RxPG News : Dialysis

Intradialytic hypotension associated with increased incidence of haemodialysis vascular access thrombosis

Sat, 30 Jul 2011 19:42:44 PST

( from http://www.rxpgnews.com ) A sudden drop in blood pressure while undergoing dialysis (intradialytic hypotension) is a long standing problem in haemodialysis patients. Side effects associated with this situation over the long term range from stroke to seizure to heart damage to death. Patients also suffer in the short term with gastrointestinal, muscular and neurologic symptoms.

A study led by researchers at the Stanford University School of Medicine reports an increased risk of thrombus(clot) formation in the vascular access which is used for haemodialysis as a consequence of intradialytic hypotension. Researchers from the University of Utah also contributed to the study, which is to be published online July 29 in the Journal of the American Society of Nephrology.

"Our analysis shows another adverse consequence associated with a fall in blood pressure during dialysis for patients," said Tara Chang, MD, a Stanford nephrologist and lead author of the study. "Vascular access is their lifeline. It's required for dialysis and without dialysis, they'll die."

As the kidneys fail, their ability to eliminate the excess fluid and toxins from the body decreases. The function of the kidneys deteriorates to the point at which an alternate form of elimination needs to be provided in the form of hemodialysis or peritoneal dialysis. Hemodialysis involves cleaning out the blood by passing the blood through a dialysis machine. This is ideally done for four-hour sessions, thrice weekly. The blood vessels of the patient are attached to the dialysis machine through a vascular access.

One of the most common forms of vascular access is a fistula, which is created surgically from the patient's own blood vessels. The tubes used to take blood to and from the body to the dialysis machine are connected to the body at this access point.

Clotting is one of the primary complications of an access point and can lead to its closure.

"These access points don't last forever," said Chang, a postdoctoral scholar. "Many patients go through multiple access points moving from the right to left arm, or into the legs if necessary after repeated failures in the arms. When a patient runs out of access points, it becomes an emergency situation. Anything you can do to extend the life of the access point is important."

The study was based on results from the Hemodialysis study, known as HEMO — a National Institutes of Health-sponsored randomized clinical trial that collected data from 1,846 patients on hemodialysis from 1995 to 2000. In the present study, researchers analyzed data from a subset of 1426 HEMO study subjects to determine whether more frequent intradialytic hypotension and lower predialysis systolic BP were associated with higher rates of vascular access thrombosis. The researchers found that patients who had the most frequent episodes of low blood pressure during dialysis were two times more likely to have a clotted fistula than patients with the fewest episodes.

About $2 billion a year is spent on vascular access in dialysis patients in the United States. Low blood pressure during dialysis occurs in about 25 percent of dialysis sessions.

"Physicians already try to avoid low blood pressure during dialysis through various means," Chang said. "This is just one more good reason to continue these efforts.

"There is so much we don't know about blood pressure in people on dialysis," she added. "We need future blood pressure management studies to look at not only mortality and hospitalization, but also consider vascular access survival as another important endpoint to study."

Low Phosphate diet not helpful in dialysis patients

Fri, 10 Dec 2010 08:34:21 PST

( from http://www.rxpgnews.com ) Doctors often ask kidney disease patients on dialysis to limit the amount of phosphate they consume in their diets, but this does not help prolong their lives, according to a study appearing in an upcoming issue of the Clinical Journal of the American Society Nephrology (CJASN). The results even suggest that prescribing low phosphate diets may increase dialysis patients' risk of premature death.

Blood phosphate levels are often high in patients with kidney disease, and dialysis treatments cannot effectively remove all of the dietary phosphate that a person normally consumes. Because elevated phosphate can lead to serious complications and premature death, dialysis patients are advised to restrict their phosphate intake and/or take phosphate binder medications. Kidney specialists and dietitians have long espoused dietary phosphate restriction; however, there have been few studies of its long-term effects on patient survival and health.

To investigate the issue, Steven Brunelli, MD, MSCE (Brigham and Women's Hospital and Harvard Medical School), Katherine Lynch, MD (Beth Israel Deaconess Medical Center), and their colleagues analyzed data from 1751 patients on dialysis who were followed for an average of 2.3 years. Prescribed daily dietary phosphate was restricted to levels < 870 mg, 871-999 mg, 1000 mg, 1001-2000 mg, and not restricted in 300, 314, 307, 297 and 533 participants, respectively.

