please help! calculation question

Nurses General Nursing

Published

How would you set up and solve this problem?

problem:

Order: Lasix 120 mg, IV, STAT

Drug Available: Lasix 10 mg/ml. IV infusion not to exceed 40 mg/min.

The way my book set it up really confuses me. Someone please show me how they would set it up and maybe it will make more sense.

Thanks so much :)

Up Vote Up Vote ×
Specializes in Pediatrics, Nursing Education.
How would you set up and solve this problem?

problem:

Order: Lasix 120 mg, IV, STAT

Drug Available: Lasix 10 mg/ml. IV infusion not to exceed 40 mg/min.

The way my book set it up really confuses me. Someone please show me how they would set it up and maybe it will make more sense.

Thanks so much :)

Ok... you're going to put

120mg

--------

X ml

because you need 120 mg but you don't know how many ML.

and then you're going to do your stock -

10 mg of Lasix

-------

per 1 ml

Cross multiply it out 1 ml x 120, and 10 x (times) X (your variable) and you should get -

120 = 10x

so then you divide 120 by ten leaving "x" on the other side of the equation. Finish out the equation and you should have x= and the answer.

You should be able to set up other meds this way.

Up Vote Up Vote ×
How would you set up and solve this problem?

problem:

Order: Lasix 120 mg, IV, STAT

Drug Available: Lasix 10 mg/ml. IV infusion not to exceed 40 mg/min.

The way my book set it up really confuses me. Someone please show me how they would set it up and maybe it will make more sense.

Thanks so much :)

I don't know if I can explain this very well or not, but I will try.

First, solve your problem to see how many ml you would give total.

120mg equals 12 multiplied by 1ml which equals 12ml

10mg

Now I'm sure there's a way to set this up but I don't know it. I think it through in my head.

12 ml is a total of the 120mg you want to give. So that means that 4ml equals 40mg. So you would give 4ml/min because that would be 40mg/min. So that is the most you could give in a minute.

I don't know if this makes any sense to read, but I hope it helps.

Up Vote Up Vote ×
Specializes in Telemetry & Obs.
How would you set up and solve this problem?

problem:

Order: Lasix 120 mg, IV, STAT

Drug Available: Lasix 10 mg/ml. IV infusion not to exceed 40 mg/min.

The way my book set it up really confuses me. Someone please show me how they would set it up and maybe it will make more sense.

Thanks so much :)

10 mg/1 mL : 120 mg/x mL = 10x/10 : 120/10 = 12 mL amount to give; then

40 mg/1 min : 120 mg/x min = 40x/40 : 120/40 = 3 min; then

12 ml/3 min : x ml/1 min = 3x/3 : 12/3 = 4 ml/min

I think I have a headache :rotfl:

Up Vote Up Vote ×
Specializes in ORTHOPAEDICS-CERTIFIED SINCE 89.

How about writing here how your book presented the solution? Perhaps we could make it more clear if we understand their teaching method.

Up Vote Up Vote ×
How about writing here how your book presented the solution? Perhaps we could make it more clear if we understand their teaching method.

Here is what they said in the book:

a. DA: ml= 1ml X 120mg / 10 mg X 1 = 12 ml of Lasix

b. Known drug: known minutes :: desired drug : desired minutes

40 mg : 1 min :: 120 mg : x

40x= 120

x = 3 min

~That's all they said, so I didn't know how to interpret those two answers together into a real life scenario of how much you'd run per minute, etc.

*edit: Then I guess you'd take 12/3 and get 4 ml/minute? as what'd you'd actually do

Up Vote Up Vote ×
I don't know if I can explain this very well or not, but I will try.

First, solve your problem to see how many ml you would give total.

120mg equals 12 multiplied by 1ml which equals 12ml

10mg

Now I'm sure there's a way to set this up but I don't know it. I think it through in my head.

12 ml is a total of the 120mg you want to give. So that means that 4ml equals 40mg. So you would give 4ml/min because that would be 40mg/min. So that is the most you could give in a minute.

I don't know if this makes any sense to read, but I hope it helps.

that helped alot, thanks!

Up Vote Up Vote ×
How would you set up and solve this problem?

problem:

Order: Lasix 120 mg, IV, STAT

Drug Available: Lasix 10 mg/ml. IV infusion not to exceed 40 mg/min.

The way my book set it up really confuses me. Someone please show me how they would set it up and maybe it will make more sense.

Thanks so much :)

Hello,

Here is my way:

120 mg X ml X 40 mg

--------------------

10mg X mg X 1 min

answer = ml/mins

my teacher taught us the following:

First, what do you what to get? ml/mins = 120 mg X ml X 40 mg

---------------------

X 10 mg X 1 min

Second, across out like terms and you should have - 12 X 4 X ml

-------------

10 X min x 1

Third, multiple across the top set of number and you shuld have - 48 ml

-----

10 min

Fourth, divide the bottom set of numbers and you should recieve - 4.8 ml/min

and the answer would be 4.8 ml/min and it does not exceed 40 mg/min.

