The role of peritoneal dialysis as the first-line renal replacement modality.

Twenty years after its introduction, peritoneal dialysis (PD) is a well-established alternative to hemodialysis (HD) as a modality of renal replacement therapy. Much debate and research is apparent in the literature, comparing hemodialysis and PD as "opposite" modalities and trying to ascertain which modality should be more optimal. In our opinion, HD and PD are two distinct modalities, each with its own advantages and disadvantages. In addition, it is clear that for both HD and PD, rates of technique failure are high, causing patients to transfer between modalities. The question is thus not which modality is best, but rather, which flow-chart of modalities makes best use of the advantages of each modality, while avoiding its disadvantages. In this respect, HD and PD appear to be complementary modalities. The better preservation of residual renal function, lower risk of infection with hepatitis B and C, better outcome after transplantation, preservation of vascular access, and lower costs are arguments to promote PD as a good initial treatment. When PD-related problems arise (adequacy, ultrafiltration, peritonitis, patient burnout), a timely transfer to HD has to be planned. This editorial tries to review arguments supporting the complementary nature of both modalities, and especially the role of PD as the first-line renal replacement therapy.     

Choice of renal replacement therapy modality and dialysis dependence after acute kidney injury: a systematic review and meta-analysis

Purpose

Choice of renal replacement therapy (RRT) modality may affect renal recovery after acute kidney injury (AKI). We sought to compare the rate of dialysis dependence among severe AKI survivors according to the choice of initial renal replacement therapy (RRT) modality applied [continuous (CRRT) or intermittent (IRRT)].

Methods

Systematic searches of peer-reviewed publications in MEDLINE and EMBASE were performed (last update July 2012). All studies published after 2000 reporting dialysis dependence among survivors from severe AKI requiring RRT were included. Data on follow-up duration, sex, age, chronic kidney disease, illness severity score, vasopressors, and mechanical ventilation were extracted when available. Results were pooled using a random-effects model.

Results

We identified 23 studies: seven randomized controlled trials (RCTs) and 16 observational studies involving 472 and 3,499 survivors, respectively. Pooled analyses of RCTs showed no difference in the rate of dialysis dependence among survivors (relative risk, RR 1.15 [95 % confidence interval (CI) 0.78–1.68], I ² = 0 %). However, pooled analyses of observational studies suggested a higher rate of dialysis dependence among survivors who initially received IRRT as compared with CRRT (RR 1.99 [95 % CI 1.53–2.59], I ² = 42 %). These findings were consistent with adjusted analyses (performed in 7/16 studies), which found a higher rate of dialysis dependence in IRRT-treated patients [odds ratio (OR) 2.2–25 (5 studies)] or no difference (2 studies).

Conclusions

Among AKI survivors, initial treatment with IRRT might be associated with higher rates of dialysis dependence than CRRT. However, this finding largely relies on data from observational trials, potentially subject to allocation bias, hence further high-quality studies are necessary.     

Renal recovery after acute kidney injury: choice of initial renal replacement therapy modality still matters

