Help with Dosage!

You might want to go back and edit your post to include what calculations you've already attempted.

What have you come up with so far? We are here to help you, but we are NOT going to do your homework for you.

What is it that you are having problems with.

Do you understand how to work the problem

or

have you worked the problems and have a different answer than the book?

Sounds like you might be having trouble with conversions. Here are some basics that it is good to memorize. You will use them endlessly.

1. 1g=1000 mg

2. 1 mg = 1000 mcg

2. 1kg = 2.2lb.

3. Lbs/2.2 = kg

4. Dosage calculations are D / H x V. Desired amount (D) divided by the amount you have on hand (H) multiplies by the volume the med is supplied in (V). V could be the volume of an IV solution, the number of pills, or a liquid medicine concentration.

Ao here are some tips for your specific questions:

1. First calculate the patient's weight in kilograms. Plug that number into the rate of your drip to calculate how much medication you would give in one hour.

2. For this problem, you know there are 250mls of fluid for 175 mg. You need to know how many mls of fluid there is in 10mg of medication. Do this by cross multiplying the concentration that you have and the concentration that you want. 175/250 cross multiplied with 10/x. Solve for x.

3. Convert dopamine mg into dopamine mcg. Then find out how much domapine is in one ml of the fluid. Then calculate how many mcg of dopamine the patient is getting per hour if the rate is 28mls. Compare this to: Find the patient's weight in kgs. Plug this into your formula 10mcg/kg/hr) and find out how many mcg of dopamine the patient should be receiveing per hour. Compare this to your first answer. Are they the same?

4. Very similar to number 3 but you don't need the patient's weight.

Hope this helped. In the future when you post questions like this, include the answer that you came up with as well as some information about how you tried to solve the question. Then we can more easily help you correct your mistakes. I'm happy to help, but I will not just give you the answers to questions. Otherwise, you are not learning anything.

1. Convert weight from lbs to kg:

95lbs/2.2kg/lb = 43.2kg

mg/hr = 0.7mg x 43.2kg = 30.2mg/hr

mg/min= 30.2mg/hr / 60min/hr = 0.50mg/min

ml/hr = 1000mg = 30.2mg

1000ml X

1000X = 30,200

1000 1000

X = 30.2ml/hr

2. Set up as a ratio like part 3 in problem # 1

175mg = 10mg

250 ml X

175X = 2500

175 175

X = 14.3ml/hr

3. 10mcg/kg/hr = 0.010mg/kg/hr

The patient weighs 130lbs or 130lbs/2.2lbs/kg = 59.1kg

0.010mg X 59.1kg/min = 0.6mg/ min

0.6 X 60 = 36mg/hr (converted the above from mg/min to mg/hr)

Now you have to set up a ratio to see if the pump is set correctly.

400mg = 36mg

500 ml X

400X = 18000

400 400

X = 45ml/hr

So, NO…28ml/hr is wrong. The pump should have been set on 45ml/hr.

4. mg/hr Okay….you have 110mcg/min. This needs to be converted to mg/hr. So, 110mcg is the same as 0.110mg. 0.110mg X 60 = 6.6mg/hr. Since the original question stated mcg per min…you have to multiply by 60 to convert to hour.

ml/hr. You have to perform a ratio again.

250mg = 6.6mg

250ml X

250X = 1650

250 250

X = 6.6ml/hr. If the pump is infusing at 12ml/hr, it is running too fast. The correct infusion rate should be 6.6ml/hr.

I hope this helps…if not, respond and I will be happy to explain the steps.

Sounds like you might be having trouble with conversions. Here are some basics that it is good to memorize. You will use them endlessly.

1. 1g=1000 mg

2. 1 mg = 1000 mcg

2. 1kg = 2.2lb.

3. Lbs/2.2 = kg

4. Dosage calculations are D / H x V. Desired amount (D) divided by the amount you have on hand (H) multiplies by the volume the med is supplied in (V). V could be the volume of an IV solution, the number of pills, or a liquid medicine concentration.

