Solute and Water Transport in Peritoneal Dialysis: A Case-Based Primer.

Peritoneal dialysis (PD) is an effective therapy for patients with end-stage kidney disease. Dialysis solutions containing physiologic concentrations of electrolytes and base, as well as glucose often at supraphysiologic concentrations, are infused into the peritoneal cavity for solute and water exchange, and the patient's own peritoneal membrane is used for dialysis. The peritoneal membrane is dominated by small pores, which allow transport of water and small-molecular-size solutes, including electrolytes, by way of both diffusion and convection. Through small pores, diffusion allows the movement of solutes from the high-concentration compartment to a lower-concentration region. Also, through small pores, water and solutes move together by convection in response to an osmotic force. The glucose in the dialysis solution generates osmotic force to drive convection. In addition to small pores, the peritoneal membrane contains a specialized water channel, aquaporin 1, which is also present in capillaries of the peritoneal membrane. These specialized water channels, which are upregulated by glucose, allow water transport without solute (free water) in response to the osmotic force induced by glucose in the PD solution. During a PD exchange, net loss or gain of electrolytes and base is determined by both their gradient between capillary blood and dialysis solution and the net ultrafiltration volume. Developing a PD prescription, including the amount of glucose used, and changing the prescription in response to dietary changes and/or loss of residual kidney function requires a sound understanding of the peritoneal physiology. The case studies presented here help solidify the basic elements of PD prescription and how the PD prescription should be altered in response to changing clinical situations.

Diagnostic Dilemma: A Case of Endogenous Peritonitis.

Endogenous peritonitis resulting from inflammation or perforation of an abdominal viscus-a result, for example, of diverticulitis, cholecystitis, or acute appendicitis-can be a complication in patients undergoing peritoneal dialysis (PD), with significant morbidity and a high incidence of catheter loss.Here, we describe an end-stage renal disease patient on PD who presented with acute abdominal pain and who was diagnosed with uncomplicated PD peritonitis. His clinical course was complicated by development of eosinophilic peritonitis because of an allergy to vancomycin. Subsequently, when he failed to show clinical improvement, abdominal and pelvic imaging revealed severe appendicitis, which necessitated emergent surgical intervention.

Bleeding Peritoneum During Peritoneal Dialysis: A Case of Early Encapsulating Peritoneal Sclerosis?

Complications of peritoneal dialysis (PD) create a significant burden for patients and providers. Some complications, such as infections and leaks, are preventable or easily treatable; however, potential fatal complications, such as encapsulating peritoneal sclerosis (EPS), cost patients their lives. Here, we present the case of a PD patient who might have had early, subtle, but ominous symptoms and signs of EPS, diagnosed in its early stages and promptly managed.A 57-year-old man who had been receiving PD for 6 years began having recurrent episodes of abdominal pain, blood-tinged effluent, and peritonitis. Even after successful treatment of his peritonitis episode, his dialysate effluent would be intermittently hazy or pinkish. When he presented with similar complaints for the third time, he was diagnosed with EPS after laparoscopy for further evaluation during his hospitalization.Encapsulating peritoneal sclerosis is a rare complication of PD. The advanced stages of EPS with "EPS syndrome" portend a grave prognosis because of small-bowel obstruction, malnutrition, infection, and death. Early recognition and timely intervention can be a strategy to potentially prevent the progression of EPS.

Continuous Ambulatory Peritoneal Dialysis and Automated Peritoneal Dialysis: What, Who, Why, and How? Review and Case Study.

Peritoneal dialysis (PD) is an umbrella term that encompasses a variety of techniques such as continuous ambulatory PD, automated PD, tidal PD, and intermittent PD, among others. The various techniques exist to tailor the PD prescription to meet the goals of individual patients. Various clinical and nonclinical factors can change over time, requiring a change to the PD prescription. This article uses a practical case study to highlight the intricacies of the calculations behind PD prescription to achieve clearance goals. The objective is to demonstrate that all modalities of PD should be considered in the spectrum of clinical tools for achieving adequate dialysis.

