# IV calculations

- 0Feb 11, '08 by momtojoshok......we started IV flow rates and the like last week.....and i have a hard time with math.....once i get it and do it often i am comfortable.....til then...this hit and miss with calculations kill me.....i am 45 and way out of touch.......other than math i LOVE school.....

here is a question....perhaps someone can explain it better or in a way i might grasp it......dont laugh....it is probably a very easy question

doc orders xxxxx @ a rate of 40mg/hr. the concentration of med is 600mg per liter of IV fluid. Calculate how many mg/min of the drug the PT is receiving: ALSO calculate what the drip rate is(gtts/min) if an infusion set c a drop factor of 60 gtts/ml is used......

is that c a typo......am i not getting a abreviation? otherwise this is just mumble jumble to me........sad arent i?

thanks all in advance for your help!!

paula - 6,676 Visits
- 0Feb 11, '08 by
*Daytonite*Quote from momtojoshHow many mg/min of the drug is the patient receiving?Doctor orders xxxxx @ at a rate of 40mg/hr. The concentration of the medication is 600mg per liter of IV fluid. Calculate how many mg/min of the drug the patient is receiving. Also calculate what the drip rate is in gtts/min if an infusion set has a drop factor of 60 gtts/ml

Calculate the drip rate in gtts/minute for an infusion set with a drop factor of 60 gtts/mL**40mg/hour**(dose patient is receiving)**x 1 hour/60 minutes**(conversion factor)**= 0.666 mg/minute**, rounded off to__0.66mg/minute__

**0.66mg/minute**(dose desired)**x 60 gtts/mL**(drop factor of IV tubing)**x 1 liter/600 mg**(dose on hand)**x 1000 mg/1 liter**(conversion factor)**=**(drip rate)__66 gtts/minute__ - 0Feb 12, '08 by momtojoshHow many mg/min of the drug is the patient receiving?

Calculate the drip rate in gtts/minute for an infusion set with a drop factor of 60 gtts/mL**40mg/hour**(dose patient is receiving)**x 1 hour/60 minutes**(conversion factor)**= 0.666 mg/minute**, rounded off to__0.66mg/minute__

**0.66mg/minute**(dose desired)**x 60 gtts/mL**(drop factor of IV tubing)**x 1 liter/600 mg**(dose on hand)**x 1000 mg/1 liter**(conversion factor)**=**(drip rate)__66 gtts/minute__

still not seeing it......i divide 40 by 60 and get 0.66,what is the x 1hrdivided by 60........i plugged in all the calcs you have and got it.....but also i got it from just dividing 40/60.....

what am i not seeing......

try just pluggin in the number without all the ( )...something is confusing me......sorry.....but i DO appreciate the help!!

thanks

- 0Feb 12, '08 by OBXRNJessokay I am confused now! I understand the first part of the problem How you got .66..but if you are just trying to find the number of drips/min don't you ignore the mg? I am setting it up like this..

60gtts/1ml X 1000ml/60min =1000gtts/min ??? Have I looked at this too long?? Since there is 1000ML in 1 liter - 0Feb 13, '08 by
*carolinapooh*Quote from DaytoniteWhen I did this according to my old calc book from first semester (because the problem bothered me, so I drug out the old book!), I got 40 gtts/min.How many mg/min of the drug is the patient receiving?

Calculate the drip rate in gtts/minute for an infusion set with a drop factor of 60 gtts/mL**40mg/hour**(dose patient is receiving)**x 1 hour/60 minutes**(conversion factor)**= 0.666 mg/minute**, rounded off to__0.66mg/minute__

**0.66mg/minute**(dose desired)**x 60 gtts/mL**(drop factor of IV tubing)**x 1 liter/600 mg**(dose on hand)**x 1000 mg/1 liter**(conversion factor)**=**(drip rate)__66 gtts/minute__

According to the book,*Essential Drug Dosage Calculations*:

-first determine the number of mLs/min to get the prescribed dose, which here is 40 mgs/hr out of 600mgs/liter. I did it the long way to check myself, and got the 0.67 (well, actually 0.666666.....).

The book now says to multiply the mLs/minute by the drip factor:

0.67(60) = 40.2 gtt/minute to give you 40 mg/hr.

All of the problems in the book are done this way, this is how we did them in school, and I never got a math problem wrong - either in didactic or in clinical. I also never killed anyone or had any med errors in clinical. So if I'm doing something wrong now, please show me - and that's a sincere request. Sometimes this stuff confuses me because I over-think it...and it is late besides!

ETA: OH YES, I AM A TOOL - I left out half the calculation - remind me not to do math this late...Last edit by carolinapooh on Feb 13, '08 :**Reason**: self-correction - 0Feb 13, '08 by momtojoshthanks!!! guess alot of people in class today were confused by this one......just too wordy........in my opinion......just a med error waiting to happen if this is an order......do we really have to figeure this out in the field? I know you have to know it for the nclex.......but are thy like this??

Yup..the instructor got o.66 for the first half....and 67 for the 2nd

40(dose desired)/600(dose on hand)x1000 volume=66.66 rounded to 67.....

thanks again.... - 0Aug 26, '10 by courtneylpnhello this is my 1st time on ths website and im wondering i someone can help me i moved to fl from ny and there eqipment n way o doing things are way different...theyre iv pupms are very outdated n i cannot figure how to calculate on them...i have an ive bag that says its a 100ml bag of fluid n to inuse over 30 min..thats about all the info i get!!!! so on the pump u have to enter the pri rate and the vtbi now i know the vtbi is 100ml's but how am i figuring out the pri rate if i have no drip factor or anything??? the other day i had one that said 600mg/300ml infuse over 1hr can you please help me figure out theses iv issues!!! i feel like a complete mouron!!! i basically need to know how to figure out the pri rate

thanks so much!!!