Ao here are some tips for your specific questions:

1. First calculate the patient's weight in kilograms. Plug that number into the rate of your drip to calculate how much medication you would give in one hour.

2. For this problem, you know there are 250mls of fluid for 175 mg. You need to know how many mls of fluid there is in 10mg of medication. Do this by cross multiplying the concentration that you have and the concentration that you want. 175/250 cross multiplied with 10/x. Solve for x.

3. Convert dopamine mg into dopamine mcg. Then find out how much domapine is in one ml of the fluid. Then calculate how many mcg of dopamine the patient is getting per hour if the rate is 28mls. Compare this to: Find the patient's weight in kgs. Plug this into your formula 10mcg/kg/hr) and find out how many mcg of dopamine the patient should be receiveing per hour. Compare this to your first answer. Are they the same?

4. Very similar to number 3 but you don't need the patient's weight.

Hope this helped. In the future when you post questions like this, include the answer that you came up with as well as some information about how you tried to solve the question. Then we can more easily help you correct your mistakes. I'm happy to help, but I will not just give you the answers to questions. Otherwise, you are not learning anything.

I agree with you to a certain extent. Generally with math, I know I need to see the problems worked out so that I can see where the steps come into play. If I don't understand the steps, then I can work the problems backwards to understand.

I agree with you to a certain extent. Generally with math, I know I need to see the problems worked out so that I can see where the steps come into play. If I don't understand the steps, then I can work the problems backwards to understand.

What Ashley, and everyone else, was trying to say that we can be more help to the OP if they posted their answer and where they are having trouble. The OP just listed their homework questions straight from the book with nothing else and appears that the OP wanted the work done for them, for which you kindly obliged them and did EVERYTHING for them. We are here to help these students, not to do their homework for them.

I agree with you to a certain extent. Generally with math, I know I need to see the problems worked out so that I can see where the steps come into play. If I don't understand the steps, then I can work the problems backwards to understand.

I explained the formula and the steps that the OP needed to take to answer the questions. He/she is free to respond again if they still have questions. If a person just posts there homework questions, receives a full answer and copies that answer they then get a 100 on their homework but learn nothing and may not be a safe nurse. So that's why I explain the formula and the steps using variables or examples. I'm not going to just go the OP's homework questions knowing there is a (good) chance they will just take the answers.

Of course, it's totally up to you if you want to do the homework questions for the poster.

I have recently started teaching Dosage Calculations to nursing students. It is my experience that simply giving hints doesn’t help the students to learn. People become good at math by practicing the problems. It is kind of hard to do if you don’t know where to start. To say that the OP came to the site and posted problems to simply have someone else to do the work for her/him is premature. You don’t know that for certain. The story sounds similar to the ED nurses suggesting that patients who come into the ED with back pain are drug seekers.

Perhaps you are correct. Maybe the OP wanted someone to do the work. If that is the case, then I suppose I am the sucker. I don’t care if the OP gets a 100% on her/his homework without doing the work. That is on her/his conscious. I answered the questions…what the OP does with the information is no longer my concern. Quite honestly, after reading the steps posted of how to solve the problems, I was confused.

I have recently started teaching Dosage Calculations to nursing students. It is my experience that simply giving hints doesn’t help the students to learn. People become good at math by practicing the problems. It is kind of hard to do if you don’t know where to start. To say that the OP came to the site and posted problems to simply have someone else to do the work for her/him is premature. You don’t know that for certain. The story sounds similar to the ED nurses suggesting that patients who come into the ED with back pain are drug seekers.

Perhaps you are correct. Maybe the OP wanted someone to do the work. If that is the case, then I suppose I am the sucker. I don’t care if the OP gets a 100% on her/his homework without doing the work. That is on her/his conscious. I answered the questions…what the OP does with the information is no longer my concern. Quite honestly, after reading the steps posted of how to solve the problems, I was confused.

