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Biomedical subjects

G Torsello

Publications and source records attributed to G Torsello.

At least 19 recordsLinked to original sources

The origin of highly efficient selective emission in rare-earth oxides for thermophotovoltaic applications.

Rare-earth oxide materials emit thermal radiation in a narrow spectral region, and can be used for a variety of different high-temperature applications, such as the generation of electricity by thermophotovoltaic conversion of thermal radiation. However, because a detailed understanding of the mechanism of selective emission from rare-earth atoms has so far been missing, attempts to engineer selective emitters have relied mainly on empirical approaches. In this work, we present a new quantum thermodynamic model to describe the mechanisms of thermal pumping and radiative de-excitation in rare-earth oxide materials. By evaluating the effects of the local crystal-field symmetry around a rare-earth ion, this model clearly explains how and why only some of the room-temperature absorption peaks give rise to highly efficient emission bands at high temperature (1,000-1,500 degrees C). High-temperature emissivity measurements along with photoluminescence and cathodoluminescence results confirm the predictions of the theory.

Computer Simulation↗

[Treatment of aortic aneurysm with a complete percutaneous technique].

BACKGROUND AND OBJECTIVE: The treatment of aortic aneurysms is achievable also without laparotomy. With a special technique it is now possible to perform the endovascular aneurysm repair totally percutaneous using an endovascular suture device. With the purpose to reduce the invasiveness of the treatment of abdominal aneurysms, the new technique was used also during procedures requiring large bore devices up to 14-27F. The aim of this retrospective study was to report on results after performing the new technique in 80 patients and on the benefits and limits of its use. PATIENTS AND METHODS: From 1.10.1999 to 31.12.2001, 102 patients with aneurysm disease were treated by endovascular techniques. In 80 cases (68 men, 12 women; mean age 71.3 years) a completely percutaneous procedure was planned. The diameter of the introducer sheaths was 18-27F for the main body of the stent-graft and 14-18F for the contralateral limb. Most patients were operated under spinal anesthesia. Postoperative control included complete physical examination and duplex ultrasound scans. RESULTS: In 5 of 80 cases the implantation of the endograft could not be performed percutaneously. In 5 of 145 femoral arteries (3.4 %) effective hemostasis could not be achieved. Complications requiring surgery (two pseudoaneurysms, two arterial occlusions) occurred in 4 cases (2.8 %). By duplex ultrasound normal findings were detected in the remaining 136 cases (93,8 %). In 68 of 80 treated patients (85 %) complete percutaneous technique was successful. CONCLUSIONS: Using the preclose-technique it was possible to suture the artery even after using large bore introducer sheaths without cut down. Patient selection, exact puncture technique and accurate use of the device are important factors for success. The technological improvement of the arterial closure devices will allow a more frequent use of the percutaneous technique for aneurysm repair in the future.

Aged↗

[Aneurysm treatment with the "Talent stent graft". An update after 4 years of experience].

INTRODUCTION: The negative experience with stent grafts of the first generation shows the important role of the endograft in the treatment of abdominal aortic aneurysm. The midterm results of a stent graft (Talent) widely used in Germany were analyzed up to 4 years after the first implantation. PATIENTS AND METHODS: We report on 73 patients treated at our department using the Talent stent graft. The study analyzes patient data before, during, and after the operation as well as the results of clinical follow-up and CT scan examinations performed 3-47 months after treatment. RESULTS: In 72 cases the implantation was successful. Endoleaks were found in three cases (type I n = 2, type III n = 1). Three patients had a complication at the vascular access site (3.9%). In one patient the short contralateral leg did not open. During the follow-up five patients died (7%). In two patients the graft limb occluded (3.3%). A migration of the graft components did not occur. In two cases a persistent type II endoleak was found (3.3%). CONCLUSIONS: The Talent stent graft showed good stability and easy adjustment. Even patients with a large aneurysm neck have been successfully treated. Problems while implanting the graft were only observed in cases of kinking of the iliac artery. A greater flexibility of the introducer system and a better rotational stability of the graft inside the introducer would be advisable.

