Is lower extremity revascularization worthwhile in patients with end-stage renal disease?

BACKGROUND: The purpose of this study was to review the results of lower extremity revascularization in patients with end-stage renal disease and to determine in these patients the functional benefit and cost of an aggressive approach to limb preservation. METHODS: During a 5-year period at our institution, 33 bypass operations were performed on 31 limbs of 23 dialysis-dependent patients. Indications for revascularization were limited (18) or extensive (12) tissue loss or ischemia without tissue loss (3). Procedures included aortobifemoral bypass (1), femoropopliteal bypass (10), and femorotibial/pedal bypass (22). A digital or transmetatarsal amputation was performed in 57% of limbs. RESULTS: The 30-day primary patency was 100%. Cumulative primary and secondary patency rates at 2 years were 65% and 79%, respectively. Limb salvage was 67% and 59% at 1 and 2 years, respectively. Patient survival was poor (47% at 2 years). Peritoneal dialysis was predictive of poor survival (P <.001). Four of 5 patients on peritoneal dialysis died within 3 months of intervention. Extensive tissue loss was predictive of a diminished rate of limb salvage (P =.027). Only 39% of limbs with extensive tissue loss were salvaged at 1 year compared with 78% and 100% of limbs with limited and no tissue loss, respectively. The average hospital cost was $44,308 per year of limb salvage. CONCLUSIONS: Although revascularization of ischemic limbs in dialysis patients can be achieved with an excellent initial graft patency and reasonable limb salvage, patient survival is poor and costs are high. A selective approach to revascularization in these complicated patients may be indicated. For patients treated with peritoneal dialysis and for those with extensive tissue loss, primary amputation may be the preferred approach.     

Should we quantify insulin resistance in patients with renal disease? (Review Article)

Cardiovascular disease is a major cause of morbidity and mortality in dialysis patients. Vascular disease develops before the initiation of dialysis, and it is now recognized that chronic kidney disease (CKD) is an independent risk factor for cardiovascular disease. Death from cardiovascular disease is a more common endpoint of CKD than progression to dialysis. There are multiple mechanisms that contribute to the increased vascular risk of CKD, one of which is the presence of insulin resistance (IR). CKD is characterised by many features of the metabolic syndrome, and features of IR are also observed in dialysis and transplant patients. IR may be quantified by several different methods. One such method is homeostatic model assessment (HOMA) technique, which derives a measurement of IR from fasting plasma glucose and insulin concentrations. The HOMA index has been demonstrated to be an independent predictor of survival in dialysis patients. CKD is characterised by a chronic inflammatory response and abnormalities in the production and regulation of adipose tissue derived proteins, which may contribute to the development of IR. There are a range of interventions including diet and exercise programmes or medications that may influence IR; however, the impact of these interventions in the context of CKD has not been systematically evaluated.     

Infrainguinal bypass grafting in patients with end-stage renal disease: improving outcomes?

OBJECTIVE: This study was undertaken to examine recent trends in the outcomes of patients with end-stage renal disease (ESRD) undergoing infrainguinal bypass grafting (IBG) with autogenous vein. METHODS: A retrospective analysis of all IBGs performed on patients with ESRD at a single tertiary care institution during the interval 1993 to 1999 was undertaken. The comparison groups consisted of concurrent series of patients with elevated creatinine (creatinine level > 1.2 mg/dL) and patients with normal renal function undergoing IBG. Procedural variables, angiographic runoff scores, and extent of tissue necrosis at presentation were correlated with outcome. Categoric parameters were compared with chi(2) analysis; rates were computed with life-table analysis. RESULTS: Of an overall cohort of 622 IBGs performed during this interval, 78 IBGs (12.5%) were performed on 60 patients with ESRD, with a perioperative mortality rate of 1.3% that was comparable to controls. All reconstructions in the ESRD cohort were for limb salvage indications. Four-year survival, primary, assisted primary, and secondary patency rates for the ESRD group were 51% +/- 9%, 60% +/- 11%, 86% +/- 5%, and 86% +/- 5%, respectively; these were not statistically different from the control groups. Limb salvage in the ESRD group was 77% +/- 6% at 4 years and was significantly less then either the elevated creatinine (92% +/- 4%; P <.02) or the normal renal function group (90% +/- 2%: P <.02). Of 16 amputations in the ESRD group, nine were performed in limbs with patent grafts. The only absolute predictor of limb loss despite a patent graft was the presence of a heel ulcer more than 4 cm in diameter. Age, runoff score of the International Society for Cardiovascular Surgery/Society for Vascular Surgery, isolated tibial bypass graft, and location of distal anastomosis were not predictive of hemodynamic failure. CONCLUSIONS: Patients with ESRD constitute an increasing proportion of patients undergoing IBG in a tertiary care setting. Four-year survival, perioperative mortality, and graft patency rates are similar to patients with normal renal function and support an aggressive approach to this population. Major limb amputation despite a patent graft remains a problem of unique frequency in patients with ESRD. Adequate predictors of hemodynamic failure of IBG in this group do not exist, although a heel ulcer more than 4 cm may indicate an unsalvageable foot.     

