Predictive Values of Transcutaneous Oxygen Tension for Above-the-ankle Amputation in Diabetic Patients with Critical Limb Ischemia

ObjectiveTo assess the values of transcutaneous oxygen tension (TcPO2) capable of predicting above-the-ankle amputation in diabetic patients diagnosed for critical limb ischemia (CLI) according to the criteria of the TransAtlantic Inter-Society Consensus.DesignRetrospective study.MethodsFrom January 1999 to December 2003, 564 diabetic patients were consecutively hospitalized for CLI in one limb. Revascularization with angioplasty or bypass graft was performed when possible and, if not possible, prostanoid therapy was used. In patients in whom therapies did not relieve the rest pain or the gangrene was extended above the Chopart joint, an above-the-ankle-amputation was performed. After treatment TcPO2 values were evaluated in all patients at the dorsum of the foot.ResultsFifty-five (9.8%) patients underwent an above-the-ankle amputation: 22 of 420 patients who underwent angioplasty, 17 of 117 patients who underwent bypass (14.5%) and 16 of 27 patients in whom revascularization was not possible. Post-treatment TcPO2, measured by a receiver operating characteristic (ROC) curve, showed a value 34mmHg as the best threshold for determining the need for revascularization, with an area under the curve of 0.89 (95%CI 0.85–0.94).Using logistic regression analysis the probability of above-the-ankle amputation for this threshold is 9.7% and reduces to 3% for TcPO2>40mmHg.ConclusionTcPO2 levels<34mmHg indicate the need for revascularization, while for values ≥ 34<40mmHg this need appears less pressing, although there remains a considerable probability of amputation. TcPO2 levels greater than 40mmHg suggest that revascularization is dependent on the severity of tissue loss and possible morbidity caused by the procedure

Long-Term Prognosis of Diabetic Patients With Critical Limb Ischemia: A population-based cohort study

OBJECTIVE\u2014 To evaluate the long-term prognosis of critical limb ischemia (CLI) in diabetic patients. RESEARCH DESIGN AND METHODS\u2014 A total of 564 consecutive diabetic patients were hospitalized for CLI from January 1999 to December 2003; 554 were followed until December 2007. RESULTS\u2014 The mean follow-up was 5.93 1.28 years. Peripheral angioplasty (PTA) was performed in 420 (74.5%) and bypass graft (BPG) in 117 (20.6%) patients. Neither PTA nor BPG were possible in 27 (4.9%) patients. Major amputations were performed in 74 (13.4%) patients: 34 (8.2%) in PTA, 24 (21.1%) in BPG, and 16 (59.2%) in a group that received no revascularization. Restenosis occurred in 94 patients, bypass failures in 36 patients, and recurrent ulcers in 71 patients. CLI was observed in the contralateral limb of 225 (39.9%) patients; of these, 15 (6.7%) required major amputations (rate in contralateral compared with initial limb, P 0.007). At total of 276 (49.82%) patients died. The Cox model showed significant hazard ratios (HRs) for mortality with age (1.05 for 1 year [95% CI 1.03\u20131.07]), unfeasible revascularization (3.06 [1.40\u20136.70]), dialysis (3.00 [1.63\u20135.53]), cardiac disease history (1.37 [1.05\u20131.79]), and impaired ejection fraction (1.08 for 1% point [1.05\u20131.09]). CONCLUSIONS\u2014 Diabetic patients with CLI have high risks of amputation and death. In a dedicated diabetic foot center, the major amputation, ulcer recurrence, and major contralateral limb amputation rates were low. Coronary artery disease (CAD) is the leading cause of death, and in patients with CAD history the impaired ejection fraction is the major independent prognostic factor

Advantages of myocardial revascularization after admission for critical limb ischemia in diabetic patients with coronary artery disease : data of a cohort of 564 consecutive patients