Aged↗

Systemic and local antibiotic prophylaxis in the prevention of prosthetic vascular graft infection: an experimental study.

AIM: to determine if local, in addition to systemic antibiotic prophylaxis (compared to that provided by systemic prophylaxis alone) provides additional benefit in terms of reducing graft infection. METHODS: gelatin-sealed Dacron grafts were interposed in the infrarenal aorta of 36 mongrels and inoculated with 1 ml of a S. aureus suspension. Group 1 (control group) received no prophylaxis and were inoculated with 1 ml containing 10(9)cfu/ml. Group 2 (n=6) received systemic prophylaxis (1 g cephamandole) and were inoculated with 10(5) cfu/ml (n=3) or 10(7) cfu/ml (n=3). Group 3 received systemic prophylaxis (1 g cephamandole) and were inoculated with 109 cfu/ml. Group 4 received systemic prophylaxis (2 g cephamandole) and were inoculated with 10(9)cfu/ml. In group 5 and 6 grafts were soaked in a rifampicin solution before use and inoculated with 10(9) cfu/ml. Group 5 received no systemic prophylaxis and group 6 received systemic prophylaxis (1 g cephamandole). Grafts were harvested at 2 weeks, and peritonitis, perigraft abscess, anastomotic disruption and graft occlusion recorded. Swabs were taken of the graft, the perigraft tissues and the peritoneal fluid. Graft segments were incubated in broth medium. RESULTS: inoculation with 10(9) cfu/ml ensured graft infection. Systemic or local prophylaxis alone failed to prevent graft infection. Only systemic and local antibiotic prophylaxis provided significant better results than no prophylaxis at all (p<0.01) and local prophylaxis alone (p<0.05). However, total "graft sterility" was not achieved as bacteriologic analysis of the graft segments showed low bacterial counts (<10 bacteria/graft) in 5 of 6 grafts. CONCLUSION: local and systemic prophylaxis provided more protection as demonstrated by the significant decrease in the incidence of "overt" graft infection. Total "graft sterility" cannot be expected in the case of an overwhelming bacterial challenge.

Animals↗

[First experiences with clinical pathways in carotid surgery].

The introduction of guidelines for carotid surgery into praxis. Early experiences with the clinical pathway. With the use of DRG's for reimbursements, a new organization of clinical pathways may play an increasingly important role in the delivery of health care. The impact of clinical pathways as a management tool in the treatment of patients with carotid occlusive disease was studied. Representatives of all involved disciplines identified in which sequence, where, when, by whom and which care a patient with carotid disease should receive. The individual steps of care were analysed, estimating their utility and determining a new plan for a patient's care. The clinical pathway specifies a target time window, defining exactly the internal and external logistics. The early experiences demonstrate that clinical pathways can be a useful tool for improving the quality of health care by improving cost and process transparency. Hospital length of stay was reduced by 2.3 days.

Carotid Stenosis↗

[How competence are Germany's carotid surgeons. Evaluation after 15,000 interventions].

With the aim of assuring the quality of surgical treatment of carotid stenoses--also in conformity with legal requirements--the German Vascular Society (DGG) has established the recording of surgical data of patients prior to, during and following carotid reconstructive procedures. Since its inception, the data from 158 centers covering 15,116 interventions are now available. In comparison with data in the literature, the rate of severe post-operative neurological deficits was found to be only 1.9%, and the mortality rate 1%. Statistical analysis has shown that the risks of morbidity and mortality depend on the patient's risk profile and on the nature and morphology of the carotid lesion.

Carotid Stenosis↗

[Solitary metastasis of a clear cell renal cell carcinoma after a 20 year latency clinically simulating a vascular tumor].

