Ultrafiltration and Dry Weight—What Are the Cardiovascular Effects?

Abstract

Long-term prognosis in dialysis is poor compared to that in healthy control persons. A worsening of the prognosis is noted especially for patients who at initiation of dialysis have congestive heart failure, ischemic heart disease, or left ventricular dysfunction or hypertrophy. This is the main reason that cardiovascular causes are the most common for morbidity in these patients. The weight obtained when normal urine output is present is the dry weight. With reduced ability to excrete the volume by the kidneys in end-stage renal disease (ESRD), the body will retain water and the patient will gain weight. This extra weight is due to volume overload. While volume overload may induce a rise in blood pressure, if the heart is in acceptable condition, a fast removal of fluid by ultrafiltration (UF) during dialysis may instead cause hypotension. Ultrafiltration failure in peritoneal dialysis (PD) patients may lead to successive water retention and overhydration with subsequent cardiac failure, while volume overload may occur over a few days in hemodialysis (HD) patients. Anemia or even too-high hematocrit may impair cardiac function further and worsen conditions caused by wrong dry weight. Thus, during long-term and sustained volume overload, left ventricular (LV) hypertrophy will occur in an eccentric manner. A sustained overload then may lead to cell death and LV dilatation and, eventually, systolic dysfunction. Once a severe left ventricular dilatation has developed, the blood pressure may decrease during volume overload. A worsened prognosis is seen if malnutrition and low albumin levels are present. Volume overload necessitates ultrafiltration to achieve dry weight. Thereby, volume contraction contributes to exaggerated stimulation of or response to activation of the RAS and alpha-adrenergic sympathetic systems. If ultrafiltration goes beyond these compensatory mechanisms, hypotension will occur and increase the risk for hypoperfusion of vital organs. Such episodes may cause cardiac morbidity, aspiration pneumonia, vascular access closure, or neurological complications (seizures, cerebral infarction), besides a more rapid lowering of residual renal function. Preventive measures are, first, finding the right dry weight; second, minimizing interdialytic weight gain; third, optimizing the target for hemoglobin (110-120 g/l); fourth, lowering dialysate calcium (1.25 mmol/l); and fifth, eventually using higher dialysate potassium if long dialyses are performed.

Cardiorenal Syndrome Type 4: A Review

“…A third component concerns the possible presence of catheters or synthetic grafts with tunnel or exit site infection, which represents a source of infection and inflammation [28,29]. Additionally, fluid overload should also be considered an important cardiovascular risk factor responsible for extracellular volume expansion and ventricular enlargement [30,31]. …”

Long-term efficacy of intermittent peritoneal dialysis using various doses

“…However, the increased removal of small solutes fails to improve the high mortality following dialysis (16). Volume load is closely related to hypertension, left ventricular hypertrophy, inflammation and malnutrition, and has been an important indicator predicting the mortality of PD patients (17,18). These findings demonstrate the importance of management of exchange volume and blood pressure control.…”

The value of sequential dialysis, mannitol and midodrine in managing children prone to dialysis failure

“…Abnormal baroreflex sensitivity, altered vascular physiology and reduced coronary flow reserve are integral to cardiovascular decompensation during dialysis [1,12]. The consequence is myocardial dysfunction secondary to a reduction in global and regional myocardial blood flow [13] and failure to preserve the central blood volume, with resultant hypotension.…”

“…The development of intradialytic symptoms and hypotension can result in premature discontinuation of treatment and delivery of sub-optimal dialysis with an attendant adverse impact on health [1]. Broadly speaking, dialysis failure (in the absence of clotting the extracorporeal circuit) has two etiologies, dialysis disequilibrium and ultrafiltration (UF)-mediated cardiovascular decompensation.…”