Chooses fluid for MIV/Bolus

[Jlucasrn92]

Hello,

I'm a new grad starting in an ICU through an extended preceptorship program. I was wondering what the thought process is when a Dr/NP are choosing what fluids to use for MIV as well as when giving a Bolus. For example, my pt had liver failure and ascites and continued to become hypotensive. The Dr ordered a Bolus of LR and a MIV of 5% dextrose in .45 NS. Is there any rationale behind choosing these specific fluids? Is it only based on osmolality of the fluid and how you're trying to shift fluids in the body? Are there any resources that explained when each fluid would be used?

Thanks!

[Okami_CCRN, BSN, RN]

Fluid Boluses are usually given in an isotonic solution, .9% NS is usually the go to and LR is usually the surgeons go to IVF bolus. The goal of a bolus isn't to shift fluid around but to increase the volume of the intravascular space to help increase CO. Maintenance fluid is used when patients aren't taking in enough fluids PO. Maintenance fluid depends on the patients condition, for example do they need a carb source, is the sodium trending up, what about fluid overload?

[PaSSiNGaS, MSN]

Fluids have much different osmolalities and if you bolused someone with a hypotonic solution you wouldn't be doing anything to help keep fluid in the intravascular space. That is why the MD asked to bolus LR and not the dextrose solution. The D5W.45%NS is actually hypertonic with an osmolality over 300 (normal in body is 275-295) but the dextrose gets rapidly metabolized and the solution because mostly free water which doesn't stay intravascular.

You can simply google the osmolality of IV fluids and get a nice chart explaining all this.

[PaSSiNGaS, MSN]

If giving large amounts of fluid as a bolus NS is definitely a bad choice and will lead to hyperchloremic metabolic acidosis. That is why surgeons and us in anesthesia prefer LR or something like Plasmalyte. It has less sodium and doesn't have as much chloride.

Fluid Boluses are usually given in an isotonic solution, .9% NS is usually the go to and LR is usually the surgeons go to IVF bolus. The goal of a bolus isn't to shift fluid around but to increase the volume of the intravascular space to help increase CO. Maintenance fluid is used when patients aren't taking in enough fluids PO. Maintenance fluid depends on the patients condition, for example do they need a carb source, is the sodium trending up, what about fluid overload?

[Dranger]

If giving large amounts of fluid as a bolus NS is definitely a bad choice and will lead to hyperchloremic metabolic acidosis. That is why surgeons and us in anesthesia prefer LR or something like Plasmalyte. It has less sodium and doesn't have as much chloride.

Eh I get what you are saying but the dangers of a hyperchloremic state aren't as volatile as lactic acidosis for a patient. This is why in septic shock and metabolic acidosis the gold standard is a fluid trial of 3ish liters with usually NS. Have I seen mild hyperchloremia in the ICU? Sure, but never have I seen the treatment team take an aggressive approach to corrected it other than maybe adjusting MIV. Too much LR can also cause metabolic alkalosis as well. I understand the rationale behind LR but some hospitals just don't stock it in mass as much as NS even if it is a more balanced isotonic fluid. For some reason protocols still suggest NS but maybe that is just my hospital system. Perhaps we will see more LR in severe sepsis/septic shock as studies come out?

LR in my area is pretty exclusive to surgical areas or maybe trauma. The ICU is usually the other hyper/iso crystalloids.