HISTORY AND CLINICAL FINDINGS: A 72-year-old woman was referred because of progressive skin discoloration with venectasia and swelling in the left lower leg, the possible diagnosis being atypical varicose veins. 20 years before she had a right nephrectomy for "clear-cell" renal adenocarcinoma with subsequent tele-cobalt radiotherapy. On examination a pulsating swelling was palpated over the hyperpigmented area of the skin with venectasia. INVESTIGATIONS: She had hypercholesterolaemia (254 mg/dl) and hyperuricaemia (uric acid 6.2 mg/dl). Duplex sonography, angiography and computed tomography of the lower leg revealed a vascular tumour with infiltration of the right head of the gastrocnemius. DIAGNOSIS, TREATMENT AND COURSE: Because an arteriovenous fistula within a vascular soft-tissue tumour of unknown histology was suspected, a wide resection was performed. Histopathological examination revealed a metastasis of a clear-cell adenocarcinoma. Postoperative diagnostic tests discovered no other findings suspicious of malignancy. It is therefore to be assumed that the resected tumour was a solitary metastasis of the renal adenocarcinoma removed 20 years previously. CONCLUSION: Even rare causes should be considered in the differential diagnosis of vascular tumour, as this case of a solitary metastasis after a latency of 20 years demonstrates.

Adenocarcinoma, Clear Cell↗

[Ipsilateral pneumothorax in one-lung respiration. A rare, recently diagnosed and atypical complication of a double lumen tube].

The authors report a rare, recently diagnosed and atypical mishap during one-lung ventilation (OLV) via a double lumen tube (DLT) and left-sided thoracotomy: an ipsilateral pneumothorax during ventilation of the right lung. This occurred in a 63-year-old patient with chronic obstructive airway disease who was scheduled for urgent repair of a descending thoracic aortic aneurysm. Anaesthesia and surgery were uneventful until aortic cross-clamping release. The common presentation of increased intrathoracic extrapleural pressure owing to a pneumothorax in patients with mechanically ventilated lungs is a rapid decrease in oxygen saturation, followed or paralleled by haemodynamic deterioration. Although the above presentation could be seen in this case, the diagnosis of a tension pneumothorax was delayed twice. First, symptoms were initially obscured by haemodynamic changes resulting from a head-down tilt and aortic declamping. Second, since the lack of consolidation after aortic declamping focused attention on the airway problems, complications resulting from the use of a DLT were primarily considered. In particular, since breathing sounds were detectable initially, malposition or torsion of the DLT had to be excluded by fibre-optic bronchoscopy, which involved a further delay. Finally, two observations led to the diagnosis of a right-sided tension pneumothorax: (1) bullae of the contralateral lung, detected during thoracotomy; (2) the finding that ventilation of both lungs and the left lung subsequently increased arterial (SaO2) and mixed venous oxygen saturation (SvO2) and the circulatory status, but ventilation of the right lung caused a deterioration. Chest radiography and insertion of a chest tube with drainage of air, thereafter, validated our hypothesis. The time course of oxygen desaturation during OLV and tension pneumothorax was as severe as expected; the time course of haemodynamic deterioration, however, appeared quicker and had more impact than expected. Assuming that mediastinal deviation was not hindered by contralateral intrathoracic pressure during thoracotomy, we believed that circulation should be depressed later or to a lesser extent in patients with an intraoperative pneumothorax. Yet, during thoracotomy, decrease in cardiac filling and output during tension pneumothorax in OLV obviously results primarily from the immovability of the mediastinum owing to mediastinal fixation and is at least as decisive as the contralateral intrathoracic pressure in closed-chest patients. In summary, a tension pneumothorax during one-lung ventilation and thoracotomy is a rare, but disastrous complication during the use of a DLT, which has not, to our knowledge, been reported previously. We recommend that tension pneumothorax be added to the list of complications and problems during OLV by the use of a DLT, especially in patients with structural lung diseases.

Anesthesia↗

[Acute compartment syndrome of the tibia--complication of popliteal artery aneurysm].

