ive been told that dimensional analysis is full proof and is the way to go to do dosage calculations.
im on my last two prereqs before nursing school. i need to get an 80 or above on 3 out of 5 dosage exams. my first i missed due to illness my second i got a 77 i now have to get 80+ on the next three dosage exams in a row otherwise i have to drop the class and take it a 3rd time.
this is the second time im taking the class the first time i couldnt get the dosages so i had to take it again. if i dont get an 80 or above on the next three i have to take this class again which puts me behind a WHOLE YEAR in applying for nursing school.
please im reaching out to everyone...help me
ive got the conversion factors down perfectly its just setting up and knowing which numbers to put where in the dimensional analysis method.
the exams are 4 parts....conversions, dosages calculations, reconstitutions, IV flow rates.
you cant see me right now but i swear im crying as a i type this i feel so stupid and hopeless. please please help me with this your advice and knowledge and tutoring/explanations tips will directly be impacting the rest of my life.
you all are my last hope really. ive tried the tutors available to me and they cant help.
Specializes in nursing home, home health, hospital.
I have a system that has helped me throughout nursing school and on the job as needed. I'm not sure if it's what your looking for but either way I hope you pass your next three tests!! Everything in the same row is equal like 1000g = 1kg = 2.2lbs ... You'll see
500mg 0.5g 71/2 gr lb=pound dr=dram gtt=drops L=liter pt=pint
250mg 0.25g 33/4 gr Qt=quart oz=ounze tbsp= tablespoon
100mg 0.1mg 11/2 gr tsp=teaspoon
60mg - 1gr
1kg 1000g 2.2lb
1000ml 1L 1Qt
500ml 1pt 16oz
250ml 1glass 8oz
30ml 8drs 2tbsp
15ml 4drs 1tbsp
5ml 1dr 1tsp
1gtt 1mx -
1ml 15-16gtt 15-16mx
2.5cm 1in -
those are the tables i memorized so that i could convert equations
then i memorized the following
V multipled by D but when you say it, it just flows out V over T times D
T thats how i calculate IV drop factors
The V is for the total amt of volume to be infused in militers
the T is for the total time in minutes
and the D is for the gtt they give you in the question then you just do some math and you get the gtt/min
As far like oral dosages go...
i take what available and put it in the first () and take the ordered dose & put it in the second () As follows...
lets say the doc orders 2mg of something and you have 1mg/tablet available
(1mg : 1tablet)::(2mg:x) x is what your looking for then i just do some order of operations
1x = 2 inside x the inside so 1x2= 2
1 1 outside x outside so 1xX= 1x
then you have to ge the variable (x) by itself so you divide the number with x by it's side to free the variable so then your answer would be x=2tablets
if this didn't help I'm sorry but there is an excellent website that explains it and has practice questions with answers available to and it's free it's called
Specializes in nursing home, home health, hospital.
wow so some of the stuff i just posted shifted to the side a bit sorry about that it looked good and easy to read before I posted it. ahh well hope it helps anyway
I have a system that has helped me throughout nursing school and on the job as needed. I'm not sure if it's what your looking for but either way I hope you pass your next three tests!! Everything in the same row is equal like 1000g = 1kg = 2.2lbs ... You'll see
500mg 0.5g 71/2 gr lb=pound dr=dram gtt=drops L=liter pt=pint
250mg 0.25g 33/4 gr Qt=quart oz=ounze tbsp= tablespoon
100mg 0.1mg 11/2 gr tsp=teaspoon
60mg - 1gr
1kg 1000g 2.2lb
1000ml 1L 1Qt
500ml 1pt 16oz
250ml 1glass 8oz
30ml 8drs 2tbsp
15ml 4drs 1tbsp
5ml 1dr 1tsp
1gtt 1mx -
1ml 15-16gtt 15-16mx
2.5cm 1in -
those are the tables i memorized so that i could convert equations
then i memorized the following
V multipled by D but when you say it, it just flows out V over T times D
T thats how i calculate IV drop factors
The V is for the total amt of volume to be infused in militers
the T is for the total time in minutes
and the D is for the gtt they give you in the question then you just do some math and you get the gtt/min
As far like oral dosages go...
