## Fousmc03_0131134604.qxd

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**Calculating the cc’s**
**LEARNING THE FORMULA**
Now that the first two steps of this formula have been learned—identifyingand calculating the desired dose, and calculating the concentration—we canproceed to the third step.

**STEP 3**
Calculate the amount of cc’s to be delivered.There are two purposes for this

particular calculation: (1) when giving a drug through

**SQ, IM, IV, ET, **or

**IO**

it is necessary to calculate the amount of cc’s to be drawn from a particular

container (ampule or vial) or to be pushed through a prefilled syringe so that

the desired dose can be delivered, or (2) to calculate the amount of cc’s

needed to figure gtts/min, which is required in step 4, on calculating drip

rates. For whichever reason cc’s are being calculated, the formula is:

If the route of administration is SQ, IM, ET, IO push, or IVP, only the
first three steps of this formula, (1) DD, (2) C, and (3) DD/C, need to becalculated, eliminating step 4, which is defined in chapter 4. The reason for
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eliminating step 4 when the route of administration is SQ, IM, ET, IO push,or IVP is that ultimately you need to calculate only the number of cc’s to drawfrom a given container, not the drops per minute, as required for a dripadministration. If a prefilled syringe is being used, it is necessary to calculateonly the number of cc’s to push from the syringe.

This step can be very simple because all it involves is dividing the desired
When dealing with this step, many times there are several

**zeros **in these

To simplify the division process in the above example, some zeros can
be

**canceled out. **When canceling zeros, the

**same **number of zeros must be

canceled in both the numerator (top number)

**and **denominator (bottom

number). See example:

In the above example,

**one **zero was able to be canceled in both the nu-

merator of

**500 **and the denominator of

**50. **Another example of canceling out

zeros follows:

In this last example,

**two **zeros were able to be canceled in both the

Because zeros can be canceled out,

**measurements **also can be canceled.

After canceling the mg’s, the

**only **measurement left is

**cc. **So the answer

will be in cc’s, as noted in the previous example.

Following are a few examples on the calculations involved in step 3.

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You have been ordered to give

**2.5 mg **of

**valium. **On hand is a vial

with

**2 cc **containing

**10 mg**. How many

**cc’s **would you draw?

DD ϭ

**2.5 mg**
Explanation:

**First **you identified the desired dose, which was

**2.5 **mg.

**Then, **in step 2, you calculated the concentration by dividing 10 mg by 2 cc

(remember, mg over cc

**[mg/cc] **when calculating the concentration), leaving

**5 mg/cc. **Then, in step

**3, **the desired dose of 2

**.**5 mg was divided by the con-

centration of 5 mg/cc. So 2

**.**5 mg divided by 5 mg/cc equals

**.5 cc **(remember

that the mg’s canceled), leaving

**cc **as the only measurement.

You have been ordered to give

**1 mg/kg **of

**Lidocaine **IV. Your patient

weighs

**150 **pounds. The prefilled syringe contains

**100 mg **in

**5 cc. **How

many

**cc’s **will you push?

DD = 1 mg/kg 2

**.**2 ͤ150

**0** 68 * 1 mg = 68 mg

DD ϭ

**68 mg**
Explanation: In the previous example, the desired dose was ordered

**per**
kg. So,

**first **the pounds were

**converted **to kg (by dividing the 150 pounds by

**2.2**),

leaving an answer of

**68 kg. **You then

**multiplied **the total number of

**kg, **which

was 68, by the

**desired dose **per kg, which was 1 mg

**per **kg, leaving a desired dose

of

**68 mg. **In step

**2, **you calculated the

**concentration **by dividing the number of

mg’s by the number of cc’s of the on-hand drug, which was supplied in a pre-

filled syringe. In step

**3, **you divided the

**desired dose **by the

**concentration. **The

mg’s canceled out, leaving you with

**3.4 cc **to push from the prefilled syringe.

The physician has ordered

**20 mg **of

**Lasix **IV. On hand is a vial with

**4 cc **containing

**40 mg. **How many

**cc’s **will you give?

DD ϭ

**20 mg**
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Explanation:

**First **you identified the desired dose of 20 mg. In step

**2,**
you took your on-hand medication supplied in the vial and divided the

**mg’s**

by the

**cc’s. **In step

**3, **you divided the

**desired dose **by the

**concentration. **The

mg’s

**canceled, **leaving an answer of

**2 cc. **This amount would then be drawn

from the vial and administered to your patient.