The compartment syndrome is a common complication in the traumatology of the lower limb. In vascular surgery it is observed following emergency revascularisation. It is a rare condition as an initial symptom of a peripheral clotted aneurysm. By means of a case with a complicated popliteal aneurysm the differential diagnosis of the non-traumatologic compartment syndrome is discussed.

Adult↗

Acute blockage of the renin system and differential renal vein renin determinations in the diagnosis of renovascular hypertension.

For validation of differential renal vein renin determinations in the diagnosis of renovascular hypertension (RVH), we investigated 102 patients suspected of suffering from RVH before and 1 h after administration of 25 mg captopril. Sensitivity, specificity and posterior probability for renin ratio (RR) and renin secretion (RS) were calculated based on 44 patients with proven RVH and 58 patients with primary hypertension (PH) using discriminant analysis. There is good (> 95%) and identical specificity of both variables under all conditions, whereas sensitivity remains poor even after Captopril administration (RR 23% vs. 32%; RS 20% vs. 34%). The posterior probabilities obtained by discriminant analysis revealed a cut-off point of 2.5 for the renin ratio and of 1.9 for the renin secretion. No change is observed after ACE inhibition. We conclude that the acute blockade of the renin system by captopril in differential renin sampling yields no advantages in diagnosing RVH and that there is no difference between RR and RS in the diagnosis of RVH.

Adult↗

[Infection of a vascular prosthesis--a retrospective analysis of 99 cases].

From January 1, 1980 to December 31, 1992, 7970 vascular prostheses have been implanted at the Department for Vascular Surgery and Kidney Transplantation of the University of Düsseldorf. In the same period of time, 99 patients had to be reoperated for (type Szilagyi III [14]) graft infection (1,2%), out of which 70 patients have had their previous operation in our institution (0,9%). The infection became apparent within 30 days in 14 cases, within one year in 54 cases, and in 31 cases within a maximum of 8 years postoperatively. Localisation of the infection was the groin in 70 patients, abdominal aortic prostheses were involved in 16, crural or extraanatomic prostheses in 13 cases. Treatment consisted in most cases of axillofemoral bypass (n = 23) and obturator-bypass (n = 21). In-situ-implantation of vascular prostheses was performed in 8 cases, 4 of these prostheses were intraoperatively soaked with an antibiotic. 47 patients had various reconstructions, such as cross-over bypasses, atypical reconstructions or local treatment. Postoperatively 27 amputations were necessary. 30-days mortality rate was 12%. At the end of the follow-up (May 1994) we found a 54% total mortality rate (mean follow-up: 4.6 +/- 4.59 years). Main cause of death in the first year was sepsis. In only 67% of patients discharged from hospital, the peripheral arterial conditions were described as "good" by angiography, ankle-brachial index or clinical examination. We conclude, that vascular graft sepsis threatens the patient in the early phase because of limb loss or death, and during the first year after the operation for the sequelae of sepsis or recurrence. Revascularisation with antibiotic-soaked grafts in a limited number of cases showed good results in preserving limbs and lives of our patients. Future experience will show, whether antibiotic-soaked grafts should be used more generously in vascular surgery.

Adult↗

[Intraoperative quality control after vascular surgery reconstruction of kidney and visceral arteries: personal experiences with intraoperative angioscopy].

Angioscopy was applied as a way of intra-operative assessment after surgical reconstruction of renal and visceral arteries in 15 patients. Angioscopy resulted in relevant findings, which in part, demanded immediate intra-operative consequences. Angioscopy turned out to be a sensitive way of surveillance, the findings were easy to interpret.

Angioscopy↗

[Surgical treatment of thoraco-abdominal aneurysm. Indications and results].

