# Med Math Help (IV Calculations)

1. Help! I have several questions:

1. Order: Levofloxacin 250mg every 48 hours
Available from pharmacy in 50ml NS
You are to administer over 40 minutes
Drop factor: 60gtts/ml

What are the gtts/min?
What are the ml/hr?
What is the VTBI?

2. Order Thorazine 60mg IM now
Available is a 10ml multi-dose vial, strength is 25mg/ml

How many mls will you administer?

3. Rocephin 500mg IVPB daily
Available: One gram vial. Reconstitute with 10mls SW
Further dilute in 50mls NS and administer over 20 minutes.

What are the settings for the pump?
The pump is broken. You must infuse by gravity/drop factor is 15gtts/ml. What is the gtts/min?

I'm REALLY confused,
•

Joined: Sep '08; Posts: 6; Likes: 1

3. Here's a formula to solve number 2. You put the desired amount (60 mg) over the amount you have (25 mg), then you divide, then you multiply by the quantity (1 mL). You should administer 2.4 mL.
4. hey there, here's what i got for the first two parts of #1:

you are asked to solve for gtt/min so you organize your equations so that you have gtts on the top, and minutes on the bottom. the ml's will cancel in just a moment. take a look:

60 gtt x 50 mls
----- -------
ml 40 mins

ml's cancel and you get (60gtts * 50)/40 minutes = 3000/40 = 75 gtt/min

ok, now you're asked to solve for ml/hour but you need to convert your minutes into hours by using a conversion factor of 60 mins = 1 hour. this way you'll get your "hour" on the bottom of the equation. so here we go:

you see in the question that you have 50 mls to give in 40 minutes.

so set it up:

50 ml
------
40 mins

50 ml x 60 mins
----- ---------
40 min 1 hour

minutes will cancel and you get (50 ml*60)/(40*1) = 3000ml/40mins
= 75 ml/hour.

ps, just a tip, gtt/min is equal to ml/hour.

couldnt remember how to solve the vtbi....i had a shortcut, but forgot it.

hope that helps.
5. Oh, VTBI looks like its in the question...and I wanna say its the 50mls.
6. order: levofloxacin 250mg every 48 hours
available from pharmacy in 50ml ns
you are to administer over 40 minutes
drop factor: 60gtts/ml

what are the gtts/min?
what are the ml/hr?

what is the vtbi?
dose desired: 250 mg/40 minutes
dose on hand: 250 mg/50 ml
drop factor of iv tubing used: 60 gtts/ml
conversion factor: 60 minutes = 1 hour
what are the gtts/min? . . .250 mg/40 minutes (dose desired) x 50 ml/250 mg (dose on hand) x 60 gtts/ml (drop factor of iv tubing used) = 75 gtts/minute
what are the ml/hr?. . .250 mg/40 minutes (dose desired) x 50 ml/250 mg (dose on hand) x 60 minutes/1 hour (conversion factor) = 75 ml/hour. this can also be calculated by performing a ratio like this: 50ml/40 minutes = x ml/60 minutes (remembering that 60 minutes is equal to 1 hour), then cross multiplying and solving for x.
what is the vtbi (volume to be infused)? . .this is given information. it is 50 ml.
order thorazine 60mg im now
available is a 10ml multi-dose vial, strength is 25mg/ml

how many mls will you administer?
dose desired: 60 mg
dose on hand: 25 mg/1 ml
60 mg (dose desired)/25 mg (dose on hand) x 1 ml (amount the dose on hand comes in) = 2.4 ml
rocephin 500mg ivpb daily
available: one gram vial. reconstitute with 10mls ns
further dilute in 50mls ns (this is the piggyback, or secondary, bag) and administer over 20 minutes.

what are the settings for the pump (pumps can only be programmed in mls/hour)?

the pump is broken. you must infuse by gravity. drop factor is 15gtts/ml. what is the gtts/min?
dose desired: 500 mg/20 minutes
dose on hand: 1 gram
drop factor of iv tubing used: 15 gtts/ml
conversion factor: 1 gram = 1000 mg
conversion factor: 60 minutes = 1 hour
how many mls will you add to your 50ml secondary bag? . . . reconstitution requires 10ml. you will have a mixture of rocephin that is 1 gram/10 ml, but the dose desired is 500 mg. . .
500 mg/1 gram (dose on hand) x 10 ml (amount the dose on hand comes in) x 1 gram/1000 mg (conversion factor) = 5 ml