The researchers found that patients who were prescribed more restrictive dietary phosphate levels had poorer nutritional status and were more likely to require nutritional supplements. Also, patients with more liberal dietary phosphate restrictions were less likely to die during the study. Specifically, patients prescribed 1001-2000 mg/day were 27% less likely to die and those with no specified phosphate restriction were 29% less likely to die than patients prescribed < 870 mg/day.

When comparing different subgroups of patients, the investigators found a more pronounced survival benefit of liberal dietary phosphate prescription among non-blacks, patients without elevated phosphate levels, and those not taking vitamin D.

"Our data suggest that prescription of low phosphate diets did not improve survival among hemodialysis patients and may, in fact, be associated with greater mortality," said Dr. Brunelli. "In part, this may relate to compromised intake of other essential macronutrients—such as protein—that occur unintendedly when low phosphate diets are prescribed, which may offset or supersede any beneficial effects on phosphate mitigation."

Dr. Brunelli noted that these findings apply to naturally occurring phosphate only and do not pertain to foods that are high in phosphate due to phosphate-containing food additives, which were much less abundant in foods at the time the study data were collected (1995-2001). This is very important for several reasons: 1) phosphate additives are now exceedingly common in foods and are present in high doses, 2) additive phosphate is more readily absorbed by the body than naturally occurring phosphate, and 3) foods with intrinsically high phosphate tend to be rich in other nutrients, whereas foods rendered high in phosphate are not necessarily so. Therefore, the effects of foods that are high in phosphate-containing food additives should be investigated in future studies.

Nephrologist care prior to starting dialysis reduces risk of death

Wed, 25 Mar 2009 16:13:58 PST

( from http://www.rxpgnews.com ) For patients with end-stage renal disease (ESRD), receiving care from a nephrologist in the months before starting dialysis reduces the risk of death during the first year on dialysis, reports a study in the May 2009 issue of the Journal of the American Society of Nephrology (JASN). The study also shows geographic "clusters" where pre-dialysis care for patients with advanced chronic kidney disease (CKD) is not optimal. "Assistance to improve pre-dialysis care might be profitably targeted to specific treatment centers and the health care systems they serve," comments William McClellan, MD (Emory University School of Medicine, Atlanta, GA).

Dr. McClellan and colleagues analyzed data on more than 30,000 patients starting dialysis in five of the 18 US ESRD Network regions. The researchers evaluated the quality of the patients' medical care in the months before their CKD progressed to ESRD, and how that affected the patients' outcomes on dialysis.

Just over half of the patients received at least six months of pre-dialysis care from a nephrologist, as recommended by current guidelines. For these patients, the chances of surviving the first year on dialysis were about 50 percent higher than for patients who did not receive at least six months of nephrologist care. Survival rates were higher at dialysis centers where more patients received recommended care.

The researchers also unexpectedly discovered that dialysis centers with the lowest rates of recommended pre-dialysis care tended to be "clustered geographically." For example, there was a "significant circular cluster" of low pre-dialysis care centers located in Alabama and Mississippi.

Although the reasons for the geographic variations in care are unclear, the results identify specific regions that might benefit from efforts to improve care for advanced CKD patients. "The Centers for Medicare & Medicaid Services are currently conducting a pilot quality improvement initiative in ten states to determine the feasibility of such efforts," says Dr. McClellan

Lower death rate in dialysis patients living at higher altitude

Tue, 03 Feb 2009 23:16:02 PST

( from http://www.rxpgnews.com ) Compared to dialysis patients living near sea level, dialysis patients living at an altitude higher than 4,000 feet have a 12-15 percent lower rate of death, according to a study in the February 4 issue of JAMA.

A recent study found that patients with end-stage renal (kidney) disease (ESRD) living at higher altitude achieved greater hemoglobin concentrations (a protein in red blood cells that primarily transports oxygen from the lungs to the rest of the body) while receiving lower doses of erythropoietin (a hormone that stimulates the production of red blood cells). Increased iron availability caused by activation of hypoxia-induced (oxygen deficiency) factors at higher altitude may explain this finding, according to background information in the article.

