Rule of three

Pediatric Critical Care Columnist · Oct 11, 2006

It's actually pretty simple. It applies to standard concentrations for infusions that run as mcg/kg/min. Multiply the desired mcg/kg/min by the patient's weight then multiply that by 3 and it gives you the number of mg you need to mix in 50 ml (total volume) of diluent to obtain an infusion that will give you a concentration of 1 ml/hr = X mcg/kg/min. For example, dobutamine at 5 mcg/kg/min for a 6 kg patient = 5X6X3 = 90 mg in total volume 50 ml. The infusion running at 1 ml/hr will then give you 5 mcg/kg/min. Try it the long way if you want... 5 mcgX6kgX50mlX60 min/1000 to make it mcgs... 5X6X50X60 = 90000/1000 = 90. Another one... epinephrine at 0.1 mcg/kg/min would be 0.1X6X3 = 1.8 mg. Check it out!

dawngloves, BSN, RN · Oct 13, 2006

Places still do this? I though JCHAO said it was a :nono:

Pediatric Critical Care Columnist · Oct 13, 2006

You're probably right about that, dawngloves. In Canada JCHAO has nothing to do with us, and in our unit it isn't taught as the rule of threes or the rule of sixes or any other permutation. We're taught the long way to calculate our drips... which works out to fit perfectly with the rule of threes...

RaggedyRN · Oct 21, 2006

Thanks for the replies. Yup...places still do this. I'm just learning. It seems doable. My preceptor is going to go over it with me this week.

Thanks Again:thankya:

dawngloves, BSN, RN · Oct 23, 2006

Don't get too comfortable with it. JCAHO is requiring standardized concentrations of drugs (National Patient Safty Goal 3b) by December 31st, 2008.

We stopped doing this last year when they made the announcement.I thought it was already "law".

RaggedyRN · Oct 23, 2006

Great advice...thanks. You're right about them phasing the Rule of three out. Some of the nurses are not comfortable with the standardized or computer calculated doses and prefer to "Do their own math" My preceptor is just showing me how to do it so I have a way to check the computer or how to do it if the computer is down. Always a good thing to know!

Thanks Again!

sara52g · Oct 25, 2006

Rule of 3 is helpful for a drip that will be staying at the same dose for quite a while. In reality, most mcg/kg/min drips need to be titrated up or down several times throughout the shift, so it really is worth it to know how to do the calculations to change the rate, rather than hanging a new drip with each change in dose

Pediatric Critical Care Columnist · Oct 25, 2006

We mix our drips so that 1 mL/hour gives us a standard concentration for that patient. For example, we mix epinephrine and norepinephrine so that 1 mL/hour = 0.1 mcg/kg/min, dopamine is 5, milrinone is 0.5, midazolam is 2, morphine is 50 (per hour), and so on. Scenario: baby weighs 4.7 kg and needs an epi drip. 4.7 kg x 0.1 mcgs desired concentration x 3 (50 mL x 60 min / 1000 mcg to get mg)= 1.4 mg in 50 mL diluent. We run all our titratable drugs on syringe pumps that can deliver as little as 0.1 mL/hr. So baby starts off at 0.05 mcg/kg/min, which is our usual order. The pump runs at 0.5 mL/hr. We can titrate up or down by 0.01 mcgs/kg/min by adjusting the pump by 0.1 mL/hr. And we can tell at a glance what dose the kid is getting just by checking the rate. It's easy as pie. If the milrinone is running at 1.5 mL/hr, the kid's getting 0.75 mcg/kg/min. If the dopamine is running at 2.5 mL/hr the kid's getting 12.5 mcg/kg/min. If the morphine is running at 1.8 mL/hr, the kid's getting 90 mcg/kg/hr. Does that make sense?

heathIam, RN · Nov 6, 2006

The rule of 6 never made any sense to me when I started 17 years ago, but I memorized the formula and did the math and made the drips. Finally about 4 years ago i had an epiphany and i discovered where the 6 came from and it was alright after that.

In reality though it works better to avoid the 6s or the 3s and go with the standard formula

1mcq/k/min = 1ml/hr or

1mcq/k/hr = 1ml/hr

You can make up anything with these two formulas and it is easy to increase the concentration to provide you with whole numbers making it easy to calculate the increases and decreases.

JAHCO doesn't like the formula, but fortunately we in canada are not governed by them

LeAnthonyRN · Dec 22, 2006

I know that when I was at U. Maryland and U. Mississippi the "rules" systems was a major issue before the JCAHO visit. A lot of nurses and doctors lived by it. Now that standardization is about to become manditory in 2008 you might want to look at your system and see what the plans are to convert. You also may want to get involved in the conversion. ICUdrips.Org shows our issues. Just my $0.02. LeAnthony

aleanth · Jan 18, 2007

I am pretty certain JCAHO does not approve of that any longer. Personally i was never fond of the whole rule of 3 or 6.