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Dialysis Disequilibrium Syndrome


Dialysis Disequilibrium Syndrome

Article Author:
Binita Bhandari
Article Editor:
Saketram Komanduri
Updated:
6/10/2020 9:45:18 AM
For CME on this topic:
Dialysis Disequilibrium Syndrome CME
PubMed Link:
Dialysis Disequilibrium Syndrome

Introduction

Dialysis disequilibrium syndrome (DDS) refers to an array of neurological manifestations that are seen during or following dialysis, primarily after the new initiation of dialysis.[1][2] However, it can also be seen in chronic dialysis patients who miss their regular dialysis treatments. This syndrome is thought to arise from fluid shifts during hemodialysis, causing cerebral edema and a wide variety of neurological symptoms. In continuous renal replacement therapies (CRRT), where fluid shift is limited, dialysis disequilibrium syndrome is rarely reported.[3]

Etiology

The common risk factors that predispose a patient to dialysis dysequilibrium syndrome are listed as follows:[2][4][5][6][7][8] 

  • First hemodialysis treatment
  • High blood urea nitrogen (BUN) (above 175 mg/dL or 60 mmol/L) before initiation of dialysis
  • Extremes of age – children and elderly
  • Sudden change in dialysis regimen
  • Pre-existing neurological diseases such as stroke, malignant hypertension, head trauma, or seizure disorder
  • Presence of other conditions causing cerebral edema (hyponatremia, hepatic encephalopathy)
  • Conditions causing increased permeability of blood-brain barrier (sepsis, meningitis, encephalitis, hemolytic uremic syndrome, vasculitis)

Epidemiology

The first case of dialysis disequilibrium syndrome was reported in the literature in 1962.[1] The incidence of the syndrome is not clearly defined because of non-specific manifestations and difficulty in confirming the diagnosis, making it likely that DDS is underreported.[4] It is more likely to occur after rapid hemodialysis and in high-risk groups.[9] The overall incidence is believed to have decreased with time due to awareness of this condition and the implementation of preventive strategies.[2][5]

Pathophysiology

Dialysis disequilibrium has been recognized for more than a half-decade, but the pathogenesis is not clearly understood. Below are the two commonly proposed theories:

  • The reverse urea effect: Small solutes like urea are rapidly removed during hemodialysis, particularly in the setting of marked azotemia. Urea is usually considered an “ineffective” osmole because of its free diffusion across cell membranes. However, its natural diffusion lags behind the rapid removal of urea from the serum during hemodialysis, creating a transient osmotic gradient between plasma and brain cells. This leads to water shift into brain cells producing cerebral edema. Cerebral edema is further enhanced by the adaptive increase of brain aquaporin channels and the decrease of urea channels in advanced chronic kidney disease.[10][11] Studies in rat models of DDS demonstrated that brain to plasma urea gradient is increased after hemodialysis, and was associated with increased brain water content.[12][13] 
  • Intracerebral acidosis: Studies have shown that there is a fall of intracellular pH in brain cells with concomitant carbon dioxide (PCO2) retention among patients after initiation of dialysis. The fall in pH causes sodium and potassium that are bound to proteins to disassociate, making them osmotically active.[14][15] Additional contributing factors to intracerebral acidosis are adaptive retention of brain organic osmolytes like glutamine, glutamate, taurine, and myoinositol. Retention of these osmolytes causes a paradoxical fall of intracellular pH leading to increased brain osmolality and cerebral edema.[10][12][14][16]

History and Physical

Symptoms are commonly seen in patients with high blood urea nitrogen levels, in patients with chronic kidney disease (CKD) versus acute kidney injury, and with aggressive urea removal after initial dialysis treatment.[1] Most cases of DDS can be mild and self-limited, with patients reporting headache, nausea, or blurred vision as well as other CNS symptoms such as restlessness and confusion.[17] These symptoms usually begin soon after the initiation of dialysis and resolve within hours in most cases. Some symptoms, such as dizziness and muscle cramps that occur towards the latter part of dialysis, are also considered to be part of DDS.[18][19][20][21] Rarely, DDS can present as increased intraocular pressure.[22] In severe cases, symptoms can progress to seizure, somnolence, stupor, or coma leading to mortality.[17]

