Table 3.

Rationale and therapeutic targets of IUF in heart failure

Rationale	Therapeutic target	Comments
Fluid balance regulation	More rapid relief of systemic and pulmonary congestion as compared to usual therapy with diuretics	The main component of the rationale for IUF in heart failure38,63–66,68
Solute regulation	Correction of hyponatremia, hyperkalemia, and metabolic acidosis Reduced incidence of hypokalemia Correction of azotemia Higher clearance of sodium, with more effective reduction of sodium pool in comparison with diuretics	Because of its operational characteristics, IUF is unable to correct serum electrolyte/acid-base derangements40,44,45 IUF leaves serum potassium levels unchanged and does not correct the azotemia.40,44,45 The ultrafiltrate has a higher sodium concentration if compared to urine after loop diuretics; the former is isotonic whereas the latter is hypotonic compared with the plasma68
Homeostasis control	Restoring sensitivity to diuretics Osmoceptor resetting Decreased neurohormonal activation (reduced activation of the macula densa mechanisms and tubuloglomerular feedback mechanism, reduced stimulation of sympathetic nervous system, and RAAS axis)	Scarce evidence Not demonstrated An important determinant of the favorable therapeutic profile of IUF in heart failure45,68
Reduced costs	Shortened hospital length of stay Decreased rate of readmission	Partially supported by the cost-effectiveness analyses available so far38,68,69

Abbreviations: IUF, isolated ultrafiltration; RAAS, renin–angiotensin–aldosterone axis.