So according to your logic I can be a student in your class, cheat on every test and ace the class and you would be ok with that because it would be on my conscious? Do you think you do students any favors by giving them the answers. It's not hard to deduce that the op is asking for the answers based on join date and similar posts. If they truly wanted help in finding the answer they probably would have posted some type of leg work showing he/she attempted to do the work on their own. And using your analogy about back pain for someone in the ER, yes if someone has been to ER 20 times in a month, has allergies to all NSAIDs, and states only Dilaudid 4mg works for them, than yes you can deduce they are in fact a drug seeker.

Would you want to be the patient sitting on the other end of a nurse that was given all the answers throughout school? Who wouldn't know what to do when you needed it most because they don't know the how to come up with an answer.

"so according to your logic i can be a student in your class, cheat on every test and ace the class and you would be ok with that because it would be on my conscious?"

where did you dream of this response? nowhere in any of my responses did i allude to the fact that i support students cheating. let's exercise a little critical thinking skills here, okay? the op makes a post needing help with some problems. i think it is safe to assume the op is not sitting in class taking an exam. i would also venture to say the op doesn't have a take home test as the accrediting bodies and higher education institutions frown upon that practice. i think it is perfectly acceptable for a student to come to the website and ask for help. i also think it is acceptable for a member of the website to provide answers. the student is learning how to use his/her resource to his/her advantage; a skill that is often times not taught in higher education.

i really don't give a damn if my students receive answers from other classmates or by other means for their homework. that is why the homework is only worth 10% of my student's final grade. if the students do not put forth the effort in learning the material, it is reflected on their exam grades. there are multiple learning styles and teaching styles. if you have never had a class of 30 students with varying needs, then i don't expect you to understand.

"do you think you do students any favors by giving them the answers. it's not hard to deduce that the op is asking for the answers based on join date and similar posts. if they truly wanted help in finding the answer they probably would have posted some type of leg work showing he/she attempted to do the work on their own."

if i don't work the problems out and provide answers, how in the world would you expect students to learn? how do you think math or dosage calculations is taught? it is taught by working out example problems. how do you expect a student to provide any leg work if he/she is clueless of how to start?

"and using your analogy about back pain for someone in the er, yes if someone has been to er 20 times in a month, has allergies to all nsaids, and states only dilaudid 4mg works for them, than yes you can deduce they are in fact a drug seeker."

you labeled the op with limited information. that is the point i am making. you cannot, with complete certainty, say the op's intention was to get the answers to the problems. if a patient comes to the er 20 times because of their back, perhaps the md's are missing something. if a patient asks for dialudid 4mg, maybe they have a built up tolerance because no one is committed to find out what is really wrong with the patient. if a patient shows up that many times, either they have a back problem, mental problem, or an addiction. to simply jump to the latter option is premature.

mass:

mcg → mg → g → kg ( ÷ by 1,000 )

mcg ← mg ← g ← kg ( x by 1,000 )

lb → kg ( ÷ by 2.2 )

lb ← kg ( x by 2.2 )

volume:

mcl → ml → l → kl ( ÷ by 1,000 )

mcl ← ml ← l ← kl ( x by 1,000 )

time:

min → hr ( ÷ by 60 )

min ← hr ( x by 60 )

example: convert 5,000 mcg to mg.

mcg → mg → g → kg ( ÷ by 1,000 )

5,000 mcg ÷ 1,000 = 5 mg

example: convert 44 lb to kg.

lb → kg ( ÷ by 2.2 )

44 lb ÷ 2.2 = 20 kg

example: convert 0.003 l to mcl.

mcl ← ml ← l ← kl ( x by 1,000 )

0.003 l x 1,000 = 3 ml

3 ml x 1,000 = 3,000 mcl

example: convert 5 hours to minutes.

min ← hr ( x by 60 )

5 hr x 60 = 300 min

mass for mass questions

given an amount of mass per tablet, how many tablets do you require?

formula:

ordered

have

= y (tablets required)

example: metroprolol (lopressor), 25 mg po, is ordered. metropolol is available as 50 mg tablets. how many tablets would the nurse administer?

ordered

have

= y (tablets required)

25 mg

50 mg

= 0.5 tablets

example: potassium chloride is available as 10 mg per tablet. potassium chloride (k-dur), 40 mg, is ordered. how many tablets would the nurse administer?