Evaluation

DDS is a clinical diagnosis. There is no specific laboratory testing or imaging. It remains a diagnosis of exclusion in suspected patients who develop symptoms after initial dialysis or resumption of dialysis after a period of non-compliance. Clinical conditions causing similar manifestations should be considered as a part of the differential diagnosis.

Treatment / Management

Management of DDS is primarily aimed at prevention rather than treatment after the onset of symptoms. Once a patient develops symptoms, below are the measures that should be considered:

  • Initiate sodium remodeling: Regardless of severity, DDS is initially treated by modifying the dialysis prescription. This is done by changing the sodium dialysate bath or engaging the changed prescription on the dialysis machine.[17] The symptoms should resolve as quickly as within 30 minutes. Therefore, dialysis need not be stopped. Residual symptoms (nausea, vomiting) after modification of prescription and sodium remodeling can be treated symptomatically. However, if symptoms do not resolve with treatment, it may be required to stop the dialysis occasionally to evaluate for other underlying causes of the symptoms. 
  • Failure of sodium remodeling: In patients with severe symptoms of DDS despite sodium remodeling, a trial to decrease intracerebral pressure could be taken. Some experts suggest using 5 milliliters of 23% saline or 12.5 milligrams of intravenous mannitol to increase the plasma osmolarity and simultaneously decrease further osmotic shift, but these are based on anecdotal evidence and limited data. The addition of urea to the dialysate has also been reported to allow for repeated and intensive dialysis sessions, avoiding potential neurological problems.[23]

Modalities to prevent the development of DDS include implementing a slow and gentle initial hemodialysis, limiting the clearance of urea to prevent the development of an osmotic gradient, increasing dialysate sodium level, and administration of osmotically active substances. Evidence-based guidelines are lacking, but most experts agree on the gradual clearance of urea.

For patients new to dialysis, short two-hour sessions at 150-200ml/min or sustained low-efficiency dialysis can be done, which can be followed by consecutive dialysis sessions in the following days.[24] The blood flow and dialysate flow can be simultaneously increased in small amounts if patients do not develop DDS during the first session. Blood flow can be further increased to match outpatient settings in successive treatments. Considerations should be given to inpatient initiation of dialysis in cases where BUN is > 100mg/dl or in patients with neurological symptoms such as altered mental status or myoclonus.

In patients who frequently miss dialysis, it is not always possible to repeatedly hospitalize them to initiate slow dialysis;  thus, the sodium modeling technique is used in such patients.[17] Some dialysis machines have sodium modeling capability, in which case linear or exponential features can be utilized to prevent hypertonicity at the end of the session.

Differential Diagnosis

The differential diagnosis of DDS includes uremia, stroke, subdural hematoma, metabolic disturbances (hyponatremia, hypoglycemia), drug-induced encephalopathy, or infection (meningitis, encephalitis). Tests like electroencephalography have been studied to improve the diagnosis, but have limited potential.[25][26] MRI imaging, especially with diffusion-weighted images that help in evaluating brain water content, could be helpful to support the diagnosis.