Wolfgang C. Winkelmayer, M.D., Sc.D., of Brigham and Women's Hospital and Harvard Medical School, Boston, and colleagues examined whether increased altitude would be associated with a reduced rate of death for patients initiating chronic dialysis. Using a comprehensive dialysis registry, the researchers identified 804,812 patients with ESRD who initiated dialysis between 1995 and 2004 and who met the study entry requirements. Most patients resided below an altitude of 250 ft. (40.5 percent) or between 250-1,999 ft. (54.4 percent). Only 1.9 percent of incident dialysis patients lived between 4,000 and 5,999 ft. and 0.4 percent higher than 6,000 ft. Patients were stratified by the average elevation of their residential zip code.

Compared with patients living at lower altitudes (less than 250 ft.), the rate of death was reduced for patients living from 250-1,999 ft. by 3 percent; from 2,000 through 3,999 ft. by 7 percent; from 4,000 to 5,999 ft. by 12 percent; and higher than 6,000 ft. by 15 percent.

Actuarial 5-year survival was 34.8 percent for patients living at or near sea level but was 42.7 percent among those living at an altitude higher than 6,000 ft.; patients in the highest elevation group experienced a 7.9 percent greater absolute or 22.7 percent greater relative 5-year survival. Median (midpoint) survival after initiation of dialysis was 3.1 years for those living lower than 250 ft. but was 4.0 years for those living at an altitude higher than 6,000 ft., for a difference in median survival of 0.9 years between these 2 groups.

While a decrease in age- and sex-standardized mortality at higher altitude was also observed in the general population, the magnitude of the risk reduction was half of that observed in the ESRD population.

"In conclusion, we found a graded reduction in mortality from any cause in ESRD patients residing at greater altitude, a finding that was not explained by differences in observed patient characteristics. The magnitude of this observation was markedly greater than the observed small reduction in mortality at higher altitude in the general population. We propose that hypoxia-inducible factors are persistent at high altitude in patients with ESRD and may confer protective effects," the authors write.

Clear advantage of high efficacy Haemodiafiltration over conventional hemodialysis

Sat, 29 Nov 2008 03:19:20 PST

( from http://www.rxpgnews.com ) Suffering from end-stage renal disease (ESRD), a growing number of patients at the Centre hospitalier de l'Université de Montréal (CHUM), have become the beneficiaries of a North American breakthrough: high efficacy hemodiafiltration (HDF).

An extracorporeal blood purification technique, HDF is indicated for ESRD patients. Since the HDF unit was introduced in CHUM's Nephrology section, preliminary results show a clear advantage of high efficacy HDF over conventional hemodialysis in several areas, including the following:

Improved removal of uremic toxins;
Decreased number of hospitalization days;
A better tolerance for patients;
Minimizes the state of chronic inflammation that too often may lead to complications over a long course of dialysis;
Diminished need for certain medications.
Increased biocompatibility across the blood-dialysis system interface.

"Conventional hemodialysis continues to save lives, but we now have the technology to improve the lot of dialysis patients," says Dr. Rénee Lévesque, nephologist and lead physician in the HDF program at CHUM, and a professor with the medical faculty of the Université de Montréal. "At CHUM, we're proud to soon be accepting a cohort of forty patients undergoing HDF." Dr. Lévesque added that the CHUM Nephrology section is putting much efforts behind the new process, and hopes that one day soon all dialysis patients will be treated in this fashion.

Recent retrospective clinical data indicate 1, 2 that HDF reduces the mortality rates of dialysis patients and randomized studies are under way to provide clear proof of increased survival rates for patients. Among these, the CONTRAST3 study compares hemodialysis with online hemodiafiltration HDF in overall performance relative to cardiovascular morbidity and mortality. The study seeks to recruit seven hundred test subjects and follow them over a three-year period. CHUM is the only medical centre in North America to take part in this study, currently the largest in terms of the size of the randomized cohort.

Hemodiafiltration : the best of both worlds

HDF combines the elements of two processes, conventional hemodialysis (HD) and hemofiltration (HF). Renal replacement therapy for ESRD is based on two processes: diffusion and convection.