ordered

have

= y (tablets required)

40 mg

10 mg

= 4 tablets

mass/liquid for liquid questions

given an amount of mass per liquid, how much liquid do you require?

formula:

ordered

have

x volume per have

= y (liquid required)

example: phenytoin (dilantin), 0.1 g po, is ordered to be given through a nasogastric tube. phenytoin is available as 30 mg / 5 ml. how much would the nurse administer?

ordered

have

x volume per have

= y (liquid required)

convert 0.1 g to mg.

mcg ← mg ← g ← kg ( x by 1,000 )

0.1 g x 1,000 = 100 mg

100 mg

30 mg

x 5 ml

= 16.7 ml

example: ordered lasix 40 mg iv push now. available: 80 mg in 1 ml. how much will the nurse draw up?

ordered

have

x volume per have

= y (liquid required)

40 mg

80 mg

x 1 ml

= 0.5 ml

amount in iv fluid questions

given a volume of iv fluid and a dosage expressed in percent, what is the mass of a particular dosage?

formula:

concentration %

100

x volume (ml) = y (dosage amount in g)

example: calculate the amount of dextrose in 1000 ml d5w.

concentration %

100

x volume (ml) = y (dosage amount in g)

5%

100

x 1000 ml = 50 g

example: calculate the amount of sodium chloride in 2000 ml ns.

recall ns is 0.9% nacl (sodium chloride)

concentration %

100

x volume (ml) = y (dosage amount in g)

0.9%

100

x 2000 ml = 18 g

volume/time - iv ml rate questions

given a certain amount of liquid and a time period, what is the necessary iv flow rate in ml/hr? measurement used when iv regulated electronically by infusion pump.

formula:

volume (ml)

time (hr)

= y (flow rate in ml/hr)

example: infuse 250 ml over the next 120 minutes by infusion pump.

volume (ml)

time (hr)

= y (flow rate in ml/hr)

convert 120 minutes to hours.

min → hr ( ÷ by 60 )

120 min ÷ 60 = 2 hr

250 ml

2 hr

= 125 ml/hr

example: ordered 1000 ml d5w iv to infuse in 10 hours by infusion pump.

volume (ml)

time (hr)

= y (flow rate in ml/hr)

1000 ml

10 hr

= 100 ml/hr

volume/time - iv drop rate questions

given a certain amount of liquid, a time period, and a drop factor (gtts/ml), what is the necessary iv flow rate in gtts/min? measurement used when iv is regulated manually. because it is not possible to give a patient a fraction of a drop, it is typical to round answers for these problems up or down to the nearest whole number.

formula:

volume (ml)

time (min)

x drop factor (gtts/ml) = y (flow rate in gtts/min)

example: calculate the iv flow rate for 1200 ml of ns to be infused in 6 hours. the infusion set is calibrated for a drop factor of 15 gtts/ml.

volume (ml)

time (min)

x drop factor (gtts/ml) = y (flow rate in gtts/min)

convert 6 hours to minutes.

min ← hr ( x by 60 )

6 hr x 60 = 360 min

1200 ml

360 min

x 15 gtts/ml = 50 gtts/min

example: calculate the iv flow rate for 200 ml of 0.9% nacl iv over 120 minutes. infusion set has drop factor of 20 gtts/ml.

volume (ml)

time (min)

x drop factor (gtts/ml) = y (flow rate in gtts/min)

200 ml

120 min

x 20 gtts/ml = 33 gtts/min

fluid maintenance requirement questions

given the weight of a child or infant, calculate the necessary amount of fluid per day. different hospitals may have different policies, but for learning how to perform these pediatric dosage calculations, the following commonly used table of fluid requirements may be used.

weight range

required daily fluid

0-10 kg

100 ml per kg

10-20 kg

1,000 ml + 50 ml per each kg above 10 kg

20-70 kg

1,500 ml + 20 ml per each kg above 20 kg

over 70 kg

2,500 ml (adult requirement)

example: an infant weighs 4 kg. what is the required amount of fluid per day in ml?

