Reconstitution HELP Pleaseeeeeee!!!!!!! :(

allnurses Guide · Nov 6, 2012

How much sterile water should the nurse add to the vial?

I got 2.75mL (i just halfed the 5.5mL for this answer)

Look again.

If we follow your logic, to give 200,000 units, we would just 1/2 the diluent amount for 400,000 units.

As you can see in your example above, that's incorrect.

You see the sterile water amount INCREASES as we dilute the medication.

If you 1/2'd the 5.5mls... you've actually haven't diluted enough, hence the concentration is stronger.

allnurses Guide · Nov 6, 2012

I think your answer is right, but the thinking about the dilution is wrong.

I would figure to make a full vial and give 1/2.

kaydensmom01 · Nov 6, 2012

I agree that I would pick one, but in order to yield the 600,000 un/ml you would have to add in the full 5.5 ml. It says "add 5.5ml to equal 600,000un/ml". If you add in less it will not equal that concentration. You would add in the 5.5 ml and then take 1/2 ml since 1 ml equals 600,000un.

loriangel14, RN · Nov 6, 2012

You would have to dilute the entire vial and then draw up half of it. You can't reconstitute just part of a vial.

metal_m0nk, BSN, RN · Nov 7, 2012

One of the reasons we dilute medications is to be able to administer the medication at a rate that allows optimal onset of action (pharmacokinetics) with the lowest risk for adverse events. Potassium chloride for example, gives the patient a burning sensation when it is administered intravenously. For that reason, it is diluted when administered, which effectively reduces the amount of solute that is in contact with any portion of the vasculature at one time. Dilution gives the body time to respond and adjust without being overloaded with solute.

Think of it like baseball. You're the pitcher, the batter is your patient and your medication is a certain number of balls (like a certain number of units of medication). If you pitch one ball at a time, the batter has time and opportunity to react to each pitch, swing and make contact with each ball you throw. As you increase the number of balls you throw (say, throwing 3 balls at once instead of just one at a time), your batter can easily become overwhelmed and has very little chance of hitting any of the balls you throw at him.

A dilution of 600,000 units in 6mL is equal to 10,000 units per mL. If you administer one mL at a time x 6, your patient will receive 10,000 units with each administration. Now, a dilution of 600,000 units in 3mL is equal to 20,000 units per mL. If you administer one mL at a time x 3 your patient is actually receiving twice as many units with each administration - even though the same number of total units was administrated in each case.

Esme12, ASN, BSN, RN · Nov 7, 2012

I'm having a hard time understanding a certain group of reconstitution problems and my ATI is useless...
Here's the question:
A patient is to receive 300,000 units of a medication. The reconstitution directions read:
1) Add 5.5 ml to yield a concentration of 600,000 units/mL
2)Add 6.3 ml to yield a concentration od 400,000 units/mL
3) Add 7.6 ml to yield a concentration of 200,000 units/mL
Which concentration should the nurse use? Why?
I chose #1 and said b/c it's easier to withdraw half of one vial than to withdraw 1/3 or use 2 vials
How much sterile water should the nurse add to the vial?
I got 2.75mL (i just halfed the 5.5mL for this answer)
How many mL should the nurse administer to the patient?
I got 0.5mL (i did the D/H x mL, but idk if i'm even supposed to use it for this?!)
I have a bunch of these questions and I really think i'm doing them wrong b/c how can what the nurse administers be less than the mL that was added to the reconstitution in the first place?! Am I missing something blatantly obvious (this is a major possibility, which is why can someone please please pleaseee help me!)

DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

Which concentration should the nurse use?

You are right there.

How much sterile saline?

The answer is in the question......5.5ml right?

How much do you give?

Half ......2.5mls.....right?

Watch your calculations......DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

Formula:

[TABLE=class: formula]

[TR]

[TD] [TABLE=class: fraction]

[TR]

[TD=class: numerator] Ordered/need[/TD]

[/TR]

[TR]

[TD=class: denominator] Have[/TD]

[/TR]

[/TABLE]

[/TD]

[TD] = Y (dose)[/TD]

[/TR]

[/TABLE]

EDITED TO ADD: TEACHING MOMENT!!!!!!!!!!

I could delete this and pretend I didn't answer this incorrectly and totally screwed up the question. Save myself embarrassment.... But I will NOT!!!!

