Wall shear stresses remain elevated in mature arteriovenous fistulas: a case study.

Maintaining vascular access (VA) patency continues to be the greatest challenge for dialysis patients. VA dysfunction, primarily due to venous neointimal hyperplasia development and stenotic lesion formation, is mainly attributed to complex hemodynamics within the arteriovenous fistula (AVF). The effect of VA creation and the subsequent geometrical remodeling on the hemodynamics and shear forces within a mature patient-specific AVF is investigated. A 3D reconstructed geometry of a healthy vein and a fully mature patient-specific AVF was developed from a series of 2D magnetic resonance image scans. A previously validated thresholding technique for region segmentation and lumen cross section contour creation was conducted in MIMICS 10.01, allowing for the creation of a 3D reconstructed geometry. The healthy vein and AVF computational models were built, subdivided, and meshed in GAMBIT 2.3. The computational fluid dynamic (CFD) code FLUENT 6.3.2 (Fluent Inc., Lebanon, NH) was employed as the finite volume solver to determine the hemodynamics and shear forces within the healthy vein and patient-specific AVF. Geometrical alterations were evaluated and a CFD analysis was conducted. Substantial geometrical remodeling was observed, following VA creation with an increase in cross-sectional area, out of plane curvature (maximum angle of curvature in AVF=30 deg), and angle of blood flow entry. The mean flow velocity entering the vein of the AVF is dramatically increased. These factors result in complex three-dimensional hemodynamics within VA junction (VAJ) and efferent vein of the AVF. Complex flow patterns were observed and the maximum and mean wall shear stress (WSS) magnitudes are significantly elevated. Flow reversal was found within the VAJ and efferent vein. Extensive geometrical remodeling during AVF maturation does not restore physiological hemodynamics to the VAJ and venous conduit of the AVF, and high WSS and WSS gradients, and flow reversal persist. It is theorized that the vessel remodelling and the continued non-physiological hemodynamics within the AVF compound to result in stenotic lesion development.

Vascular trauma in an Irish regional hospital.

BACKGROUND: Vascular trauma is a common cause of mortality and morbidity worldwide. There are few accurate quantitative data available presently on the nature and outcome of these injuries. The aim of this study was to determine the incidence, aetiology, management and outcome of vascular injuries which required surgical intervention at a regional vascular unit. METHODS: All patients who suffered a vascular injury requiring surgical intervention between January 1992 and December 2005 were included. RESULTS: A total of 35 patients who underwent operative intervention for vascular trauma were reviewed. There were 26 men and 9 women with a median age of 26 years (range 3-80 years). Road traffic accidents accounted for 15 (43%) of all cases and 16 patients (47%) had an associated fracture. The brachial artery was most frequently injured, constituting 36% of all cases. Interposition grafting using the autogenous long saphenous vein was the most common procedure performed (11 patients). Eleven patients required a secondary procedure while the overall limb amputation rate was 8.5%. There was one mortality following an IVC injury. Seventy-four per cent of the cohort was asymptomatic at last follow-up. CONCLUSION: While vascular trauma is relatively uncommon in our catchment area it can be successfully managed. Most of the cases occur in young fit patients.

Popliteal-to-distal artery bypass for diabetic limb salvage.

BACKGROUND: Poor long-term survival and significant co-morbidity among diabetic patients with limb ischaemia makes the shortest, simplest revascularisation procedure desirable. AIM: Evaluate limb salvage, primary graft patency and peri-operative morbidity rates in diabetic patients undergoing popliteal-to-distal artery bypass for limb salvage. METHODS: Patients undergoing popliteal-to-distal artery bypass for critical limb ischaemia over a seven-year period were retrospectively identified. Patients operative and follow-up data were entered into a database and limb salvage and patient survival determined using Kaplan Meier survival analysis. RESULTS: During the study period 21 popliteal-to-distal artery bypasses were performed on 19 diabetic patients. Mortality rate after one year was 11%. Primary graft patency rates among surviving patients was 81%, 67% and 48% at 1, 2 and 6 years respectively. Amputation was required in three patients. CONCLUSION: Popliteal-to-distal artery bypass produces favourable results in high-risk diabetic patients with critical limb ischaemia.

