What are you struggling with in nursing school?NURSING.com is the BEST place to learn nursing. With over 2,000+ clear, concise, and visual lessons, there is something for you! Show The Ultimate Guide to Fluid Balance in the BodySometimes the most basic concepts are made so complex during nursing school. Tonicity is one of these. Fluid BalanceFluid and Electrolyte eBookWe’ve literally written the book on Fluid and Electrolyte balance. You can view the book on Amazon by clicking here. So let’s break it down and make this simple . . . what is the difference between hypertonic vs hypotonic . . .and what is isotonic? What is all This Tonic?A quick easy way to remember the difference between Hypotonic and Hypertonic is to think of HYPERtonic as someone who is hyper and works out a lot so they get skinny so the cells will shrink but with HYPOtonic think of a hippo and it wants to eat everything and get really big so the cells will swell. Let’s start with definitions for some of the most important terms:
Now let’s define what solutions’ tonicity can be:
Next, let’s address a few ideas:
So what does this all mean? How do I apply this to nursing? It’s actually pretty simple, ever see someone who has +3 pitting edema? Well, they have a bunch of solvents in their tissues that need to get back into their veins and then urinated out. You do this by giving them a hypertonic solution in their veins. Thus in the vein is a solution with a high ratio of solute and outside the vein is a bunch of solution with a low ratio of solute to solvent. The ratio of hypertonic to hypotonic will create pressure and water will pull out of the tissues into the vein to attempt to create a better ratio of water and solute (notice the water followed the salt). The same is true of people who are dehydrated. We give them an isotonic solution to try to expand the volume of their blood but we don’t want it to necessarily move solvent out of the vein into their tissues. Conversely, the hypotonic solution is used when we need to put fluids into the cells for example if your patient is in Diabetic Ketoacidosis. RELATED ARTICLE: NURSING NCLEX® LAB VALUES STUDY GUIDE Try not to overthink the questions that your instructors are asking. Simplify it by following a couple of steps:
IV Solutions CheatsheetLook, we get that this is a complex topic and many students (and nurses) struggle with it. To help keep it straight we have created a Cheatsheet that covers the most common IV fluids and dives a bit deeper into this topic. What is Osmosis:Try these examples:
A semipermeable membrane between the two solutions creates movement of solution number one solvent to solution number twos solution creating:
But what if the solvents are different numbers? The concept stays the same!
The semipermeable membrane between the two creates movement of solution number ones solvent to solution number twos solution creating:
Fluid and Electrolyte Lab Values:
Hypertonic, Hypotonic, Isotonic IV solutionsYou want to give your patients a solution that has the tonicity that is opposite their problem most of the time. For example, if your patient is dehydrated their blood is hypertonic. They will need a hypotonic solution to bring their tonicity back within normal ranges. The following is a list of solutions by their tonicity:
Why is D5W listed under two categories? Well because it is a trickster. The actual solution in the bad is isotonic, but once you give D5W to patients the body metabolizes the glucose molecules that were once causing the solution to be isotonic. The solution is now missing solute, causing it to become a hypotonic solution. What’s in your IV bag?
Should you memorize this chart? NO! I put this chart here to help you visualize why the IV solution is hypertonic, hypotonic or isotonic. The number of particles in the D5W is 50, and this is a hypotonic solution. Whereas D5 + Ringer’s is a hypertonic solution and has 361 particles. Patient scenariosYour patient has had nausea, vomiting, and diarrhea for 4 days. The blood work shows this patient is dehydrated but their electrolytes have managed to stay within normal limits.
Your patient comes in with bilateral +2 pitting edema on the lower extremities. The blood work confirms congestive heart failure (CHF).
Your patient is hypotensive, dizzy, weak, and reports abdominal pain. The blood work confirms adrenal insufficiency.
RELATED ARTICLE: 17 Must Know Normal Lab Values for NCLEX® Conclusion and Your Thoughts:Did this help? What else about tonicity confuses you? Let me know! Let’s start a discussion and turn this topic into something you understand! |