AIM: To evaluate the survival benefit from myocardial revascularization in diabetic patients with critical limb ischemia and coronary artery disease (CAD) in a consecutive series of 564 diabetic patients hospitalized from 1999 to 2003 and followed up until December 2005. METHODS: Three hundred and thirteen patients had a history of CAD, 60 of them (19.2%) with previous myocardial revascularization. Sixty-one patients with an ejection fraction of 40% or less underwent subsequent myocardial revascularization. Five hundred and fifty-seven patients (98.8%) were followed up until December 2005, including 310 of the 313 patients with a history of CAD. RESULTS: One hundred and ten patients died because of CAD, 25 of the 251 patients without a history of CAD and 85 of the 313 patients with a history of CAD. Specifically, 74 (86.9%) of these 85 deaths occurred in the 192 patients without previous myocardial revascularization, nine (10.7%) in the 60 patients with previous myocardial revascularization, and two (2.4%) in the 61 patients in whom myocardial revascularization was performed after hospital admission for critical limb ischemia. The Cox model showed significant hazard ratio for mortality associated with age [hazard ratio 1.06 for 1 year, P = 0.003, confidence interval (CI) 1.02-1.09], history of CAD (hazard ratio 2.16, P < 0.001, CI 1.53-3.06), dialysis (hazard ratio 3.52, P < 0.001, CI 2.08-5.97), and impaired ejection fraction (hazard ratio 1.08 for one point percentage, P < 0.001, CI 1.05-1.09). Myocardial revascularization appeared to have a protective role: hazard ratio 0.29, P < 0.001, CI 0.33-0.93. CONCLUSION: Paying attention to CAD in diabetic patients during their hospitalization for critical limb ischemia is useful for a subsequent myocardial revascularization, and it may increase survival in these patient

The role of early surgical debridement and revascularization in patients with diabetes and deep foot space abscess : retrospective review of 106 patients with diabetes

One hundred-six patients underwent emergency debridement of a deep foot space abscess. While 43 patients were admitted after an outpatient visit with immediate surgical debridement (group A), 63 patients were transferred from other hospitals after a mean stay of 6.2 \ub1 7.5 days without debridement (group B). No significant differences were observed in the demographic and clinical features between the 2 groups, except for the following differences in group B: higher blood glucose level on admission (P = .015), lower serum albumin level (P = .005), and a more frequent extension of the infection to the heel (P = .005). Eradication of the infection was obtained in group A without amputation in 9 patients, with an amputation of 1 or more rays in 21, with metatarsal amputations in 12, and with a Chopart amputation in 1. In group B, incision and drainage alone were performed in 4 patients, amputation of 1 or more rays in 21, metatarsal amputations in 10, Chopart amputations in 23, and an above-the-ankle amputation in 5. The amputation level was significantly more proximal in group B (\u3c7 2 = 24.4, P < .001). There was no significant difference in the presence of peripheral arterial occlusive disease between the 2 groups (P = .841). Regression logistic analysis showed a significant relationship between the amputation level and the number of days elapsed before debridement (odds ratio, 1.61; P = .015; confidence interval, 1.10-2.36), but not with the presence of peripheral occlusive disease (odds ratio, 1.73; P = .376; confidence interval, 0.29-15.3). These data show that a delay in the surgical debridement of a deep space abscess increases the amputation level. Accuracy in the diagnosis of peripheral occlusive disease and immediate revascularization yield similar outcomes in patients with or without peripheral occlusive disease

Incidence of critical limb ischemia and amputation outcome in contralateral limb in diabetic patients hospitalized for unilateral critical limb ischemia during 1999-2003 and followed-up until 2005

We studied the incidence of critical limb ischemia (CLI) and amputation outcome of the contralateral limb in 533 diabetic patients hospitalized in our diabetic foot centre because of CLI from 1999 to 2003 and followed-up until 2005. The cumulative incidence rate during the 6-year period reached 49.8% (CI confidence interval=40.6-59.6). All patients underwent arteriography and in 181 (98.4%) the revascularization was performed without different feasibility (p=0.077) compared to that (95.3%) in the initial patients. The severity of lesion evaluated with Wagner grade was lower (chi(2)=33.5, p<0.001) and also the frequency of midfoot and above-the-ankle amputations was lower (p<0.001 and p=0.022, respectively) in contralateral patients. There was no evidence from the logistic analysis to support the association between any of the investigated variables and incidence of CLI in the contralateral limb. Over a 6-year period, almost 50% of the diabetic patients with unilateral CLI developed a CLI in the contralateral limb: however, both severity of foot lesion and amputation level was significantly lower. This fact can be due to prompt therapeutic interventions, made possible thanks to an increased patient awareness acquired by training during the treatment of the unilateral limb

Normal zone propagation in a MgB2 conduction cooled test magnet

In order to investigate the quench behavior of conduction cooled magnets, a 100 mm inner bore diameter, 0.84 T at 20 K magnet has been built and tested. The test magnet consists of 4 double pancakes wound with the tape produced by Columbus. Each coil is cooled by means of a 2 mm thick copper disk placed during winding at the middle of the double pancake; after winding the double pancakes have been separately epoxy impregnated. Several experiments have been per- formed inducing a local transition in the coil by means of a con- trolled heater placed on the double pancake surface. The propagation of the normal zone has been monitored by means of 8 voltage probes positioned along the tape during coil manufacturing. Each voltage probe detects the voltage drop across a tape length of 30 mm. The experiments have been performed at different temperatures while keeping the magnet current constant during quench. In the paper we report an analysis of the quench propagation velocity measurements and a numerical investigation of the thermal and electrical behavior of the magnet

Design and Test of a Compound Persistent-Pulsed Magnet for Fast Field Cycling NMR

In order to investigate the possibility of using superconducting magnets for Fast Field Cycling (FFC) NMR Relaxometry, a NbTi magnet able to achieve high field variation rates in a constant background field has been designed and tested. The design layout consists in an outer superconducting magnet working in persistent mode and an inner superconducting magnet working in pulsed mode. The layout of the inner magnet has been optimized taking into account field strength, field homogeneity, stray field and inductive coupling with outer magnet. A demonstration pulsed magnet has been tested in a background field, achieving the main desired working features

Performance Evaluation for a HTS Transformer

The adoption of High Temperature Superconductors (HTS) tapes is becoming a suitable and interesting alternative to copper for windings in transformers, thanks to the improvement in performance and the lowering of costs. Of course, optimized designs, different with respect to usual layouts, must be considered, due to the additional requirements of HTS tapes, such as minimization of orthogonal magnetic fields and consideration of additional losses in the HTS. In the framework of a scientific cooperation among some Italian Universities and private companies, a test model for a 10KVA transformer with HTS secondary windings has been developed, and validated against a demonstrative prototype, manufactured during the project. In the paper, the device model performance is assessed, with particular care to the HTS losses modeling, and some comparisons to the experimental results are presented

HIGH DENSITY MgB2 BULK MATERIALS OF DIFFERENT GRAINS SIZE: SUPERCURRENTS INSTABILITY AND LOSSES IN VARIABLE MAGNETIC FIELDS

The bulkMgB2 material shows very promising characteristics to be applied in many AC devices, i.e. as electric motors, as magnetic field screening apparatus or as variable inductor or resistor for Fault Current Limitation. In all these cases the evaluation of supercurrents persistency and of the AC losses represents the first practical issue to be addressed. We report on the evaluation of these characteristics on very high densityMgB2 bulk materials, obtained by reactive liquid Mg infiltration of Boron powders preform. Varying the granularity of the original Boron powders, bulks of very different grains size distribution are produced that show different current carrying capability in magnetic field and temperature, indicating a different flux structure and dynamics. Performing AC susceptibility analysis in the low frequency range, the losses have been evaluated on several shapes of the probe materials from the cylindrical one to the slab one type and for several temperatures below Tc. For ring type samples the screening effect of the superconducting currents has been evaluated, in presence of static and variable magnetic fields. The results have been interpreted in term of the critical state model, evidencing the large effects of the thermal instability erasing from the thickness of the samples