A review of technological approaches to venous ulceration.

Leg ulceration is a chronic condition affecting about 1-2% of the adult population. The main causes of leg ulceration are venous hypertension, arterial insufficiency, diabetes, or a combination of these aetiologies (causes) or malignancy. Venous ulcers account for approximately 80% of all leg ulcers and are a result of venous hypertension. The current mainstay of treatment of venous ulcers is the application of graduated compression bandaging to the limb. In spite of the application of the best evidence-based therapy, healing rates for venous leg ulcers remain disappointing, at 50-70% after 12 weeks of treatment, depending on initial size and chronicity of the ulcer. Thus, a large number of ulcers are unhealed by this time, and many patients suffer from long-term leg ulceration, some remaining for years, and those that heal often recur. There is an obvious need to develop new treatments that would improve healing rates. This review provides a complete overview of the anatomy of venous circulation and the physiology pertaining to it, the pathophysiology of venous disease, the pathogenesis of ulceration, and a review of treatments currently employed in healing venous leg ulcers and their supporting evidence. The aim of this article is to encourage a fresh look at this chronic problem and stimulate ideas on how healing rates can be improved.

Information leaflets for venous leg ulcer patients: are they effective?

OBJECTIVE: To validate the usefulness of written information for patients with venous leg ulcers and test the hypothesis that patients who receive written information retain more knowledge than those who receive verbal information alone. METHOD: Twenty patients newly diagnosed with venous leg ulcers were recruited into this prospective trial. Patients were randomised either to the control group (given verbal information on their condition) or the intervention group (same verbal information and an information leaflet). The verbal information was in the same format as in the leaflet. Patients' knowledge of the condition was ascertained at an initial interview and at follow-up four to six weeks later. RESULTS: At follow-up both groups showed an overall improvement in knowledge, with no statistical difference between them. CONCLUSION: The results indicate there is limited value in providing information leaflets to this patient group, who were predominantly older patients with low levels of education. The relatively small sample size may explain the disappointing results. Further research may reveal a benefit of providing these leaflets to carers.

Health-related quality of life during four-layer compression bandaging for venous ulcer disease: a randomised controlled trial.

BACKGROUND: Venous leg ulceration is a chronic debilitating condition which negatively impacts on patients' quality of life. Despite the application of gold standard treatment a number of patients suffer from 'slow to heal' ulcers, which can require treatment for years. AIMS: The aim of this study was to compare the effects of four-layer compression bandaging (4LB) for treating venous leg ulcers with other available treatments on health-related quality of life duringtreatment. METHODS: In this pragmatic trial, 200 patients with venous leg ulceration were randomised either to 4LB (intervention group; n = 100) or to continue their usual system of care (control group; n = 100). Analysis was by intention to treat; quality of life measurements were taken at randomisation and after six weeks of treatment. RESULTS: 4LB provided greater quality of life benefits than the control group particularly in the area of physical activity and social functioning. CONCLUSION: Due to the long-term nature of treatment for many of these patients, the effects on quality of life should be considered when prescribing treatment. This study has shown that 4LB significantly improves the quality of life of patients during treatment for venous leg ulceration.

The role of venous diameter in predicting arteriovenous fistula maturation: when not to expect an AVF to mature according to pre-operative vein diameter measurements? A best evidence topic.

This best evidence topic was investigated according to a described protocol. We asked the question: what is the minimal vein diameter that can successfully predict maturation of an arteriovenous fistula (AVF) in patients undergoing dialysis. Using the reported search 804 papers were found, of which five represented the best evidence to answer the clinical question. All studies assessed the association between successful AVF maturation and the size of vein used. The strongest evidence came from a nonrandomised controlled follow-up study in which 76% of fistulas created using >2 mm cephalic vein successfully matured compared to 16% when the vein measured ≤2 mm. Another prospective, multicentre study showed 65% successful maturation using veins >4 mm compared to 45% with veins <3 mm. Vein diameter was found to be an independent predictor of maturation in multivariate regression analysis in two retrospective observational studies. Another retrospective observational study found that using venous measurements of ≥2.5 mm following tourniquet application resulted in more fistulas been created that would have otherwise been denied based on venous ultrasound mapping. A large multicentre randomised clinical trial assessing the use of different vein sizes both with and without tourniquet application using proper statistical tools - such as receiver operating characteristic - is required to make a final recommendation. Until then, a vein diameter of <2.5 mm should be considered inadequate for formation of an AVF, particularly if those measurements remain unchanged following the use of tourniquet.

