28 research outputs found
Autologous deep vein reconstruction of infected thoracoabdominal aortic patch graft
No full textGraft infection remains a serious complication of prosthetic aortic repair. Infection of thoracoabdominal aortic prosthetic grafts, in particular, is a significant clinical challenge and is associated with high mortality. We report successful in situ reconstruction of an infected thoracoabdominal aortic prosthetic patch graft with autogenous superficial femoral vein. To our knowledge, this is the first such case described in the North American and English language surgical literature. At 24-month follow-up the patient remains well, with no evidence of sepsis or graft complication at clinical and radiologic assessment
Prediction of outcome after abdominal aortic aneurysm rupture
No full textMost vascular surgeons practice a selective policy of operative intervention for patients with ruptured abdominal aortic aneurysm (AAA). The evidence on which to justify operative selection remains uncertain. This review examines the prediction of outcome after attempted open repair of ruptured AAA
Ruptured inflammatory abdominal aortic aneurysm: insights in clinical management and outcome
No full textAbstractBackgroundRuptured inflammatory abdominal aortic aneurysm (AAA) is relatively rare, and little has been written on the outcome of operative treatment.MethodsPatients undergoing attempted repair of ruptured inflammatory AAA between 1995 and 2001 were included in a retrospective case-cohort study. Demographic, clinical, and operative factors were analyzed, together with in-hospital morbidity, in-hospital mortality, and duration of postoperative hospital stay.ResultsOf 297 patients who underwent attempted operative repair of ruptured AAA, 24 (8%) had an inflammatory aneurysm. Twenty-two patients were men, and two were women; median age was 69 years (range, 51-85 years). Operative findings revealed a contained hematoma in 16 patients (70%), free rupture in 3 patients (13%), aortocaval fistula in 4 patients (17%), and aortoenteric fistula in 1 patient (4%). Of 273 noninflammatory ruptured AAAs, only 2 AAA (1%) were associated with primary aortic fistula. Ten patients (42%) with inflammatory AAA died in hospital, compared with 117 of 273 patients (43%) without inflammation. Median postoperative stay was 10 days (range, 0-35 days). Of the 14 patients with inflammatory lesions who survived, 11 had postoperative complications; 4 patients had acute renal failure, three of whom required temporary renal replacement therapy.ConclusionsRuptured inflammatory AAA is associated with a higher incidence of aortic fistula than is ruptured noninflammatory AAA. Repair of ruptured inflammatory AAA is not associated with increased operative mortality compared with repair of ruptured noninflammatory AAA
Regarding “Prediction of 30-day mortality after endovascular repair or open surgery in patients with ruptured abdominal aortic aneurysms”
No full textRegarding “Derivation and validation of a practical risk score for prediction of mortality after open repair of ruptured abdominal aortic aneurysms in a U.S. regional cohort and comparison to existing scoring systems”
No full textFunctional outcome after open repair of ruptured abdominal aortic aneurysm
No full textBackgroundOutcome after operative repair of ruptured abdominal aortic aneurysm (AAA) has traditionally been assessed in terms of survival. This study examines the functional outcome of patients who survive operation.MethodsConsecutive patients who survived open repair over an 18-month period were entered into a prospective case-control study. Age- and sex-matched controls were identified from patients undergoing elective AAA repair. The Short Form-36 health survey was administered to both groups of patients at 6 months after operation. Results were compared with the expected scores for an age- and sex-matched normal UK population.ResultsFifty-seven patients underwent open repair of a ruptured AAA, and 30 survived; no patient was lost to follow-up. There were no significant differences in quality of life between patients who had an emergency repair and those who had an elective repair. Both of these groups had poorer health-related quality of life outcomes than the matched normal population. Surprisingly, compared with the normal population, patients after elective repair had poorer outcomes in more health domains than patients who survived emergency operation.ConclusionsSurvivors of ruptured AAA repair have a good functional outcome within 6 months of operation
Prognostic scoring in ruptured abdominal aortic aneurysm: A prospective evaluation