Peritoneal dialysis peritonitis: common presentation by an uncommon organism.

Peritonitis remains a leading complication of peritoneal dialysis (PD). About 18% of the infection-related mortality in PD patients is a result of peritonitis. We present a case of peritonitis in a patient on automated PD in whom the infection was not related to a break in PD technique, but to an unusual cause: retrograde transmission of a gonococcal organism.

Nanotechnology and adeno-associated virus-based decorin gene therapy ameliorates peritoneal fibrosis.

Peritoneal dialysis (PD) is a life-sustaining therapy for end-stage renal disease (ESRD), used by 10-15% of the dialysis population worldwide. Peritoneal fibrosis (PF) is a known complication of long-term PD and frequently follows episodes of peritonitis, rendering the peritoneal membrane inadequate for dialysis. Transforming growth factor (TGF)-ß is an inducer of fibrosis in several tissues and organs, and its overexpression has been correlated with PF. Animal models of peritonitis have shown an increase in expression of TGF-ß in the peritoneal tissue. Decorin, a proteoglycan and component of the extracellular matrix, inactivates TGF-ß, consequently reducing fibrosis in many tissues. Recently, gold nanoparticles (GNP) have been used for drug delivery in a variety of settings. In the present study, we tested the possibility that GNP-delivered decorin gene therapy ameliorates zymosan-mediated PF. We created a PF model using zymosan-induced peritonitis. Rats were treated with no decorin, GNP-decorin, or adeno-associated virus-decorin (AAV-decorin) and compared with controls. Tissue samples were then stained for Masson's trichrome, enface silver, and hematoxylin and eosin, and immunohistochemistry was carried out with antibodies to TGF-ß1, α-smooth muscle actin (α-SMA), and VEGF. Animals which were treated with GNP-decorin and AAV-decorin gene therapy had significant reductions in PF compared with untreated animals. Compared with untreated animals, the treated animals had better preserved peritoneal mesothelial cell size, a significant decrease in peritoneal thickness, and decreased α-SMA. Quantitative PCR measurements showed a significant decrease in the peritoneal tissue levels of α-SMA, TGF-ß, and VEGF in treated vs. untreated animals. This study shows that both GNP-delivered and AAV-mediated decorin gene therapies significantly decrease PF in vivo in a rodent model. This approach has important clinical translational potential in providing a therapeutic strategy to prevent PF in PD patients.

Decompensated high-output congestive heart failure in a patient with AVF and the role of right heart catheterization: a case study.

A 70-year-old Caucasian male presented 8 months postcadaveric renal transplant with slowly progressive shortness of breath, abdominal distention, and cough for a duration of a few days. Thorough evaluation found him to have severe pulmonary hypertension (PH) on echocardiogram with decompensated high-output congestive heart failure. A right heart catheterization was done, which confirmed elevated right-sided pressures and high cardiac output. The mean pulmonary artery pressure, on a Swan-Ganz catheter, improved from 37 to 30 mmHg on partial manual occlusion of his still functioning hemodialysis arteriovenous fistula. Subsequently, the patient underwent ligation of the fistula and this led to gradual improvement in his symptoms. Follow-up right heart catheterization and echocardiogram showed marked improvement and normalization of right heart pressures. We recommend that patients with arteriovenous fistula should undergo close monitoring for development of early signs and symptoms of congestive heart failure and screening for PH by echocardiography post-kidney transplant. Right heart catheterization should be considered if screening is positive. Risk and benefit of fistula closure should be weighed in face of reduced survival from PH in dialysis patients and closure should be considered in post-transplant patients.

Post-transplant Lymphoproliferative Disorder--a case of late-onset T-cell lymphoma after failed renal transplant.

Post-transplant lymphoproliferative disease (PTLD) is a rare but life-threatening complication after solid organ transplantation. The risk of PTLD varies with recipient age, serostatus of the donor and the recipient for Epstein-Barr virus, type of organ transplanted, and intensity of immunosuppression. The risk of PTLD is highest in the early post-transplant period, but the cumulative risk increases with time. We report a case of PTLD occurring 17 years after renal transplantation in a 59-year-old woman.

