Haemodialysis, not Ultrafiltration, can Correct Hyponatraemia in Heart Failure

Hyponatraemia is present in a significant subset of patients with heart failure (HF), and its association with adverse outcomes is well established in this population. It is still not clear whether hyponatraemia is merely a marker for severity of HF, or if it has a causal impact on the progression of the disease. The therapeutic strategies for hyponatraemia in this setting remain extremely limited and challenging. Current guidelines on management of HF from the American Heart Association/American College of Cardiology or Canadian Cardiovascular Society do not address this complication. In the most recent guidelines of the European Society of Cardiology on management of HF published in 2008, ultrafiltration has repeatedly been presented as a treatment option for hyponatraemia in HF.1 Ultrafiltration is an extracorporeal therapy that does not use any exchange or substitution solution; it extracts isotonic fluid from blood via convective forces, hence reducing intravascular volume. Consistent with its mechanism of action, studies have confirmed that the fluid extracted from blood (i.e. ultrafiltrate) has a sodium concentration similar to serum.2 Numerous trials have so far demonstrated that ultrafiltration does not affect concentration of serum electrolytes, and this has actually been considered a notable advantage over the use of diuretics in this setting.3,4 Moreover, since diuretics produce hypotonic urine (urinary sodium of ∼60 mEq/L), it has been suggested that for similar volumes of fluid removed, ultrafiltration extracts more sodium, and is therefore more efficient in reducing the total body sodium content.3 In contrast, in diffusion-based extracorporeal therapies such as haemodialysis, there is a significant exchange of electrolytes and solutes between dialysate solution and blood across a semi-permeable membrane (i.e. dialyzer). This transfer is indeed the major mechanism of clearance provided by haemodialysis therapy; combination of dialysis and ultrafiltration often used in patients with renal failure provides volume control, correction of electrolytes, and clearance.5 With the advent of newer portable ultrafiltration devices that have led to an increased interest in this modality for management of HF, the physicians' recognition of the above-mentioned distinction is crucial. In contrast to conventional haemodialysis machines that are capable of providing dialysis, ultrafiltration, or a combination of the two techniques, these devices exclusively provide ultrafiltration and, therefore, have no role in the correction of hyponatraemia (or other electrolyte abnormalities). This point merits being taken into consideration for the forthcoming updated version of the guidelines.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.