You have a patient who has been shot in the abdomen and is pale, cool, and diaphoretic. They have the following vitals:
Pulse/ECG: 150 sinus tachycardia
Pulse Oximetry: 89%
Obviously the patient is experiencing hypovolemic shock and you need to act fast. When referencing normal saline, the old saying “run it until their blood is pink” is no longer acceptable. Thankfully, most places now practice research based medicine. So why is pumping liters of saline into a patient such a terrible thing?
First, we need to remember the lethal trauma triad which is hypothermia, acidosis, and coagulopathy.
Next, we need to do some research into what normal saline is. Normal saline has been around since 1831 and is basically nine grams of salt in one liter of fluid (0.9% solution). Room air is typically 20-25 degrees Celsius (68-77 degrees Fahrenheit) and normal saline has a pH of around 5.5 (normal for the body is 7.35-7.45). So when you pull that normal saline off the shelf, you’re not only making the patient more acidic, but you’re simultaneously lowering their body temperature. So why do we give saline (especially in the prehospital setting)?
Well for starters, normal saline is extremely cheap. Depending on the source, a patient with extensive trauma should have a BP from 80-90 systolic.. But we need to remember that normal saline is NOT blood… obviously.. which means it doesn’t carry oxygen. The literature use to say that the administration of normal saline would help push the RBCs around the body which would in turn perfuse the body’s organs. Newer literature debunks this and even states that large amounts of crystalloid administration doesn’t improve the perfusion of organs. So let us see how normal saline impacts acidosis and coagulation in the lethal triad.
Normal Saline Acidosis
As stated before, normal pH is 7.35-7.45 and the pH of saline is around 5.5 due to the amount of carbon dioxide that is infused into the solution. When bodily tissues are deprived of oxygen, they start to break down and create lactic acid and extracellular wastes which negatively impacts the pH. “Not so normal saline” can lead to hyperchloremic metabolic acidosis which is a fancy term that means there’s a decrease in plasma bicarbonate concentration and an increase in plasma chloride concentration. Now how is this such a big deal for our trauma patients? With the previously described acidosis, the heart’s contractility can decrease along with overall cardiac function due to the lack of effectiveness of catecholamines (such as epinephrine) that are having a harder time circulating.
Coagulation with Normal Saline
Here is a review of the coagulation cascade for all of you proactive learners:
Coagulation is an extremely important factor in regards to trauma because clotting allows the body to plug the holes and reduce the amount of blood it loses. In reference to trauma induced coagulopathy there are two main branches: acute traumatic coagulopathy (ATC) and iatrogenic coagulopathy. Normal saline can exacerbate iatrogenic coagulopathy by increasing the acidity in the body and impacting inflammatory markers.
If you do research on coagulation, you will see thrombin and fibrin are essential in clotting. Normal saline impairs both of these which inhibits the body to adequately clot. Normal saline has also been shown to cause vasodilation and an increase of serum potassium (potassium loves an acidic environment). Something we may need to consider is lactated ringers. LR has been proven time and time again to be superior to normal saline. Here’s great article to review on this is: https://www.ijcmr.com/uploads/7/7/4/6/77464738/ijcmr_1756_v1.pdf
And an absolutely fantastic podcast:
In the prehospital setting, it’s often difficult to gain access to blood products for our trauma patients. Luckily hospitals (especially trauma centers) usually have a decent blood bank for these types of patients. We should keep normal saline administration to an absolute minimum. I’ve heard normal saline referred to as battery acid (Dan Rauh) which honestly makes sense.
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This site is meant to be used for educational use only. We strive to push evidence based medicine with no bias to help you obtain all the important information. You should always follow your protocols that have been set in place.
–Scopeducation Team (Matt)
Davenport, R. (n.d.). Pathogenesis of Acute Traumatic Coagulopathy. Retrieved July 08, 2020, from https://pubmed.ncbi.nlm.nih.gov/23301969/
Fisher, A. D., & Carius, B. M. (2019, September 02). Three Reasons Not to Use Normal Saline or Crystalloids in Trauma. Retrieved June 25, 2020, from https://www.jems.com/2018/03/14/three-reasons-not-to-use-saline-or-crystalloids-in-trauma/
Kushimoto, S., Kudo, D. & Kawazoe, Y. Acute traumatic coagulopathy and trauma-induced coagulopathy: an overview. j intensive care 5, 6 (2017). https://doi.org/10.1186/s40560-016-0196-6
Reddi, B. (2013, April 17). Why is saline so acidic (and does it really matter?). Retrieved June 25, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3638298/