This is an example of pull you head out of your behind, put that phone down AND PAY ATTENTION!!!!! It doesn't matter what I was distracted by and how important what I was doing at the time and that I ALWAYS check my answers and that I have NEVER, EVER, EVER done this before.......doesn't matter. It doesn't matter if you are fighting with your boyfriend, the dog died, the baby kept you awake last night, or you couldn't see because you were crying because you lost a beloved family member.......you still gave the wrong dosage because you did the wrong calculation.

Nursing is all about the details and PAYING ATTENTION to the task at hand. I was distracted in answering the question...took the obvious short cut and never sat down and did the actual calculation, as I "ALWAYS" DO, I just OD's this patient and probably killed them.

Had this been a real patient and I gave 2.5ml of this concentration I would have given the patient a HUGE OVERDOSE and actually given 1,500,000 units (that's 1.5 MILLION units instead of the required dosage of 300,000 units (300 thousand units) and just killed someone.

I know this isn't a "real patient" but that is not the point. Every thing you do should be considered the "real" patient. It's a dangerous job we do everyday and I just hypothetically ended my career.

PLEASE pay attention. Put that phone down. ALWAYS Check your calculations with a trusted peer.

I stand humbly corrected.

HalfMoons · Nov 8, 2012

Ooooh. Wow. I'm an idiot. For some reason I see all of these #'s and get so confused and my common sense flies right out of the window!

Thank you so much!!! :)

Double-Helix, BSN, RN · Nov 10, 2012

Reconstitution problems can be difficult. I find it helpful when doing math problems to highlight (or circle) the information that you need, and cross out the information that you don't.

In a reconstitution problem, you need to pay the most attention to your final concentration (in this case, units/mL). It's easy to get thrown off by how much liquid you need to add to the vial.

1) Add 5.5 ml to yield a concentration of 600,000 units/mL

2)Add 6.3 ml to yield a concentration od 400,000 units/mL

3) Add 7.6 ml to yield a concentration of 200,000 units/mL

Now, when you need to give 300,000 units it's easy to look at those options and think, "I need half the vial in option 1, because it's got 600,000 units in the vial." Or "I need more than one vial in option 3, because there's only 200,000 units in that vial."

But that's nt the case at all. Each vial contains the same amount of medication, but different amounts of fluid. Remember that those values are concentrations which tells you how much medication you have in one mL. It does not tell you how much is in the whole vial. Think about it- in each option you start out with the same sealed vial of powdered medication. All you're doing is adding water. You aren't removing anything. How can you get less total medication by just adding water? You can't.

So in option 1, you have 600,000 units in ONE mL. You have more than one mL in the vial, so the entire vial contains more than 600,000 units. You can't just say, "I need to give half that vial." You need to look at the concentration: 600,000 units in one mL/ SO there are 300,000 units in 0.5mLs, NOT in half the vial.

In option 2, you add more fluid so you dilute the medication more until you've got 400,000 units in one mL (not the whole vial). So if you need to give 300,000 units than you have to give 0.75 mL. (300,000u / 400,000u x 1mL = 0.75)

In option 3, you add even more fluid so that your final concentration is 200,000 units/mL (NOT per vial). So in order to give 300,000 units you would need 1.5mLs of medication. (300,000u / 200,000u x 1mL = 1.5)

So, which concentration should you use? In my opinion, you should use the most diluted medication, or option 3. Why? Because it's easier to be more precise with your measurements. It's easier to accurately draw up 300,000 units if you're using a bigger volume. In the case of the 600,000u/mL concentration, there are 60,000 units in 0.1mL. In the lower concentration, there are only 20,000 units in 0.1mL. If your measurement is slightly imprecise, the patient get's much more of the medication if you're drawing from a higher concentration than a lower concentration. Make sense?

How much fluid you need is in the problem.

How much fluid do you give? You do need to use the D/H x V formula to find the answer, but remember to use your final concentration as your HAVE amount, not the amount of fluid you added. Your original answer was correct, your thinking was just a little mixed up.