Aortic replacement for thoraco-abdominal aneurysms remains a major challenge in vascular surgery. Related symptoms, maximal diameter > 6 cm, progression, aneurysm sac containing none or excentric thrombi and uncontrollable hypertension are factors in favour of surgery, if the general condition of the patient allows the operation. Patients with aneurysms < 5 cm maximal diameter, tube-size aneurysms, heavy calcification of the aortic wall, concentric thrombi within the aneurysmal sac and significant cardiopulmonary risks should be treated conservatively. Patients in good general condition with aneurysms around 5 cm maximal diameter should be controlled by computed tomography in 6 to 12 months intervals and in the case of progression surgery can be recommended despite missing symptoms. Crawford developed the 'graft-inclusion-technique', which combines the 'ingraft'-technique with reattachment of renal, visceral and segmental arteries. The 'clamp and repair' principle is used in patients with sufficient cardiac function. Otherwise shunt or left sided heart bypass are used to reduce cardiac afterload. According to the literature local cooling (flush perfusion), cytoprotective drugs and numerous methods to maintain or ameliorate distal aortic perfusion during clamping ischemia have been used in patients successfully for prevention of ischemic spinal complications. In physiological settings these methods may prove valuable, but under pathophysiological conditions of TAAA-repair one must doubt the efficacy, because the individual risk is difficult to assess. In our hands flush perfusion and cooling of the kidneys proved to be helpful. In animal experiments we have shown prolongation of ischemia tolerance time using eicosanoides to protect the kidneys and the spinal cord. If shunt or left-sided heart bypass can protect the spinal cord during clamping, is unknown, because the risk of paraplegia in the individual patient can be known only, if the function of the spinal cord is monitored. We have developed a spinal neuromonitoring system and found, that only one third of all TAAA-patients is at high risk to develop paraplegia during aortic clamping. The surgeon is guided by continuous recording of spinal evoked somatosensory potentials and can adapt the operative technique by early reimplantation and eventually subsequent separate reimplantation of segmental arteries supplying blood to the spinal cord, in order to reduce spinal ischemia time. Our results in 260 TAAA-patients are presented. In a high-risk population of patients with aneurysms type I-III (Crawford's classification) it was possible, to reduce the paraplegia rate from 7 to 3.5%, the risk of paraparesis from 15 to 6%, while the operative mortality was only reduced from 19 to 10%.

Adult↗

[Surgical therapy of occlusions of the brachiocephalic trunk: long-term follow-up after transthoracic reconstruction].

Hemodynamically relevant lesions of the innominate artery can be treated either by extraanatomic bypass or by intrathoracic repair. 32 patients were retrospectively evaluated after ascending aorta to innominate artery interposition graft. In all except 6 cases additional bypass-procedures to extracranial vessels were necessary for complete revascularisation. The patency rate was 100% after a mean follow up period of 871 days. Only one patient suffered from a perioperative stroke with upper extremity paresis which resolved after 2 weeks. There were 3 wound complications which required reoperation. In conclusion we believe that direct intrathoracic repair for innominate artery occlusion can be recommended as a treatment of choice with a high long-term patency rate.

Adult↗

Complications following caval interruption.

Caval interruption is widely regarded as the treatment of choice for the prevention of recurrent pulmonary embolism (PE). The safety, ease of insertion and "convenience" of the devices are the main arguments for filter placement. Today many filters are placed for prophylactic reasons, sometimes without an established diagnosis of pulmonary embolism or underlying deep venous thrombosis. Early and late complications have been published but the rate is reported to be low, although only limited numbers of patients have been followed. In an 18-year period 11 patients with problems following caval interruption were treated, 10 with acute complications, one with chronic caval occlusion. Six were treated conservatively, five underwent venous thrombectomy and a.v.-fistula. The device was removed in four. During the same period only three permanent filters were placed in our hospital (two with complications). Caval interruption is useful in selected high-risk patients and is the least invasive but not necessarily the best treatment. Provided stringent criteria are applied, the early and late complications can be accepted in order to prevent sudden death in patients with threatening massive PE. Extended or more liberal indications for caval interruption are neither necessary nor justified.

Adult↗