what are the settings for the pump (pumps can only be programmed in mls/hour)? . . .recompute the amount you need to infuse
dose desired: 500 mg/20 minutes
dose on hand: 500 mg/55 ml
conversion factor: 60 minutes = 1 hour
500 mg/20 minutes (dose desired) x 55 ml/500 mg (dose on hand) x 60 minutes/1 hour (conversion factor) = 165 ml/hour
the pump is broken. you must infuse by gravity. drop factor is 15gtts/ml. what is the gtts/min? . . .500 mg/20 minutes (dose desired) x 55 ml/500 mg (dose on hand) x 15 gtts/1ml (drop factor of iv tubing used) = 41.25 gtts/minute, round to 41 gtts/minute
Last edit by Daytonite on Sep 21, '08
7. I got 2.4 mL on the second one...
8. Quote from beth66335
I got 2.4 mL on the second one...
That is correct. I corrected my post. I copied it from the paper that I did my calculations on incorrectly.
9. Quote from daytonite
order: levofloxacin 250mg every 48 hours
available from pharmacy in 50ml ns
you are to administer over 40 minutes
drop factor: 60gtts/ml

what are the gtts/min?
what are the ml/hr?

what is the vtbi?
dose desired: 250 mg/40 minutes
dose on hand: 250 mg/50 ml
drop factor of iv tubing used: 60 gtts/ml
conversion factor: 60 minutes = 1 hour
what are the gtts/min? . . .250 mg/40 minutes (dose desired) x 50 ml/250 mg (dose on hand) x 60 gtts/ml (drop factor of iv tubing used) = 75 gtts/minute
what are the ml/hr?. . .250 mg/40 minutes (dose desired) x 50 ml/250 mg (dose on hand) x 60 minutes/1 hour (conversion factor) = 75 ml/hour. this can also be calculated by performing a ratio like this: 50ml/40 minutes = x ml/60 minutes (remembering that 60 minutes is equal to 1 hour), then cross multiplying and solving for x.
what is the vtbi (volume to be infused)? . .this is given information. it is 50 ml.
order thorazine 60mg im now
available is a 10ml multi-dose vial, strength is 25mg/ml

how many mls will you administer?
dose desired: 60 mg
dose on hand: 25 mg/1 ml
60 mg (dose desired)/25 mg (dose on hand) x 1 ml (amount the dose on hand comes in) = 2.4 ml
rocephin 500mg ivpb daily
available: one gram vial. reconstitute with 10mls ns
further dilute in 50mls ns (this is the piggyback, or secondary, bag) and administer over 20 minutes.

what are the settings for the pump (pumps can only be programmed in mls/hour)?

the pump is broken. you must infuse by gravity. drop factor is 15gtts/ml. what is the gtts/min?
dose desired: 500 mg/20 minutes
dose on hand: 1 gram
drop factor of iv tubing used: 15 gtts/ml
conversion factor: 1 gram = 1000 mg
conversion factor: 60 minutes = 1 hour
how many mls will you add to your 50ml secondary bag? . . . reconstitution requires 10ml. you will have a mixture of rocephin that is 1 gram/10 ml, but the dose desired is 500 mg. . .
500 mg/1 gram (dose on hand) x 10 ml (amount the dose on hand comes in) x 1 gram/1000 mg (conversion factor) = 5 ml
what are the settings for the pump (pumps can only be programmed in mls/hour)? . . .recompute the amount you need to infuse
dose desired: 500 mg/20 minutes
dose on hand: 500 mg/55 ml
conversion factor: 60 minutes = 1 hour
500 mg/20 minutes (dose desired) x 55 ml/500 mg (dose on hand) x 60 minutes/1 hour (conversion factor) = 165 ml/hour
the pump is broken. you must infuse by gravity. drop factor is 15gtts/ml. what is the gtts/min? . . .500 mg/20 minutes (dose desired) x 55 ml/500 mg (dose on hand) x 15 gtts/1ml (drop factor of iv tubing used) = 41.25 gtts/minute, round to 41 gtts/minute

thank you soo much for your help!
i was really frustrated yesterday trying to do all the problems,
and now i feel soooooo much better about it all :]

thank you again!

A physician writes and order for aminosyn 2.5% 500 ml

you have only aminosyn 8.5% 500ml. How are you going to prepare this order using a sterile evaucated container?

and

How many 30mg KMN04 tablets are needed to make the following solution? KMN04 1:50000 600ml

thanks so much
11. Thank you so much! Those problems was very hard.