Alpha-1-antichymotrypsin is an effective inhibitor of pancreatitis-induced lung injury.

BACKGROUND: Pancreatitis-induced adult respiratory distress syndrome (ARDS) may result from an imbalance between leucocyte proteases, produced by infiltrating neutrophils, and endogenous protease inhibitors. OBJECTIVE: The aim of this study was to evaluate the role of recombinant alpha-1-antichymotrypsin (rACT P3-P3'), an endogenous serine protease inhibitor, in ameliorating lung injury associated with pancreatitis. DESIGN: Sprague-Dawley rats were randomly divided into control (saline infusion) and pancreatitis groups, which were treated immediately with saline or rACT P3-P3' (50 mg/kg body weight). METHODS: Myeloperoxidase (MPO) was employed as a monitor of neutrophil traffic in the lung, and wet-dry lung weights as a measure of pulmonary endothelial permeability. Lungs were also evaluated histologically. RESULTS: Caerulein (5 micrograms/kg body weight/h) induced pancreatitis in all animals, with an increase in serum amylase from 1851 +/- 208 IU (control) to 5198 +/- 924 IU (pancreatitis), P < 0.05. Pancreatitis caused a significant increase in MPO activity (7.8 +/- 1.1 units compared with 2.08 +/- 0.5 units in controls, P < 0.001) and wet-dry lung weight ratios (12.8 +/- 3.3 compared with 3.2 +/- 0.1 in controls, P < 0.001), indicating significant pulmonary neutrophil influx and microvascular leakage, respectively. These increases in MPO activity and wet-dry ratios were decreased in the pancreatitis group treated with rACT P3-P3' (MPO 4.68 +/- 0.7 units, wet-dry ratio 4.2 +/- 0.5, P < 0.05 compared with the untreated pancreatitis group). CONCLUSION: These data support the hypothesis that deficient endogenous protease inhibition may be responsible for the neutrophil-mediated lung injury observed in pancreatitis and suggest that there may be a therapeutic role for recombinant protease inhibitors such as alpha-1 antichymotrypsin.

Nutritional, respiratory, and psychological effects of recombinant human growth hormone in patients undergoing abdominal aortic aneurysm repair.

BACKGROUND: Recombinant human growth hormone (rhGH) has been shown to have powerful anabolic effects and to reduce or even prevent nitrogen catabolism in stressed patients. The effects of rhGH on functional parameters are less clearly defined. The aim of this study was to assess the effects of perioperative rhGH on nutritional markers, skeletal muscle function, and psychological well-being in patients undergoing infrarenal, abdominal aortic aneurysm repair. METHODS: Thirty-three patients undergoing elective infrarenal abdominal aortic aneurysm repair were randomized to one of three groups: (1) control (n = 12): placebo for 6 days before and after surgery; (2) preop + postop (n = 10): rhGH (Genotropin; Pharmacia Ltd, Uppsala, Sweden) 0.3 IU/kg/d for 6 days before and after surgery; and (3) postop (n = 11): placebo for 6 days before and rhGH 0.3 IU/kg/d for 6 days after surgery. Patients were assessed on days -7 and -1 before surgery and days 7, 14, and 60 after surgery. RESULTS: Administration of rhGH resulted in increased insulin-like growth factor 1 levels, the increase being significantly more marked in the group given rhGH preoperatively. Preoperative and postoperative rhGH reduced the postoperative decrease in both serum transferrin and grip strength at day 7 by 30% and 70%, respectively. Postoperative respiratory function and arterial oxygenation also were improved, with significant differences in arterial oxygenation between rhGH-treated and untreated groups. No difference in mood was seen between groups after surgery, nor was there any difference between subjective assessment of fatigue scores between groups. CONCLUSIONS: This pilot study indicates that rhGH administered preoperatively has beneficial effects on skeletal muscle and respiratory function and may be more useful than postoperative rhGH administration alone.

