drug calculation

ejm99 · Jan 23, 2011

I would love to see this problem worked out. As a student just beginning dosage calc and Pharm...it freaked me out just reading it..lol...

2ndyearstudent, CNA · Jan 23, 2011

Hi everyone, it's nice to be here. Please can someone help me with this drug calculation, will like to know what fomula to get the answer too, thanks in advance.
A patient who weighs 125 lbs. And has IV heparin ordered per the following weight based heparin protocol:
Heparin IV infusion: Heparin 25,000 U in 250 ml of ½ NS
IV Boluses: Use heparin 1000 u / ml
Bolus with heparin 80 u/kg. Then initiate heparin drip at 18 u/kg/h. Obtain APTT every 6 hours and adjust dosage and rate as follows:
If APTT is
If APTT is 36-44 seconds: Rebolus with 40 u/kg and increase rate by 2 u/kg/h.
If APTT is 45-75 seconds: Continue current rate.
If APTT is 76-90 seconds: Decrease rate by 2 u/kg/hr.
If APTT is > 90 seconds: Hold heparin for one hour and then decrease rate by 3 u/kg/h.

Part I: Convert the patient's weight to kg: ____ kg
Calculate the initial heparin bolus dosage: _____ u
Calculate the bolus dose: ____ ml
Calculate the initial heparin infusion rate: ____ u/h or ____ ml/h

Part II: At 0930, the patient's APTT is 77 seconds. According to the protocol, what will your action be?

This question looks right off my recent Dosage Calc Test.

Part I:

Pt's wt in kg = 125/2.2 = 56.8 kg (They usually tell you to round kg to nearest 10kg. If my answers seem wrong, you forgot to include that instruction in your post.)

Initial Bolus Dosage: 80 units/kg x 56.8 kg = 4545 units

Bolus Dose Volume: 4545 units x 1ml/1000 units = 4.5 ml

Initial heparin infusion rate: Dose = 18units/kg/hr x 56.8 kg = 1022 units/hour.

Use D/H x Q to find the Rate. H = 25,000 units in the supply bag. Q = volume in the supply bag = 250ml.

So 1022 units/h /25000 units x 250ml = 10.22 ml/h

Part II

APTT is 77 seconds so decrease rate by 2 units/kg/hour.

Your new dose is 18-2 = 16 units/kg/hr x 56.8 kg = 909 units per hour.

Same equation as above 909 units/h / 25,000 units x 250 ml = 9.1 ml/h

Esme12, ASN, BSN, RN · Jan 23, 2011

Hi everyone, it's nice to be here. Please can someone help me with this drug calculation, will like to know what fomula to get the answer too, thanks in advance.
A patient who weighs 125 lbs. And has IV heparin ordered per the following weight based heparin protocol:
Heparin IV infusion: Heparin 25,000 U in 250 ml of ½ NS
IV Boluses: Use heparin 1000 u / ml
Bolus with heparin 80 u/kg. Then initiate heparin drip at 18 u/kg/h. Obtain APTT every 6 hours and adjust dosage and rate as follows:
If APTT is
If APTT is 36-44 seconds: Rebolus with 40 u/kg and increase rate by 2 u/kg/h.
If APTT is 45-75 seconds: Continue current rate.
If APTT is 76-90 seconds: Decrease rate by 2 u/kg/hr.
If APTT is > 90 seconds: Hold heparin for one hour and then decrease rate by 3 u/kg/h.

Part I: Convert the patient's weight to kg: ____ kg
Calculate the initial heparin bolus dosage: _____ u
Calculate the bolus dose: ____ ml
Calculate the initial heparin infusion rate: ____ u/h or ____ ml/h

Part II: At 0930, the patient's APTT is 77 seconds. According to the protocol, what will your action be?

even though you already have the answer........ This is comming only from a place of love and caring......

you need to learn how to do these yourself, not scan them into a computer and post them for someone else to figure out. Drugs and dosages are apart of eveyday nursing and an important skill to learn. I realize schoolis overwhelming but this is one short cut you cannot afford to take.

Here is a really good website!

http://www.dosagehelp.com/

JenRN1821 · Nov 13, 2016

First of all nurses making comments and getting upset about other nurses working out the problem. You need to relax! First of all this student is trying to learn and trying to work out a math problem!!!!!!!ðŸ˜ˆ As a RN, former student. Every nurse used examples from math problems to learn and work out future problems. Even as a nurse now I have to refer to examples or get stuck on some math problem while furthering my education. Even doctors can't figure out some of the math in our in-house hospital test! It's not about working out the problem for someone. It's showing someone step by step how they worked out that particular math problem so they can work out the next problem. Giving them links is helpful of course but they might not have that exact problem. The fact that this student is coming on here to ask for help shows initiative And wanting to learn.

chare · Nov 13, 2016

No one is getting upsetâ€ because someone worked the problem. The concern, if we work the problem without asking the OP to post what he or she has done, is that he or she doesn't learn anything by this. When the OP posts what he or she has done, this allows us to see where they are having problems, and best allows us to help them.

I appreciate your comment regarding using examples, and agree. In my opinion, however, a better method of providing an example is to work a similar problem, rather than the one that was posted. This accomplishes two things. First, this shows the OP how the problem can be set up and worked and then allows them the opportunity to work the original problem. Thus having seen a similar problem completed.

AliNajaCat · Nov 13, 2016

What my dear friend Esme means is that we can help people learn how to think about these kinds of problems (and they can be broken down into smaller solvable bits with a minimum of critical thinking) but we can't help them unless we see what they know already. Give a man a fish and he eats for a day; teach him to fish and he eats for a lifetime.

You have just handed the OP the fish, but she (and anybody else who wants to learn this) doesn't yet know how to catch it, and doesn't know that having "an equation" or "a formula" will mislead you in other contexts-- we see it often. How could that be?

Nursing word problems often have extraneous information in them, things that aren't necessary to know to obtain the answer. So if you have a long "formula" and plug in every number in the word problem, you will get a wrong answer. The people who write the test questions know this, and know that the people who will choose a wrong answer will do so because they don't really understand what the question is asking. So the test includes three wrong choices that would result from such an error.

Example: Give 275mg of miraclecillin in 500cc over 30 minutes QID, using an IV set with a gtt factor of 15gtts/cc. Miraclecillin comes in vials of 1 gm. The label states, "Reconstitute with 6.5cc sterile saline for a final concentration of 100mg/cc." How many cc will your patient receive in 24 hours?

You should be able to do this in your head. Why, how, with all those numbers? Because you're going to give 500cc four times a day, and that's all they're asking you. If you take a big dimensional analysis formula and plug in all those numbers they way they got plugged into other problems, you'll get all sorts of oddness.

(I borrowed this example from https://allnurses.com/general-nursing-student/dosage-calculations-966424.html. There are other really good things in it.)