Renal replacement therapy can be applied either in an intermittent fashion or in a continuous fashion in severe acute kidney injury. To date, no modality has been shown to consistently improve patient survival. In the study recently reported by Sun and colleagues, continuous application of renal replacement therapy was associated with improved renal recovery, defined by lower risk of long-term need for chronic dialysis therapy. This association between nonrecovery and intermittent renal replacement therapy may be explained by a higher rate of hypotensive episodes and the lower capacity for fluid removal during the first 72 hours of therapy. Altogether, this study adds to the growing body of evidence to suggest improved likelihood of recovery of kidney function in critically ill survivors of AKI with continuous modalities for renal replacement therapy.In recent years, there has been increased interest in the long-term outcomes for patients who survive an episode of critical illness. For those survivors who experienced severe acute kidney injury (AKI) during the course of their critical illness, renal recovery is of upmost importance. Indeed, nonrecovery or incomplete recovery of renal function can translate into a need for long-term dialysis – a treatment associated with low quality of life and representing a major burden for healthcare systems.In the previous issue of Critical Care, Sun and colleagues have compared the outcomes of 145 patients who required renal replacement therapy (RRT) for sepsis-related AKI [1]. Their findings suggest that recovery of kidney function to dialysis independence at 60 days was strongly associated with the initial RRT modality applied. Indeed, application of RRT in a continuous fashion (continuous venovenous hemodiafiltration (CVVHDF)) was associated with a higher rate of renal recovery than its application in a prolonged intermittent fashion (extended daily hemofiltration (EDHF)). After accounting for relevant confounding variables in multivariable analysis, initial treatment with CVVHDF was associated with significant 3.8-fold higher odds of recovery of kidney function when compared with initial therapy with EDHF. This difference was evident despite the fact that patients receiving CVVHDF had significantly lower initial mean arterial pressures, more oliguria and lower serum pH at the time of RRT initiation. There was no difference in adjusted mortality rates between the two modalities.The findings of Sun and colleagues are consistent with those obtained in several large cohort studies [2-4] in which higher rates of recovery to dialysis independence were found in survivors of critical illness complicated by AKI initially treated with continuous renal replacement therapy (CRRT) compared with those treated with intermittent renal replacement therapy (IRRT). In a systematic review including 50 studies reporting dialysis dependence in AKI survivors [5], IRRT as an initial modality was associated with a 1.7 times greater risk for dialysis dependence when compared with CRRT (odds ratio, 1.73; 95% confidence interval, 1.35 to 1.68). However, these results are susceptible to treatment allocation bias, as the effect was largely driven by observational studies and was nonsignificant when the analysis was restricted to randomized controlled trials (odds ratio, 1.15; 95% confidence interval, 0.73 to 1.68; n = 7). Recently, a large, population-based Canadian study (not included in the meta-analysis) similarly compared renal recovery among survivors of severe AKI according to the initial RRT modality and included a propensity matched analysis to adjust for treatment allocation [6]. In this study, initial treatment with IRRT, when compared with CRRT, was also associated with a significantly higher likelihood of dialysis dependence at 90 days (21% vs 16%) and during long-term follow-up (27% vs 21%).One shortcoming of these studies was the fact that data were sourced from administrative databases or population registries and that these could not provide patient-level data. The study from Sun and colleagues therefore provides further insights and granularity on patient characteristics at the time of RRT initiation and details on treatment provision [1]. Their data provide plausible explanations for the higher rate of renal recovery associated with initial treatment with CRRT.First, use of CRRT was associated with a trend for fewer episodes of hypotension (15% vs 26%, P = 0.112) and higher average mean arterial pressure during the first 72 hours of therapy (89.7 mmHg vs 83.8 mmHg, P = 0.137) when compared with IRRT. Although these differences failed to reach statistical significance, they were clinically important. This nonsignificance is presumably due to the higher delivered hourly ultrafiltration rate necessary with IRRT to achieve fluid homeostasis targets compared with CRRT (241 ml/hour in the EDHF group vs 149 ml/hour in the CVVHF group, P <0.001). Indeed, Conger and colleagues have long established the loss of autoregulation of renal blood flow in AKI, and the impact of hypotension contributes to further histological damage [7,8]. The increased occurrence of iatrogenic hypotension induced by IRRT to achieve fluid removal targets can logically be expected to contribute to delayed or reduced likelihood of renal recovery.Second, despite a higher hourly ultrafiltration rate, the use of EDHF was associated with a lower ability to remove fluids in the first 72 hours. This is demonstrated by the net negative fluid balance obtained in the CVVHDF group but not in the EDHF group (–0.46 l vs +0.15 l, P = 0.019). The capacity to safely remove fluid in critically ill oligoanuric patients is limited in IRRT compared with CRRT. Fluid accumulation and overload are now recognized as important complications of critical illness and are associated with adverse outcomes [9,10] and reduced renal recovery [10,11]. A direct causal relationship between positive fluid balance and worse renal outcome has yet to be determined; however, these factors may be related to increased pressure exerted by extravascular fluid within an encapsulated organ [12].Finally, the continuous application of RRT mathematically translated into almost double the delivered RRT dose during the first 72 hours (replacement flow: CVVHDF group 4.64 l/day vs EDHF group 2.65 l/day, P <0.001). Whether this higher and more consistently delivered dose early in a patient’s course of critically illness translates into better metabolic homeostasis remains speculative and should be explored in randomized trials, despite prior trials showing no significant impact on survival or recovery by delivered dose [13-15]. The role of enhanced clearance of inflammatory molecules on renal recovery remains to be evaluated.Overall, the study by Sun and colleagues further contributes to the growing body of evidence to suggest that initial treatment with CRRT compared with IRRT in critically ill patients with AKI may confer superiority for increased likelihood of renal recovery. The physiologic reasoning for this conclusion is biologically plausible: CRRT is associated with better hemodynamic stability through reduced episodes of hypotension and improved fluid homeostasis. In the absence of a suitable powered randomized trial with renal recovery as a primary endpoint, the evidence supporting the superiority of initial treatment with CRRT with renal recovery in mind will be derived from observational data such as these. However, given the current burden of evidence suggesting better recovery with CRRT as the initial therapy, physicians should seriously consider moving away from potentially deleterious therapies before proof of their non-inferiority is established. While lower healthcare costs associated with intermittent hemodialysis are often advocated for their primary use in critically ill patients with AKI, formal economic analyses taking long-term dialysis costs into account are necessary to establish the real cost of IRRT in the ICU.     

