Paucis Verbis: Composition of intravenous fluids

Paucis Verbis: Composition of intravenous fluids


iv bagThere has been a lot of discussion on the ideal intravenous fluids (IVF) for resuscitation in the Emergency Department and ICU. This was highlighted by the landmark study in JAMA on ICU patients who received chloride-rich versus chloride-restricted IVFs. This got me to thinking, what exactly comprises the common IVFs that we order? We so often take for granted what’s in 1 liter of normal saline. As it turns out, normal saline is not really “normal”. Dr. Scott Weingart has a great podcast on “chloride poisoning” using IVFs.

This PV card helps remind me what’s in each liter bag of fluids we order (composition of intravenous fluids). At the bottom half of the card is a brief summary of the JAMA findings.

PV Card: IV Fluid Formations

Adapted from 1
Go to the ALiEM Cards site for more resources.

Update 1/4/13

After the posting of this PV card, there was intense discussion about why the D5W osmolarity was 252 mOsm/L instead of 272 mOsm/L, which is found on various medical calculators. See the discussion by Dr. Joel Topf.

Has this JAMA study changed your approach to ED intravenous fluid management?

It sure has for me. After 2 liters of normal saline, I consider switching patients to a more chloride-restrictive fluid (we have Plasma-Lyte in our ED). Examples include patients with DKA, AKA, sepsis, and severe dehydration.

Yunos N, Bellomo R, Hegarty C, Story D, Ho L, Bailey M. Association between a chloride-liberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults. JAMA. 2012;308(15):1566-1572. [PubMed]

Michelle Lin, MD
ALiEM Editor-in-Chief
Academy Endowed Chair of EM Education
Professor of Clinical Emergency Medicine
University of California, San Francisco
Michelle Lin, MD
Michelle Lin, MD

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  • The unit of Osmolality is mOsm/kg, or you can rename it to Osmolarity (with a ‘r’ if you keep mOsm/L).

    • Thanks for catching this. Chemist, I am not. I’m glad that there are smarter people out there! Fixed.

  • I don’t think the Yunos et al sequential study design can establish causation – it is more accurate to state that chloride-rich fluids were associated with acute kidney injury, rather than caused it.

    • Thanks Chris. Great catch. I subconsiously inserted my personal opinion on the issue. Fixed on this page.

      On an aside, I wonder if this will be how the process of peer-review will go. While journal manuscripts are peer-reviewed BEFORE to decide if they are worthy of publication, blogs will be peer-reviewed AFTER they are “published” and then revised on a dynamic and ongoing basis. Hmm..

    • I think the latter method of peer review will be better. Instead of a few people commenting before a product is finished, now there will be many people commenting on an ever-improving product. The downside is that nothing that is reviewed in this way will ever be completely “finished.” But isn’t that the nature of knowledge anyway? It will take a major paradigm shift for the majority to accept this but once they do I think the results will be amazing.

    • @Jeffmedic – Agreed. The challenge is in defining this process better for (1) “outsiders of FOAM” to build credibility especially in academics and (2) people new to social media for medical education so that they know how to navigate the sea of social media material.

  • I’ve jettisoned NS in favor of P-lyte in all my OR and ICU patients, excepting those with ICP issues and severe hyperkalemia (although quietly, I think it would probably be OK/better to use in many of them, too). I am already seeing, and think we will see more of, a switch to p-lyte in more places. I’ll use LR if it’s the only alternative, but widen the exclusion criteria to all neuro patients.

    How do I know the tide is shifting? A comment from my (very bright) CA-1 resident in the OR a few weeks ago during a kidney transplant: [thinks over surgeon’s request for high-volume chloride poisoning] “aren’t we just worsening the respiratory demand and hyperkalemia by creating metabolic acidosis?”

    • Wow, what a great story. Thanks for sharing your practice of exchanging NS for P-lyte now in the OR and ICU. You definitely know when a change is coming when residents/interns start mentioning it as if it’s standard practice. Keep up the great work!