The artificial kidney: past, present, and future

World War II can be taken as a turning point after which the introduction and development of several new diagnostic and therapeutic discoveries have revolutionized medicine and improved the expectancy of life for millions. Notable amongst those technological therapeutic achievements is that of the artificial kidney, first used successfully in the closing years of the war. As a result of the improvements that followed, the kidney was the first solid organ whose function could be replaced, at least partially, by a machine. What started then as exploratory efforts to sustain life evolved over the next few decades into life saving replacement therapy for millions worldwide. Chronic maintenance hemodialysis has certainly changed the prognosis of the otherwise fatal end stage kidney disease that had afflicted humans theretofore. Unfortunately, many of the challenges and problems that had to be overcome in making artificial kidney treatment available continue to plague end-stage kidney disease patients on maintenance hemodialysis. Concerted investigative efforts are currently underway to improve the replacement of kidney function with artificial kidneys that better mimic kidney function. This article reviews the beginnings, evolution, and current challenges of the artificial kidney.

Chronic kidney disease as a global public health problem: approaches and initiatives - a position statement from Kidney Disease Improving Global Outcomes

Chronic kidney disease (CKD) is increasingly recognized as a global public health problem. There is now convincing evidence that CKD can be detected using simple laboratory tests, and that treatment can prevent or delay complications of decreased kidney function, slow the progression of kidney disease, and reduce the risk of cardiovascular disease (CVD). Translating these advances to simple and applicable public health measures must be adopted as a goal worldwide. Understanding the relationship between CKD and other chronic diseases is important to developing a public health policy to improve outcomes. The 2004 Kidney Disease Improving Global Outcomes (KDIGO) Controversies Conference on 'Definition and Classification of Chronic Kidney Disease' represented an important endorsement of the Kidney Disease Outcome Quality Initiative definition and classification of CKD by the international community. The 2006 KDIGO Controversies Conference on CKD was convened to consider six major topics: (1) CKD classification, (2) CKD screening and surveillance, (3) public policy for CKD, (4) CVD and CVD risk factors as risk factors for development and progression of CKD, (5) association of CKD with chronic infections, and (6) association of CKD with cancer. This report contains the recommendations from the meeting. It has been reviewed by the conference participants and approved as position statement by the KDIGO Board of Directors. KDIGO will work in collaboration with international and national public health organizations to facilitate implementation of these recommendations.

The Kidney Disease: Improving Global Outcomes website: Comparison of guidelines as a tool for harmonization

Chronic kidney disease (CKD) is a worldwide public health problem with significant comorbidity and mortality. Improving quality of life and survival of CKD patients necessitates a large number of preventive and therapeutic interventions. To resolve these issues several organizations have developed guidelines, which are difficult to compare comprehensively. The Kidney Disease: Improving Global Outcomes website at http://kdigo.org compares five major guidelines. The section 'compare guidelines' covers 41 topics distributed over five major subjects: (1) general clinics; (2) hemodialysis (HD); (3) vascular access for HD; (4) peritoneal dialysis; and (5) chemistries. The tables compare guideline recommendations and the evidence levels on which they are based, with direct links to each of the guidelines. These data show that the different guideline groups tend to propose similar targets, but that nuances in the guideline statements, their rationale, and grading of evidence levels present some discrepancies, although most guidelines are based on the same literature. We conclude that there is an urgent need to harmonize existing guidelines, and for a global initiative to avoid the parallel development of conflicting guidelines on the same topics. The tables displayed on the website offer a basis for structuring this process, a procedure which has recently been initiated by a body composed of the five guideline development groups.

Grading evidence and recommendations for clinical practice guidelines in nephrology. A position statement from Kidney Disease: Improving Global Outcomes (KDIGO)

Considerable variation in grading systems used to rate the strength of guideline recommendations and the quality of the supporting evidence in Nephrology highlights the need for a uniform, internationally accepted, rigorous system. In 2004, Kidney Disease: Improving Global Outcomes (KDIGO) commissioned a methods expert group to recommend an approach for grading in future nephrology guidelines. This position statement by KDIGO recommends adopting the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach for the grading of evidence and guidelines on interventions. The GRADE approach appraises systematic reviews of the benefits and harms of an intervention to determine its net health benefit. The system considers the design, quality, and quantity of studies as well as the consistency and directness of findings when grading the quality of evidence. The strength of the recommendation builds on the quality of the evidence and additional considerations including costs. Adaptations of the GRADE approach are presented to address some issues pertinent to the field of nephrology, including (1) the need to extrapolate from studies performed predominantly in patients without kidney disease, and (2) the need to use qualitative summaries of effects when it is not feasible to quantitatively summarize them. Further refinement of the system will be required for grading of evidence on questions other than those related to intervention effects, such as diagnostic accuracy and prognosis.