**THE TIME FACTOR**
Note that when a

**drip **has been indicated for a particular drug administra-

tion, the desired dose will be ordered over a certain

**time **frame, normally per

minute. See examples:

10 g/kg

**/min**
You should

**never **leave out any part of the problem to “cut corners”

when calculating on paper. Consistently

**label **each number or figure accord-

ingly. See examples:

**DD **ϭ 2 mg/min

**C **ϭ 4 mg/cc

**DD **ϭ 10 g/kg/min

**C **ϭ 800 g/cc

Never leave out any measurements or time factors. Failure to include
any identifying factors, such as DD ؍, C ؍, DD/C ؍, mg’s, cc’s, or minutes,will only confuse and complicate the calculation learning process.

Concerning

**step 3 **of this formula on calculating cc’s, if a

**time factor **has

been given in the desired dose, be sure to always include it throughout each

step, especially this one. But don’t let the time factor confuse you, because it

has absolutely nothing to do with the calculation of this step. However, it has

everything to do with

**step 4. **This is why it is so important not to leave this

**factor **out at any time throughout your calculations.

Again, be sure to place it

**(min) **properly in the equation, but disregard

it when figuring your math through step 3. See example:
DD ϭ 2 mg

**/min**
**.**5 cc

**/min**
In reference to the preceding example,

**cc’s **is the only measurement left

after canceling the

**mg’s. **The time factor

**always **goes on the

**bottom **of any

**answer **throughout any equation. See example:

1Top2 2 mg

**/min (bottom) **ϭ (Top)

**.**5 cc

**/min (bottom)**
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Since the

**minute **is part of the desired dose, it must

**remain **with the

desired dose, as noted in 2 mg/min, until you have calculated the answer in

step

**3 **of the formula.The time factor then

**moves **to the bottom in the

**answer**

in step

**3, **as shown previously in

**.**5 cc

**/min.**
When calculating

**cc’s **to further be used in the calculation of step 4, your

answer will usually involve

**decimal fractions, **especially in drips such as

Dopamine. When this is the case, it is necessary that you divide only to the

nearest 1000th, which is the

**third **decimal fraction (

**.**22

**2**). Rounding off to the

nearest whole number is not suggested at this point when working with drip

calculations. See examples:

=

**.**18

**7** cc/min DD =

=

**.**21

**2** cc/min

**SUMMARY**
Just as you have learned, the third step of this process consists simply of

dividing the desired dose

**by **the concentration. Always remember to

**label**

figures and equations and don’t

**“cut corners.” **This will only confuse you. So

far, three of the four steps consists of:

**C **(always weight/cc)

e.g.—

**mg/cc**
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Following are a few practice questions pertaining to step 3. Simply completethe first three steps of the formula that you have learned so far. Remember,some of the answers may seem obvious to you, but it would be very much toyour advantage to work out each and every step.

An order has been given for a particular

**drip **delivering

**10 **

**g/min. **On

hand is

**1 mg, **a

**250 cc **bag of fluid, and a minidrip administration set.

How many

**cc’s **per minute must be delivered to give the DD?

You have been ordered to give

**8 mg **of

**Decadron **IV. On hand, you have

a

**5 cc **vial containing

**20 mg. **How many

**cc’s **must you draw to give your

DD?

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A physician has given you an order for a

**Lidocaine drip **to be run at

**2 mg/min. **On hand are

**two grams **of

**Lidocaine, **a

**500 cc **bag of normal

saline, and a minidrip administration set. How many

**cc’s **per

**minute**

must be delivered to give the DD?

