PERITONEAL DIALYSIS
By Jose Diaz-Buxo, MD

What do you want in a therapy? Surveys from patients and medical professionals generated the following list: freedom, flexibility, mobility, convenience, ability to perform therapy at home, safety, being pain free, minimal dietary restrictions, better diabetic control, preservation of renal function, reduced exposure to institution-related (nosocomial) infections, stability, better survival and better quality of life (QOL). While no single therapy fulfills all these demands, home therapies – both peritoneal dialysis (PD) and hemodialysis (HD) – satisfy many of these requirements. Let us concentrate on PD.

The two predominant modalities of PD, continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) are relatively simple to master, allow a high degree of freedom, flexibility and mobility, are convenient for a large group of patients desiring self-therapy at home and are relatively painless. In addition, PD offers other advantages over HD.

BETTER PRESERVATION OF RENAL FUNCTION
Many studies have suggested that patients undergoing PD maintain better levels of residual kidney function and urine outputs longer than patients on HD. Some potential reasons for this finding are minimal changes in blood pressure and body fluids and less toxicity – since a biologic membrane is used instead of an artificial membrane. The preservation of kidney function has been shown to be extremely important because the contributions from the natural kidneys are more important than the contributions of any dialytic therapy to survive. Aside from toxin and fluid removal, the kidneys provide many other benefits including natural vitamin D, erythropoietin and other regulatory factors that contribute to steady maintenance. Residual renal function reduces many complications of renal failure including cardiovascular disease, bone disease and anemia. There is a direct correlation between the amount of residual renal function, survival and quality of life.

PD patients require less iron, EPO (a synthetic hormone that stimulates the bone marrow to produce red blood cells) and blood transfusions than HD patients to maintain the same hemoglobin levels. An important reason for these findings, aside from better preservation of kidney function and secretion of natural erythropoietin, is PD patients do not lose blood, while HD patients always lose blood in tubing and used filters. HD patients also lose more blood from blood tests that are more frequent for diagnostic purposes.

PD patients have a lower incidence of hepatitis B, C and G compared to center HD patients. There are two likely reasons for this difference: the less frequent need for blood transfusions among PD patients and their lack of exposure to other patients with these infectious diseases.

INFECTIOUS COMPLICATIONS
The rate of peritonitis has markedly dropped during recent years thanks to better connections and improved delivery systems for PD, but it remains an important and common complication of PD. Although peritonitis may be common, septicemia (generalized infection through the blood) is more frequent among HD patients. According to a recent study by Powe and coworkers, the incidence of septicemia is lower among PD patients compared to HD patients. Infections arising from the blood access, particularly temporary necklines, and the reuse of hemodialyzers may be partly responsible for the higher incidence among HD patients. Septicemia carries a high risk of death. Early referral to a nephrologist, improving nutrition, avoiding temporary vascular access and prevention of peritonitis may decrease the incidence of septicemia.

The continuous nature of PD results in stability, a steady state in blood concentrations of solutes and a reduction in complications. Better and continued control of fluid volume leads to improved blood pressure control and fewer cardiovascular complications. A steady state is also associated with less nausea, vomiting, lightheadedness and other symptoms related to blood pressure fluctuations. Most significantly, the continuous nature of PD also allows a more liberal diet since the excessive accumulation of certain solutes, such as potassium, is less likely.

Diabetes accounts for 35 percent to 45 percent of all causes of end-stage renal disease (ESRD). A wealth of information on the treatment of diabetic patients with HD and PD is available. PD markedly increases the glucose load since glucose is used in the peritoneal fluids to achieve fluid removal. The glucose absorbed from the solution may account for as much as one-third of the total daily calories. These additional calories may help some patients, but the constant glucose absorption may also cause too much insulin secretion and increased triglycerides and other lipid concentrations in the blood. PD patients have a more atherogenic lipid profile triggered by a tendency to have higher total cholesterol, low-density lipoprotein (bad cholesterol) and triglycerides. This is a potential disadvantage of PD, particularly for diabetics. Despite the concern of a higher rate of cardiovascular complications among diabetics due to the increased glucose load, it is reassuring that a large study by Locatelli and coworkers did not show a significant difference between the risk of mortality and new development of cardiovascular disease for new patients (diabetics and non-diabetics) undergoing HD or PD.