Definition, evaluation, and classification of renal osteodystrophy: a position statement from Kidney Disease: Improving Global Outcomes (KDIGO)

Disturbances in mineral and bone metabolism are prevalent in chronic kidney disease (CKD) and are an important cause of morbidity, decreased quality of life, and extraskeletal calcification that have been associated with increased cardiovascular mortality. These disturbances have traditionally been termed renal osteodystrophy and classified based on bone biopsy. Kidney Disease: Improving Global Outcomes (KDIGO) sponsored a Controversies Conference on Renal Osteodystrophy to (1) develop a clear, clinically relevant, and internationally acceptable definition and classification system, (2) develop a consensus for bone biopsy evaluation and classification, and (3) evaluate laboratory and imaging markers for the clinical assessment of patients with CKD. It is recommended that (1) the term renal osteodystrophy be used exclusively to define alterations in bone morphology associated with CKD, which can be further assessed by histomorphometry, and the results reported based on a unified classification system that includes parameters of turnover, mineralization, and volume, and (2) the term CKD-Mineral and Bone Disorder (CKD-MBD) be used to describe a broader clinical syndrome that develops as a systemic disorder of mineral and bone metabolism due to CKD, which is manifested by abnormalities in bone and mineral metabolism and/or extra-skeletal calcification. The international adoption of these recommendations will greatly enhance communication, facilitate clinical decision-making, and promote the evolution of evidence-based clinical practice guidelines worldwide.

The importance of early treatment of the anaemia of chronic kidney disease

The beneficial effects of treating the anaemia of dialysis-dependent patients with erythropoietin on the improvement of cardiac status, exercise capacity, cognitive function and quality of life are well established. Equally, if not more important is the reduction in morbidity and mortality that accompanies the treatment of anaemia with epoietin. These documented improvements in outcomes of care notwithstanding, mortality and morbidity due to cardiovascular disease (CVD) remain high in dialysis patients. Recent epidemiological evidence indicates that: (i) the prevalence of CVD is very high in patients at the start of dialysis; (ii) pre-existing CVD is the major risk factor for mortality and morbidity on dialysis; (iii) CVD begins early in the course of kidney disease, shows an inverse relationship to kidney function and increases in prevalence and severity with progression of kidney disease; and (iv) corrective measures, which take 3-5 years to show a favourable effect, must be instituted well before the initiation of dialysis. Hypertension and anaemia, which develop in the course of progressive reduction in kidney function, are the principal risk factors for the prevalence of left ventricular hypertrophy (LVH) in those with chronic kidney disease, and their treatment has been shown to arrest or reverse LVH in these individuals. Whereas the treatment of hypertension early in the course of kidney disease has been incorporated into clinical practice, there has been reluctance in the treatment of anaemia because of the possibility of worsening kidney function with epoietin, as shown in rats. There is now convincing evidence that epoietin has no potential adverse effect on kidney function in humans. While the most compelling reason for the early treatment of the anaemia of kidney disease is its beneficial effect on cardiovascular function, other documented potential benefits are improvements in exercise capacity, cognitive function and quality of life.

The national epidemic of chronic kidney disease. What we know and what we can do

The alarming increase in the incidence and mortality rate of end-stage renal disease (ESRD) over the past several years has prompted concerned physicians to ask why--and to ponder what can be done to ameliorate the situation. This article, the first in a seven-part series coordinated by the National Kidney Foundation, examines the factors surrounding the epidemic of chronic kidney disease and introduces readers to the organization's new clinical practice guidelines developed through its Kidney Disease Outcomes Quality Initiative. These recommendations emphasize early detection and treatment and offer a new avenue of communication between primary care physicians and nephrologists.

Does the choice of renal replacement therapy adversely affect the hypercoagulability associated with renal disease?