Conventional HD is diffusive; blood is circulated in an artificial kidney machine on one side of a semi-permeable membrane, while a special dialysis fluid is circulated on the other side. Small molecules of metabolic waste seep out into a dialysis solution flowing in the opposite direction on the other side of the membrane, mimicking the kidneys and washing wastes and toxins out of the bloodstream. One major toxin is urea. HD is the most widely used renal replacement function technology for ESRD.

Hemofiltration (HF) or ultrafiltration is exclusively convective, forcing blood through a filter under high pressure. The principle consists of applying a hydrostatic pressure gradient (high pressure on one side, low pressure on the other) across the membrane or filter. This results in an ultrafiltrate (water and electrolytes) on the other side. The quantity of ultrafiltrate lost in this process must be compensated by a matching infusion of replacement fluid. HF is used primarily in continuous mode and in acute care or intensive care.

In HDF, the diffusive component of HD is combined with the convective component of HF. As is the case in HF, the excessive loss of liquid must be compensated by the reinfusion of a sterile and apyrogenic fluid. Recent developments have led to the "on-line" production of large volumes of ultrapure liquid of high quality. This has led to higher quality physicochemical and microbiological properties in these solutions, in comparison with HD.

Dialysis patients may be overmedicated

Wed, 30 Nov 2005 15:35:00 PST

( from http://www.rxpgnews.com ) Changes in a widely used assay (blood test) for parathyroid hormone (PTH) have made its use with the established guidelines for end stage renal disease clinical management both inappropriate and potentially harmful to patients. This research is published in the journal Seminars in Dialysis.

A PTH assay measures levels of parathyroid hormone, produced by the parathyroid gland, which helps diagnose conditions such as hyperparathyroidism or to determine causes of abnormal regulation of calcium by the bones of patients with renal disease, which can lead to arterial calcification. Levels of PTH that are too high or too low can affect calcium metabolism, bone integrity and cause vascular disease.

In 2003, the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (K/DOQI) published the Clinical Practice Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease. These guidelines, for both diagnoses and treatments, are based on use of a manual iPTH assay that is not widely used for routine clinical analysis.

According to an editorial in Seminars in Dialysis, the iPTH assay that is now widely used by nephrologists has shifted significantly compared to the assay on which K/DOQI guidelines are based, generating much different results. Currently, almost all testing of dialysis patient specimens in the United States are performed at one of seven centralized labs. None use the PTH test on which the K/DOQI bone metabolism guidelines are based.

As a result, evidence shows that rates of parathyroidectomy may have been increased, patients have been over treated with expensive medications, and adynamic bone disease has become more prevalent, now affecting half of dialysis patients.

Tom Cantor, author of the editorial, and his research team have tracked changes in the most commonly used PTH assay. The team has also developed a more specific assay for PTH.

They have found important inconsistencies in testing results, Cantor states, indicating that "careful attention to the comparability of PTH assays is required by nephrologists and those who serve [patients] in this area."

Dialysis patients often have close family members also on dialysis - Study

Wed, 02 Nov 2005 12:12:00 PST

( from http://www.rxpgnews.com ) Nearly one-fourth of all dialysis patients have a close relative on dialysis, researchers at Wake Forest University Baptist Medical Center, and others, report in the current online edition of the American Journal of Nephrology. The researchers suggest screening other relatives for undetected kidney disease.

Barry I. Freedman, M.D., reports that many relatives in these families have silent kidney diseases that can be treated at early stages, leading to slowed progression or prevention of future dialysis treatments or kidney transplants.

"Physicians caring for patients with chronic kidney disease should consider focusing screening efforts on high-risk family members in an attempt to slow the exponential growth rate of kidney failure," said Freedman, nephrology section head.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, the rate of end stage kidney disease jumped from 219 persons per million in 1991 to 334 per million in 2000.

"Family members of individuals with chronic kidney disease also have an increased prevalence of high blood pressure, diabetes, excess protein in the urine, and undetected kidney disease," Freedman said. Excess protein in the urine is a sign that kidney disease is present and also a major risk factor for heart attack and stroke.