Another concern among diabetic patients undergoing dialysis is the loss of vision due to diabetic retinopathy. Several studies show that preservation of vision correlates best with overall blood pressure and blood sugar control rather than with modality of dialysis utilized. Tight glycemic control is both essential and possible for patients undergoing PD with the use of insulin pumps, divided doses of subcutaneous insulin or with intraperitoneal insulin. The latter has the advantage of not requiring injections and being absorbed through the portal circulation that simulates the normal absorption of insulin secreted by the pancreas.

Who makes the decision to switch therapies? The dynamics of therapy selection are complex. The decision should always be made by the patient and their family with the input of the medical team; unfortunately, this is not always the case. Two factors are essential to empower the patient to make a judicious and well-informed decision: early and appropriate referral to a nephrologist and adequate education on therapeutic options. Being under the care of a nephrologist long before dialysis is necessary and always an advantage. It provides necessary time to inform the patient on all possible modalities of treatment, to refer him or her to the transplant team for evaluation and registration on the waiting list (if the patient is a candidate), to obtain adequate vascular or peritoneum (peritoneal catheter) access and start the patient on the best regimen to control or prevent complications of uremia. These practices significantly influence the clinical outcomes of the patient.

It has been shown that patients referred to a nephrologist at least six months before dialysis is required, participate more in selecting the modality of dialysis, select PD more often, suffer fewer early complications and have a better survival during the early period of dialysis than those who start dialysis in an emergency and had not seen a nephrologist until it is time to start. Finally, the concept of “integrated care” is known to improve patient survival. Integrated care implies that patients have the opportunity of selecting therapy and home therapies (most likely PD) first and may later transfer to either center HD or preferably home HD. As time goes on, many patients require a change in therapy from PD to HD. This can stem from changes in the natural peritoneal membrane that reduce the efficiency of PD to remove waste products and extra fluid from the circulation, difficulty in maintaining a good peritoneal catheter, a change of lifestyle that makes PD more difficult, recurrent infections or simply elect to change therapies. The option of home HD should always be considered if the patient is a reasonable candidate. Maintaining a capable patient at home allows incomparable independence and control. However, the success is only possible through proper education on the options of therapy and the support of a dedicated team of medical professionals with knowledge and experience.


Hemodialysis
By Robert Provenzano, MD, FACP

THE PAST
The luxury of exploring one’s options to choose or change hemodialysis therapies depends on research and patient participation. Few patients remember or know that until the early 1960s end-stage renal disease (ESRD) was lethal. Dialysis was not offered, and once diagnosed, patients were often sent home to die. It was only with the connection of several independent factors that brought us to where dialysis is today. This includes visionary leaders, such as Drs. Scribner, Quintin & Dillard working at the University of Washington Hospital in Seattle. In addition, technological breakthroughs, such as a Teflon shunt (Scribner shunt) allowing access for chronic dialysis, and changes in the public perception that patients could and should be treated, allowed the establishment of early dialysis centers.

Initially, only large universities could afford to treat these patients. There was very little understanding of chronic kidney disease (CKD) or its progression to ESRD, and dialysis access continued as a major limiting factor to the provision of hemodialysis services.

Slowly but surely, in-center dialysis was provided and patients were typically treated 12 to 16 hours two times a week with large Kiil dialyzers. Because of the great expense and lack of insurance covering dialysis, “death” committees were established. These anonymous committees were created to determine the “worth” of candidates to their families and communities, dependence of others on the candidates continued existence, potential for rehabilitation and moral value. These committees hit the national press and were featured in Life magazine in 1962. Thankfully, as public and political attention became more focused on the plight of patients with ESRD, Congress interceded and revised the Medicare Benefits Act and in 1973 allowed payment for hemodialysis services to ESRD patients, regardless of their age.

With that, dialysis was offered to a wider range of patients and an explosion of technology helped develop more sophisticated equipment. All of this helped stabilize mortality rates of patients on dialysis, as well as improved comfort of patients on dialysis and significantly shortened dialysis time to an average of three hours and 45 minutes, three times a week.