初探对终末期肾病患者选择透析方式的指导

目的探寻通过有效的方法指导终末期肾病患者正确地选择透析方式。方法2003～2004年在北京大学第三医院就诊的终末期肾病患者共104例,采用全新的理念对该组患者进行有关透析方式选择方面的指导,并统计透析方式的选择情况。结果该组患者对腹膜透析和血液透析的选择处于等同的状态,并明显区别于国内血液透析治疗比例远远大于腹膜透析的现象。结论采用有效的指导方式可以促使终末期肾病患者对透析方式的进行合理的选择,并在尿毒症的治疗收到良好的成本-效益比。     

Continuous renal replacement therapy: the treatment of choice for acute renal failure

The health care issues facing society today are complex. Access to care, quality of life, relative value scales, diagnosis related groups, and cost containment demands have had an impact on the decision-making processes of health care professionals. The availability of alternative therapeutic treatment modalities adds additional considerations when prescribing medical therapy. This is especially true when a patient is diagnosed with renal failure. In the past, either peritoneal dialysis or hemodialysis have been the only therapies for supporting patients with acute renal failure. This article explores continuous renal replacement therapy for the management of acute renal failure: what it is, when and where it should be used, and the responsibilities of nephrology and critical care nurses and physicians.     

Clinical review: Timing of renal replacement therapy

Acute kidney injury is common in intensive care patients and continuous renal replacement therapy is the preferred treatment for this in most centres. Although these techniques have been adopted internationally, there remains significant variation with regard to their clinical application. This is particularly pertinent when one considers that the fundamental questions regarding any treatment, such as initiation, dose and length of treatment, remain a source of debate and have not as yet all been fully answered. In this narrative review we consider the timing of renal replacement therapy, highlighting the relative paucity of high quality data regarding this fundamental question. We examine the role of the usual biochemical criteria as well as conventional clinical indications for commencing renal replacement therapy together with the application of recent classification systems, namely RIFLE and AKIN. We discuss the potential role of biomarkers for acute kidney injury as predictors for the need for renal support and discuss commencing therapy for indications other than acute kidney injury.     

Bench-to-bedside review: treating acid-base abnormalities in the intensive care unit--the role of renal replacement therapy

