Anyone offer a CLEAR explanation of IV solutions?


What I am looking for is a clear, easy to understand explanation of the different types of IV solutions...Isotonic, hypotonic, & hypertonic and the effects as far as pulling vascular fluid, etc.

I am at the beginning of 2nd level & getting started with IV's...I pretty well breezed through 1st level but for some reason when I hit a question about this, I get it wrong everytime! Just something confusing about it to me...

9livesRN, BSN, RN

1,570 Posts

Specializes in SNU/SNF/MedSurg, SPCU Ortho/Neuro/Spine. Has 2 years experience.

HYPOTONIC- HYPO”TONNED” THERE IS LESS PARTICLES AND MORE WATER (LIKE WATERED DOWN JUICE) so it will make your blood more watery, (in case you had hypernatremia too much sodium or else) they also use these solution to rehydrate superficial tissue.

Isotonic - the particle concentration here on this fluid is close to the human blood, so this is a filler! It will restore vascular fluids, re-hydrate your veins, get the volume back to your body (dehydration, blood loss…)and resume hypovolemic issues

Hypertonic – in this case the concentration of particles to water (osmolarity) is higher then what we find in blood, so, when you give something like this, it will pull fluids into your veins (pulmonary edema, cardiac, kidney issues…)

Understand osmolarity – it is the relationship between particles and fluid, the concentration!


Tell me if you understand these, and let me know if you need more iv info! These are the basic basic basic…


71 Posts

I think it throws me off when it starts talking about moving water into or out of the first thought is "what" cells!

I understand the hypo, hyper, iso & what each is when the questions start asking about moving fluid here & there that I get lost.

I will see if I can find a question I keep missing...

9livesRN, BSN, RN

1,570 Posts

Specializes in SNU/SNF/MedSurg, SPCU Ortho/Neuro/Spine. Has 2 years experience.

isotonic examples: LR - lactated Ringers and 0.9%NS (normal saline)

these have similar osmolarity to your blood.

anything less concentrated such as .45%NS will be HYPOTONIC

anything more concentrated such as 3%NS (not commonly used) or D5with0.9%NS or D10... would be HYPERTONIC because they are more concentrated then LR and 0.9%NS

9livesRN, BSN, RN

1,570 Posts

Specializes in SNU/SNF/MedSurg, SPCU Ortho/Neuro/Spine. Has 2 years experience.

ok i get it! you dont undederstand osmosis, which means : "the balancing force"

osmosis will try to balance osmolarity (concentration of particles) between your veins and your body!

so then if you give some one a hypotonic solution it will decrease the blood osmolarity (because you just added watered down juice to it)than osmosis will kick in and try to balance it out, because your blood became less concentrated than your body, so it will pull water out of the veins.

when you give them isotonic solutions it will not move anywhere since it is around the same osmolarity of the blood, it will only increase your intra vascular volume

when you give them hypertonic you make their blood more concentrated (think as if you just added a whole bunch of sugar to a half a cup of water!) now your osmosis will bring in some water (pull from tissue to blood) so that it gets to where it wants to be, which is balanced out!


71 Posts

I got that part...I think I may be making this harder than it is! LOL!

Renal Pt is prescribed a transfusion of 0.45% sodium chloride, this type solution is appropriate because it...

-- pulls fluid from the cells & increases vascular volume

-- dilutes extracellular fluid & rehydrates the cells

-- replaces extracellular volume & maintains intravascular volume

-- draws fluid into blood vessels & reduces interstitial compartments



71 Posts

WOW...I feel like a retard!!! I totally get it now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! One quick refresher on osmosis & it all clicks!

Thank You so much...

9livesRN, BSN, RN

1,570 Posts

Specializes in SNU/SNF/MedSurg, SPCU Ortho/Neuro/Spine. Has 2 years experience.



364 Posts

Specializes in Cardiac, Derm, OB.

Isotonic- is used for rehydration and to increase volume.

Hypotonic- moves water from vascular space (vessel) to inner cells. (pushes it in)

Hypertonic- moves water from inner cells to vascular space (vessel). (sucks it out)

About as simple as I can make it, hope that helps.


228 Posts

Fluid and Electrolytes Made Incredibly Easy has very good, easy to understand information on this.

This thread reminds me of the "I don't see why I need to know chemistry to be a nurse!" discussion.

Daytonite, BSN, RN

4 Articles; 14,603 Posts

Specializes in med/surg, telemetry, IV therapy, mgmt. Has 40 years experience.

this information is on a sticky thread of allnurses. see post #17 on this sticky thread: - any good iv therapy or nursing procedure web sites. you can also open and print out these charts which are listed on post #5 of the same thread: