NephMadness 2014: Is normal saline bad for the kidneys?

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SkepticalScalpelSkeptical Scalpel

The Skeptical Scalpel has been a surgeon for 40 years and was a surgical department chairman and residency program director for over 23 of those years. He is board-certified in general surgery and a surgical sub-specialty and has re-certified in both several times.

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Answer: Yes.

In October of 2012, JAMA featured a paper describing the effect of two intravenous fluids on the incidence of renal failure in critically ill ICU patients.

The paper compared normal saline (relative to human plasma, a high chloride-containing solution) administration to more physiologic, low chloride-containing IV fluids such as Hartmann’s solution (very similar to Ringer’s lactate) or Plasma-Lyte 148.

It found that using the low chloride intravenous infusions led to a statistically significant decrease in the incidence of acute kidney injury and the need for renal replacement therapy.

There was no significant difference in mortality rates related to the various solutions used.

The JAMA paper was based on research from a single hospital in Melbourne in 2008-2009 and was a before-and-after trial.

A 2012 randomized, double-blind crossover trial in 12 human subjects showed that compared to Plasma-Lyte 148, infusions of normal saline caused more sustained hyperchloremia and significantly decreased renal blood flow velocity and renal cortical perfusion.

Note that Plasma-Lyte 148 costs about 3 times as much as Ringer’s lactate, about $12 vs. $4 respectively. That doesn’t sound like much until you realize that 200 million liters of normal saline are used yearly in the US.

So what is a clinician to do? Normal saline is not really “normal.” Solutions containing amounts of chloride closer to that of human plasma are the correct ones to use.

See the table for the amounts of sodium, chloride and buffer in standard IV solutions.

Table of Fluids

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