Significance of Interdialytic Weight Gain versus Chronic Volume Overload: Consensus Opinion

Abstract

Predialysis volume overload is the sum of interdialytic weight gain (IDWG) and residual postdialysis volume overload. It results mostly from failure to achieve an adequate volume status at the end of the dialysis session. Recent developments in bioimpedance spectroscopy and possibly relative plasma volume monitoring permit noninvasive volume status assessment in hemodialysis patients. A large proportion of patients have previously been shown to be chronically volume overloaded predialysis (defined as >15% above ‘normal' extracellular fluid volume, equivalent to >2.5 liters on average), and to exhibit a more than twofold increased mortality risk. By contrast, the magnitude of the mortality risk associated with IDWG is much smaller and only evident with very large weight gains. Here we review the available evidence on volume overload and IDWG, and question the use of IDWG as an indicator of ‘nonadherence' by describing its association with postdialysis volume depletion. We also demonstrate the relationship between IDWG, volume overload and predialysis serum sodium concentration, and comment on salt intake. Discriminating between volume overload and IDWG will likely lead to a more appropriate management of fluid withdrawal during dialysis. Consensually, the present authors agree that this discrimination should be among the primary goals for dialysis caretakers today. In consequence, we recommend objective measures of volume status beyond mere evaluations of IDWG.

Lung Congestion as a Risk Factor in End-Stage Renal Disease

“…Mild-to-moderate degrees of volume expansion may go undetected or are overlooked in ESRD [4], but marked fluid overload in these patients is eventually a medical emergency demanding hospitalization and extradialyses in these patients [5]. Even though interdialysis weight gain is not necessarily tantamount to volume expansion [6], this simple parameter has been associated with an excessive death risk [7]. Improving volume control in the dialysis population is perceived as an urgent public research issue [8].…”

Prescriptions for home hemodialysis

“…3. Avoidance of high interdialytic weight gains (>3-4 kg) and chronic fluid overload is associated with improved survival [12][13][14] 4. Avoidance of a long 3-day interdialytic break is associated with improved survival 15,16 HD = hemodialysis.…”

“…High interdialytic weight gains may be an indicator of improved nutritional status, but also remain a source of ongoing cardiovascular stress that may counteract the effects of improved control of other uremic toxins. [14][15][16] Interdialytic weight gains greater than approximately 3-4 kg and ultrafiltration rates higher than 10-13 mL/kg/h have been associated with increased mortality in adult long-term HD patients. This is the result of extracellular fluid expansion, which promotes hypertension and congestive cardiac failure, and high ultrafiltration rates, which promote cardiovascular instability and organ ischemia during dialysis sessions.…”

Hemodynamic effects of succinate-containing dialyzing solution

“…Основной причиной развития АГ у этой группы пациентов служит перегрузка жидко-стью, напрямую связанная с задержкой натрия в организ-ме [5][6][7]. Важность строгого контроля гидратации у боль-ных, находящихся на ГД, подтверждается существенно более высокой выживаемостью тех больных, у которых удается достичь такого контроля [8,9]. Сложность кор-рекции натриевого баланса в условиях ЗПТ обусловлена в том числе тем, что у большинства больных, находящихся на хроническом ГД, формируется индивидуальное, труд-но поддающееся изменению заданное значение уровня натрия в крови [10,11].…”