Should we use diuretics in acute renal failure?

Because oliguria is a bad prognostic sign in patients with acute renal failure (ARF), diuretics are often used to increase urine output in patients with or at risk of ARF. From a pathophysiological point of view there are several reasons to expect that loop diuretics also could have a beneficial effect on renal function. However, clinical trials on the prophylactic use of loop diuretics rather point to a deleterious effect on parameters of kidney function. In patients with established ARF loop diuretics have been shown to increase urine output, which may facilitate patient management. A beneficial effect on renal function has, however, not been demonstrated. On the other hand, such an effect cannot be excluded because the available trials lack statistical power. Possible explanations for the absence of a renoprotective effect are discussed. The evidence for a renoprotective effect of mannitol is restricted to the setting of renal transplantation.     

Carotid endarterectomy in patients with renal insufficiency: Should selection criteria be different in patients with renal insufficiency?

The objective of this study was to elucidate the relationship between outcomes from carotid endarterectomy (CEA) in patients with and without renal insufficiency. Carotid endarterectomy is one of the most commonly performed vascular procedures. The role of cardiac comorbidity in carotid endarterectomy has been extensively studied. The relationship between renal failure and surgical outcomes has also been studied for both coronary artery bypass grafting and lower extremity occlusive disease. However, the role of renal insufficiency in relationship to decision making regarding surgical intervention for carotid stenosis is not well defined. The authors hypothesized that the outcomes from CEA were negatively influenced by renal dysfunction. A retrospective review was made of consecutive CEAs performed at their institution from 1990 to 1995. Patients were grouped into 2 categories according to their renal function. Group A, 448 patients (90%) with creatinine level 1.8 mg/dL or less, and group B, 49 patients (10%) with creatinine levels more than 1.8 mg/dL. Data from patients on dialysis are presented but were excluded for the purpose of analysis. Included in the study were 497 patients with a mean age of 70 +/-8.9 and 74 +/-8.9 for groups A and B, respectively. Preoperative creatinine was 1.1 (+/-0.25) mg/dL for group A and 2.5 (+/-0.81) mg/dL for group B. Outcomes were as follows: perioperative cardiac events 5.4% vs 28.6%, stroke rates 2.7% vs 2.0%, and mortality rates 0.9% vs 8.2%, for groups A and B, respectively. At 60-month follow-up the stroke rates were 7.6% vs 6.1 %, and the mortality rates 22.8% vs 59.2%, for groups A and B, respectively. While patients with chronic renal insufficiency have no increased risk of perioperative or long-term neurologic events, perioperative and long-term mortality rates are significantly increased. This significant reduction in survival should prompt a more cautious application of CEA in patients with increased creatinine.     

Infrainguinal bypass grafting in patients with end-stage renal disease and critical limb ischaemia: is it worthwhile?