i take what available and put it in the first () and take the ordered dose & put it in the second () As follows...
lets say the doc orders 2mg of something and you have 1mg/tablet available
(1mg : 1tablet)::(2mg:x) x is what your looking for then i just do some order of operations
1x = 2 inside x the inside so 1x2= 2
1 1 outside x outside so 1xX= 1x
then you have to ge the variable (x) by itself so you divide the number with x by it's side to free the variable so then your answer would be x=2tablets
if this didn't help I'm sorry but there is an excellent website that explains it and has practice questions with answers available to and it's free it's called
Specializes in nursing home, home health, hospital.
we were taught 240 or 250ml for 8oz and 480 or 500ml for 16oz and 4 or 5ml per 1 tsp due to the fact that different ppl use different calculations. so i always just try the equation with both numbers to see which one the question is asking for.
Here are some notes we were given before we took our Caculations test . I hope that they will help. I do not know if they will but no one failed in our class. just let me know if they are any help if not have some web sites we were also given that had plenty of practice problems and ways to do the problems. good Luck. Just relax before the test.
Calculating drops/minute
Multiply the mL to be infused by the drop factor of the tubing and divide by the number of minutes over which you are infusing the fluid.
x gtts/mL = gtts/minute
So, if you have 1000 mL to infuse in 6 hours and the gtt factor for the tubing is 15 gtts per mL:
x 15= 41.6 or 42 gtts/minute
Calculating the flow rate for an intermittent infusion like a minibag using an infusion pump:
Volume (in mL) x minutes = mL/hr to set on infusion pump
Time (in minutes) 1 hour
Examples:
1.Order: Rocephin 1 gram in 100 mL NS to run over 30 minutes. (The volume is 100 mL.)
100 mL x 60 min = 200 mL/hr
30 min 1 hour
You would set the infusion pump at 200 mL/hr.
2.Order: Rocephin 1 gram in 100 mL NS to run over 20 minutes. (The volume is 100 mL.)
100 mL x 60 min = 300 mL/hr
20 min 1 hour
You would set the infusion pump at 400 mL/hr.
3.Order: Rocephin 500 mg in 50 mL NS to run over 30 minutes.
50 mL x 60 min = 100 mL/hr
30 min 1 hour
You would set the infusion pump at 100 mL/hr.
Calculating volume of a suspension or oral liquid medication:
Desired amount in mg (or other measurement) x mL = mL/dose
Amount on hand in mg (or other measurement)
Example:
Order: Prednisone 9 mg po. On hand, you have Prednisone 15 mg/5 mL.
9 x 5 = 3 mL/ dose
15
Remember Rounding Rules!
NOTE: Blood Glucose is abbreviated as "BG"
1. The order reads: Vancomycin 500 mg IV every 24 hours. The Nursing Drug Handbook
states that the medication should be administered over 1 hour. On hand is
Vancomycin 500 mg in 250 mL of D5W. At what rate would the nurse set the infusion
pump to administer the medication?
___250____________ mL/hr
Answer: 250 mL ÷ 60 min x 60 = 250 mL/hr
2. The order reads: Tegretol 600 mg by mouth every 8 hours. On hand you have Tegretol 150
mg per 5 mL. How many mL per dose will you administer?
__20_________mL/dose
Answer: 600 mg ÷ 150 mg x 5 mL = 20 mL/dose
3. The order reads: Motrin 10 mg per kg of body weight by mouth now for pain. The patient
weighs 66 pounds. On hand is Motrin 200 mg/teaspoonful. How many mL will you
administer?
__7.5__________ mL
Answer: 66 lb ÷ 2.2 lb/kg = 30 kg
30 kg x 10 mg/kg = 300 mg
One teaspoonful = 5 mL
300 ÷ 200 x 5 = 7.5 mL/dose
4. The order reads: Sliding Scale Humalog Insulin four times a day using the following
formula:
BG (Blood Glucose) - 120 = # of Units of Humalog Insulin per dose
20
If the patient's blood glucose is 600 at 5:00 pm and dinner is served at 5:30 pm, how many
units of Humalog Insulin will the nurse administer to the patient?