THE PRESENT
So where has this brought us today? Interestingly, in the 1970s, a great number of patients were treated with home dialysis. They were trained to provide dialysis to themselves, including the set-up and teardown of machines, and often performed dialysis on a daily basis. These patients did very well! They were highly motivated, well trained, had few graft problems – including infections – and mortality rates were lowest among dialysis patients at that time. No doubt there was some selection bias in these patients; however, it is important to note the ability to dialyze at home was established very early. During the late 1970s, 80’s and 90’s, as the number of patients with ESRD soared, “institutionalization of dialysis” developed. Dialysis facilities opened in great numbers in an attempt to serve the geographic needs of patients. Dialysis times were often shortened and mortality rates increased in the United States to as high as 28 percent in the 1980s. Dialysis cost continued to increase, and now exceeds $29 billion dollars a year – 25 percent goes to access care. The number of patients continues to increase and is estimated to exceed 600,000 patients by 2010. Despite this, mortality rates remain unacceptably high, as do costs.

So where do we go from here? Although I could bore you with a complicated speech on various levels of patient and physician responsibility to help improve patients’ outcomes, it is only through a combination of cooperation and understanding that I believe we can positively impact dialysis outcomes, which reflects the title of this article, “Exploring My Options.”

Why should we even address the issue of options? After all, we can continue to “punch out” dialysis centers to offer three times a week dialysis for three hours and 45 minutes and hope that identifying patients before ESRD would bring healthier patients to dialysis and improve mortality. We could also hope that breakthroughs in technology may assist in improving outcomes. However, I see the provision of dialysis services coming full circle. More and more data is accumulating that more frequent dialysis results in better outcomes.

DAILY DIALYSIS – SHORT TERM DIALYSIS
This dialysis method can be provided either in-center or at home. Typically, you dialyze two hours, five or six days a week. Blood and dialysate flows are kept high to improve clearance.

NOCTURNAL HEMODIALYSIS
Typically, nocturnal hemodialysis is provided six to eight hours, three or four days a week. These therapies are provided at home or in-center. If provided at home, special communication equipment is required to monitor you while you sleep. There is a central monitoring center staffed with trained personnel who monitor your treatment via the Internet. Sensors and alarms on your machine can be viewed from these centers. Should anything arise that requires your input, the center calls and notifies you at once. You are required to have an “assistant” with you during the treatments, such as a spouse or significant other. Blood and dialysis flows are lower than for short daily dialysis.

So why would you choose one of these modalities over conventional hemodialysis? There are many issues to consider. Two important issues to consider are convenience and outcomes. Although initially the convenience issue of daily dialysis seems counter-intuitive, data suggests that patients who receive daily dialysis do have improved lifestyles. Their volume status is much improved, decreasing peripheral edema, shortness of breath and sleep apnea allowing them to sleep more comfortably. Their diets are much more liberal allowing improved nutrition and a sense of well-being. Blood pressure, anemia and phosphorus control improve and decrease the number and/or dose of medications, as well as any unpleasant side affects. Additionally, active patient participation in dialysis helps the psychological barriers that often result in feelings of hopelessness and depression. Most importantly, daily dialysis decreases the wide swing in metabolic and volume profiles patients endure with traditional dialysis. Accumulating data suggests that more frequent dialysis methods may decrease cardiovascular mortality, which is the primary cause of death in ESRD patients.

Current Available Therapies

THE FUTURE
The future is upon us. As we speak, technological breakthroughs in dialysis equipment, including cartridge-type dialysis systems that make it easy for a patient to snap in a cartridge in a machine and provide dialysis to him/herself are being tested. These tools will empower patients to provide care to themselves or to have their families assist them in their care at home, which will allow them the option of when and how long to dialyze themselves, rather than being forced into a “cookie-cutter” situation currently so common.

CONCLUSIONS
Dialysis therapy has come full circle. We have moved from outpatient dialysis where patients took primary responsibility for their care, to outpatient “industrialized” dialysis where patients were passive participants, back to situations where patients are taking more responsibility for their care. Daily dialysis, whether in-center or home, nocturnal or daytime, offer an opportunity for improved patient outcomes.

Robert Provenzano, MD, FACP is Chief of Nephrology at St. John Hospital and Medical Center in Detroit.

Dr. Diaz-Buxo is responsible for the medical/scientific affairs for Fresenius Medical Care-North America, Dialysis Products Division and Global Advisor for Home Therapies for Fresenius Medical Care-AG.

This article originally appeared in the November 2004 issue of aakpRENALIFE, Vol. 20, No. 3.

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