Both a bleeding diathesis and a tendency to hypercoagulability occur in the course of renal disease. More common and consistent in occurrence during the progression of renal failure to end-stage renal disease is the hemostatic defect. The principal cause of this abnormality is the uremic state and, as a rule, it is reversible following the institution of adequate renal replacement therapy and correction of the anemia with epoietin. By contrast, the tendency to hypercoagulability is usually encountered in patients with the nephrotic syndrome and shows a correlation to the degree of hypoalbuminemia, being more evident at serum albumin levels of < 2 g/dl. Although the coagulopathy is complex in pathogenesis, a defect in the fibrinolytic process plays a critical role in its development. A tendency to pro-thrombosis due to abnormal fibrinolysis has been identified also in patients on renal replacement therapy with continuous ambulatory peritoneal dialysis (CAPD). The observed coagulation abnormalities resemble those of the nephrotic syndrome. Although its etiology remains undefined, a role for the albumin losses in the peritoneal dialysate has been implicated in the prothrombotic state that occurs in some CAPD patients.

Design and statistical issues of the hemodialysis (HEMO) study

The Hemodialysis Study is a multicenter clinical trial of hemodialysis prescriptions for patients with end stage renal disease. Participants from over 65 dialysis facilities associated with 15 clinical centers in the United States are randomized in a 2 x 2 factorial design to dialysis prescriptions targeted to a standard dose or a high dose, and to either low or high flux membranes. The primary outcome variable is mortality; major secondary outcomes are defined based on hospitalizations due to cardiovascular or infectious complications, and on the decline of serum albumin. The Outcome Committee, consisting of study investigators, uses a blinded review system to classify causes of death and hospitalizations related to the major secondary outcomes. The dialysis dose intervention is directed by the Data Coordinating Center using urea kinetic modeling programs that analyze results from dialysis treatments to monitor adherence to the study targets, adjust suggested dialysis prescriptions, and assist in trouble-shooting problems with the delivery of dialysis. The study design has adequate power to detect reductions in mortality rate equal to 25% of the projected baseline mortality rate for both of the interventions.

Santorio Sanctorius (1561-1636) - founding father of metabolic balance studies

The intellectual renaissance of the closing decades of the sixteenth century provided the fertile ground in which the budding spirit of scientific inquiry emerged in the seventeenth century. Direct observation, soon augmented by instrumentation that allowed for quantification and, therefore, verification, became the revelatory medium for the progress of the sciences. In medicine, progress depended on the application of the exact sciences of chemistry, mathematics and physics to the study of function. One of the medical luminaries of this early scientific revolution was Santorio Sanctorius (1561- 1636), whose principal contributions were his studies on insensible perspiration and his instrumental inventions. To study insensible perspiration, he designed a movable platform attached to a steelyard scale that allowed for the quantification of changes in body weight of subjects who partook in their daily activities on the platform. After years of self-experimentation, he applied his device to the study of patients. Unfortunately, his records are lost. What survives is a summary of his observations in a series of aphorisms published under the title of Ars de statica medicina, in 1614; 3 years after he was appointed Ordinary Professor of Theoretical Medicine in Padua. To enhance the bedside evaluation of patients, he also designed instruments to quantify the pulse, temperature, and environmental humidity. For his pioneering and detailed balance studies, Sanctorius clearly deserves the title of founding father of metabolic balance studies.

The kidney in ancient Egyptian medicine: where does it stand?

Driven by their deep-seated desire for eternal life in a healthy body, ancient Egyptians were one of the first civilizations to begin collecting and recording medical lore and medicinals that were effective for a healthy body. With its religious origins, medical care was initially provided by priests, but evolved over time into an independent discipline practiced by the swnw (sounou) or physician. What has been preserved of their knowledge in extant medical papyri reflects the great capacity of Egyptians for practical achievement in treating symptoms, but lacks the abstract thought that was to come with the advent of the more rational Greek medicine. The number of prescriptions and incantations for the management of urinary disorders (hematuria, retention, frequency, infection) and dropsy that are mentioned in extant medical papyri likely reflect the frequency with which these problems were encountered. Urine was thought to be formed in the region of the bladder, by a process considered akin to purification. Available studies on preserved mummies indicate that kidney disease was not uncommon. Whether a functional role of the kidney was appreciated at all is highly doubtful. On the other hand, the available evidence suggests an awareness of the kidney (ggt) to which was ascribed a mythological role that may well account for why the kidneys and the heart were the only organs not removed during the process of mummification.