____24_____ units
Answer: 600 - 120 ÷ 20 = 24 units
At what time should the nurse administer the Humalog Insulin?
A.5:00 pm
B.5:30 pm--The onset of action for Humalog insulin is 5-15 minutes. The patient should have food in front of him or her before receiving Humalog insulin.
C.6:30 pm
D.8:00 pm
TEST YOUR KNOWLEDGE: What is the appropriate abbreviation for "units?"
Answer: There is no acceptable abbreviation for "units." It should be written as "units".
5. The order reads: Sliding Scale Humalog Insulin four times a day using the following
formula:
BG- 120 = # of Units of Humalog Insulin per dose
25
If the patient's blood glucose is 420 at 5:00 pm and dinner is served at 5:00 pm, how many
units of Humalog Insulin will the nurse administer to the patient?
____12________ units
Answer: 420 - 120 ÷ 25 = 12 units
6. The order reads: Tylenol 80 mg by mouth now. On hand, you have
Tylenol 160 mg per 5 mL. How many mL will you administer?
_________2.5_____mL
Answer: 80 ÷ 160 x 5 = 2.5 mL
If you only have a teaspoon with which to measure, how many teaspoonsful will you give?
__0.5 or 1/2____ teaspoon(s)ful
Answer: One teaspoonful = 5 mL, so 2.5 ÷ 5 = 0.5 teaspoonsful (or ½ teaspoonful)
7. The order reads: Motrin 15 mg per kg of body weight by mouth now for pain. The patient
weighs 44 pounds. On hand is Motrin 200 mg/teaspoonful. How many mL will you
administer?
_______7.5___ mL
Answer: 44 lb ÷ 2.2 lb/kg = 20 kg
20 kg x 15 mg/kg = 300 mg
300 ÷ 200 x 5 = 7.5 mL/dose
TEST YOURSELF: How many teaspoonsful are equal to 7.5 mL?
Answer: 1.5 or 1 ½ teaspoonsful
8. You are the LPN staffing the Advice line in the Pediatric Clinic. The mother of a nine-year-
old calls to ask how much Tylenol to give to the child for fever. Your written protocol states
that the appropriate dose is: Tylenol 10 mg per kg of body weight by mouth now for fever.
The patient weighs 105.6 pounds. On hand is Tylenol 160 mg per 5 mL. How many
teaspoonsful of Tylenol will the nurse tell the mother to give? (The mother has only spoons
with which to measure the medication.)
_____3_________ teaspoonsful
Answer: 105.6 ÷ 2.2 = 48 kg
48 x 10 = 480 mg
480 ÷ 160 x 5 = 15 mL
One teaspoonful = 5 mL, so 15 mL = 3 teaspoonsful
TEST YOURSELF: Convert the teaspoonsful above to tablespoonsful.
______1____ tablespoonsful
Answer: One tablespoonful ( 15 mL) = 3 teaspoonsful
9. The order reads: Kefzol 1 Gm IV every 8 hours. The package instructions state that the
medication should be given in 50 mL of NS over 30 minutes. At what rate will the nurse
set the infusion pump?
__100________ mL/hr
10. The order reads: Kefzol 1 Gm IV every 8 hours. The package instructions state that the
medication should be given in 50 mL of NS over 15 minutes. At what rate will the nurse
set the infusion pump?
________200____ mL/hr
11.The order reads: Give IV bolus of 625 mL of LR IV now. The unit protocol states that an IV bolus will be given over one hour. At what rate will the nurse set the infusion pump to infuse the bolus?
____625____mL/hr
Answer: 625 ÷ 60 x 60 = 625 mLl/hr
12. The order reads: Levaquin 750 mg IV every 24 hours. The Nursing Drug Handbook states that the medication should be administered over 2 hours. On hand is Levaquin 750 mg in 250 mL of 0.9 % NS. At what rate would the nurse set the infusion pump to administer the medication?
______125___ mL/hr
13. You are the LPN staffing the Advice line in the Pediatric Clinic. The mother of a nine-year-
old calls to ask how much Tylenol to give to the child for fever. Your written protocol states
that the appropriate dose is: Tylenol 15 mg per kg of body weight by mouth now for pain.