Acid–base disorders are common in critically ill patients. Metabolic acid–base disorders are particularly common in patients who require acute renal replacement therapy. In these patients, metabolic acidosis is common and multifactorial in origin. Analysis of acid–base status using the Stewart–Figge methodology shows that these patients have greater acidemia despite the presence of hypoalbuminemic alkalosis. This acidemia is mostly secondary to hyperphosphatemia, hyperlactatemia, and the accumulation of unmeasured anions. Once continuous hemofiltration is started, profound changes in acid–base status are rapidly achieved. They result in the progressive resolution of acidemia and acidosis, with a lowering of concentrations of phosphate and unmeasured anions. However, if lactate-based dialysate or replacement fluid are used, then in some patients hyperlactatemia results, which decreases the strong ion difference and induces an iatrogenic metabolic acidosis. Such hyperlactatemic acidosis is particularly marked in lactate-intolerant patients (shock with lactic acidosis and/or liver disease) and is particularly strong if high-volume hemofiltration is performed with the associated high lactate load, which overcomes the patient's metabolic capacity for lactate. In such patients, bicarbonate dialysis seems desirable. In all patients, once hemofiltration is established, it becomes the dominant force in controlling metabolic acid–base status and, in stable patients, it typically results in a degree of metabolic alkalosis. The nature and extent of these acid–base changes is governed by the intensity of plasma water exchange/dialysis and by the 'buffer' content of the replacement fluid/dialysate, with different effects depending on whether lactate, acetate, citrate, or bicarbonate is used. These effects can be achieved in any patient irrespective of whether they have acute renal failure, because of the overwhelming effect of plasma water exchange on nonvolatile acid balance. Critical care physicians must understand the nature, origin, and magnitude of alterations in acid–base status seen with acute renal failure and during continuous hemofiltration if they wish to provide their patients with safe and effective care.     

特发性肾脏替代性脂肪瘤(附1例报告并文献复习)

目的探讨特发性肾脏替代性脂肪瘤(RRL)的临床特点、诊断和治疗方法。方法回顾性分析1例肾脏替代性脂肪瘤患者的临床资料。男性,48岁,体检发现左肾占位入院,超声提示左肾实质破坏,肾盂内强回声团伴声影,左肾被高回声软组织影包裹。CT提示左肾占位,可见明显负值,无明显强化,肾盂内可见高密度影,肾实质不均匀破坏。结果患者行手术治疗,术中探查见左肾被巨大脂肪组织包裹,行肾脏切除术。病理所见患肾皮质高度萎缩,肾脏体积明显增大,肾脏被过度增生的脂肪纤维组织所替代,光镜下可见到大量异常肥大的脂肪细胞。患者术后1周痊愈出院,随访18个月未见肿物复发转移。结论 RRL临床极为罕见,目前国内外文献仅见少数个案报道。RRL需要与慢性感染性肾脏疾病、脂肪瘤、脂肪肉瘤、血管平滑肌脂肪瘤和畸胎瘤等含有脂肪组织的肾脏肿瘤、黄色肉芽肿性肾盂肾炎、肥胖及Cushing综合征等疾病相鉴别。治疗以手术为主,通常需要行肾脏切除术。     

微小病变样原发性肾淀粉样变性1例误诊报告并文献复习

目的 探讨微小病变样原发淀粉样变肾病的临床病理特点及电镜检查在老年肾病中的诊断价值.方法 1例报道结合文献复习.结果 早期轻微病变样淀粉样变肾病可以没有明显的临床特征,光镜下可以表现为微小病变样,确诊必须依赖电镜诊断.结论 对中老年肾病综合征患者治疗前一定要做病理诊断,即使光镜检查为微小病变,也应做电镜检查是否存在淀粉样变.电镜检查对早期淀粉样变肾病而言可能是惟一可靠的诊断手段.     

Status of renal replacement therapy and peritoneal dialysis in Mexico.

Mexico is struggling to gain a place among developed countries; however, there are many socioeconomic and health problems still waiting for resolution. While Mexico has the twelfth largest economy in the world, a large portion of its population is impoverished. Treatment for end-stage renal disease (377 patients per million population) is determined by the individual's access to resources such as private medical care (approximately 3%) and public sources (Social Security System: approximately 40%; Health Secretariat: approximately 57%). With only 6% of the gross national product spent on healthcare and most treatment providers being public health institutions that are often under economic restrictions, it is not surprising that many Mexican patients do not receive renal replacement therapy. Mexico is still the country with the largest utilization of peritoneal dialysis (PD) in the world, with 18% on automated PD, 56% on continuous ambulatory PD (CAPD), and 26% on hemodialysis. Results of PD (patient morbi-mortality, peritonitis rate, and technique survival) in Mexico are comparable to other countries. However, malnutrition and diabetes mellitus are highly prevalent in Mexican patients on CAPD programs, and these conditions are among the most important risk factors for a poor outcome in our setting.     

