More on the dialysis disequilibrium syndrome

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Author: Allen I. Arieff
Date: July 1989
From: The Western Journal of Medicine(Vol. 151, Issue 1)
Publisher: BMJ Publishing Group Ltd.
Document Type: Editorial
Length: 1,972 words

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More on the Dialysis Disequilibrium Syndrome IN PATIENTS WITH RENAL FAILURE, there are several central nervous system disorders that may occur not as a consequence of the uremic state but, rather, because of dialytic therapy. One such disorder is the dialysis disequilibrium syndrome, which can occur in patients being treated with hemodialysis. [1-3] The dialysis disequilibrium syndrome (DDS) is a clinical syndrome that can be observed in patients with renal failure following a rapid lowering of blood urea levels by dialysis therapy. From a purely mechanical and technical standpoint, it is possible to correct most of the abnormal blood chemistry values found in uremic patients to acceptable levels in much less time than is commonly done. The efficiency of hemodialysis can be increased by increasing blood or dialysate flow rates. When this is done, however, and the blood urea nitrogen level is rapidly lowered, DDS often develops. The syndrome has been reported most frequently after rapid hemodialysis but occasionally after peritoneal dialysis. Although DOS has been reported in all age groups, it is more common among younger patients, particularly children. [4] The symptoms of DDS, which characteristically occur late in the course of the dialysis procedure, may include such manifestations as headache, nausea, emesis, blurring of vision, muscular twitching, and disorientation. Seizures and coma have been reported, but it is unclear if they are actually a manifestation of DDS or are related to underlying central nervous system disease. [1,3,5] In the past decade, the original description of the dialysis disequilibrium syndrome has been expanded to include milder symptoms, such as muscle cramps, anorexia, restlessness, and dizziness. [6-8] In the original descriptions of the dialysis disequilibrium syndrome, [9] abnormal electroencephalogram findings were noted, but more recent studies have suggested that the electroencephalogram is probably unaffected by DDS. [3,10,11]

Although the syndrome has been recognized for more than 25 years, [9] the pathogenesis is still not fully understood. A rise in cerebrospinal fluid (CSF) pressure, intracellular acidosis of brain, or brain edema may all be contributory. The CSF pressure in both uremic patients and animals with experimentally induced DDS is normal. Following hemodialysis of uremic persons (or laboratory animals) with renal failure, the CSF pressure generally rises, regardless of the presence of symptoms of DDS. An elevated CSF pressure is felt by many to indicate cerebral edema, but such an inrease may be secondary to an increased brain volume of either CSF or blood, or increased brain water content (cerebral edema). In experiments with animals, it has been consistently observed that the CSF pressure will increase during hemodialysis, whether or not cerebral edema is present. The most likely explanation for this phenomenon is that during hemodialysis, urea is removed more rapidly from brain and plasma than from CSF. The rate of the removal of urea from brain closely parallels its rate of removal from plasma, but the clearance of urea from CSF is delayed, which probably accounts for the formation of an osmotic gradient between...

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Gale Document Number: GALE|A7781669