Dosage Calculations - page 8

I am in a desperate situation. I thought I was getting my calculations correctly and today I got back my math results and i got a 70% :crying2: :crying2: :crying2: I am so disappointed I dont know... Read More

1. order is to give amoxicillin 125mg suspension p.o. every 6 hours. you have available 250mg/5ml of amoxicillin. how many ___ml will you give each dose? how many ___mg/24 hours will this patient receive?
125 mg/1 (dose desired) x 5 ml/250 mg (dose desired) = 2.5 ml (amount to give for one dose)

if a dose is being given every 6 hours and there are 24 hours in a day then there are 24/6 = 4 doses being given in a 24 hour period. if each dose is 125 mg, then 125 mg x 4 doses = 500 mg being given/24 hours.
the physician orders 500ml of 5%dw to run 150ml per hours. how many drops per minute should the iv drip (15 gtt/ml set)?
150 ml/1 hour (amount to give) x 15 gtts/1 ml (drip factor) x 1 hour/60 minutes (conversion factor) = 37.5 gtts/minute, rounded off to 38 gtts/minute
order 500ml 20% dw iv are to be infused in 4 hours. the drop factor is 15 gtt = 1ml. how many milliliters per hour will the patient receive?
this is a simple fracture/ratio reduction problem:
500 ml/4 hours = 125 ml/1 hour
the physician orders 1000 ml of lr to run over a 24 hour period. how many microdrops per minute should the iv drip (60 gtt/ml set)
1000 ml/24 hours (amount to give) x 60 gtts/1 ml (drop factor) x 1 hours/60 minute (conversion factor) = 41.666 gtts/minute, rounded off to 42 gtts/minute
order: 500 ml 5% d/w, with 4 g of mgs04 20% solution. patient to receive 1 g per hour. calculate the infusion rate if the drop factor is 15 gtt = 1 ml. how many ml/hr?
500 ml/4 grams (dose on hand) x 1 gram/1 hour (dose desired) x 15 gtts/1 ml (drop factor) x 1 hour/60 minute (conversion factor) = 31.25 gtts/minute, rounded off to 31 gtts/minute
order: 50 cc 5% d/w with 1 g ampicillin (omnipen) iv in 20 minutes. calculate the rate of flow in ml/per hour and gtts/min using 15 gtt/ml?
50 cc/20 minutes (dose to give) x 60 minutes/1 hour (conversion factor) = 150 cc (ml)/hour

150 ml/1 hour (dose to give) x 15 gtts/1 ml (drop factor) x 1 hour/60 minutes (conversion factor) = 37.5 gtts/minute, rounded off to 38 gtts/minute
the patient must receive 500 u of heparin iv every hour. if the order is "add 10,000 u of heparin to 1000 ml of 5% d/w." how many drops per minute will the patient receive? drop factor 15 gtt = 1 ml. hint: the patient would be on an iv pump so you would basically solve for the ml/hr.
500 units/1 hour (dose desired) x 1000 ml/10,000 units (dose on hand) = 50 ml/hour (dose to give)
the iv in progress is 1000 ml of normal saline with 10 meq of kci, and 800 ml remain to be infused. the order is to increase the kci to 40 meq per liter. how many meq of kci will you add to the 800 ml remaining? this might occur in a critical care unit, but unlikely out on a med-surg floor.
10 meq/1000 ml = x meq/800 ml, solve for x = 8 meq of kci
40 meq/1000 ml = x meq/800 ml, solve for x = 32 meq of kci
you need 32 meq of kci in the current iv to bring the concentration to 40 meq of kci/1000 ml, so 32 meq (dose desired) - 8 meq (dose on hand) = 24 meq (amount of kci to add to the infusion)
doctor has ordered heparin infusion of 25,000 units in 500 ml of 5% dw to run at 75 u/min. how many ____units will you be administering per hour? how many ___ ml will you be infusing per hour?
75 units/1 minute (dose being given) x 60 minutes/1 hour (conversion factor) = 4500 units/1 hour

4500 units/1 hour (amount being given) x 500 ml/25,000 units (dose on hand) = 90 ml/hour (infusion rate)
physician's order: 500cc 5% d/w with 2 gm of lidocaine iv. how many drops per minute would you administer if the patient must receive 2mg/min? the drop factor is 15 gtt = 1 ml.
2 mg/1 minute (dose desired) x 500 cc, or ml/2 grams (dose on hand) x 1 gram/1000 mg (conversion factor) x 15 gtts/1 ml (drop factor) = 7.5 gtts/minute, rounded off to 8 gtts/minute
order 1000cc 5% d/w are to be infused with 10,000 u heparin iv. if the rate of flow 30 gtt/min and the drop factor is 10 gtt = 1 ml, how many milliliters per hour will the patient receive?
30 gtts/minute (flow rate) x 1 ml/10 gtts (drop factor) x 60 minutes/1 hour (conversion factor) = 180 ml/hour (amount being given)
order 500 ml 5%d/w with 4 g of mgso4 20% solution. patient to receive 1 g per hour. calculate the infusion rate if the drop factor is 15 gtt = 1 ml/hr?
1 gram/1 hour (dose desired) x 500 ml/4 grams (dose on hand) x 1 hour/60 minutes (conversion factor) x 15 gtts/1 ml (drip factor) = 31.25 gtts/minute, rounded off to 31 gtts/minute
the patient must receive 500 u of heparin iv every hour. if the order is "add 10,000 u of heparin to 1000 ml of 5% d/w, how many drops per minute will the patient receive? drop factor 15 gtt = 1 ml.
500 units/hour (dose desired) x 1000 ml/10,000 units (dose on hand) x 15 gtts/1 ml (drop factor) x 1 hour/60 minutes (conversion factor) = 12.5 gtts/minute, rounded off to 13 gtts/minute
Last edit by Daytonite on Dec 16, '07
2. I understand exactly how you feel I'm currently in my third nursing semester; last semester I did not pass my first dosage calc test, however I ended up Aceing the second one. I know that right now it feels like you just can't do it! But YOU CAN DO IT!!! As you may already be familiar w/the process of nursing school of having to pull it together and continue on. As a matter of fact I was just surfing the web for dosage calc problem to practice (I have an exam in a couple of weeks) all you need to do is type in nursing dosage calculations and a lot of sites will come up, I've found some really helpful sites.
Hang in there, I know you can do this!!!
3. I hope you guy dont mind but I am practicing for my first exam and I get lost on problems just like these. I like to gather this information and use it to help me to understand how to do IV drips.
4. Quote from shauntaebrit
i hope you guy dont mind but i am practicing for my first exam and i get lost on problems just like these. i like to gather this information and use it to help me to understand how to do iv drips.
you will find information and links to websites that have practice problems on how to do iv drip problems on post #6 of this thread in the student forums: http://allnurses.com/forums/f205/any...es-127657.html - any good iv therapy or nursing procedure web sites
5. Quote from Nrs_angie
Hello