Prognosis

Dialysis disequilibrium syndrome is usually self-limited, with symptoms resolving in a short interval. The prognosis is generally favorable, and dialysis does not need to be stopped in the majority of cases. In severe cases, symptoms can progress to seizure, somnolence, stupor, or coma leading to death.[17]

Complications

The complications of dialysis disequilibrium syndrome include consequences from delay in recognition of the condition and delay in implementing prevention strategies. In rare cases, with the progression of cerebral edema, the symptoms can progress to severe neurological manifestations such as seizures, coma, or death in severe cases.[17]

Deterrence and Patient Education

Dialysis disequilibrium syndrome refers to a range of symptoms that may occur during dialysis, especially in patients in whom dialysis is initially started or who have missed frequent sessions of dialysis. It is believed to occur due to the rapid clearance of substances such as urea that get accumulated in the blood. This can lead to an imbalance in the level of fluid inside the cells of the brain, causing swelling and symptoms such as headache, nausea, restlessness, confusion, or in severe cases, seizures, coma, and death. Although uncommon with increasing awareness, dialysis disequilibrium syndrome can be uncomfortable and distressful to patients. Patients should be advised to report any symptoms after dialysis is started so that preventative measures can be implemented. It is also important to educate patients and their families to maintain regular dialysis sessions to help minimize the risk of DDS.

Enhancing Healthcare Team Outcomes

An interprofessional team approach to caring for patients undergoing hemodialysis is vital to improve patient outcomes. The team should consist of a nephrologist, nephrology nurse practitioners and physician assistants, and dialysis nurses. All providers caring for patients with end-stage renal disease should be aware of dialysis disequilibrium syndrome as a cause of neurological symptoms during the initiation of dialysis. Although the majority of presentations may be mild, it is important to prevent severe manifestations, which can be fatal. Preventive measures should be implemented, especially in patients who are at higher risk, to limit further morbidity and mortality in end-stage renal disease patients.