No full textBackgroundProspective validation of prognostic scoring systems for ruptured abdominal aortic aneurysm (AAA) is lacking. This study assesses the validity of three established risk scores and a new prognostic index.MethodPatients admitted with ruptured AAA during a 26-month period (August 2002-December 2004) were recruited prospectively. The Glasgow Aneurysm Score (GAS), Hardman Index, Physiological and Operative Severity Score for enUmeration of Mortality and Morbidity (POSSUM) scores, and the Edinburgh Ruptured Aneurysm Score (ERAS) were recorded and related to outcome.ResultsDuring the study period, 111 patients were admitted with ruptured AAA. Of these, 84 (76%) underwent attempted operative repair and were included in the study; 37 (44%) died after operation. The GAS, Hardman Index, and the ERAS were statistically related to mortality. However, analysis by receiver-operator characteristic curve revealed the ERAS to have an area under the curve (AUC) of 0.72 (95% confidence interval [CI], 0.61-0.83). The vascular (V)-POSSUM and ruptured AAA (RAAA)-POSSUM models had an AUC of 0.70 (95% CI, 0.59-0.82). The Hardman Index and GAS had an AUC of 0.69 (95% CI, 0.57-0.80) and 0.64 (95% CI, 0.52-0.76), respectively. Although the V-POSSUM equation predicted mortality effectively (P = .086), the RAAA-POSSUM derivative demonstrated a significant lack of fit (P = .009).ConclusionProspective validation shows that the Hardman Index, GAS, and V-POSSUM and RAAA-POSSUM scores do not perform well as predictors for death after ruptured AAA. The ERAS accurately stratifies perioperative risk but requires further validation
Fibrinogen Concentrate Therapy Guided by Thromboelastometry as an Alternative to Fresh Frozen Plasma in Major Vascular Surgery
No full textNumerical Investigations of Air Flow and Heat Transfer in Axial Flux Permanent Magnet Electrical Machines
No full textIn this study an investigation of heat transfer in air cooled Axial Flux Permanent Magnet (AFPM) electrical machines is carried out. Efficiency of electrical machines is strongly influenced by an effective cooling which is provided by forced convection: air enters the generator through the opening in the machine enclosure and leaves it radially, as it is forced out by the rotating discs. The main goal is the enhancement of the heat transfer from the stator where heat is generated in the copper windings. On the other hand the heat transfer to the rotor needs to be minimised in order to keep the magnets' temperature as low as possible.
The cooling can be improved by acting on design parameters, such as the distance between the stator and the rotors (commonly named running clearance), the magnet depth, and by acting on operational parameters, such as the rotational speed.
The investigation is carried out by using Computational Fluid Dynamics (CFD) software to model air flow and heat transfer inside the AFPM machines. The experimental validation of the numerical models confirmed the capability of the CFD software in predicting the air mass flow rate and the heat transfer in the AFPM machines.
The thesis describes the effects of the above mentioned parameters on target quantities, such as the heat transfer coefficients on the generator surfaces, the air mass flow rate through the machine, and the resistive torque.
General correlations in non-dimensional form are obtained for the calculation of the heat transfer on the generator surfaces in the AFPM machines as a function of the above parameters. General correlations have also been obtained for the calculations of the non-dimensional air mass flow rate through the machine and for the non-dimensional resistive torque.
It was found that the corresponding relationships between the peripheral Reynolds number and local Nusselt numbers on the generator surfaces and the non-dimensional mass flow rate are linear. However, the dependency of Nusselt number on the non dimensional clearance and the magnet depth is non-linear.
For the investigated range of the parameters the following was established: an increase in the peripheral Reynolds number results in higher Nusselt number on both the rotating and stationary surfaces of machines; an increase in the running clearance results in the reduction of the Nusselt number on the machine surfaces; the magnetic segments installed on the surface of the flat rotor act as blades of a radial compressor increasing the air mass flow rate and the corresponding Nusselt number on the stator surface.
The combination of the non-dimensional running clearance equal to 9 10-3 and the non-dimensional magnet depth equal to 7.3 10-2 was found to be the one which provides the maximum heat transfer from the stator. This piece of information can be used in the design stage for improving the cooling of AFPM electrical machines without increasing the windage losses and contribute in this way to the enhancement of the overall efficiency of this type of machines
