Hypothermic, initially oxygen-free, controlled limb reperfusion for acute limb ischemia.

BACKGROUND: Controlled limb reperfusion has been shown to prevent the deleterious effects of ischemia-reperfusion (IR) syndrome following revascularization of acute limb ischemia (ALI). To reduce the production of cell-toxic oxygen-free radicals, we have established a new initially oxygen-free, hypothermic, heparin-coated perfusion and hemofiltration system and report on our first results. METHODS: In a retrospective single-center study, controlled limb reperfusion was applied in 36 patients (64.7 ± 15 years) with ALI of category IIA to III (33.7 ± 20.7 hr ischemic time). 52.8% had central (aortic and bifurcation) and 47.2% had peripheral (common iliac artery and distal) vascular occlusions. The common femoral artery and vein were cannulated, and a hypothermic (22°C), initially oxygen-free, potassium-free ringer's solution was perfused using a heparin-coated extracorporeal membrane oxygenation (ECMO) and hemofiltration system with low-dose heparinization. Thirty-day mortality, clinical recovery of neurological dysfunction, limb amputation, and fasciotomy rate were analyzed. Laboratory parameters associated with ischemia and IR injury were determined. RESULTS: Average perfusion time was 94 ± 35 min. Thirty-day mortality was 27.8%. 55.5% of patients showed complete recovery of motor and sensory dysfunction. A total of 27.8% of patients developed a compartment syndrome and required fasciotomy. Lower leg amputation was necessary in 11.1% of patients. Lactate levels were reduced in ischemic limbs by 25.3% within 60 min (P < 0.05). Preoperative negative base excess of -1.96 ± 0.96 mmol/L was equalized after 12 hr (P < 0.05), while pH stayed balanced at 7.4. Serum potassium stayed within normal limits throughout 24 hr, and therefore systemic hyperkalemia was prevented and imminent metabolic acidosis was corrected. CONCLUSIONS: An initially oxygen-free, hypothermic, heparin-coated ECMO counteracts local and systemic effects of IR injury. Reduced mortality and morbidity might result from this new treatment, although this could not be conclusively proven in our study. A prospective, randomized controlled trial is needed to prove superiority of this new concept.

Paraincisional subcutaneous infusion of ropivacaine after open abdominal vascular surgery shows significant advantages.

BACKGROUND: Opiates are widely used for postoperative pain relief. Unfortunately, their side effects such as inhibited gastrointestinal motility and respiratory depression may compromise or delay postoperative recovery after laparotomy. We used paraincisional subcutaneous catheters (PSCs) and applied 0.25% ropivacaine infusion to improve pain relief and decrease postoperative morphine consumption in patients after open surgery for aortic aneurysm. METHODS: A retrospective single-center study including 58 patients treated by open surgery for aortic aneurysm between October 2006 and June 2012. Overall, 28 patients (control group) received standard postoperative pain management including opiates, and 30 patients (PSC group) were treated with paraincisional continuous local analgesia with 0.25% ropivacaine administrated via bilateral subcutaneous catheters along with additional ad libitum opiates administration, at first intravenously and then orally. RESULTS: Patients characteristics as well as perioperative and postoperative outcomes were comparable between the groups during the first 5 days after surgery. Patients of the PSC group received significantly less morphine, although the patients in both groups reported a similar pain intensity. Neither wound-healing disorder nor catheter-associated subcutaneous infection was reported. High serum concentration of ropivacaine was detected in 2 patients (6%) with end-stage renal disease, who developed temporary neurologic symptoms. Length of intensive care unit (ICU) stay was significantly shorter in the PSC group (2 [0-23] vs. 4.5 [0-32] ICU days). CONCLUSIONS: This is the first report about PSCs for analgesia after laparotomy. This case/control study shows that continuous paraincisional subcutaneous infusion of 0.25% ropivacaine after open surgery for aortic aneurysm repair is a feasible method of postoperative analgesia. This technique allows sustained pain relief with significant reduction of opiate requirement and faster recovery after surgery. Prospective randomized controlled trial is necessary for the assessment of safety and efficacy of this method.

Teleconsultation in vascular surgery: a 13 year single centre experience.