Patients with end-stage renal disease (ESRD) constitute an increasing proportion of patients undergoing infrainguinal bypass surgery for critical limb ischaemia (CLI). The aim of this retrospective study was to determine graft patency, healing of pedal lesions, limb salvage and survival following infrainguinal arterial reconstruction in this high-risk subset of patients. 34 patients with ESRD undergoing 37 bypass procedures for CLI (rest pain 2; tissue loss 35) were identified from the vascular registry. These included 13 femoropopliteal and 24 femorotibial bypasses with autogenous (67.6%) or prosthetic (32.4%) materials. The median age in this series was 62 years and 79% were diabetics. Using life-table analysis, the cumulative primary patency rate was 88% at 1 month and 81% at 2 years. The resulting limb salvage rate amounted to 94 and 86% at 1 month and 2 years, respectively. Healing of the pedal lesions was accomplished in only 50% of patients at 6 months. Toe lesions could be treated more successfully than forefoot and deep heel defects (p = 0.04). With a perioperative mortality of 3/37 cumulative survival rate declined to 21% at 2 years. Late mortality correlated significantly with a history of previous myocardial infarction or congestive heart failure (p = 0.001). Infrainguinal revascularisation can be performed in dialysis-dependent patients with acceptable patency and limb salvage rates. However, bypass grafting should be mainly reserved to patients without severe cardiac disease and to those without extensive tissue loss.     

Should we shift toward higher blood pressure targets in patients with chronic kidney disease?

Hypertension is the leading cause of death worldwide and is responsible for a significantly increased burden of cardiovascular events and progression to end-stage kidney disease in patients with chronic kidney disease (CKD). The fundamentals of therapeutics in patients with hypertension and CKD are both the use of specific renal protecting agents and the achievement of tight blood pressure control - i.e., blood pressure values below 130/80 mm Hg. When the evidence underpinning a "tight blood pressure target control" recommendation is analyzed, hypertension guidelines appear to be largely extrapolating to people with CKD the key findings of large trials conducted in the general population and other high cardiovascular risk populations, while renal societies guidelines are primarily influenced by observational data reporting renal outcomes and small-scale randomized studies, and have not always incorporated recent evidence from systematic reviews. In this narrative review, we present existing guidelines and evidence for 2 crucial clinical questions in the management of hypertension of CKD: (i) should we, and by how much should we, lower blood pressure in people with CKD and (ii) are there agents which are specifically beneficial in the CKD population, independent of blood pressure control.     

Should we use kidneys from donors with acute kidney injury for renal transplantation?

The scarcity of donor organs for transplant results in long waiting times for kidney transplantation and low transplant rate worldwide. Utilization of kidneys from donors with acute kidney injury (AKI) is one of the strategies that has attracted attention recently. This article reviewed the outcomes of transplanted renal allografts from donors with acute kidney injury. Key findings about the transplant outcomes included a higher incidence of delayed graft function and primary non function, but respectable outcomes in the context of similar acute rejection rates, and graft function and graft survival. Against this background and with evidence of high mortality for patients remaining on waiting list of transplant, we advocate consideration of AKI donors for kidney transplantation.     

Are older patients with mechanical heart valves at increased risk?

Background. Controversy exists regarding the use of mechanical valves in older patients. Many authorities believe that the use of anticoagulants in the elderly is associated with an increased risk of warfarin-related complications. Therefore, we compared the results with mechanical valves in older patients to a cohort of younger patients.

Methods. Aortic (AVR) or mitral valve replacement (MVR) with a mechanical valve was performed in 1,245 consecutive patients who were followed prospectively. They were grouped by age (group 1, ≤ 65 years; group 2, > 65 years). The study groups consisted of AVR (group 1, 459 patients; group 2, 323 patients) MVR (group 1, 313 patients; group 2, 150 patients).

Results. The average age for the groups was: AVR (group 1, 51 years; group 2, 70 years; p = 0.03) and MVR (group 1, 53 years; group 2, 70 years; p = 0.03). For AVR the incidence of thromboembolism was 0.050 (group 1) and 0.038 (group 2) (p = 0.37) and the actuarial freedom from thromboembolism was 83.0% ± 3.0% and 86.5% ± 1.0%, respectively (p = 0.13). The incidence of bleeding after AVR was 0.021 for group 1 and 0.028 for group 2 (p = 0.49). For MVR the incidence of thromboembolism was 0.059 for group 1 and 0.051 for group 2 (p = 0.75) and the actuarial freedom from thromboembolism was 78.8% ± 3.0% and 75.4% ± 8.7%, respectively (p = 0.71). The incidence of bleeding after MVR was 0.020 for group 1 and 0.027 for group 2 (p = 0.62).