References

[1] KENNEDY AC,LINTON AL,EATON JC, Urea levels in cerebrospinal fluid after haemodialysis. Lancet (London, England). 1962 Feb 24;     [PubMed PMID: 14455152]
[2] Arieff AI, Dialysis disequilibrium syndrome: current concepts on pathogenesis and prevention. Kidney international. 1994 Mar;     [PubMed PMID: 8196263]
[3] Tuchman S,Khademian ZP,Mistry K, Dialysis disequilibrium syndrome occurring during continuous renal replacement therapy. Clinical kidney journal. 2013 Oct;     [PubMed PMID: 26120445]
[4] Bagshaw SM,Peets AD,Hameed M,Boiteau PJ,Laupland KB,Doig CJ, Dialysis Disequilibrium Syndrome: brain death following hemodialysis for metabolic acidosis and acute renal failure--a case report. BMC nephrology. 2004 Aug 19;     [PubMed PMID: 15318947]
[5] Zepeda-Orozco D,Quigley R, Dialysis disequilibrium syndrome. Pediatric nephrology (Berlin, Germany). 2012 Dec;     [PubMed PMID: 22710692]
[6] Flannery T,Shoakazemi A,McLaughlin B,Woodman A,Cooke S, Dialysis disequilibrium syndrome: a consideration in patients with hydrocephalus. Journal of neurosurgery. Pediatrics. 2008 Aug;     [PubMed PMID: 18671622]
[7] PETERSON H,SWANSON AG, ACUTE ENCEPHALOPATHY OCCURING DURING HEMODIALYSIS. THE REVERSE UREA EFFECT. Archives of internal medicine. 1964 Jun;     [PubMed PMID: 14131977]
[8] Marshall MR,Golper TA, Low-efficiency acute renal replacement therapy: role in acute kidney injury. Seminars in dialysis. 2011 Mar-Apr;     [PubMed PMID: 21517979]
[9] Arieff AI, More on the dialysis disequilibrium syndrome. The Western journal of medicine. 1989 Jul;     [PubMed PMID: 2763543]
[10] Silver SM,Sterns RH,Halperin ML, Brain swelling after dialysis: old urea or new osmoles? American journal of kidney diseases : the official journal of the National Kidney Foundation. 1996 Jul;     [PubMed PMID: 8712203]
[11] Trinh-Trang-Tan MM,Cartron JP,Bankir L, Molecular basis for the dialysis disequilibrium syndrome: altered aquaporin and urea transporter expression in the brain. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2005 Sep;     [PubMed PMID: 15985519]
[12] Silver SM, Cerebral edema after rapid dialysis is not caused by an increase in brain organic osmolytes. Journal of the American Society of Nephrology : JASN. 1995 Dec;     [PubMed PMID: 8749686]
[13] Silver SM,DeSimone JA Jr,Smith DA,Sterns RH, Dialysis disequilibrium syndrome (DDS) in the rat: role of the     [PubMed PMID: 1635345]
[14] Arieff AI,Massry SG,Barrientos A,Kleeman CR, Brain water and electrolyte metabolism in uremia: effects of slow and rapid hemodialysis. Kidney international. 1973 Sep;     [PubMed PMID: 4750910]
[15] SITPRIJA V,HOLMES JH, Preliminary observations on the change in intracranial pressure and intraocular pressure during hemodialysis. Transactions - American Society for Artificial Internal Organs. 1962;     [PubMed PMID: 13913503]
[16] Arieff AI,Guisado R,Massry SG,Lazarowitz VC, Central nervous system pH in uremia and the effects of hemodialysis. The Journal of clinical investigation. 1976 Aug;     [PubMed PMID: 8469]
[17] Port FK,Johnson WJ,Klass DW, Prevention of dialysis disequilibrium syndrome by use of high sodium concentration in the dialysate. Kidney international. 1973 May;     [PubMed PMID: 4792047]
[18] Pagel MD,Ahmad S,Vizzo JE,Scribner BH, Acetate and bicarbonate fluctuations and acetate intolerance during dialysis. Kidney international. 1982 Mar;     [PubMed PMID: 7087286]
[19] Rodrigo F,Shideman J,McHugh R,Buselmeier T,Kjellstrand C, Osmolality changes during hemodialysis. Natural history, clinical correlations, and influence of dialysate glucose and intravenous mannitol. Annals of internal medicine. 1977 May;     [PubMed PMID: 851303]
[20] Glenn CM,Astley SJ,Watkins SL, Dialysis-associated seizures in children and adolescents. Pediatric nephrology (Berlin, Germany). 1992 Mar;     [PubMed PMID: 1571218]
[21] Van Stone JC,Meyer R,Murrin C,Cook J, Hemodialysis with glycerol dialysate. Transactions - American Society for Artificial Internal Organs. 1979;     [PubMed PMID: 524607]
[22] van Brussel MS,Koppius PW,Schut NH, Headache during hemodialysis - an uncommon cause for a common problem. Clinical nephrology. 2008 Mar;     [PubMed PMID: 18397722]
[23] Doorenbos CJ,Bosma RJ,Lamberts PJ, Use of urea containing dialysate to avoid disequilibrium syndrome, enabling intensive dialysis treatment of a diabetic patient with renal failure and severe metformin induced lactic acidosis. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2001 Jun;     [PubMed PMID: 11390747]
[24] Marshall MR,Golper TA,Shaver MJ,Alam MG,Chatoth DK, Urea kinetics during sustained low-efficiency dialysis in critically ill patients requiring renal replacement therapy. American journal of kidney diseases : the official journal of the National Kidney Foundation. 2002 Mar;     [PubMed PMID: 11877575]
[25] Hampl H,Klopp HW,Michels N,Mahiout A,Schilling H,Wolfgruber M,Schiller R,Hanefeld F,Kessel M, Electroencephalogram investigations of the disequilibrium syndrome during bicarbonate and acetate dialysis. Proceedings of the European Dialysis and Transplant Association. European Dialysis and Transplant Association. 1983;     [PubMed PMID: 6410380]
[26] Basile C,Miller JD,Koles ZJ,Grace M,Ulan RA, The effects of dialysis on brain water and EEG in stable chronic uremia. American journal of kidney diseases : the official journal of the National Kidney Foundation. 1987 Jun;     [PubMed PMID: 3591793]