# rate calculation - page 2

Just wondering how you all calculate the rate to run drips at. Do you do the long hand math, do your docs calculate and you run at prescribed mL/hr? Personally, we have IV pumps that we... Read More

1. Our educational services dept have made up cards about the common drugs we use in the critical care areas. We also have drug calculation cards where we figure out the dose (based on the formula found on the drug card), a 2nd nurse verifies the calcs and then co-signs the card. The card is then put with the Med Mar. This way, any nurse can check and verify the dose being given. We also have infusion pumps that can determine the dose. I use them to double check my figures only - I don't want to rely on something mechanical when it comes to giving critical drugs.
2. The ICU I work in uses a formula to figure out a "Konstant". It may be like the core numbers mentioned. I'm not sure. Our iv pumps don't figure out anything for us. We just tell them how many Milliliters to infuse per hour. The Konstant (K) works like this:

K=contentration of drug/patient's weight in Kg/60
The prescribed dose (mcg/kg/min) divided by K = cc/hr

Say the Dopamine concentration is 1600mcg/cc, the patient's weight is 75kg, and the order is to infuse at 4mcg/kg/min.

1600/75/60=0.36---(Konstant will always be 0.36 for this patient at this weight)

4/0.36=11.1 (set pump to infuse at 11.1cc/hr)

same patient needs dose titrated up to 6mcg/kg/min
6/0.36=16.7cc/hr

I've never seen this anywhere else.
3. Our computerized documentation can calculate our IV drug dosages. We just need to make sure that our rate is current. It also gives us the option to change concentrations. We can also calculate in our bedside monitors. And of course there is good old fashioned long hand as a double check.
4. It is nice that we all now havavailable technology that will make these calculations for us. However, my personal beief is that one has a better understand of the infusion if one knows how to calculate the dosage manually. In a similar issue, it is OK to have your computer calcualte your SVR, as long as you understand the components that go into the calculation, so that you have a thorough understanding of what influences variations in the SVR. Yea for technology.... but always know what goes into that technology!
5. I use a Palm with the program "Infusicalc". It is great, I can pre-program it to my hospital standard concentrations for any drug. Plug in weight (if weight based) and dose needed and BAM I have a drip rate. If the drip is double concentrated it takes a couple of seconds to change the concentration and BAM I once again have the drip rate!

No muss, no fuss, no errors!!!!!

Can do boluses and drips!
6. Did anyone ever feel like nursing school would never end?
Question - what should I do to win over all of the nurses when I start preceptorship? Think brownies will work?
7. Quote from healingtouchRN
Hi, In my CCU, our docs tell us the mcg/kg/min or mcg/min or units/hr they want & we figure it out. Daily weights are essential, as we do lots of weight based protocol (Lovenox & heparin). Not too hard once ya learn how. always nice to have a second pair of eyes check your math before you deliver your dose. Just like checking Insulin, double check can save ya a law suit. Ciao!
Exactly as we do in our facility. We also have Horizon NXT infusion pumps that calculate the dose-but we still double check because you can have errors programming the pump.
8. Quote from Pete495
Our monitors can figure out certain drip rates if they are programmed in. We have short cuz methods too that we use for our most common drips.

the short cut is cc/hr x core number / kg body weight = mcg's/kg/min

Also, mcgs/kg/min x kg body weight/ core number = cc/hour

each drip has a different core number. If you'd like the core numbers, let me know. I have a lot of them.

Anyway, I use that to calculate drips. Our IV pumps can calculate drips, but I don't use them. I don't think it is good practice to use them. If it is heparin or vasopressin or something, I like to figure it out long hand even if it takes a minute. That way I know in my mind it was done right, and I can always ask someone else to check my method. If you plug in the wrong numbers too fast on a machine, you might screw yourself.

Pete495
Pter495-- This may be a regional difference but I'm not understanding what you mean by 'core number'. Looks like this is the same as concentration. Is this right??
9. Quote from critcarenurse16
Pter495-- This may be a regional difference but I'm not understanding what you mean by 'core number'. Looks like this is the same as concentration. Is this right??

I'm not sure how pter495 gets his core number but maybe this formula I use will be helpful:

Core number = (mg of med x 1000 / ml of solution) / 60 / pt's wt in kg

the core number is specific to that pt( it won't change unless the concentration changes)

core # X ml/hr = mcg/kg/min

example:

dopamine 400mg in 250 ml and pt wt is 70 kg

Core # = (400 X 1000) / 250 / 70

4000/ 250 / 70

16 / 70

0.228 (0.23) is the core #

then:
0.23 X 10 ml/hr = 2.3 mcg/kg/min

you just multiply the core number by the pump rate with each rate change.
It helps me...I hope I didn't confuse you.
10. Quote from awsnow
I'm not sure how pter495 gets his core number but maybe this formula I use will be helpful:

Core number = (mg of med x 1000 / ml of solution) / 60 / pt's wt in kg

the core number is specific to that pt( it won't change unless the concentration changes)

core # X ml/hr = mcg/kg/min

example:

dopamine 400mg in 250 ml and pt wt is 70 kg

Core # = (400 X 1000) / 250 / 70

4000/ 250 / 70

16 / 70

0.228 (0.23) is the core #

then:
0.23 X 10 ml/hr = 2.3 mcg/kg/min

you just multiply the core number by the pump rate with each rate change.
It helps me...I hope I didn't confuse you.
Crystal clear. (just too much math for this nurse's taste) :uhoh21:
11. Personally I love those pumps that do the figuring for you, but never do I completly trust it. The safe way is to always figure out your drips. I made a chart for potent drips and keep it with me all the time. It only takes a few seconds to figure out and it may save you a lot of trouble with a lawsuit or more importantly a patient's life. I will be more than happy to send the chart to you by email if you want it.
12. Quote from TexasCCRN
Personally I love those pumps that do the figuring for you, but never do I completly trust it. The safe way is to always figure out your drips. I made a chart for potent drips and keep it with me all the time. It only takes a few seconds to figure out and it may save you a lot of trouble with a lawsuit or more importantly a patient's life. I will be more than happy to send the chart to you by email if you want it.
Could I get a copy of your chart, as well?

Last edit by sirI on May 23, '06
13. this is the way i do it....

i use concentration numbers as a common didvidend...

epi 1 mg in 250 is 4
levo 4 mg in 250 is 16
ntg 50mg in 250 is 200
dopa 400mg in 250 is 1600
neo 40 in 250 is 160 160
nipride 50 in 250 is 200 200

let's say they order a drug to run at 10 mcg/min

well i just take 10 times 60 and then divide that answer by the above concentration number.
so if they wanted levophed at 10 mcgs
i do 10x60=600
and then divide 600 by 16 to get the drip rate...
37

now bc dopa needs the wt i just throw the weight in as well...
so if they want dopa at 10mcg per kilo per minute (pretend pt is 75 kilos)
i do 75 x 10 x 60 = 45000
and divide 45000 by 1600 to get a drip rate ...
27

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