# help w/ IV calculations

- 0Jan 19, '08 by ilovematt48we were supposed to study iv calculations friday in class but all we got was a woman stranding up there for about 7-8 minutes who never gave us a fully worked out problem nor the full formula to work the problem, so needless to say i am stumped and VERY frustrated. i have looked up some formulas in the books i have but i just recieved a practice test from my teacher and the formulas in the book won't work for the problems she gave us, or maybe it's just me and i'm just having a bad day!!!! either way i need some help please!!! here is as example of a problem i am stumped on:

*Give Bretylium 1g in 250 ml D5W at 2mg/min. Drop factor=15 gtt/ml. Calcualte the volume per hour.

The answer is supposed to be 30 ml/hr, but i don't know how to get that!???

i also need help w/ this one: give insulin 100 units in 1000ml NS at 6 units/hr. calculate the volume per hr. - 1Jan 19, '08 by mixyRNQuote from ilovematt48Ok, I am great at math but not so great at teaching so bear with me!we were supposed to study iv calculations friday in class but all we got was a woman stranding up there for about 7-8 minutes who never gave us a fully worked out problem nor the full formula to work the problem, so needless to say i am stumped and VERY frustrated. i have looked up some formulas in the books i have but i just recieved a practice test from my teacher and the formulas in the book won't work for the problems she gave us, or maybe it's just me and i'm just having a bad day!!!! either way i need some help please!!! here is as example of a problem i am stumped on:

*Give Bretylium 1g in 250 ml D5W at 2mg/min. Drop factor=15 gtt/ml. Calcualte the volume per hour.

The answer is supposed to be 30 ml/hr, but i don't know how to get that!???

i also need help w/ this one: give insulin 100 units in 1000ml NS at 6 units/hr. calculate the volume per hr.

Let's start with the 2nd one-it's easier.

#2: insulin 100u per 1000ml = 100u/1000ml, and the rate is 6u/hour so the calculation is:

(1000ml/100u) x 6u/hr = 60ml/h

now back to the first prob. it's asking for volume per hour which is a rate so the information given 15gtt/ml is extraneous and you don't use it.

#1: Bretylium 1g in 250 ml = 1g/250ml, and the rate is 2mg/min so to find volume/hr we want an answer in ml/h.

(2mg/m) x 60m/hr = 120mg/h (which is .120g/h)

(.120g/h) x (250ml/g) = 30ml/h

Hope this helps!!:spin:Last edit by mixyRN on Jan 19, '08ilovematt48 likes this. - 1Jan 20, '08 by
*Daytonite*give bretylium 1 gram in 250 ml d5w at 2mg/min. drop factor=15 gtt/ml. calculate the volume per hour.**dose desired**: 2 mg/1 minute

**dose on hand**: 1 gram/250 ml

**conversion factor**: 1 gram = 1000 mg

**conversion factor**: 60 minutes = 1 hour

you want to end up with**ml/hour**. the drip factor of the iv tubing is a red herring (distracter information) in calculating the volume per hour this iv will run and is not necessary information in determining the answer:

**2 mg/1 minute**(dose desired)**x 60 minutes/1 hour**(time conversion factor)**x 250 ml/1 gram**(dose on hand)**1 gram/1000 mg**(conversion factor)**=**(dose to give, or volume per hour)__30 ml/hour__give insulin 100 units in 1000ml of ns at 6 units/hour. calculate the volume per hour.i worked these by dimensional analysis which is, i think, is a much more efficient way to deal with problems, particularly when the information starts to get more complicated and involve more factors. still, the basic formula**dose desired**: 6 units/hour

**dose on hand**: 100 units/1000 ml

**6 units/1 hour**(dose desired)**x 1000 ml/100 units**(dose on hand)**=**(dose to give, or volume per hour)__60 ml/hour__that formula will never steer you wrong. you only have to determine which terms are which. it could have easily worked for the second problem:__dose desired divided by the dose on hand times the amount the dose on hand comes in gives you the amount (or dose) to give__.

there are tutorials on medication calculation plus weblinks to sites that have practice problems on post #3 of this sticky thread of the student forums: http://allnurses.com/forums/f50/nurs...ad-264395.html -**6 units**(dose desired**)/100 units**(dose on hand)**x 1000 ml**(amount the dose on hand comes in)**=**__60 ml__**the nursing math thread**(in the general nursing student discussion forum). several of the tutorials are really good and you should take advantage of them. you can also see a whole bunch of problems worked out on this sticky thread:

http://allnurses.com/forums/f205/dos...ons-88867.html -**dosage calculations**(in the nursing student assistance forum).

ilovematt48 likes this.