Esme12, ASN, BSN, RN · Nov 11, 2012

Reconstitution problems can be difficult. I find it helpful when doing math problems to highlight (or circle) the information that you need, and cross out the information that you don't.
In a reconstitution problem, you need to pay the most attention to your final concentration (in this case, units/mL). It's easy to get thrown off by how much liquid you need to add to the vial.
1) Add 5.5 ml to yield a concentration of 600,000 units/mL
2)Add 6.3 ml to yield a concentration od 400,000 units/mL
3) Add 7.6 ml to yield a concentration of 200,000 units/mL
Now, when you need to give 300,000 units it's easy to look at those options and think, "I need half the vial in option 1, because it's got 600,000 units in the vial." Or "I need more than one vial in option 3, because there's only 200,000 units in that vial."
But that's not the case at all. Each vial contains the same amount of medication, but different amounts of fluid. Remember that those values are concentrations which tells you how much medication you have in one mL. It does not tell you how much is in the whole vial. Think about it- in each option you start out with the same sealed vial of powdered medication. All you're doing is adding water. You aren't removing anything. How can you get less total medication by just adding water? You can't.
So in option 1, you have 600,000 units in ONE mL. You have more than one mL in the vial, so the entire vial contains more than 600,000 units. You can't just say, "I need to give half that vial." You need to look at the concentration: 600,000 units in one mL/ SO there are 300,000 units in 0.5mLs, NOT in half the vial. (300,000u / 600,000u x1ml = 0.5ml)
In option 2, you add more fluid so you dilute the medication more until you've got 400,000 units in one mL (not the whole vial). So if you need to give 300,000 units than you have to give 0.75 mL. (300,000u / 400,000u x 1mL = 0.75)
In option 3, you add even more fluid so that your final concentration is 200,000 units/mL (NOT per vial). So in order to give 300,000 units you would need 1.5mLs of medication. (300,000u / 200,000u x 1mL = 1.5)
So, which concentration should you use? In my opinion, you should use the most diluted medication, or option 3. Why? Because it's easier to be more precise with your measurements. It's easier to accurately draw up 300,000 units if you're using a bigger volume. In the case of the 600,000u/mL concentration, there are 60,000 units in 0.1mL. In the lower concentration, there are only 20,000 units in 0.1mL. If your measurement is slightly imprecise, the patient get's much more of the medication if you're drawing from a higher concentration than a lower concentration. Make sense?
How much fluid you need is in the problem.
How much fluid do you give? You do need to use the D/H x V formula to find the answer, but remember to use your final concentration as your HAVE amount, not the amount of fluid you added. Your original answer was correct, your thinking was just a little mixed up.

:banghead:.........Oh Ashley...you are one smart cookie. I TOTALLY MISSED the final concentration yield of X units per ml. What a totally blonde moment!!!!!!!!!!!!!! The final concentration yield......I am an idiot . I totally didn't see that. Distracted posting. See another reason not to text at work. Thank goodness I always double check my calculations when I am at work before I give anything. I am such an idiot.... :wideyed:

How much saline added to the vial has no bearing on the answer.

1) Add 5.5 ml to yield a FINAL concentration of 600,000 units/mL

2)Add 6.3 ml to yield a FINAL concentration of 400,000 units/mL

3) Add 7.6 ml to yield a FINAL concentration of 200,000 units/mL

OP I am sooooo sorry.

Double-Helix, BSN, RN · Nov 11, 2012

:banghead:.........Oh Ashley...you are one smart cookie. I TOTALLY MISSED the final concentration yield of X units per ml. What a totally blonde moment!!!!!!!!!!!!!! The final concentration yield......I am an idiot . I totally didn't see that. Distracted posting. See another reason not to text at work. Thank goodness I always double check my calculations when I am at work before I give anything. I am such an idiot....
How much saline added to the vial has no bearing on the answer.
1) Add 5.5 ml to yield a FINAL concentration of 600,000 units/mL
2)Add 6.3 ml to yield a FINAL concentration of 400,000 units/mL
3) Add 7.6 ml to yield a FINAL concentration of 200,000 units/mL

OP I am sooooo sorry.

I'm sure you will agree that one miscalculation in one post (out of the thousands, no doubt, you have answered) hardly makes one an idiot. The baby let me sleep last night. :-) You are forgiven.

tokebi · Nov 12, 2012

I don't get what this question is really asking for. If it claims there's one correct answer, that's BS.

You can go with option 1 and draw up 0.5ml.

You can go with option 2 and draw up 0.75ml.

You can go with option 3 and draw up 1.5ml.

While Ashley has a good point, the matter of accuracy can be solved simply by using a syringe that's appropriately sized. For example, you wouldn't use 10-ml syringe to draw up 0.5ml.

Maybe i'm just flying off tangent here, but sometimes I get frustrated with nursing school questions that are so arbitrary and rigid to the point of ridiculousness.

Another thought is that if there is an extra info on how this med is to be given, that could be a deciding factor too. If it were to be given subQ, for example, 0.5ml would be better than 1.5ml. If it were given IV, it wouldn't really matter. Disregard this though OP. Just for the sake of nursing school, what I just did is a great sin, known as reading into questions too much.