Normal inspiratory muscle strength is restored more rapidly after laparoscopic cholecystectomy.

Respiratory complications after laparotomy cholecystectomy may result from generalised muscle weakness and fatigue, or from reduced respiratory muscle function secondary to an upper abdominal incision. In a prospective study we compared maximal inspiratory effort (Pimax/mmHg) and dominant hand grip strength (kPa) (expressed as a percentage of zero hour value) in patients undergoing open cholecystectomy (OC) (n = 12), laparoscopic cholecystectomy (LC) (n = 25) and a control group of patients undergoing lower limb surgery (n = 12). Of the 12 OC patients, three suffered respiratory complications: two had atelectasis and one a chest infection, compared with no such complications in the other two groups (P < 0.05). Pimax decreased postoperatively in all groups (P < 0.05) and had returned to normal by 48 h in the LC and control groups. In contrast, in the OC group Pimax fell from 112.5 +/- 17.8 mmHg to as low as 81.3 +/- 16.5 mmHg at 72 h and only returned to preoperative levels at 120 h. The hand grip strength fell significantly in all groups at 24 h (P < 0.05) but normal levels were achieved again by 48 h in all groups, and there was no significant difference in the hand grip strength between the groups over the 5 days. These results suggest that generalised muscle fatigue after surgery is similar after open and laparoscopic cholecystectomy. Open cholecystectomy does, however, cause a more prolonged reduction in respiratory muscle function and this is likely to contribute to the higher incidence of respiratory complications in this group of patients.

Post-cholecystectomy symptoms after laparoscopic cholecystectomy.

Abdominal symptoms persist in up to 40% of patients after laparotomy cholecystectomy and biliary lithotripsy. Laparoscopic cholecystectomy is now the treatment of choice for symptomatic gallstone disease. However, no data exist as to the influence of laparoscopic cholecystectomy on symptoms. We analysed 100 patients who had undergone laparoscopic cholecystectomy at a median of 12 months (range 10-19 months) previously. Pre- and postoperative symptoms were compared and patient satisfaction was graded from 1 (best) to 5 (worst). Time to resumption of full activity (mean +/- SD) was recorded. All patients had more than two symptoms preoperatively. Postoperatively, 61 patients had complete absence of symptoms, 14 patients complained of only one symptom during the postoperative period and 25 patients continued to have at least two symptoms. The mean time taken to return to full activity was 2.4 +/- 1.7 weeks. In patients without any symptoms postoperatively, time taken to return to full activity was 2.3 +/- 1.5 weeks, 2.7 +/- 1.4 weeks for patients with one symptom postoperatively, while patients with two or more symptoms returned to full activity in 2.3 +/- 1.3 weeks and 2.6 +/- 1.7 weeks, respectively. Notwithstanding that 25% of patients reported two or more symptoms postoperatively, most patients (n = 84) considered the procedure to be a complete success. A further 10 patients had significant improvement after laparoscopic cholecystectomy. Five patients considered themselves only slightly improved, while a single patient was no better off postoperatively. These data indicate that after laparoscopic cholecystectomy most patients return to full activity within 3 weeks. Thus, the incidence of post-cholecystectomy symptoms is similar after laparoscopic and laparotomy cholecystectomy and biliary lithotripsy.Patients should be advised of the risk of persistent symptoms after these procedures.

Early results with restorative proctocolectomy.

The first 25 restorative proctocolectomies (RP) performed by one surgeon since 1986 are reviewed. Ulcerative colitis (23) and idiopathic megarectum (2) were the indications for surgery. The initial seven patients had a submucosal proctectomy and transanal hand sewn pouch-anal anastomosis. Eighteen patients had a totally stapled RP. One patient with malignancy died from factors unrelated to surgery. Complications developed in eight patients after pouch-anal anastomosis and in four patients after ileostomy closure. There was one pouch failure due to pelvic sepsis. No pelvic sepsis has occurred following a stapled ileal pouch-anal anastomosis with defunctioning ileostomy. After a mean follow up period of 20.5 months all patients are continent (mean stool frequency = 4/day and 0.5/night). Soiling occurred in three patients who had a transanal hand sewn pouch-anal anastomosis. All patients in the stapled group have satisfactory control. Restorative proctocolectomy produces satisfactory operative and functional results which have improved as our experience has increased.