Methods used to evaluate the quality of evidence underlying the National Kidney Foundation-Dialysis Outcomes Quality Initiative Clinical Practice Guidelines: description, findings, and implications

This report describes the approach the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) used to assess the strength of published evidence pertinent to individual NKF-DOQI Clinical Practice Guidelines, as well as the relationship between that approach and methods used by the US Preventive Services Task Force, the Cochrane Collaboration, and the Agency for Health Care Policy and Research to rate the quality and/or strength of evidence. We also present the results of an analysis of the strength of evidence underlying the NKF-DOQI Guidelines showing that one cannot infer the quality of evidence reported in a study (rated either on a 0-to-1 scale or categorically as excellent, very good, good, fair, or poor) simply by knowing the type of study design used (randomized trial, nonrandomized trial, natural experiment, cohort study, cross-sectional study, case-control study, case report). Issues related to assessment of the strength of evidence underlying a practice guideline opposed to that reported in an individual study are highlighted.

The dialysis outcomes quality initiative: history, impact, and prospects

Rigorously developed clinical practice guidelines have the potential to improve patient outcomes. It is toward that end that the National Kidney Foundation (NKF) launched in March 1995 the Dialysis Outcome Quality Initiative (DOQI), an ambitious effort to develop evidence-based clinical practice guidelines for the care of patients with end-stage renal disease (ESRD). Independent, interdisciplinary work groups conducted a structured review of the content and methodologic rigor of all the published literature pertinent to four selected topics: hemodialysis adequacy, peritoneal dialysis adequacy, vascular access, and anemia. Following expert, organizational, and public review, the guidelines were issued in September and October 1997. An implementation plan that called for widespread dissemination of the guidelines and facilitation of adoption of them has resulted in their broad acceptance and Integration into quality improvement efforts. Additional guidelines on nutrition have recently been completed, while others on bone disease, hypertension, and hyperlipidemia are in various stages of planning or development. A major determinant of poor outcome of maintenance dialysis patients is the debilitated state of many individuals with ESRD at the time that they commence dialysis therapy. The recognition of this problem has stimulated an interest in extending the guidelines to management of patients with less severe renal insufficiency, well before they need renal replacement therapy; and to the early detection of renal insufficiency by a proteinuria and albuminuria risk assessment, detection, and elimination (PARADE) program. What started as an initiative to improve the quality of care of dialysis patients has evolved into a considerably expanded effort to making lives better for all individuals with any level of renal insufficiency.

Michelangelo: art, anatomy, and the kidney

Michelangelo (1475-1564) had a life-long interest in anatomy that began with his participation in public dissections in his early teens, when he joined the court of Lorenzo de' Medici and was exposed to its physician-philosopher members. By the age of 18, he began to perform his own dissections. His early anatomic interests were revived later in life when he aspired to publish a book on anatomy for artists and to collaborate in the illustration of a medical anatomy text that was being prepared by the Paduan anatomist Realdo Colombo (1516-1559). His relationship with Colombo likely began when Colombo diagnosed and treated him for nephrolithiasis in 1549. He seems to have developed gouty arthritis in 1555, making the possibility of uric acid stones a distinct probability. Recurrent urinary stones until the end of his life are well documented in his correspondence, and available documents imply that he may have suffered from nephrolithiasis earlier in life. His terminal illness with symptoms of fluid overload suggests that he may have sustained obstructive nephropathy. That this may account for his interest in kidney function is evident in his poetry and drawings. Most impressive in this regard is the mantle of the Creator in his painting of the Separation of Land and Water in the Sistine Ceiling, which is in the shape of a bisected right kidney. His use of the renal outline in a scene representing the separation of solids (Land) from liquid (Water) suggests that Michelangelo was likely familiar with the anatomy and function of the kidney as it was understood at the time.

Cardiovascular mortality and morbidity in dialysis patients

Dialysis patients constitute a high-risk group for cardiovascular disease, which accounts for 40% of deaths in these patients. After stratification for age, race and gender, cardiovascular mortality is several orders of magnitude (10-20 times) higher in dialysis patients than in the general population. A clustering of risk factors renders dialysis patients especially susceptible to cardiovascular disease. Their morbidity and mortality can be favorably altered by interventional measures which systematically address and modify each individual risk factor. It is necessary to institute intervention during the course of progressive renal failure, well before the onset of end-stage renal disease and the initiation of dialysis.