Conclusions. Mechanical valves perform well in selected older patients with no increased risk of bleeding or thromboembolism.     

Patient safety in end-stage renal disease: How do we create a safe environment?

The Institute of Medicine estimated that 44,000 to 98,000 hospitalized patients die annually as a direct result of preventable medical errors. Errors occur because competent practitioners are human, and the systems we design are imperfect. Improving patient safety requires acknowledging medical errors, encouraging the reporting of errors, and improving systems to reduce the likelihood of future errors. Several challenges must be addressed to accomplish this goal. The definition of medical errors must be widely agreed on and accepted. Adverse outcomes are often the result of multiple systems failures. Therefore systems analysis, not blaming an individual, should be the focus of error reduction. A "culture of safety" should be created, which encourages reporting errors and "near-misses." An effective reporting system has 2 components, one for public accountability for errors that result in serious injury and another for confidential reporting of mistakes that have the potential for serious injury. Regulatory protection from discovery must be established for voluntary error and near-miss reporting systems. In the nephrology community, novel uses of technology should be sought to prevent errors, human factors leading to errors should be identified and anticipated, and patterns of interaction at the machine-human interface should be studied. Progress in improving patient safety has occurred in some areas, such as pharmacy services. Such known and tested patient safety practices should be deployed in dialysis facilities. Success in improving patient safety will require leadership, collaborative efforts among the many stakeholders in the ESRD program, and adequate allocation of resources.     

Should we use stents in subarachnoid hemorrhage?

Based on findings from the International Subarachnoid Aneurysm Trial (ISAT), coiling of ruptured cerebral aneurysms is associated with the lowest immediate morbidity and mortality rates compared to other treatment options.1, 2 Whenever anatomy permits, coiling is the preferred method for repair. Unfortunately, not all cerebral aneurysms are suitable for coiling, and the best treatment for aneurysms that cannot be coiled remains unclear. Adjunctive techniques such as surgical clipping, balloon remodeling,3 use of two microcatheters,4 and intracranial stents 5 can increase the likelihood of aneurysm thrombosis and parent vessel patency. The goal of this article is to describe our current practice using intracranial stents in appropriately selected patients with subarachnoid hemorrhage (SAH) as a result of aneurysm rupture.     

Epidemic of end-stage renal disease in people with diabetes in the United States population: do we know the cause?

BACKGROUND: The number of individuals initiating renal replacement therapy in the United States population grew exponentially over the past two decades. Cases of end-stage renal diseae (ESRD) attributed to diabetes accounted for most of this increase. In this report we examined factors that may account for the increase to determine whether it truly represents an epidemic of ESRD due to diabetes. METHODS: We reviewed time trends in data of the United States Renal Data system, the Diabetes Surveillance Program of the Centers for Disease Control and Prevention, and diabetes literature. RESULTS: Recent growth of the number of individuals with diabetes accounted for less than 10% of the increase in the number of diabetes-related ESRD. Instead, most of it was due to a threefold increase in risk of ESRD in people with diabetes and, therefore, qualifies as an epidemic. Curiously, this epidemic occurred despite widening implementation of effective renoprotective therapies. Individuals with type 2 diabetes, regardless of gender, age, or race, experienced the greatest increase in risk. There is no evidence that diabetic patients have been surviving longer, so the increased risk was not attributable to the high risk associated with long duration diabetes. CONCLUSION: We hypothesize that an epidemic of ESRD has occurred in people with diabetes in the United States population over the last two decades. The nature of the factor responsible for the epidemic and the reasons it affects patients with type 2 diabetes particularly are unknown. Research efforts to identify the putative factor deserve high priority, as does a commitment of resources to provide care for the burgeoning number of patients with ESRD and type 2 diabetes.     

Is ghrelin a biomarker for mortality in end-stage renal disease?