That was easy for me to learn it. Yes, you can cancel out the dosage amount and the numbers.

Thanks To Dr. Barb at AACC....she was the greatest teacther I ever had.

Buttons

Up Vote Up Vote ×

You have not provided us with the drop factor. The drop factor is the number of drops/ml for your infusion set. Assume a drop factor of 15 (15 gtts/ml).

Since there is Lasix 10 mg/ml available and 120 mg to be infused, 120mg/10 mg/ml= 12ml of Lasix is to be infused. If the infusion is not to exceed 40/mg/min, then more than or equal to 120mg/40mg/minute must be infused per minute which equals 3 minutes (or longer). Therefore, 3 minutes is the minimum time in which this medication should be infused .

Given the aforementioned, we can utelize the following formula:

Amount to infuse= 12 ml; Desired duration= 3 minutes (or more); drop factor=15 gtt/ml (assumed).

With the aforementioned we obtain the rate at which we should set the infusion which is a maximum of 60 gtt/min.

12mlx15gtt/3 minutes=60gtts/minutes. If you decrease the number of drops per minutes you must increase the number of minutes of infusion as a result.

You must adjust your calculations for the drip factor and for any extension of time for the infusion.

I suggest that you purchase a PDA and put a calculation program on the same called MedCalc. It contains many useful medical arithmetic formulas, including those especially useful to nurses such as calculating IV rates.

How would you set up and solve this problem?

problem:

Order: Lasix 120 mg, IV, STAT

Drug Available: Lasix 10 mg/ml. IV infusion not to exceed 40 mg/min.

The way my book set it up really confuses me. Someone please show me how they would set it up and maybe it will make more sense.

Thanks so much :)

Up Vote Up Vote ×
You have not provided us with the drop factor. The drop factor is the number of drops/ml for your infusion set. Assume a drop factor of 15 (15 gtts/ml).

Since there is Lasix 10 mg/ml available and 120 mg to be infused, 120mg/10 mg/ml= 12ml of Lasix is to be infused. If the infusion is not to exceed 40/mg/min, then more than or equal to 120mg/40mg/minute must be infused per minute which equals 3 minutes (or longer). Therefore, 3 minutes is the minimum time in which this medication should be infused .

Given the aforementioned, we can utelize the following formula:

Amount to infuse= 12 ml; Desired duration= 3 minutes (or more); drop factor=15 gtt/ml (assumed).

With the aforementioned we obtain the rate at which we should set the infusion which is a maximum of 60 gtt/min.

12mlx15gtt/3 minutes=60gtts/minutes. If you decrease the number of drops per minutes you must increase the number of minutes of infusion as a result.

You must adjust your calculations for the drip factor and for any extension of time for the infusion.

I suggest that you purchase a PDA and put a calculation program on the same called MedCalc. It contains many useful medical arithmetic formulas, including those especially useful to nurses such as calculating IV rates.

that is correct I forgot my gtt/min factor as well.

So the gtts/min/ml would be 60 because it is pump tubing.

Then I would have to re-do it and this is how I would do it bascially the same way:

I want ml/min in my answer

ml/min = 120 mg X ml X 40 mg X 1 gtts X ml X min

----------------------------------------

1 mg X 10 mg X min x 60 gtts X min X ml

Next step is to cancel out likes and numbers if you wish too and you will have this:

120 X ml X 40 20 X ml X 40

------------- Equal -----------

10 10

Next step is to multiply across and you would get this:

2 X ml X 40 = 80

----------------

10

Next to divide and you will get this

80 = 8

---

10

and your answer is 8mls/min

Buttons

Up Vote Up Vote ×
that is correct I forgot my gtt/min factor as well.

So the gtts/min/ml would be 60 because it is pump tubing.

Then I would have to re-do it and this is how I would do it bascially the same way:

I want ml/min in my answer

ml/min = 120 mg X ml X 40 mg X 1 gtts X ml X min

----------------------------------------

1 mg X 10 mg X min x 60 gtts X min X ml

Next step is to cancel out likes and numbers if you wish too and you will have this:

120 X ml X 40 20 X ml X 40

------------- Equal -----------

10 10

Next step is to multiply across and you would get this:

2 X ml X 40 = 80

----------------

10

Next to divide and you will get this

80 = 8

---

10

and your answer is 8mls/min

Buttons

Hello,

Basically, it is how you are comfortable of setting up your equations. I have never forgotten the rules that my professor had taught me at AACC and I have never went wrong. I kept confusing myself in the various ways that was presented to me. She told me to do it her way and no other way. I was less confuse and able to show other students that were having trouble this way. They thought it was much better than their teacher's way and I showed several of professor and they show it to the students who did not get it no other way.

Good Luck,

Buttons

Up Vote Up Vote ×
Specializes in Med-Surg, OB/GYN, L/D, NBN.

I always set mine up with what do you need? cc/hr...what do you have 10 mg/ml Lasix. However, wouldn't this be a push and therefore follow the rule of no more than 1 cc per min. If that was true you would push it over 12 mins.

Up Vote Up Vote ×
+ Add a Comment