prolonged vomiting replacement fluid?

[Lanesmama]

Our teacher gave us 2 topics to choose from to write a critical thinking paper on. I am choosing the harder one because I think I will learn more... but I need help!

The question is: Suggest the best choice for fluid replacement after prolonged vomiting and explain why.

Here is what I know. Vomiting causes PH to go up due to loss of stomach acid. Vomiting causes metabolic alkalosis. The body will try to compensate by keeping CO2 in (slow, shallow breathing.) The fluid will need to be replaced intravenously if the patient can't keep fluid down. The patient will also need electrolytes because of the loss from vomiting. Vomiting causes hyponatremia.

Here is my guess as to the best choice: a hypotonic sodium chloride solution because being hypotonic, the fluid will be forced into the cells and the sodium chloride will replace the sodium lost.

HOWEVER... I have read some stuff saying that hypotonic solutions are dangerous and to use isotonic... ? Any clues here would be greatly appreciated. (by the way... I'm only in my 4th week so I don't know much yet! )

[Idaho Murse]

Any hypotonic solution caries a risk of cellular lysis. If it goes on too much you can cause some major problems. hydrocephalus comes to mind

[halkogirl]

Potassium chloride and normal saline would be my guess. If a person is suffering from dehydration, there will be a loss of fluids in both the cells and extracellularly. Hypotonic and hypertonic solutions will leave one or the other still depleted. Normal saline will help restore the natural balance of fluids.

Sodium and potassium are the two electrolytes that are most concerning during prolonged vomiting and/or metabolic alkalosis.

I may be totally wrong but that would be my guess. HTH!

[haganwood]

Yes, you will use an Isotonic solution for fluid replacement due to prolonged vomiting. Basically, you are going to be replacing the fluids for dehydration. As you stated the body is going to compensate for the "metabolic acidosis". We want to get them rehydrated. Also, google up some sources for your paper so that you have something to back up your stance.

[Lanesmama]

so why isotonic vs hypotonic? I get both answers when googling but can't seem to find a why... ty guys!

[yuzzamatuzz]

so why isotonic vs hypotonic? I get both answers when googling but can't seem to find a why... ty guys!

Isotonic solutions are pretty safe to give in boluses. Hypotonic solutions are usually used to correct cellular dehydration and hypernatremia. It can be dangerous though because it causes water to shift out of the vasculature and could actually worsen hypotension and edema. Hypotonic solutions are usually used in cases where there is severe hypernatremia (such as with Diabetes Insipidus or with excessive diuretic use when excess water is excreted from the body and sodium is retained). As you said, a patient with prolonged vomiting probably lost sodium and potassium and at the same rate as fluid loss, using a hypotonic solution could actually worsen the situation. The safest bet would be to give an isotonic crystalloid solution (normal saline or lactated ringers). If potassium is confirmed to be low, I would given normal saline plus potassium.

This might be a bit more information than what your teacher wants at this point, but for your own knowledge this might be helpful. If the patient is in shock from dehydration, you need to give just normal saline boluses (and fast!) with no potassium because potassium cannot be given faster than over an hour as it can cause disrhythmias. If the patient is both in shock and has critically low potassium that could cause the patient to arrest, you could set up two IVs and give boluses of fluid through one and potassium over an hour through the other.