IV math question- help...

Mossback · Dec 31, 2009

your patient in hypertensive crisis has been ordered to have nipride (nitroprusside) infusion. the 190 pound patient has a 500ml bag of ns with 100mg of nipride hanging with the pump running at 8ml/hr. what is the dosage that the patient is receiving?

i think the inclusion of the patient's weight may have thrown you off. note that the dosage is absolute, rather than being given in terms of mg/kg. like many medical math problems, this one contains some useless information that so that the correct formula isn't immediately obvious.

here's one way of attacking this problem:

you have 100 mg in 500 ml. determine the quantity of drug per ml by dividing 100 by 500, which equals 0.2 mg per ml.

now multiply 0.2 by your flow rate of 8 ml/hr. that gives you 1.6 mg/hr.

divide 1.6 by 60 minutes, and you arrive at 0.026 mg per min, which is the same as 26 mcg per min.

hope this helps.

CRIMSON · Jan 2, 2010

your patient in hypertensive crisis has been ordered to have nipride (nitroprusside) infusion. the 190 pound patient has a 500ml bag of ns with 100mg of nipride hanging with the pump running at 8ml/hr. what is the dosage that the patient is receiving?

formula
mg x 1000 / 60(minutes) / kg / infusion rate
_________________________________
volume of bag
100mg (drug) x 1000 (to get mcg) / 60 (to get minutes) / 86 kg x 8ml/hr
_________________divided by_____________________________
volume of bag ( 500 ml)
when i worked out the problem this way i get 0.31 mcg/kg/min
then i plugged the numbers into a different formula to check and got...
concentration ( 200 ug/ml) x 8 ml/hr (pump setting) / 60/ 86.36 kg = 0.31
mcg/kg/min
i thought this question should be answered as mcg/kg/min
answer sheet says the correct answer is 0.26 mg/min...how is this the correct answer??
pull out info so as not to confuse yourself: avail-100mg/500ml wt-190# pump rate-8ml/hr . next identify what the answer is they are looking for (by your info they did not properly indentify this).....
mg/min = 100mg/500ml x 8ml/1hr x 1hr/60min = 800/30,000 = 0.2666 which correctly rounds to 0.27mg/min
(i know they are showing 0.26 but this would not be correct by rounding rules)

melmarie23, MSN, RN · Jan 2, 2010

your patient in hypertensive crisis has been ordered to have nipride (nitroprusside) infusion. the 190 pound patient has a 500ml bag of ns with 100mg of nipride hanging with the pump running at 8ml/hr. what is the dosage that the patient is receiving?

100mg/500ml=xmg/8ml

500x=800

x=1.6mg, so the pt is receiving an infusion of 1.6mg/hr.

to get the dose they are receiving in minutes, divide 1.6 by 60 and you get 0.026mg/min (26mcg).

the patient has an order to receive lidocaine (xylocaine) for pvc's. the pharmacy has sent you lidocaine 2 grams iv in 1000 ml d5w at 4mg/min. what is the pump setting to deliver the desired dosage?

2g=2000mg

on hand 2000mg/1000ml

ordered 4mg/min---> but you set the pump in ml/hr, so multiply 4mgx60 to get the dose needed per hour. so we need to infuse 240mg/hr

i use ratio and proportion

2000mg/1000ml=240mg/x ml, solve for x

x=120ml

so set the pump at 120ml/hr. i don't know why they want the answer in ml/min...pumps are always set ml/hr. if they specifically asked for the answer to be in ml/min, sure, i would give them the answer of 2ml/min, but they did not. my answer is 120ml/hr, just as you had

yooperPN · Jan 3, 2010

also....
the patient has an order to receive lidocaine (xylocaine) for pvc's. the pharmacy has sent you lidocaine 2 grams iv in 1000 ml d5w at 4mg/min. what is the pump setting to deliver the desired dosage?
i got an answer of 120 ml/hr
however the answer is 2ml/min
ok, so if i divide my answer by 60 i would get the correct answer however i would have put my answer as 120 ml/hr and would have gotten it wrong- how would i know that this answer should be in ml/min?
thank you so much for any assistance and happy new year!!

since everyone else helped with the first part of your question, i would think the reason behind answering the 2nd question with ml/min is because that's what is given in the problem. it says 4mg/min, so i would assume they want the answer in minutes. hope that helps!

kgh31386, BSN, MSN, RN · Jan 3, 2010

I probably would have put it in ml/hr instead of ml/min because it said what would you set the pump at...and it's in ml/hr..I would ask the teacher about that one

dream2blpn · Jan 5, 2010

I am a little confused by the math questions. On our dosage tests the question always tells you what they are looking for, gtts/min, ml/hr, etc.. They do however throw information in the questions that is not needed like the clients weight and we have to figure out what info is needed and what is not. They also tell you whether or not to round to the nearest tenth or hundreth even though the rounding rules says how to round each number.