Ghrelin is involved in the pathogenesis of protein-energy wasting (PEW), inflammation, and cardiovascular complications in end-stage renal disease (ESRD). Plasma ghrelin may prove to be a powerful biomarker of mortality in ESRD but should be considered in the context of assay specificity, other weight-regulating hormones, nutritional status, systemic inflammation, and cardiovascular risk factors. ESRD patients with PEW, systemic inflammation, and low ghrelin and high leptin concentrations have the highest mortality risk and may benefit the most from ghrelin therapy.     

Are bioprostheses associated with better outcome than mechanical valves in patients with chronic kidney disease requiring dialysis who undergo valve surgery?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether patients with chronic kidney disease who required dialysis that undergo valve surgery have better surgical recovery rates with bioprostheses than with mechanical valves. Altogether more than 96 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Patients with end stage renal disease (ESRD) undergoing cardiac surgery are very fragile, with high in-hospital mortality rates (13-36%) and limited life expectancy (15-42?months in selected studies). Two studies outlined that diabetic ESRD, neurological impairment, age at the operation and poor ventricular function are the strongest predictors of early and late morbidity and mortality. Based on American Heart Association/American College of Cardiology (AHA/ACC) 1998 valvular guidelines, bioprostheses were considered a contraindication in dialysis patients; this statement derived from anecdotal reports of accelerated valve degeneration. Structural valve deterioration was reported in only 5 of 1347 patients who received bioprosthesis through the studies and independent from implantation site. Likelihood of degeneration is low, with a calculated valve-excision rate of 7%, and occurred in a broad range of time (from 10 to 156?months). The AHA/ACC 2006 valvular revised guidelines removed the previous statement (1998) of class IIa recommendation for mechanical valves and class III for tissue valves; in the focus update of 2008, there is still no specific indication for valve selection in dialysis patients, but difficulties in maintaining anticoagulation in these patients was noted. Stroke, haemorrhage and gastro-intestinal bleeding events occurred in almost 15% of patients with mechanical valves during the follow-up, while bioprostheses showed an average event rate of 3.9%. All but one of the selected studies reported no differences in survival between mechanical and biological valves; in five of seven studies, the patients who received bioprostheses were older (mechanical vs biological average 53?years vs 61.4?years), in one study, patients had undergone dialysis for longer period of time, and, in another study, they had suffered from more previous myocardial infarction (mechanical vs biological 9.1% vs 36.2%). Therefore, survivals have been biased in favour of mechanical valves. Taking together these data, biological valves are a suitable treatment for dialysis-dependent patients and, while not superior to mechanical valves in survival due to the aforementioned study biases, exhibit lower valve-related and anti-coagulation related events.     

Should we screen for coronary artery disease in asymptomatic chronic dialysis patients?

The hemodialysis population is characterized by a high prevalence of 'asymptomatic' coronary artery disease (CAD), which should be interpreted differently from asymptomatic disease in the general population. A hemodynamically significant stenosis may not become clinically apparent owing to impaired exercise tolerance and autonomic neuropathy. The continuous presence of silent ischemia may cause heart failure, arrhythmias, and sudden death. Whether revascularization of an asymptomatic dialysis patient improves outcome remains a moot point, although several observational studies and one small RCT suggest a benefit. It can therefore be defended to screen asymptomatic dialysis patients for CAD. A number of noninvasive screening tests are available, but none has proved equally practical and reliable in the dialysis population as in the general population. Myocardial perfusion scintigraphy (MPS) before and after a pharmacological stress such as dipyridamole can reveal both ischemia and myocardial scarring. When compared with coronary angiography, low sensitivities were reported and attributed to impaired vasodilation to dipyridamole in dialysis patients. A more likely explanation is that not every anatomical stenosis will lead to impaired coronary blood flow on MPS. Numerous studies have shown an incremental prognostic value of dipyridamole-MPS over clinical data for prediction of adverse cardiac events, in some studies even over coronary angiography. Pending the availability of high-quality evidence, in our opinion asymptomatic dialysis patients could undergo dipyridamole-MPS, followed by coronary angiography in case of an abnormal scan. This combined physiological and anatomical evaluation of the coronary circulation allows us to determine which coronary stenosis is clinically relevant and therefore should be revascularized.