Clinical review: Patency of the circuit in continuous renal replacement therapy

Premature circuit clotting is a major problem in daily practice of continuous renal replacement therapy (CRRT), increasing blood loss, workload, and costs. Early clotting is related to bioincompatibility, critical illness, vascular access, CRRT circuit, and modality. This review discusses non-anticoagulant and anticoagulant measures to prevent circuit failure. These measures include optimization of the catheter (inner diameter, pattern of flow, and position), the settings of CRRT (partial predilution and individualized control of filtration fraction), and the training of nurses. In addition, anticoagulation is generally required. Systemic anticoagulation interferes with plasmatic coagulation, platelet activation, or both and should be kept at a low dose to mitigate bleeding complications. Regional anticoagulation with citrate emerges as the most promising method.     

替代治疗模式对尿毒症患者血脂代谢的影响

目的比较高通量血液透析、常规血液透析与连续性非卧床腹膜透析3种不同的肾脏替代治疗模式对非糖尿病终末期肾病患者血脂代谢的影响。方法①将90例终末期肾病患者分为高通量血液透析组（HPD组）30例、常规血液透析组（CHD组）30例和连续性非卧床腹膜透析组（CAPD组）30例,分别进行维持性替代治疗并随访3年。入组后每3个月采血测定患者血浆胆固醇（TC）、三酰甘油（TG）、高密度脂蛋白（HDL）、低密度脂蛋白（LDL）、载脂蛋白A（Apo-A）、载脂蛋白B（Apo-B）。对比分析3组在透析开始时、透析1年后和透析3年后上述各项血脂指标的变化情况。②另选取血液透析与腹膜透析治疗模式相互转化的尿毒症患者各10余例,分别测定其在转变透析模式前和转变1年后上述各项血脂指标的变化情况。结果①透析开始时3组非糖尿病终末期肾病患者的血脂各项指标都基本一致,随着替代治疗时间的延长,HPD组内患者TC、TG、LDL和Apo-B逐渐降低,而HDL和Apo-A逐渐升高;CHD组和CAPD组的尿毒症患者随透析时间的延长,TC、TG、LDL和Apo-B都呈逐渐升高趋势,而HDL和Apo-A均逐渐降低,其中TG变化最明显（P〈0.01）;②常规血液透析转为腹膜透析1年后TC和TG的升高有显著性差异（均P〈0.01）。而腹膜透析转为常规血液透析1年后除Apo-B由（0.81±0.61）升至（0.94.±0.35）g/L具有统计学差异（P〈0.05）外,其余各项指标无变化。结论①常规血液透析和非卧床腹膜透析对尿毒症患者的血脂紊乱无改善,且有促进作用,尤其是腹膜透析影响更明显;②腹膜透析的尿毒症患者血脂表现的TC、TG增高比常规血液透析患者略明显,但只出现在透析治疗3年时;③高通量透析可以改善透析患者的血脂代谢。     

Clinical education: a review of the literature

In 2005, the University of Sheffield was commissioned to research the role, function and perceived impact of the clinical nurse educator role in a National Health Service Primary Care Trust. This paper presents the results of Phase I of the study, a review of the literature on clinical education and the series of research questions that were indicated. The importance of clinical education for quality nursing care has long been agreed but has gained increasing attention over the last two decades. This increased attention is the result of policy directives that place work based learning at the centre of health and social care practice. The literature is less equivocal, however, concerning the responsibility for clinical education and asserts various roles including; the lecturer employed by the University; joint appointments; mentors; ward sister; specialist and advanced practitioners including the nurse consultant; and more recently the clinical nurse educator. Clinical educators have reported to have been introduced to meet the professional educational needs of the workforce but there is little empirical or theoretical evidence to support or refute this. This paper is an attempt to begin to address this.     