Lessons from the Hemodialysis (HEMO) Study: an improved measure of the actual hemodialysis dose

The Hemodialysis (HEMO) Study is a multicenter, prospective, randomized, 2 x 2 factorial clinical trial designed to evaluate the efficacy of the dose of dialysis delivered ("standard" v "high") and dialysis membrane flux ("low" v "high") in reducing the morbidity and mortality of patients. The study is nearly half complete. Although both patients and investigators are blinded to the overall findings, which will not be available for another 3 years, important data have been generated from which a more accurate expression has been derived for the dose of dialysis received by each patient in the trial. This new expression of the effectiveness of dialysis, eKt/V, is a two-pool approximation derived from the traditional single-pool Kt/V (spKt/V) and time on dialysis. The dialysis prescription for the HEMO Study subjects is individualized to achieve the target dose for each patient and is closely monitored by measuring the more accurate and validated expression of eKt/N. Comparisons of the HEMO Study dose of dialysis with other studies have been confused by this unique expression (eKt/V) of the dialysis dose and adequacy adopted for the HEMO Study. The target eKt/V dose in the "standard" arm of the Study is 1.05 and in the "high" arm is 1.45 per dialysis thrice weekly. Based on data available from 426 subjects randomized to each arm, the target of 1.05 in the "standard" dose of the HEMO Study is equivalent to an spKt/V of 1.32, and that of the "high" dose, 1.67. Thus, volunteers in the "standard" arm of the Study are receiving a tightly controlled and closely monitored dose, which is above the current national mean spKt/V, and above that of the accepted minimum standard spKt/N of 1.2. When completed, the HEMO Study will show whether there are merits of a tightly controlled hemodialysis dose that is consistently delivered over a prolonged period and whether a high dose is beneficial and safe to prescribe.

An overview of the National Kidney Foundation-Dialysis Outcomes Quality Initiative Implementation

Rigorously developed clinical practice guidelines have the potential to improve outcomes and favorably alter practice patterns. Because of widespread community concerns over the quality of dialysis care, the National Kidney Foundation initiated a Dialysis Outcomes Quality Initiative (NKF-DOQI) in March 1995 in an effort to create evidence-based best-practice clinical guidelines. Independent interdisciplinary Work Groups reviewed the available body of scientific literature on four selected topics: hemodialysis adequacy, peritoneal dialysis adequacy, vascular access, and anemia. More than 11,000 publications were identified, of which 1,500 were considered relevant and were subjected to structured review. Draft guidelines, with supporting rationales of their evidentiary basis, were subjected to a three-stage public and organizational review process. The final guidelines were issued in the fall of 1997. Because the potential benefit of guidelines depends on their implementation, planning for the implementation of NKF-DOQI was begun simultaneously with its review process. A 3-year implementation plan, with specific priorities and estimated costs, was developed and set into action by the end of 1997. The main objectives of the rather diverse and multifaceted plan of action are translating the NKF-DOQI Guidelines into clinical practice, building on what has been accomplished, and continued evaluation and review of the Guidelines.

On the epidemic of cardiovascular disease in patients with chronic renal disease and progressive renal failure: a first step to improve the outcomes

Hundreds of thousands of individuals are alive today because of the availability of dialysis for the treatment of patients with end-stage renal disease (ESRD). From the outset, it was evident that this was a costly therapy and would require specialized training. The federal government responded by providing financial support and medicine by establishing the discipline of nephrology to provide specialized training. As a result, the center stage that ESRD has come to occupy was dictated by a successful treatment in the purview of a new discipline by a model and well-intentioned, but restrictive, law that provided support only to the terminal stage of kidney disease. That this natural evolution was short-sighted has become a belated, but well-deserved, focus of attention. The care of chronic renal disease (CRD) patients cannot start after the onset of ESRD when renal replacement therapy is initiated but must be set into motion when renal failure first begins to exert its detrimental effects on the metabolic balance, function, and structure of the body. Attentive care is needed throughout the course of progressive renal failure, because once CRD begins to progress, there is an increasing number of detrimental consequences whose cumulative burden will exert its ravages on the body simultaneously with that of the ongoing loss of renal function. Consequently, the patient with CRD who presents in ESRD has already sustained considerable, often irreversible, loss of body function. Preventive measures to circumvent this eventuality are most effective, cost-efficient, and of greatest benefit when instituted early in the course of progressive CRD. This is probably truest of cardiovascular disease, which is the leading cause of mortality of patients on dialysis and following transplantation. The report of the National Kidney Foundation Task Force on Cardiovascular Disease in CRD is a first attempt to promulgate and provide evidence-based recommendations for this holistic approach to the care of patients with renal disease.

