Dosage calc

morte, LPN, LVN · Sep 3, 2007

sometimes, as we get more exp, we go directly from A to D....lol

if you start with 20000/500= 40 units per ml......10ggtsX60min=40 mls per hour......then 40 units x 40 mls= 1600 units per hour............

1600 units per hour x 24 hours= units per day.....

Daytonite, BSN, RN · Sep 3, 2007

this is still a dose desired divided by dose on hand to get the dose you want to give kind of problem. the difference is that they have already given you the dose desired, so you need to do a little algebra (if you do it the hard way) to get the answer. i like dimensional analysis. all you need to know for dimensional analysis is that you are looking for units/hour in the final answer. that's units, in the numerator and hours in the denominator of the final answer. the other thing that you need to keep in mind with dimensional analysis is relationships. the dose on hand (20,000 units of heparin in 500 ml if ns) is a relationship that can be expressed as a ratio/fraction and you must always keep these figures together. however, the heparin or the ns can be the numerator or denominator--doesn't matter--it only matters that they are kept together in the same ratio. got that? so, we set up a dimensional analysis equation that utilizes the necessary relationships to come out with units/hour like this:

the relationships:

- dose on hand: 20,000 units/500 ml
- dose to give: 10 gtts/minute
- drop factor: 1 ml/15 gtts
- conversion of minutes to hours: 60 minutes/1 hour

the equation and answer:

20,000 units/500 ml

(dose on hand)

x 10 gtts/minute

(dose to give)

x 1 ml/15 gtts

(drop factor)

x 60 minutes/1 hour

(conversion factor)

=

1,600 units/hour

then, let's do a little algebra. . .1,600 units/1 hour =

x

units/24 hours. cross multiply. (

x

units)(1 hour) = (1600 units)(24 hours). the labels all cancel out and you are left with

x

=

38,400

which is the answer you were looking for.

you can see problems worked out in the dosage calculations thread on this forum here (https://allnurses.com/forums/f205/dosage-calculations-88867.html). if someone started a thread asking for help with a drug calculation and i responded to it, i usually write the words dimensional analysis in my post somewhere. you can use the advanced search to find these threads by using the search word "dimensional" or "analysis" and my screen name to find them to see these examples.

Music in My Heart · Sep 3, 2007

one of your patients has an iv that is flowing at a rate of 10 gtt/min. the iv bag contains a solution of 500 ml of ns with 20,000 units of heparin. the drop factor is 15 gtt/ml. how many units of heparin is the patient receiving in 24 hours?

the answer is 38,400 units of heparin every 24 hrs.

first, determine the rate at which the drug is entering the patient. multiply the rate of flow of the solution by the concentration of the solution to find how much med is flowing per minute.

(10 gtt / 1 min) x (1 ml / 15 gtt) x (20,000 units / 500 ml) = 26.67 units/min

|-------- flow rate ------------| |--- concentration ---|

now, convert your time value from "per minute" to "per hour". since you're flowing 26.67 units per minute and there are 60 minutes in an hour, you're flowing 1600 units every hour.

(26.67 units / 1 min) x (60 min / 1 hr) = 1600 units/hr

since the question wanted to know the total amount of med that flowed over 24 hours, you multiply your hourly rate by the elapsed time for your final answer. you're flowing 1600 units every hour for 24 hours so you've flowed a total of 38400 units over 24 hours:

(1600 units / 1 hr) x 24 hr = 38400 units

WDWpixieRN, RN · Sep 4, 2007

I am in the last semester of an ADN program and I'm looking for a book that will help me with advanced IV calculations. I'm looking for something I might find online or in a bookstore, I have textbooks and I find their teaching methods worthless. Anybody have any suggestions?

I like Calculate with Confidence. It's been a lifesaver many times, although I sometimes have to start back a chapter or two to understand concepts that I know that I know, lol....the majority of my 3rd semester ADN fellow students agree that it's the best!! Check Barnes, Borders, etc., for the best price. Amazon was just the site I tried first. If you plan on using the CD, make sure you get the latest edition as some of the older CDs won't work with more current OS (XP, Vista, etc.).

Good luck!!