The patient weighs 143 pounds. On hand is Tylenol 160 mg per 5 mL. How many
teaspoonsful of Tylenol will the nurse tell the mother to give? (The mother has only spoons
with which to measure the medication.)
________6.1___ teaspoonsful
14. The order reads: Sliding Scale Humalog Insulin four times a day using the following
formula:
BG- 120 = # of Units of Humalog Insulin per dose
20
If the patient's blood glucose is 340 at 5:00 pm and dinner is served at 5:05 pm, how many
units of Humalog Insulin will the nurse administer to the patient?
______11______ units
Answer: 340 - 120 ÷ 20 = 11 units
15. The order reads: 0.9% NS 1000 mL IV over 8 hours. At what rate will the nurse set the
The doctor orders dosage 9,500 units of insulin and you have on hand 5000 units/ml? The answer that i'm getting is 1.9ml would you leave it at that or change it to 2. I thought you werent supposed to round insulin?
For intake and output if you have a question that asking you to calculate intake. lets say it's asking you a pt has 4 oz of apple juice, 2 oz of water, 6 oz of chicken broth, and 4 oz of steak. The pt also has had 1liter of D5w? You add all liquid that can melt at room temperature, so exclude the steak. But what about the I.V. fluid would you add that in with the other fluids?
The doctor orders dosage 9,500 units of insulin and you have on hand 5000 units/ml? The answer that i'm getting is 1.9ml would you leave it at that or change it to 2. I thought you werent supposed to round insulin?
For intake and output if you have a question that asking you to calculate intake. lets say it's asking you a pt has 4 oz of apple juice, 2 oz of water, 6 oz of chicken broth, and 4 oz of steak. The pt also has had 1liter of D5w? You add all liquid that can melt at room temperature, so exclude the steak. But what about the I.V. fluid would you add that in with the other fluids?
I believe for the insulin you would give 1.9ml....I also don't think you're suppose to round. Yes you add whatever goes in during an IV.
i feel so stupid and hopeless. please please help me with this your advice and knowledge and tutoring/explanations tips will directly be impacting the rest of my life. 
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female12233
41 Posts
I have a system that has helped me throughout nursing school and on the job as needed. I'm not sure if it's what your looking for but either way I hope you pass your next three tests!! Everything in the same row is equal like 1000g = 1kg = 2.2lbs ... You'll see
1000mg 1g 15gr mg=milligrams g=grams gr=grains ml= mililiter
500mg 0.5g 71/2 gr lb=pound dr=dram gtt=drops L=liter pt=pint
250mg 0.25g 33/4 gr Qt=quart oz=ounze tbsp= tablespoon
100mg 0.1mg 11/2 gr tsp=teaspoon
60mg - 1gr
1kg 1000g 2.2lb
1000ml 1L 1Qt
500ml 1pt 16oz
250ml 1glass 8oz
30ml 8drs 2tbsp
15ml 4drs 1tbsp
5ml 1dr 1tsp
1gtt 1mx -
1ml 15-16gtt 15-16mx
2.5cm 1in -
those are the tables i memorized so that i could convert equations
then i memorized the following
V multipled by D but when you say it, it just flows out V over T times D
T thats how i calculate IV drop factors
The V is for the total amt of volume to be infused in militers
the T is for the total time in minutes
and the D is for the gtt they give you in the question then you just do some math and you get the gtt/min
As far like oral dosages go...
i take what available and put it in the first () and take the ordered dose & put it in the second () As follows...
lets say the doc orders 2mg of something and you have 1mg/tablet available
(1mg : 1tablet)::(2mg:x) x is what your looking for then i just do some order of operations
1x = 2 inside x the inside so 1x2= 2
1 1 outside x outside so 1xX= 1x
then you have to ge the variable (x) by itself so you divide the number with x by it's side to free the variable so then your answer would be x=2tablets
if this didn't help I'm sorry but there is an excellent website that explains it and has practice questions with answers available to and it's free it's called
www.dosagehelp.com