Assessment of structure and function in progressive renal disease

The incidence and prevalence rates of end-stage renal disease (ESRD) in the United States continue to increase. In 1995, the incidence rate was 262 per million population, with a point prevalence rate of 975 per million population. The exact number of individuals with abnormal renal function but not yet at end stage is difficult to assess. Crude estimates suggest that approximately 0.4% of the U.S. population has serum creatinine values greater than 2.0 mg/dl. In some sub-populations, such as African Americans, the estimate is + as high as 1.0%. The rate of progression, likewise, is difficult to assess. In general, renal manifestations of certain systemic diseases such as diabetes mellitus and systemic lupus erythematosus, and those with significant proteinuria (usually greater that 3.0 g/24 hr) seem to have a more rapid progressive course to end stage. If intervention is expected to be successful in halting or slowing down progression, accurate assessment of the early manifestations of renal disease, structure, and function need to be established. Currently accepted methods of assessment of renal disease include measurement of renal function such as serum creatinine and glomerular filtration rate, measurement of proteinuria, assessment of tubular function, glomerular sieving and permselectivity, radiologic imaging techniques, and evaluation of histo-morphometry. Interventions that have been shown to slow progression include control of hypertension, and treatment modalities that reduce proteinuria, such as, the use of angiotensin converting enzyme inhibitors. Further clinical and basic science studies are needed to accurately define the important predictors of progression, and interventions that are effective in slowing or halting progression.

The National Kidney Foundation Dialysis Outcomes Quality Initiative

Rigorously developed clinical practice guidelines have the potential to change practice patterns to obtain improved patient outcomes. Toward that end, in March 1995 the National Kidney Foundation initiated the Dialysis Outcomes Quality Initiative, a comprehensive effort to create literature-based clinical practice guidelines in nephrology. Independent interdisciplinary work groups reviewed the available body of scientific literature on the following topics: hemodialysis adequacy, peritoneal dialysis adequacy, vascular access, and anemia. More than 11,000 papers were identified; of these approximately 1500 were found to be relevant, requiring formal structured review. Work groups formulated draft guidelines with supporting rationales that included the evidentiary basis for the recommendations. The draft guidelines were subjected to an unprecedented three-stage review process that involved more than 50 organizations from the renal community, including end-stage renal disease networks, patients dialysis providers, managed care organizations, and government. The finalized guidelines were issued in September 1997. Planned guideline implementation activities will focus on achieving the following: cooperation from the renal community; education of patients, clinicians, policy makers, and dialysis providers; information system tools to facilitate adoption of the guidelines; and evaluation strategies to determine whether practice patterns and outcome goals are achieved.

National Kidney Foundation: Dialysis Outcome Quality Initiative--development of methodology for clinical practice guidelines

BACKGROUND

The NKF-DOQI (National Kidney Foundation--Dialysis Outcomes Quality Initiative) began in March 1995 with the following objectives: To improve end-stage renal disease (ESRF) patient survival, to reduce patient morbidity, to increase efficiency of care, and to improve quality of life for ESRF patients.

METHODS

The development of the NKF-DOQI Clinical Practice Guidelines focused on haemodialysis adequacy, peritoneal dialysis adequacy, vascular access, and anaemia. Principles guiding the methodology included scientific and methodological rigour, interdisciplinary approach, independence of the Work Groups, and an open review process. Unique features of this evidence-based guideline development process included the use of mock guidelines and rationales to guide the literature research, and an unprecedented three-stage review process.

RESULTS

Work Groups reviewed more than 11,000 articles. A total of 114 clinical practice guidelines were developed by the Work Groups; these have been reviewed by more than 1200 professionals and patients.

CONCLUSION

The NKF-DOQI Clinical Practice Guidelines has been a unifying effort for the entire renal community. The guidelines are an important step in the process of improving the quality of dialysis practice and improving ESRF patient outcomes. Priorities for implementation of the guidelines include education of ESRF professionals and patients, working with providers and insurers to encourage compliance, and follow-up evaluation of patient outcomes to quantify compliance results.