Regional vascular surgical units: a practical means of providing specialist services.

BACKGROUND: A comprehensive regional emergency and elective vascular surgical service was established in Limerick Regional General Hospital between 1994 and 1996 following the appointment of three surgeons with vascular training. AIM: To compare vascular surgical activity before and after the establishment of a regional vascular service. METHODS: This study used local and national computerised databases, clinic letters, theatre registers and radiology records to compare vascular surgical activity before (1992) and after (1997) this service was established. RESULTS: Total outpatient activity increased almost six-fold and total number of inpatient vascular procedures (including radiological) increased from 146 to 432, but the venous proportion declined from 70% to 36%. The number of major arterial procedures increased from 37 to 165 in 1997 including 10 carotid endarterectomies, 24 aortic reconstructions and 54 lower limb reconstructions representing rates of 3/100,000, 8/100,000 and 17/100,000 population respectively. CONCLUSION: As substantial changes in disease patterns are unlikely, these data indicate that patients previously diverted elsewhere for therapy are now cared for within the health board region and that further increases in workload may be expected. We suggest that these data mandate the reallocation of resources to fund appropriately staffed and audited regional vascular units.

Prevalence and aetiology of leg ulcers in Ireland.

BACKGROUND: The prevalence of leg ulcer disease in Ireland has been poorly documented. AIMS: This study aimed to investigate the aetiology and prevalence of leg ulcers in one health district. METHODS: All patients receiving healthcare for an active leg ulcer in the Mid-Western Health Board (MWHB) region of Ireland (population: 317,069) were identified in a defined two-month period. A cross-sectional survey of all healthcare workers providing care to patients with leg ulceration was carried out. Patients with leg ulcers of uncertain cause were invited for follow-up assessment to establish the underlying cause. RESULTS: There were 389 patients with leg ulcers with a mean (standard deviation [SD]) age of 72.3 (11.1) years. The prevalence was 0.12% but it was 1.03% in patients aged 70 years and over. Women were twice as likely to be affected. Venous disease accounted for 81% of ulcers, and arterial disease for 16.3%, while ulceration due to diabetic neuropathy and rheumatoid vasculitis was unusual. CONCLUSION: Leg ulcers are an important source of morbidity in our ageing population. Effective treatment programmes could diminish the impact of this debilitating disease on the health service.

Critical appraisal of the application of carotid duplex scanning.

AIMS: To evaluate the indications for carotid arterial imaging in an open access vascular laboratory. To identify those symptoms predictive of > 50% stenosis of the carotid artery in order to reduce unnecessary imaging. To test the hypothesis that duplex scanning would not be of significant benefit in the management of those patients with ill defined symptoms. METHODS: We compared the outcome of carotid duplex scanning performed on 816 consecutive patients referred for a variety of clinical indications. The medical records of 816 patients were retrospectively analysed to identify the clinical indication for carotid duplex imaging over a three-year period (1997-9). RESULTS: The indications for duplex imaging were divided into two groups: definite carotid symptoms, n=350 (transient ischaemic attack n=205, cerebrovascular accident n=66, amaurosis fugax n=49, dysphasia n=30); and non-carotid symptoms, n=466 (dizziness n=63, syncope n=63, confusion n=20, vertigo n=10 and others n=310). Less than 5% of those with definite carotid symptoms and 2% of those with ill-defined symptoms had a stenosis > 80%. CONCLUSION: Regardless of symptoms, 14% and 2.9% of patients referred for carotid duplex imaging have a stenosis of > or = 50% and > or = 80%, respectively. Patients without definite carotid symptoms are of low priority for duplex imaging.

Renal revascularisation by gastroduodenal-renal bypass as treatment of renal artery stenosis.

We report the case of a 63 year old hypertensive male who presented with acute renal failure following treatment of his hypertension with the ACE antagonist, captopril. He was documented to have bilateral renal artery stenosis, which was treated by left renal artery angioplasty and revascularisation of the right kidney by anastomosis of the right renal artery to the superior gastroduodenal branch of the hepatic artery. Postoperatively, he made an excellent recovery, with restoration of his renal function to normal and improved control of his hypertension.

