The Vitals: IV Fluids – Compositions and Choices

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Jon Pickos

Emergency Medicine Resident at Detroit Receiving Hospital, pursuing a critical care fellowship. Budding and developing passions include balanced fluid resuscitation, palliative care, and all things critical care. Outside of work, craft beer, sporadic ice hockey, learning how to brew coffee different ways, and spending time with my fiance and nearly 5 year old black lab/border collie, Maya.

The Pre-brief

Intravenous (IV) fluids are one of the most common orders for resuscitationists and an often overlooked treatment decision that can impact the initial resuscitation of critically ill patients. Multiple factors should be considered when selecting the IV fluid of choice for resuscitation including patient comorbidities (such as a history of heart failure, liver failure, or end stage renal disease), current presentation (such as septic shock, burn related injury, or ketoacidosis from diabetes, starvation, or alcoholism), and the goal to be achieved with fluids. Additionally, the composition of the fluid for resuscitation should be examined within the context of each patient.

First, a primer on fluid types:

  • A crystalloid solution is a salt based solution with various compositions (i.e. sodium chloride, lactated ringers).
  • A colloid solution can be man made (i.e. starches, dextrans, or gelatins) or naturally occurring (i.e. albumin or FFP).

In general, crystalloids are the primary fluid type for resuscitation in non-hemorrhagic critically ill patients.This brings us to another concept, balanced crystalloids:

  • A balanced crystalloid is a solution where chloride anions are replaced with bicarbonate or other buffers to reduce the acid-base disturbances associated with hyperchloremic  fluids.

Now, a brief overview of the compositions of common fluids for resuscitation with normal serum values for reference:

In the next posts on this topic, we will cover specific fluids more in depth, when they should be considered, and when they should be avoided.

The Debrief

  • Each patient’s comorbidities and presentation should be taken into consideration when selecting an IV fluid for resuscitation.
  • Fluid choice can be detrimental to a patient’s care and recovery, especially with larger volume resuscitation (such as normal saline in already acidotic states like DKA and sepsis), thus, the fluid selected can be physiologically supportive or an obstacle to overcome.
  • Mounting evidence supports balanced IV fluid resuscitation is the ideal approach for critically ill patients.


  1. Semler MW, Self WH, Wanderer JP, et al. Balanced Crystalloids versus Saline in Critically Ill Adults. The New England Journal of Medicine. 2018; 378(9):829-839. PMID: 29485925
  2. Lewis SR, Pritchard MW, Evans DJ, et al. Colloids versus crystalloids for fluid resuscitation in critically ill people. Cochrane Database Syst Rev. 2018;8(8):CD000567. Published 2018 Aug 3. doi:10.1002/14651858. PMID: 30073665.
  3. Semler MW, Kellum JA. Balanced Crystalloid Solutions Am J Respir Crit Care Med. 2019; 199(8): 952–960. PMID: 30407838.
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  7. Shrimanker I, Bhattarai S. Electrolytes. [Updated 2020 Sep 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from:


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