in the IVC. Long-term survival in these patients can be achieved by complete surgical removal (radical nephrectomy and thrombectomy).

Introduction. A percutaneous transhepatic approach has been used to place tunneled catheters in the inferior vena cava for hemodialysis. This route through the suprahepatic vein could be used to place a tunnelled catheter for permanent haemodialysis without complications and with an excellent permeability rate. Single centre expirience. From 2011 to 2020 in a Military Medical Academy we treated 4 patients with transhepatic central venous catheter for hemodialysis. All of them had exhausted approaches during period of hemodialysis. Arterio-venous fistulas had been thrombosed on the arms, thrombosis subclavian vein billateraly or superior cava veinand complications by femoral catheters was present. Peritoneal dialysis was not possible. Discusion. Limited number of papers descripted outcome of placement transhepatic catheters for hemodialysis. In our expirience one patient needed scroll catheter due hemodialysis had not well outcome, and one patient needed thrombolysis catheter.Two of them are on hemodialysis without complications for 300 and 1650 days. Conclusion. The transhepatic venous access under ultrasound and radioscopic guidance is a simple and safe method. It is an acceptable alternative for permanent haemodialysis catheters when other venous accesses are exhausted, and when it is performed by a well-trained team.

Introduction. Horseshoe kidney (HSK) is a congenital anomaly of embryonic kidneys, which occurs in early gestation when both kidneys are in close proximity. This hap-pens as a result of abnormal migration of nephrogenic cells. The presence of HSK may complicate an anterior approach to reconstructive surgery of the aorta and iliac vessels because the isthmus of the HSK lies across the aorta. HSK is often associated with anomalous renal vessels. Case report. A 71-year-old female patient was admit-ted with an abdominal aortic aneurysm, 50 mm in diameter, and HSK, and multiple aberrant renal vessels with subocluded upper left renal artery as seen on the multidetector computed tomography (MDCT). Open surgical treatment was applied. Endarterectomy of the left upper renal artery, perfusion of the right common bottom pole renal artery, and reimplantation of both bottom polar renal arteries were done. Isthmus was not divided. The co-existence of HSK and abdominal aortic aneurysm (AAA) is a rare condition. It presents a technical challenge to vascular surgeons because the surgical treatment of such an aneurysm is complicated due to the abnormal anatomy, difficulties in exposing the aneurysm, and a variable blood supply to the isthmus and lower poles of the HSK. Conclusion. Open surgical repair of AAA with HSK is a successful method and provides good exposure, the possibility of renal circulation preservation, and prevention of renal insufficiency.

Introduction. Aortoenteric fistula (AEF) is rare and extremely difficult complication of aortic surgery. We presented two cases of secondary aortoduodenal fistula (SADF) as complication after aortic surgery. Case reports. In the first patient SADF happened 11 years after open abdominal aneurysmal resection with gastrointestinal tract (GIT) bleeding. After negative esophagogastroduodenoscopy (EGDS) we performed multislice computed tomography (MSCT) which revealed contrast leakage in duodenum from 10 cm wide visceral aortic aneurysm. The patient was treated with graft excision, aneurysmal reduction, sewing of proximal and distal aortal stumps, bowel repair followed by axillobifemoral bypass (AxFF). The patient dismissed on 30th postoperative day. The second case of ADF happened five months after endovascular reconstruction of abdominal aorta with GIT bleeding and fewer. During following 8 days, he had three negative EGDS. On MSCT we found signs of endoleak, free air in aneurysmal sac, and signs of blood in the intestine. On urgent operation we extracted stent graft, sewed proximal and distal aortal stumps, performed bowel repair and AxFF. The patient died a day after operation with signs of sepsis and multiple organ failure syndrome. Conclusion. Conventional treatment of ADF means extraanatomic AxFF with complete excision of infected graft or stent graft, with closure of aorta’s proximal and distal stumps and duodenal repair. Because of high mortality, prompt diagnostic evaluation and quick decision of an adequate operative treatment is necessary. Although European Society of Vascular Surgery recommendations, as a guide, are very helpful, there is no unique attitude about management of AEF, so each patient should be specifically treated.

