HELP With Med Math Problem

Nurses General Nursing

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Hi there all you smart nurses! I need your help please I have to take a quiz tomorrow!

Wow - It feels like i've been out of school forever (it's been 7mos), I have these a quiz for a new job....Can someone pretty please help me with these? Thanks soo much!!

Your pt. (weight 72.4kg) has been ordered to have an infusion of Lasix

(50 mg/250 ml) titrated btwn. 3-6 mcg/kg/mn. What is the max. mcg/min the pt. would would receive?

***this part I understand****

prt. 2 of this question. Calculate the flow rate for the above infusion.

Next question:

A pt. is being admitted to your unit wiht a diagnosis of bilateral lower extremity cellulitis. The physician orders Ancef 1 GM IV every 6 hours.

The pharmacy dispenses a piggyback with the medication in 50 ml labeled for the drug to infuse in over 20 min. What rate would you set the IV pump. :bugeyes:

Thanks!! I am now understanding #2 it's like a lightbulb went off!

I think if it like

50ml/20min is = to xml/60min, then I cross multiply to get

20x = 3000, x=150

but i the first one yet...thanks again

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Thanks!! I am now understanding #2 it's like a lightbulb went off!

I think if it like

50ml/20min is = to xml/60min, then I cross multiply to get

20x = 3000, x=150

but i the first one yet...thanks again

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Thank you guys so much the light bulb went off !!!!!!!!!!!!!!!!! I got it, don't know why my brain is doing this to me, THANKS again, you're the BEST!!!!!!

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Specializes in med/surg, telemetry, IV therapy, mgmt.

are you a student? there are two threads on the nursing student forums to help with medication calculations:

your patient (weight 72.4 kg) has been ordered to have an infusion of lasix (50 mg/250 ml) titrated between 3-6 mcg/kg/minute. what is the maximum mcg/min the patient would receive? calculate the flow rate for the above infusion.

dose desired:
6 mcg/minute

dose on hand:
50 mg/250 ml

conversion factor:
1000 mcg = 1 mg

conversion factor:
60 minutes = 1 hour

patient weight:
72.4 kg

by dimensional analysis (factor label method)
:

6 mcg/minute
(dose desired)
x 72.4 kg
(patient's weight)
=
434.4 mcg/minute
(maximum dose patient can receive)

calculate the flow rate for the above infusion.

434.4 mcg/minute
(dose desired)
x 250 ml/50 mg
(dose on hand)
x 60 minutes/1 hour
(conversion factor)
x 1 mg/1000 mcg
(conversion factor)
= 130.32 ml/hour,
rounded off to
130 ml/hour

a patient is being admitted to your unit with a diagnosis of bilateral lower extremity cellulitis. the physician orders ancef 1 gram iv every 6 hours. the pharmacy dispenses a piggyback with the medication in 50 ml labeled for the drug to infuse over 20 minutes. at what rate would you set the iv pump?

amount to give
: 50 ml/20 minutes

conversion factor:
60 minutes = 1 hour

pump is always set at:
rate/hour

50 ml/20 minutes
(amount to give)
x 60 minutes/1 hour
(conversion factor)
=
150 ml/hour
(pump setting)

my advice: learn to do calculations by dimensional analysis! there are tutorials on how to do dimensional analysis on the nursing math thread to which the link is listed above.

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Professors, may a conscientious not-yet-in-training student ask a question?

I came up with similar answers for both parts of the first problem posed. But may I ask a question about the second problem?

Here is the question.

We are given the following question statement: "The pharmacy dispenses a piggyback with the medication in 50 ml labeled for the drug to infuse in over 20 min. What rate would you set the IV pump."

In the question statement, the pharmacy specifies the medication to be infused in OVER 20 minutes, which, if I read this direction carefully, indicates the infusion rate should be slightly LESS than 50 ml per 20 min. So to be most precise in following the pharmacy directions, should not the pump rate be set at

Setting the pump rate at 145 ml/hr would decrease the infusion rate just 3.3%, probably not a significant difference to the patient. But is this the most precise reading of the pharmacy directions or am I mistaken (most likely the case!) and reading too much into the question?

Thank you.

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Specializes in ER/ICU/Flight.
Professors, may a conscientious not-yet-in-training student ask a question?

I came up with similar answers for both parts of the first problem posed. But may I ask a question about the second problem?

Here is the question.

We are given the following question statement: "The pharmacy dispenses a piggyback with the medication in 50 ml labeled for the drug to infuse in over 20 min. What rate would you set the IV pump."

In the question statement, the pharmacy specifies the medication to be infused in OVER 20 minutes, which, if I read this direction carefully, indicates the infusion rate should be slightly LESS than 50 ml per 20 min. So to be most precise in following the pharmacy directions, should not the pump rate be set at

Setting the pump rate at 145 ml/hr would decrease the infusion rate just 3.3%, probably not a significant difference to the patient. But is this the most precise reading of the pharmacy directions or am I mistaken (most likely the case!) and reading too much into the question?

Thank you.

I just saw this thread so I"m late getting into it. Your are right about reading too much into the question. Over 20 minutes doesn't mean more than 20 min., it means exactly 20 min. You are putting some good, hard thought into it though.

When I do drug math, it's easiest for me to use ratio:proportion. How much drug do I have in each cc? How many cc/hr? You can plug in kg, mg/kg/min, ug/min....etc. I use the same basic principles for each problem. There are many different ways to do it, as long as you get the right answer then I don't think it matters how you got there.

There are a bunch of little cheats we use for different common gtts. Like dopamine, epi, dobut, etc but I always double check everything and there is never any harm in asking a colleague to check your math. It helps reduce errors and just as importantly it builds a team approach to things.

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