The doctor has ordered you to give

**25 mg **of

**diphenhydramine **IV. On

hand is a

**2 cc **vial containing

**50 mg. **How many

**cc’s **must you draw to

give the DD?

You are at the residence of a patient who requires a

**dopamine drip.**

Your protocol states to give

**2 **

**g/kg/min. **Your patient weighs

**220**

pounds. On hand is

**400 mg **of

**dopamine, **a

**500 cc **bag of normal saline,

and a minidrip administration set. How many

**cc’s **per

**minute **must be

delivered in order to give the DD?

You are on scene with a 1-year-old male requiring

**1 mg/kg **of

**Lidocaine**

IV. The mother advises you that her son weighs

**22 **pounds. Your Lido-

**caine **comes supplied in a prefilled syringe containing

**100 mg **in

**5 ml.**

How many

**ml’s **would you administer?

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You have been ordered to give

**12 mg **of

**Decadron **IV. On hand is a vial

containing

**20 mg **in

**5 cc. **How many

**cc’s **would you give?

You are en route to the hospital and your patient requires

**6 mg **of

**adenosine **rapid IVP. On hand is a

**2 cc **vial containing

**6 mg. **How many

**cc’s **would you draw?

A

**dopamine drip **has been ordered to be run at

**8 **

**g/kg/min. **On hand

is a vial containing

**400 mg, **a

**250 cc **bag of normal saline, and a minidrip.

If your patient’s weight is

**145 **pounds, how many

**cc’s **per

**minute **would

you deliver?

A

**Lidocaine drip **has been ordered to be run at

**3 mg/min. **On hand you

have a vial containing

**1 gm, **a

**250 cc **bag of normal saline, and a minidrip.

If your patient weighs

**220 **pounds, how many

**cc’s **per

**minute **do you

need to give?

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DD ϭ

**10 **

**g/min**
C ϭ 1 mg/250 cc ¡ 1 0 0 0 g/250 cc ϭ

**4 **

**g/cc**
=

**2.5** **cc/min**
C ϭ 20 mg/5 cc ϭ

**4 mg/cc**
DD ϭ

**2 mg/min**
C ϭ 2 gm/500 cc ¡ 2 0 0 0 mg/500 cc ϭ

**4 mg/cc**
=

**.5 cc/min**
DD ϭ

**25 mg**
C ϭ 50 mg/2 cc ϭ

**25 mg/cc**
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DD = 2 g/kg/min ¡ 2

**.**2 ͤ220

**0**
DD ϭ

**200 µg/min**
C = 400 mg/500 cc =

**.**8 mg/cc

¡ .8 mg ¡ 8 0 0. µg ϭ

**800 µg/cc**
=

**.25 cc/min**
DD = 1 mg/kg ¡ 2

**.**2 ͤ22

**0 **¡ 10 * 1 mg =

**10** **mg**
C ϭ 100 mg/5 ml ϭ

**20 mg/ml**
DD ϭ

**12 mg**
C ϭ 20 mg/5 cc ϭ

**4 mg/cc**
C ϭ 6 mg/2 cc ϭ

**3 mg/cc**
65

**.**9 ¡ 66

**kg**
DD = 8 g/kg/min ¡ 2

**.**2 ͤ145

**0**
DD ϭ

**528 µg/min**
C = 400 mg/250 cc ϭ 1

**.**6 mg/cc

1.6 mg ¡ 1 6 0 0

**. **g ϭ

**1600 **

**g/cc**
=

**.33** **cc /min**
**10. **STEP 1

DD ϭ

**3 mg/min**
C ϭ 1 gm/250 cc ¡ 1 0 0 0 mg/250 cc ϭ

**4 mg/cc**
=

**.75** **cc/min**
Source: http://www.prenhall.com/divisions/ECT/app/bradybooks/newbrady/catalog/content/samplechapters/0131134604.pdf

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