The study was based on dialysis patients in North Carolina, South Carolina and Georgia, which comprise End-Stage Renal Disease (ESRD) Network 6 of the Center for Medicare and Medicaid Services, one of 18 ESRD Networks in the United States. As of Dec. 31, 2003, Network 6 had 28,980 patients with end-stage kidney disease, the largest total among all 18 ESRD Networks and "accounting for approximately 7 percent of the U.S. population of individuals receiving renal replacement therapy," Freedman said.

The researchers from Wake Forest, Emory University and ESRD Network 6 undertook the largest study of its type ever performed, collecting family history information from 25,883 newly treated dialysis patients in the region. Of these, 5,901 (22.8 percent) had other close family members also with end-stage kidney failure on dialysis.

"This report demonstrated the strikingly high rates of familial clustering of the severest forms of kidney disease," he said. Patients with kidney disease due to diabetes were most likely to have close relatives with kidney disease, followed by those with kidney disease caused by high blood pressure.

Because of this clustering, "close relatives might be at increased risk for the presence of undetected chronic kidney disease or conditions that predispose to chronic kidney disease," Freedman said. "Periodically screening family members for chronic kidney disease and risk factors may be appropriate."

He said that chronic kidney disease has a long pre-clinical period, during which there are no symptoms, but when it can be easily diagnosed using blood and urine tests and treatment can be started.

"Primary care physicians need to be aware of this familial clustering and consider screening the close relatives of dialysis patients for silent kidney disease," said Freedman, who is the John H. Felts III, M.D., Professor of Internal Medicine and Head of the Section on Nephrology.

Hemodialysis causes antioxidant loss leading to long-term complications

Fri, 08 Apr 2005 01:34:00 PST

( from http://www.rxpgnews.com ) An article published in Hemodialysis International discusses the role of oxidative stress (OS) in dialysis patients, an imbalance which can result in long-term health problems. Potential therapeutic options to restore balance in patients are also reviewed.

Oxidative stress, an imbalance between toxic compounds and defense mechanisms, and prevalent in the dialysis process, has been linked to numerous adverse complications in end-stage renal disease (ESRD) patients. The imbalance is caused by the overproduction of reactive oxygen species (ROS), or toxic compounds, and lack of antioxidants to fight these toxins. In fact, the hemodialysis process can cause loss of these necessary antioxidants.

Many ESRD and hemodialysis patients are in a state of chronic inflammation induced by the dialysis process which further enhances oxidative stress. This state is strongly associated with long-term complications such as cardiovascular disease, malnutrition, poor outcome and low survival.

"It is important to prevent reactive oxygen species production by improving the biocompatibility of the hemodialysis system," states Dr. Jean-Paul Cristol, corresponding author. Antioxidant supplementation and ROS modulation by specific or non-specific drugs, such as statins, are possible solutions outlined in the article.

"Correction of OS imbalance appears to be a basic requisite to prevent complications in long-term dialysis patients" and is "a promising avenue of research."

Oxidative Stress in Dialysis Patients can Lead to Long-Term Health Problems

Sun, 03 Apr 2005 10:04:00 PST

( from http://www.rxpgnews.com ) An article published in Hemodialysis International discusses the role of oxidative stress (OS) in dialysis patients, an imbalance which can result in long-term health problems. Potential therapeutic options to restore balance in patients are also reviewed.

Oxidative stress, an imbalance between toxic compounds and defense mechanisms, and prevalent in the dialysis process, has been linked to numerous adverse complications in end-stage renal disease ( ESRD ) patients.

The imbalance is caused by the overproduction of reactive oxygen species ( ROS ), or toxic compounds, and lack of antioxidants to fight these toxins. In fact, the hemodialysis process can cause loss of these necessary antioxidants.

Many ESRD and hemodialysis patients are in a state of chronic inflammation induced by the dialysis process which further enhances oxidative stress. This state is strongly associated with long-term complications such as cardiovascular disease, malnutrition, poor outcome and low survival.

It is important to prevent reactive oxygen species production by improving the biocompatibility of the hemodialysis system, states Dr. Jean-Paul Cristol, corresponding author.

Antioxidant supplementation and ROS modulation by specific or non-specific drugs, such as statins, are possible solutions outlined in the article.

Correction of OS imbalance appears to be a basic requisite to prevent complications in long-term dialysis patients and is a promising avenue of research.