Renal replacement therapy in end-stage renal disease patients with chronic liver disease and ascites: role of peritoneal dialysis.

Chronic liver disease and cirrhosis account for several thousand deaths in the United States and often these patients have renal disease that progresses to end-stage renal disease (ESRD), necessitating renal replacement therapy. These patients provide significant challenges to their physicians, especially in the management of their ESRD with dialysis. ESRD patients with chronic liver disease and ascites are more difficult to manage on hemodialysis (HD) due to their hemodynamic status and risk of bleeding. Peritoneal dialysis (PD) offers them a viable alternative, along with a stable hemodynamic status and a lower risk of bleeding. The overall morbidity and mortality as well as the risk of peritonitis appear to be almost similar between cirrhotic and non-cirrhotic PD patients. In the absence of clinical trials comparing HD versus PD in such a population, and despite the limited clinical observations, the authors support PD as a viable and effective form of renal replacement therapy for patients with ESRD and associated chronic liver disease with cirrhosis and ascites.     

Clinical results of enzyme replacement therapy in Fabry disease: a comprehensive review of literature

Enzyme replacement therapy (ERT) has been used to treat Fabry disease - a progressive lysosomal storage disorder - since 2001. Two preparations of the enzyme alpha-galactosidase A are available in Europe: agalsidase alpha, produced in a human cell line, and agalsidase beta, produced in Chinese hamster ovary cells. To review critically the published evidence for the clinical efficacy of these two enzyme preparations. A systematic literature search was undertaken to identify open or randomised controlled trials published on Fabry disease since 2001. Eleven trials fulfilled the criteria for inclusion in this review, of a total of 586 references on Fabry disease. To date, no direct comparisons exists between the two available enzyme preparations. Significant clinical benefits compared with placebo, however, have been demonstrated with ERT, with positive effects on the heart, kidneys, nervous system and quality of life. The quality of most of these publications was less than optimal. Further prospective studies are required to confirm the long-term clinical benefits of ERT. More studies are also needed on the effects of ERT in women and on the use of ERT early in the course of Fabry disease, to prevent organ damage. Large national and international outcomes databases will also be invaluable in evaluating treatment effects and safety.     

Bench-to-bedside review: Treating acid–base abnormalities in the intensive care unit – the role of renal replacement therapy

Acid–base disorders are common in critically ill patients. Metabolic acid–base disorders are particularly common in patients who require acute renal replacement therapy. In these patients, metabolic acidosis is common and multifactorial in origin. Analysis of acid–base status using the Stewart–Figge methodology shows that these patients have greater acidemia despite the presence of hypoalbuminemic alkalosis. This acidemia is mostly secondary to hyperphosphatemia, hyperlactatemia, and the accumulation of unmeasured anions. Once continuous hemofiltration is started, profound changes in acid–base status are rapidly achieved. They result in the progressive resolution of acidemia and acidosis, with a lowering of concentrations of phosphate and unmeasured anions. However, if lactate-based dialysate or replacement fluid are used, then in some patients hyperlactatemia results, which decreases the strong ion difference and induces an iatrogenic metabolic acidosis. Such hyperlactatemic acidosis is particularly marked in lactate-intolerant patients (shock with lactic acidosis and/or liver disease) and is particularly strong if high-volume hemofiltration is performed with the associated high lactate load, which overcomes the patient's metabolic capacity for lactate. In such patients, bicarbonate dialysis seems desirable. In all patients, once hemofiltration is established, it becomes the dominant force in controlling metabolic acid–base status and, in stable patients, it typically results in a degree of metabolic alkalosis. The nature and extent of these acid–base changes is governed by the intensity of plasma water exchange/dialysis and by the 'buffer' content of the replacement fluid/dialysate, with different effects depending on whether lactate, acetate, citrate, or bicarbonate is used. These effects can be achieved in any patient irrespective of whether they have acute renal failure, because of the overwhelming effect of plasma water exchange on nonvolatile acid balance. Critical care physicians must understand the nature, origin, and magnitude of alterations in acid–base status seen with acute renal failure and during continuous hemofiltration if they wish to provide their patients with safe and effective care.