First I have to ask if you wrote the question correctly, because it is unusual to see cc's per minute.... typically IV flow rates will ask drops per minute or mL per hour...

so lets assume its drops (gtt) per minute

use the formula: DESIRED OVER HAVE ON HAND X QUANTITY

800u/hr X 500 mL = 80 mL/hr
5000 ml

to figure the drops per minute you need to know if you have macrodrop set IV tubing or microdrip set... most institutions use a macrodrip set of 15...

the shortcut method is to use a "DROP FACTOR" which = # gtt in 1 mL

shortcut formula is 60 divided by 15 to give you a drop factor of 4...

mL/hr divided by the drop factor will give you the gtt/min or drops per minute...

80 mL / Hr divided by 4 = 20 gtt/min

Now if you recheck the question, and it truely is asking for the cc's per minute...

well there are 60 minutes in an hour...

so divide 80 mL by 60 to = 1.3333

Hope this helps!

Good luck,
Angie
Actually the 5000 is units of Heparin in the 500ml of D5W,so all you have to do is divide 5000/500 and you get 10u per ml. You need to give 800u in 1 hr which will be in 80ml of solution. So to get cc(ml)/min;

80ml X 1hr = 80 = 1.33cc/min
1hr.... 60min. 60
Last edit by beth66335 on Jan 13, '08
6. I don't mind at all; if there is anything that I can help you with in particular just let me know and I will gladly help you.
7. A useful tutorial for learning about and practicing dosage calculations:
http://www.dosagehelp.com/
8. Quote from EnviroVeg
A useful tutorial for learning about and practicing dosage calculations:
http://www.dosagehelp.com/
Thank you for the tip on the dosage calculation tutorial; I have a dosage calc. exam coming up soon; and this website has a lot of useful practice questions.
9. 1. A Phsycian orders an IV of D5W to run @ 100mlls
The drop factor is 10gtt/ml
What is the flow rate??
2. Tetracycline is prepared in 50ml of an IV solution it is infusing @ 30gtts/min.
The drop factor of the infusion set is 20gtts/ml. What is the infusion time?/
10. Quote from cperg51018
1. A Physician orders an IV of D5W to run at 100 mL (per 60 minutes?). The drop factor of the IV tubing is 10 gtts/mL. What is the flow rate?
100 mL/60 minutes (amount to give) x 10 gtts/1 mL (drop factor of IV tubing) = 16.66 gtts/minute, rounded off to 17 gtts/minute (a drop must be a whole number)
Quote from cperg51018
2. Tetracycline is prepared in 50 mL of an IV solution. It is infusing at 30 gtts/minute. The drop factor of the infusion set is 20 gtts/mL. What is the infusion time?
1 minute/30 gtts (infusion rate) x 50 mL/1 (amount to give) x 20 gtts/1 mL (drop factor of IV tubing) = 33.33 minutes
11. Thank you for your help in the calculation if medication through IV, I am studying to be a CMA certified medical assistant and I am in phlebotomy now and we are into the calcultaions, Is there any way of breaking these calculations down to help understand them better?
Last edit by UM Review RN on Jan 26, '08 : Reason: Please do not post email address. Use PM instead. Thanks.
12. do many problems. read the problem carefully and pick out the terms that are in this formula: dose desired divided by dose on handed multiplied by the amount the dose on hand is in equals the amount to give. make sure you read the final line of the problem and you understand exactly what the problem is asking you to find. for iv problems you may need to factor in the drops/ml of the iv tubing to get the rate/hour. apply conversion factors as needed.

there are medication calculation tutorials on post #3 of this thread:
and you can see lots of problems that have been worked out on this thread if you go back through the posts.

i am currently taking dosage. i have been having a hard time with these questions trying to figure out the formulas but dont seem to understand how to do them. if anyone could help that would be great. i will post a few at the bottom please let me know.

a nipride drip is ordered to infuse on a pump at 2mcg/kg/min on a patient weighting 110lbs. nipride is supplied 50mg/250ml d5w. how many ml/h will the iv need to run?

a dopamine drip is ordered to infuse at 3mcg/kg/min. the solution is avaliable in 400mg in 250ml d5w. the patient weights 155lbs. using a 60gtt/ml set:
what is the mcg/min dosage?
what is the gtt/min flow rate?

an order of 250mg in 5ml is to be diluted to a total of 50ml and given over 70min. how much dilutent should be used? and what is the ml/hr rate?

i appreciate any feedback that i get. thanks