Are all fluids bad for the kidney?

PURPOSE OF REVIEW: To describe the harmful effects of intravenous fluids on kidney structure and function and summarize recent comparisons between different fluids and their effect on kidney outcome.

RECENT FINDINGS: Administration of intravenous fluids may contribute to the development and sustention of acute kidney injury. In excess, fluids cause kidney interstitial edema and venous congestion, which prevents renal blood flow and glomerular filtration rate. In contrast to balanced crystalloids, chloride-rich solutions impair renal blood flow via autoregulatory mechanisms. Synthetic colloids, such as hydroxyethyl starches, gelatins, and dextrans are potentially nephrotoxic because they can cause osmotic nephrosis, which, in susceptible patients, might precede permanent kidney damage. Albumin solutions appear well tolerated to use in septic patients, although their renal efficacy over balanced crystalloids is not established. In contrast, administration of albumin solutions to patients with decompensated liver failure effectively prevents and ameliorates hepatorenal syndrome.

SUMMARY: Being nephrotoxic, synthetic colloids should be avoided in patients with reduced renal reserve, such as in critically ill patients and in patients with preexisting renal dysfunction. Suggested adverse effects with chloride-rich solutions need confirmation from ongoing trials. Albumin solutions are well tolerated in patients with sepsis and/or liver failure and improve outcomes in the latter.