Re: IV dose rate calculation

[Guest guest]

I have posted this. Any techs out there want to give it a try before I show how

to solve it?

Jeanetta

>

> A patient weighing 110 lbs is to receive 5 mcg/kg/min of a IV solution

containing Dopamine 600 mg in 250 ml D5W. The calculated IV dosage rate is...?

>

> Answer: 0.250 mg/min

>

> I need help, I don't know how to get that answer

>

[Guest guest]

I'll give it a shot. I'm studying to become certified.

First we have a 110 lb person, which is 50.00 kg if we round up (1 pound =

0.45kg). At 5mcg / kg / min, this person needs 50.00 kg * 5 mcg/kg/min,

which is 250 mcg/min. We now need to convert mcg to mg. This is 250 mcg/min

* (1mg/1000mcg)/(min), giving us 0.250mg/min. (1000mcg = 1mg)

Regards,

~Matt

On Tue, Mar 16, 2010 at 5:41 PM, Jeanetta Mastron <rxjm2002@...>wrote:

>

>

> I have posted this. Any techs out there want to give it a try before I show

> how to solve it?

>

> Jeanetta

>

>

>

> >

> > A patient weighing 110 lbs is to receive 5 mcg/kg/min of a IV solution

> containing Dopamine 600 mg in 250 ml D5W. The calculated IV dosage rate

> is...?

> >

> > Answer: 0.250 mg/min

> >

> > I need help, I don't know how to get that answer

> >

>

>

>

[Guest guest]

Wow! I understand it now, thank you so much for explaining it very well.

I am planning to take the exam next week or the week after, and I use this study

group a lot, so thank you so much for all the helpful infos and people here.

Goodluck to us

>

> I'll give it a shot. I'm studying to become certified.

>

> First we have a 110 lb person, which is 50.00 kg if we round up (1 pound =

> 0.45kg). At 5mcg / kg / min, this person needs 50.00 kg * 5 mcg/kg/min,

> which is 250 mcg/min. We now need to convert mcg to mg. This is 250 mcg/min

> * (1mg/1000mcg)/(min), giving us 0.250mg/min. (1000mcg = 1mg)

>

> Regards,

> ~Matt

>

>

[Guest guest]

Yes, I see so much units (mcg/kg/min) that confuses me. I am practicing more of

this kind of questions to become familiar with it and has helped a lot. Thank

you guys for explaining it to me

>

> The problem wants us to calculate the IV dosage rate (mg/min)

>  

> 110 lb * (1 kg/ 2.2 lb) * 5 mcg/kg/min * (1 mg/ 1000 mcg) = 0.25 mg/ min.

>  

> The problem give abandon information, that makes us confused.

> Please concentrate on what it asks for .

>  

>  

>

>

>

>

>

[Guest guest]

Dear crazycherish92

By now you have seen several ways to solve this problem. Glad you understand it.

BUT PLEASE take a MOMENT to read ALL of this post INCLUDING the link info

provided. I have also provided two variations of this same question that are

every day IV math for the IV technician (or should I say extended math

calculations from the same problem. Therefore this post is divided into three

parts or sections:

PART I

Your question:

" A patient weighing 110 lbs is to receive 5 mcg/kg/min of a IV solution

containing Dopamine 600 mg in 250 ml D5W. The calculated IV dosage rate is...?

Answer: 0.250 mg/min "

Here is the ratio proportion method mixed with some dimensional analysis:

Find Pt's Wt:

110 lbs x 1 Kg/2.2 lb = 50 Kg

OR

2.2 lbs------110 lbs

-------- = -----------

1 Kg----------X Kg

1 x 110/2.2 = 50 Kg

Find dose/min:

5 mcg/Kg =

5 mcg/1 Kg x 50 Kg = 250 mcg

Or

5 mcg---------X mcg

--------- = ----------

1 Kg----------50 mg

5 x 50/1 = 250 mcg

NOW

Re-read question: The calculated IV dosage rate is...?

A rate is amount of drug over time.

IV dose rates are usually in mg / min, gm/min or mcg/min or gtts/min

Since gtts are not mentioned we will assume that mcg/min are required.

However the book shows an answer that would require us to convert the strength

of 250 mcg/ min to X mg/min.

Recall the dose rate in the book is in X mg/min

While all of the following are correct :

250 mcg/min

0.25 mg/ min

0.00025gm/min

0.00000025 Kg/min

The BEST answer is: 0.25 mg/ min

Why? Because it is the most commonly used or recognized for this drug.

PLEASE NOTE: The answer given in the book: " Answer: 0.250 mg/min " is also a bit

incorrect! WHY? Because it may lead to mediation error with a `trailer zero' .

According to JCT trailer zeros must be left off and beginning zeros are

necessary. Please read below:

http://www.jointcommission.org/sentinelevents/sentineleventalert/sea_23.htm

PART II

Dear All, Allow me to pose an advanced math question that may be on the PTCB

exam. This math is every day math for the IV technician, but may prove

challenging for the retail tech who seldom uses this math:

New math question:

A patient weighing 110 lbs is to receive 5 mcg/kg/min of a IV solution

containing Dopamine 600 mg in 250 ml D5W. How long will it take for the above IV

to run out? (How long will it take for the IV to finish delivering the

medication?). What is the IV Flow rate (Xml/hr)?

At the determined 0.25 mg/min

0.25 mg------600 mg

------ = ----------

1 min-------X min

1 x 60/ 0.25 = 240 min

2400 min divided by 60 min/hr

OR

2400 min x 1hr/60 min = 40 hrs

What is the IV Flow Rate in ml/hr?

It takes 40 hours to infuse 600mg, which means it takes 40 hours to infuse the

250 ml that the 600 mg of drug are disolved in.

250ml/40 hrs

250ml-----Xml

------ = -----

40 hrs----1 hr

250 x 1 / 40 = 6.25ml/hr

PART III

What would the IV Flow rate in gtt/min if the drop rate is 15 ml/gtt?

The IV Flow rate in ml/hr is 6.25 ml/hr (250ml/hr)

250 ml-------1 hr-------1 gtt

-------- x --------- x -------

1 hr--------60 min------15 ml

0.2777 gtts/min or 0.278 gtts/min or 0.28 gtts/min or 0.3 gtts/min

I hope this helps you and challenges you.

YES these calculations can be and should be on the PTCB exam, however I expect

only a few of the advanced IV math and more basic conversions.

Respectfully,

Jeanetta Mastron CPhT BS Chemisty

Pharm Tech Educator

Founder/Owner of this site

> >

> > A patient weighing 110 lbs is to receive 5 mcg/kg/min of a IV solution

containing Dopamine 600 mg in 250 ml D5W. The calculated IV dosage rate is...?

> >

> > Answer: 0.250 mg/min

> >

> > I need help, I don't know how to get that answer

> >

>

[Guest guest]

To Matt Wash and Phuc Vinh La ~~~~~~ Great Work!

I think you both did an excellent job of " showing " how you solved this problem.

PLEASE be sure to try Part II and Part III of my post to crazycherish92 who

originally

asked the question.

Thank you again,

Ms Jeanetta Mastron CPhT BS

Founder/Owner

> > >

> > > A patient weighing 110 lbs is to receive 5 mcg/kg/min of a IV solution

> > containing Dopamine 600 mg in 250 ml D5W. The calculated IV dosage rate

> > is...?

> > >

> > > Answer: 0.250 mg/min

> > >

> > > I need help, I don't know how to get that answer

> > >

> >

> >

> >

>

>

>