This paper analyzes the effects of intercity bus suspension system oscillatory parameters on driver’s ride comfort and road damage. The analysis has been carried out through simulation by means of validated in-plane bus model with six degrees of freedom ex-cited by real road roughness signal. Low root-mean-square values of the weighted vertical acceleration (less than 0.315 m/s²) have been achieved by shock-absorbers with lower damping coefficient and softer suspension system springs. Low values of dynamic load coefficient provide low shock-absorber damping and softer springs. However, low crest factor values for both axles are accomplished for high shock-absorber damping and softer springs in bus suspension system. Results from this analysis could be used as reference for selecting proper oscillatory parameter values when designing road-friendly bus suspension system which in turn would increase vehicle energy efficiency. Presented methods, results and analyzes are the part of wider methodology for assessing the impact of bus suspension system on fuel consumption and CO2 emission. [ABSTRACT FROM AUTHOR]

This paper analyses the effect of the waviness parameter w on the oscillatory comfort of bus passengers for one road in good condition. The analysis is carried out by a validated nonlinear oscillatory 16 degrees of freedom (DOF) bus model defined in the software Matlab/Simulink and procedure from ISO 2631/1997 standard. The root-mean-square (RMS) values of the weighted vertical accelerations from the passengers' seats increase with the increase in the parameter w. On the other hand, the RMS values of the weighted vertical accelerations from bus floor decreased with the increase in the parameter w. The best oscillatory comfort has a passenger in the middle part of the bus, and the worst has a passenger in the rear part of the bus. The intensities of the vertical accelerations from the bus floor are mainly concentrated into two frequency ranges, 0 ÷ 2:5 Hz and 5 ÷ 10 Hz. The passenger seats are dampened with vertical vibrations above 4 Hz. For the narrow range w = 1:5÷2:3, nominal value of the waviness parameter (w = 2) is sufficiently precise in assessment of the bus passengers' oscillatory comfort. [ABSTRACT FROM AUTHOR]

Within the transport sector, road transport is the largest source of Carbon Dioxide (CO2) emissions. Greater use of vehicles that run on clean alternative fuels can contribute to reduce CO2 emissions. This paper gives special attention to the Compressed Natural Gas (CNG) buses and their comparison with conventional diesel buses, which in countries such as Serbia have a dominant share. Justification of using CNG buses in order to mitigate climate changes is measured by realised annual and average external costs of CO2 emissions. These external costs provide a basis for future use of economic instruments by which negative impacts of transport on the environment can be limited. Research of CO2 emissions and external costs of CO2 emissions in intercity bus service was conducted for three technical-technological concepts of CNG buses in comparison to the two types of conventional diesel buses. Analysis was carried out according to four various scenarios that define different operating conditions on the road network of the Serbia. Obtained results show that CNG buses reduce annual external costs of CO2 emissions by 2...24% compared to conventional diesel buses. Obtained average external costs of CO2 emissions per 100 bus-kms show to what extent their changes are a result of changes of external costs of CO2 emissions and to what extent they are due to changes of operating conditions on the road network. [ABSTRACT FROM AUTHOR]

The paper deals with classification and basic characteristics of vibration that act on users during bus exploitation. Some physiological and psychological effects of vibration acting on bus drivers and passengers are presented. In addition, this paper shows the results of evaluation of vibration effects on the users' comfort (the driver and three passengers) for intercity bus IK-301. Evaluation has been carried out according to the procedure and criteria prescribed by two versions of International standard ISO 2631 (1985, 1997). For the purpose of this analysis, validated bus oscillatory model developed in multibody software packageADAMS/Viewwas used. The oscillatory model was excited by road roughness (asphalt-concrete pavement in poor condition) registered on two tracks at speed of 64 km/h. It was found that the passenger seating on the seat in the bus rear overhang has the worst comfort and the shortest allowable vibration exposure time. [ABSTRACT FROM AUTHOR]

The effects of spring stiffness and shock absorber damping on the vertical acceleration of the driver's body, suspension deformation and dynamic wheel load were investigated, with the purpose to define recommendations for selecting oscillation parameters while designing the suspension system of a (intercity) bus. Oscillatory responses were analysed by means of a bus oscillatory model with linear characteristics and three degrees of freedom, with excitation by the Power Spectral Density (PSD) of the roughness of asphalt-concrete pavement in good condition. The analysis was conducted through a simulation, in frequency domain, using statistical dynamics equations. A programme created in the software pack MATLAB was used to analyse the transfer functions, spectral density and RMS of oscillatory parameters. The results of the analysis show that the parameters which ensured good oscillatory comfort of the driver were conflicting with the parameters which ensured the greatest stability of the bus and the corresponding wheel travel. In terms of the driver's oscillatory comfort, the bus suspension system should have a spring of small stiffness and a shock absorber with a low damping coefficient. In terms of active safety, it should have a spring of small stiffness and a shock absorber with a high damping coefficient, while minimum wheel motion requests for springs of great stiffness and shock absorbers with a high damping coefficient. [ABSTRACT FROM AUTHOR]