A history of edema and its management

The obvious disfigurement caused by clinically evident edema has been a matter of medical concern for ages. Most of the early writings on the subject (Sumerian, Babylonian, Egyptian, Greek) center on dropsy, its causes and management. While reference to the heart is made in the ancient texts, much of the focus is on the abdominal (ascitic) accumulation of fluid. The role of the heart and "dropsy of the chest" began to be differentiated and attract attention sometime by the end of the seventeenth century, and were well appreciated by the eighteenth century. By the beginning of the nineteenth century the reports of John Blackall and Richard Bright provided new insight by differentiating dropsy into that of cardiac and renal origins. The role of salt, initially measured and thought in terms of its anion chloride, began to be appreciated by the middle to late nineteenth century. Its mobilization, however, remained problematic. The "cure de dechloruration", which gained fame by the end of the nineteenth century, was not always a successful undertaking. The treatment of dropsy, which centered on augmenting secretions (diaphoretics, purgatives) or mechanical removal of body fluids (bleeding, leeching, lancing), remained a frustrating and chancy undertaking for much of the time that medicine has had to deal with it. Although mercury had been advocated as a diuretic in the sixteenth century, even the organic mercurials that were introduced after World War II were limited in their effectiveness. The discovery of sulfanilamide-induced sodium bicarbonate diuresis in the late 1940s was to provide the first step in the new age of clinically effective diuretics, which began in the 1950s with the introduction of chlorothiazide, the first orally effective agent to mobilize sodium chloride. The subsequent introduction of more potent diuretics was made possible by concurrent advances in renal physiology and the understanding of the sodium handling by the kidney.

Realdo Colombo (1516-1559). A reappraisal

A pupil and then the successor of Vesalius to the Chair of Anatomy and Surgery at the University of Padua, Matteo Realdo Colombo (1516-1559) was equally consumed by the flame of scientific inquiry and recognition. His sole contribution to the literature, De Re Anatomica, was published after his death in 1559. In it, he correctly describes the position of the right kidney as lower than that of the left and provides the best description of the pulmonary circulation before that of William Harvey, who in his text duly acknowledged Colombo's contributions. In the concluding chapter, he establishes the beginnings of morbid anatomy in describing diseased organs. De Re Anatomica was widely used as a textbook of anatomy, being translated into English in 1578 and German in 1609. He came to be sufficiently well known to become physician to the Vatican. One of his best known patients was Michelangelo, with whom he vainly tried to collaborate in illustrating De Re Anatomica. A regrettable eventuality, which could have reversed the fortunes of Vesalius and Colombo in the annals of the history of medicine.

Nonsteroidal anti-inflammatory drugs and acute renal failure in the elderly. A risk-benefit assessment

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most valuable groups of available medications because of their effectiveness in relieving pain, particularly that associated with rheumatoid arthritis. They are also among the most commonly prescribed drugs and, because of their availability over-the-counter, they are among the most widely consumed agents, especially by elderly people. Older individuals are more predisposed to the renal adverse effects of NSAIDs, because of: (i) age-associated changes in renal function; (ii) the prevalence of comorbid conditions (congestive heart failure, hypertension, hepatic cirrhosis, renal insufficiency); and (iii) the pervasive use of concomitant drugs that affect kidney function (diuretics, antihypertensives). However, because the incidence of NSAID-induced acute renal failure (ARF) is relatively low, and because it occurs in an identifiable and therefore preventable setting, the benefits of limited NSAID use outweigh the risks of this adverse effect. Using NSAIDs for a restricted period of time at the lowest effective dosage, and informing patients of the conditions in which ARF can occur, should minimise the risk of this effect. If the use of an NSAID in a patient at potential risk of ARF is necessary, close monitoring of renal function should further reduce the already low risk:benefit ratio for this adverse effect.

Membranous glomerulonephritis associated with inflammatory demyelinating peripheral neuropathies

A 55-year-old man with chronic inflammatory demyelinating polyradiculoneuropathy developed the nephrotic syndrome. Renal biopsy showed stage I membranous glomerulonephritis. Review of the literature revealed the association of these two rare syndromes, considered to be due to immunologic dysfunction, in two other cases, as well as several cases of the acute form of demyelinating peripheral polyradiculoneuropathy. The nephrotic syndrome appears to be persistent in the chronic form of the peripheral neuropathy but reversible in its acute form following immunosuppressive therapy. The possibility of a common immunopathogenesis in the association of membranous glomerulonephritis and inflammatory demyelinating peripheral neuropathies deserves further scrutiny.