0-10 kg

100 ml per kg

4 kg x 100 ml/kg = 400 ml

example: an infant weighs 30.8 lb. what is the required iv flow rate in ml/hr to maintain proper fluid levels?

convert 30.8 lb to kg.

lb → kg ( ÷ by 2.2 )

30.8 lb ÷ 2.2 = 14 kg

10-20 kg

1,000 ml + 50 ml per each kg above 10kg

14 kg - 10 kg = 4 kg (there are 4 kg over 10 kg).

1,000 ml + (50 ml/kg x 4 kg) = 1,200 ml/day

this is now an ordinary iv flow rate - ml rate question. the required volume is 1,200 ml and the time is one day.

volume (ml)

time (hr)

= y (flow rate in ml/hr)

there are 24 hours in one day.

1 day x 24 = 24 hr

1,200 ml

24 hr

= 50 ml/hr

dosage by weight questions

given the weight of a patient and a dosage specified in terms of weight, calculate the necessary dosage. these problems are a type of pediatric dosage calculations.

formula:

weight in kg * dosage per kg

= y (required dosage)

example: a doctor orders 200 mg of rocephin to be taken by a 15.4 lb infant every 8 hours. the medication label shows that 75-150 mg/kg per day is the appropriate dosage range. is this doctor's order within the desired range?

weight in kg * dosage per kg

= y (required dosage)

convert 15.4 lb to kg.

lb → kg ( ÷ by 2.2 )

15.4 lb ÷ 2.2 = 7 kg

7 kg * 75 mg/kg

= 525 mg (minimum desired dosage)

7 kg * 150 mg/kg

= 1,050 mg (maximum desired dosage)

24 hours in one day and the medication is ordered every 8 hours.

24 hrs / 8 hrs = 3 times per day doctor ordered medication

200 * 3 = 600 mg ordered per day

600 mg is within the desired range of 525-1,050 mg

yes doctor has ordered a dosage within the desired range.

example: solumedrol 1.5 mg/kg is ordered for a child weighing 74.8 lb. solumedrol is available as 125 mg / 2ml. how many ml must the nurse administer?

weight in kg * dosage per kg

= y (required dosage)

convert 74.8 lb to kg.

lb → kg ( ÷ by 2.2 )

74.8 lb ÷ 2.2 = 34 kg

34 kg * 1.5 mg/kg

= 51 mg

this is now an ordinary mass/liquid for liquid question. 51 mg is ordered and the medication is available as 125 mg / 2 ml.

ordered

have

x volume per have

= y (liquid required)

51 mg

125 mg

x 2 ml

= 0.82 ml

mass/time - iv ml rate questions

give an order in quantity of mass per time, determine the necessary iv flow rate in ml/hr based on the given mass per volume. these types of problems are often used in critical care nursing.

formula:

ordered per hour

have

x volume (ml)

= y (flow rate in ml/hr)

example: give patient 500 mg of dopamine in 250 ml of d5w to infuse at 20 mg/hr. calculate the flow rate in ml/hr.

ordered per hour

have

x volume (ml)

= y (flow rate in ml/hr)

20 mg/hr

500 mg

x 250 ml

= 10 ml/hr

example: aggrastat at 12.5 mg in 250 ml is prescribed to be infused at a rate of 6 mcg/kg/hr in a patient who weighs 100 kg. at what flow rate in ml/hr will you set the pump?

ordered per hour

have

x volume (ml)

= y (flow rate in ml/hr)

the first step is to convert the order per time to the amount required for this particular patient. this is a dosage by weight question. 100 kg is the weight in kg and 6 mcg/kg/hr is a dosage in terms of kg.

weight in kg * dosage per kg

= y (required dosage)

100 kg * 6 mcg/kg/hr

= 600 mcg/hr

convert 600 mcg/hr to mg/hr.

mcg → mg → g → kg ( ÷ by 1,000 )

600 ÷ 1,000 = 0.6 mg/hr

0.6 mg/hr

12.5 mg

x 250 ml

= 12 ml/hr