The impact of regional reconfiguration on the management of appendicitis.

BACKGROUND: Reconfiguration of surgical services in the Mid-West in 2009 resulted in a large increase in numbers of patients undergoing emergency surgery for appendicitis in University Hospital Limerick (UHL). AIMS: The aim of this study was to assess the impact of reconfiguration on the management of appendicitis in this area. METHODS: Data on all patients who underwent appendicectomy between January and June 2007 were compared with the corresponding data from January to June 2011. The numbers of operations, types of operations, lengths of stay (LOS), operation start times, rates of negative histology specimens and readmissions within 30 days were compared. One hundred and twenty-five appendicectomies [48 laparoscopic (38.4 %)] were performed in the 2007 group of which 32 specimens (25.6 %) were histologically negative. Three hundred and nineteen appendicectomies [238 laparoscopic (74.6 %)] were performed in the 2011 group of which 62 specimens (19.4 %) were histologically negative. The increase in numbers of laparoscopic procedures was significant (p < 0.001). The reduction in the negative appendicectomy rate was not statistically significant (p = 0.16). There were 10 conversions (20.8 %) to open surgery in the 2007 period and 12 (5 %) in the 2011 period (p = 0.001). Mean LOS for the 2007 and 2011 groups was 4.45 and 3.16 days (p < 0.001). Six (4.8 %) readmissions within 30 days occurred in the 2007 group with 20 (6.3 %) in the 2011 group (p = 0.66). CONCLUSION: Though reconfiguration of surgical services has resulted in a significant increase in workload, LOS has decreased significantly while maintaining acceptably low negative appendicectomy, conversion and readmission rates.

Assessing the quality of online information for patients with carotid disease.

INTRODUCTION: Controversy exists relating to carotid endarterectomy (CEA) versus carotid artery stenting (CAS). We aimed to assess the quality of online patient information relating to both. METHODS: The Google search engine was searched for "carotid endarterectomy" and "carotid stenting". The first 50 webpages returned were assessed. The Gunning Fog Index (GFI) and Flesch Reading Ease Score (FRES) were calculated to assess readability. The LIDA tool (Minervation Ltd., Oxford, U.K.) was used to assess accessibility, usability and reliability. RESULTS: 20% (n = 10) of the webpages returned for CEA were from peer reviewed sources with 34% (n = 17) posted by hospitals or health services. Comparatively, for CAS, 40% (n = 20) were peer reviewed with 16% (n = 8) posted by hospitals or health services. GFI and FRES scores indicated webpages for both CEA and CAS had poor general readability. Webpages for CEA were easier to read than those for CAS (mean FRES difference of 6.7 (95% CI 0.51 to 12.93, p = 0.03). Median LIDA scores demonstrated acceptable reliability, accessibility and usability of information for both CEA and CAS webpages. The more readable webpages were not associated with higher LIDA scores for either CEA or CAS webpages. CONCLUSION: Webpages providing information on carotid disease management must be made more readable. Online information currently available to patients regarding CAS is more difficult to read and comprehend than CEA.

Can augmentation index be used as an accurate tool in the diagnosis of peripheral obstructive arterial disease?

BACKGROUND: The use of radial augmentation index (rAI) as an indicator of vascular disease was investigated in the vascular imaging laboratory in a regional hospital. AIMS: The aim of this study was to investigate whether a correlation exists between ankle-brachial pressure index (ABPI) and rAI in normal subjects, patients with peripheral obstructive arterial disease, and diabetic patients. METHODS: A group of 46 patients and 14 controls had ABPI and rAI measured and factors affecting AI were assessed. RESULTS: rAI was found to have a negative correlation with ABPI (Spearman's ρ = -0.513, p < 0.01). There was significant increase in the rAI scores of diabetic patients compared to normal patients (normal median was 64% lower than diabetic median, p < 0.01) and in peripheral obstructive vascular disease patients compared to normal (normal median 69% lower, p < 0.001). Of the various affecting factors, age stood out with rAI having a positive correlation to age (Spearman's ρ = 0.68, p < 0.01). CONCLUSIONS: The augmentation index appears be a significant indicator of cardiovascular disease and may be a useful tool in the diagnosis of vascular pathology.