A Case for Early Screening for Diabetic Kidney Disease.

Chronic kidney disease (CKD) is a public health dilemma contributing to increasing global morbidity and mortality. There is increasing recognition that early detection and management of CKD is critical in delaying disease progression as well as improving mortality rates. However, kidney disease is a silent process and usually goes undetected until more advanced stages, wherein the opportunity to intervene and improve kidney-related outcome is diminished, since awareness of CKD is low in earlier stages. Herein, we will review the screening and detection strategies for CKD as well as the importance of intervention in early stages to reduce progression and also the burden of CKD.

Clinical presentation & management of glomerular diseases: hematuria, nephritic & nephrotic syndrome.

Because the differential diagnosis for glomerulonephritis (GN) is broad, using a classification schema is helpful to narrow the causes of GN in a systematic manner. The etiology of glomerulonephritis can be classified by their clinical presentation (nephrotic, nephritic, rapidly progressive GN, chronic GN) or by histopathology. GN may be restricted to the kidney (primary glomerulonephritis) or be a secondary to a systemic disease (secondary glomerulonephritis). The nephrotic syndrome is defined by the presence of heavy proteinuria (protein excretion greater than 3.0 g/24 hours), hypoalbuminemia (less than 3.0 g/dL), and peripheral edema. Hyperlipidemia and thrombotic disease may be present. The nephritic syndrome is associated with hematuria and proteinuria and abnormal kidney function and carries poorer prognosis and is typically associated with hypertension. The predominant cause of the nephrotic syndrome in children is minimal change disease. The most common causes of nephritic syndrome are post infectious GN, IgA nephropathy and lupus nephritis. Chronic GN is slowly progressive and is associated with hypertension and gradual loss of kidney function. Treatment includes non-specific measure aimed at controlling hypertension, edema, proteinuria and disease modifying immunosuppression.

Renal replacement therapies.

The kidneys perform a wide array of functions in the body, most of which are essential for life. Regulation of water and electrolytes, excretion of metabolic waste and of bioactive substances like hormones, drugs etc., which affect bodily functions; regulation of arterial blood pressure, red blood cell and vitamin D production; are some of the major functions that the kidneys perform. It is obvious then, that patients with renal failure present a steep challenge to the physician taking care of this special population. Renal replacement therapy remains only a part of treatment that helps substitute the regulation of water and electrolytes, removal of metabolic waste, and to a certain extent removal of drugs and other bioactive substances from the body. This article aims to provide an understanding of different types of renal replacement therapy, mainly to patients with end-stage renal disease (ESRD).

Peritoneal dialysis first: rationale.

The use of peritoneal dialysis (PD) has become wide spread since the introduction of continuous ambulatory PD more than 25 years ago. Over this time, many advances have been made and PD is an alternative to hemodialysis (HD), with excellent comparable survival, lower cost, and improved quality of life. The percentage of prevalent PD patients in the United States is approximately 7%, which is significantly lower compared with the 15% PD prevalence from the mid-1980s. Despite comparable survival of HD and PD and improved PD technique survival over the last few years, the percentage of patients performing PD in the United States has declined. The increased numbers of in-center HD units, physician comfort with the modality, perceived superiority of HD, and reimbursement incentives have all contributed to the underutilization of PD. In addition to a higher transplantation rate among patients treated with PD in the United States, an important reason for the low PD prevalence is the transfer to HD. There are various reasons for the transfer (e.g., episodes of peritonitis, membrane failure, patient fatigue, etc.). This review discusses the various factors that contribute to PD underutilization and the rationale and strategies to implement "PD first" and how to maintain it. The PD first concept implies that when feasible, PD should be offered as the first dialysis modality. This concept of PD first and HD second must not be seen as a competition between therapies, but rather that they are complementary, keeping in mind the long-term goals for the patient.