The University Hospital of Zurich has provided an email-based medical consultation service for the general public since 1999. We examined the enquiries in a 13-year period to identify those related to vascular surgery (based on 22 ICD-10 codes specific for vascular surgery). There were 40,062 questions, of which 643 (2%) were selected by ICD-10 codes. After exclusion of diagnoses not relevant to vascular surgery, 139 questions remained, i.e. an average rate of about one per month. The mean age of the users was 43 years (range 19-88). Most users (61%) were women. The majority of users asked questions about their own health problems (79%) with varicose veins and spider veins accounting for 63% of all questions. Arterial diseases accounted for 30%. The patient's intention in contacting the service was to obtain advice on treatment options (37%), information about a diagnosis or symptoms (27%), or a second opinion (15%). The online service responded with detailed information and advice (87%) and suggested a referral to the family doctor or a specialist in 75%. Most patients (82%) rated the service overall as good or very good. It appears likely that telemedicine and in particular email teleconsultations will increase in vascular surgery in the future.

Veno-venous perfusion to cool and rewarm in thoracic and thoracoabdominal aortic aneurysm repair.

BACKGROUND: Femoro-femoral veno-arterial perfusion is an established circulatory support and cooling method for thoracic- and/or thoracoabdominal aortic aneurysm repair. However, retrograde perfusion through femoral arteries can lead to retrograde cerebral embolization and neurologic dysfunction after surgery. To avoid these complications, we have established a femoro-femoral veno-venous perfusion technique and evaluated its safety and effectiveness in elective and nonelective patients. METHODS: Common femoral veins were cannulated bilaterally percutaneously following systemic low-dose heparinization (100 IU/kg body weight). Venous blood was drained from drainage of the inferior vena cava, and venous return followed through the superior vena cava. After proximal aortic cross-clamping, veno-venous perfusion was switched to veno-arterial antegrade perfusion through the distal descending thoracic aorta to achieve spinal and visceral perfusion or through iliac arteries for distal perfusion combined with selective renovisceral blood perfusion. After completion of aortic repair, the arterial cannula was removed and the patient rewarmed just by switching back to veno-venous perfusion. Gas and temperature exchange as well as relevant hemodynamic parameters were recorded prospectively and analyzed retrospectively in 25 consecutive patients including 15 nonelective cases. RESULTS: Percutaneous insertion of outflow (28F cannula) and inflow (18F cannula) venous cannulae was complication-free and allowed unrestricted perfusion in all 25 patients. Veno-venous perfusion allowed effective cooling (mean body temperature 36.6 ± 0.6°C to 31.6 ± 2.1°C, P = .001 compared with start of cooling) and re-warming (mean body temperature 30.5 ± 3°C to 36.3 ± 0.8°C, P = .03 compared with start of re-warming). Hemodynamic as well as pulmonary parameters remained remarkably stable during surgical dissection and single lung ventilation even in nonelective cases. There was no complication associated with the perfusion technique during surgery. CONCLUSIONS: Transfemoral veno-venous cooling and re-warming results in remarkable hemodynamic stability during open repair of thoracic- and/or thoracoabdominal aortic aneurysms and eliminates the need for retrograde arterial perfusion and its inherent risks.

Bioprosthetic tissue preservation by filling with a poly(acrylamide) hydrogel.

Glutaraldehyde (GA) fixation has been used for more than 40 years as the preferred treatment to suppress immunogenicity and increase durability of bioprosthetic tissues (BPT) used in heart valve prostheses. This fixative and its reaction products have, however, been implicated in the calcific degeneration and long-term failure of these devices. The current study investigates stabilization of BPT and the mitigation/prevention of calcification by filling aortic wall samples with a synthetic poly(acrylamide) (pAAm) hydrogel, with and without pre-treatment with GA. Histological and gravimetric analysis showed full penetration of the acrylamide (AAm) into the fresh tissue, while only partial filling could be achieved with GA pre-fixed tissue. The observed decrease in amino-group content (0.157+/-0.012-0.123+/-0.021 micromol/mg, p<0.03) and corresponding increase in shrinkage temperature (67.2+/-0.8-78.1+/-1.8 degrees C, p<0.0001) when fresh tissue was filled, indicate the participation of tissue-amines in a process that leads to BPT crosslinking. These effects were much less pronounced when the tissue was pre-fixed with GA. Filling increased the tensile stiffness of fresh tissue (to levels half that of 0.2% GA fixed tissue), but decreased the stiffness of GA pre-fixed tissue. When compared to standard 0.2% GA fixed samples, fresh tissue filled with AAm showed 88% (p<0.0001) less calcification while exhibiting similar resistance toward degradation by protease. Filling did not result in significant decreases in calcification when the tissue was pre-fixed with GA.