The Quick and Dirty Guide to Medical Math Module II
In our last installment, we just started simple with changing grams to milligrams, micrograms and back! In today's medical math lesson, we're going to add weight and concentration in 3 easy steps! If you haven't looked at module 1 in awhile, go back and check it out first!
Pounds to Kilograms
Quizsummary
0 of 10 questions completed
Questions:
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
Information
Step 1: Pounds to Kilograms
We don’t do dosages in pounds! To change pounds to kilograms, simply divide the number of pounds by 2.2
There are plenty of apps out there that do this for you on the fly, but nothing is better than just having a dollar store pocket calculator in the back of the truck. Doing it like this will also give you the ability to do it without the calculator. So, you’ll be able to express how it works in words, reports, and when teaching others. It keeps the skill up! If you’re stuck to an app and someone asks you how to calculate dopamine, you’re just going to have to plug the app. Don’t do that. Practice practice practice!
So, lets start with the easiest. 110 lbs = ____kg.
We divide 110 by 2.2, which gives us 50.
110 lbs = 50kg
220lbs = 100kg
330lbs = 150kg
All we did was plug in the number of pounds, and divide it by 2.2
Practice converting pounds to kilograms!
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
0 of 10 questions answered correctly
Your time:
Time has elapsed
You have reached 0 of 0 points, (0)
Categories
 Not categorized 0%
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 Answered
 Review
milligrams per kilogram
Quizsummary
0 of 10 questions completed
Questions:
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
Information
Ok, now we’re going to do the very basics of weightbased drugs.
When there’s a ‘mg/kg’ it is read as ‘milligrams per kilogram’ which means ‘FOR EVERY KILOGRAM that the patient weighs, you’re going to give X amount of milligrams.’ If the patient weighed 10kg, and the order was for 1mg/kg, the total desired dose would be 10 mg. Get it?
Your order is to give Succinylcholine at 1mg/kg. Your patient weighs 220 pounds.
First, change your weight to kg: 220/2.2 = 100. So your patients weight is 100kg, and your order is for 1 mg for every kg.
1 mcg x 100 = 100 mg.
So, your desired dose for this patient is 100mg.
Its not always milligrams. It can be grams, micrograms, milliequivalents or any other measurement, but it works the same way.
Sodium bicarbonate standard dose is 1 meq/kg (1 milliequivalent per kilogram)
You’re still going to multiply the dose times the number of kilograms and bring down the measurement…
So for the same 220 lb patient, you’re going to change the pounds to kg. So, 220 / 2.2 = 100. 100 kilograms.
Then, 1 meq * 100 = 100 meq.
So now you know that pushing ‘1 amp’ of Bicarb in a 220 lb patient who needs it is only HALF of the dose he needs! AND YET THIS IS FREQUENTLY all they will ever get, because his paramedic didn’t know what you now know!
This stuff is important! Practice until you’re a bad ass…
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
0 of 10 questions answered correctly
Your time:
Time has elapsed
You have reached 0 of 0 points, (0)
Categories
 Not categorized 0%
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 Answered
 Review
How Much to Deliver
Quizsummary
0 of 10 questions completed
Questions:
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
Information
In this next exercise, we’re going to draw up some medications and give you some practical situations to practice on!
SOLVE THE CONCENTRATION, THEN DIVIDE THE DESIRED DOSE BY THE CONCENTRATION. MAKE SURE YOUR grams, milligrams or micrograms are the same!
Just go slow, repeat these exercises as often as you need, and continue until you really have this down! It isnt something you learn once and you’re done…Its something you will want to review on occasion to maintain proficiency.
Example:
Your medical control orders you to give 25mg of Diphenhydramine to your patient having a mild allergic reaction. It comes packaged as 50mg/1ml in a vial. How many mls do you draw up?
In this example, the concentration is 50mg/ml. So, we don’t have to convert it. You just divide the desired dose by the amount on hand. In this case, you’re dividing 25 by 50. The answer is 0.5, so you would draw up 0.5ml in order to administer the desired dose of 25mg.
Example 2: You’re ordered to give 8mg of a drug. The vial states that there is 10mg/5ml. So, the vial contains 5ml of fluid, and that 5ml altogether contains 10mg of the drug.
First, you have to find out how much of the drug there is PER ML.
You divide the number of mg by the number of ml to find out how many mg there is in 1 ml.
So… 10/5 = 2.
Therefore, you can simplify the concentration to 2mg/ml. That means for every milliliter of fluid, there are 2mg of the drug.
Then, you divide your desired dose by the amount on hand. So… 8mg divided by 2mg/ml. Your mg on both sides cancel and you end up with 4ml.
Got it? Lets try!
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
0 of 10 questions answered correctly
Your time:
Time has elapsed
You have reached 0 of 0 points, (0)
Categories
 Not categorized 0%
 1
 2
 3
 4
 5
 6
 7
 8
 9
 10
 Answered
 Review

Question 1 of 10
1. Question
Your medical control orders you to give 25mg of Diphenhydramine to your patient having a mild allergic reaction. It comes packaged as 50mg/1ml in a vial. How many mls do you draw up?
Correct
Incorrect
Desired dose 25mg
Concentration 50mg/1ml
25mg divided by 50mg/ml = 0.5 ml 
Question 2 of 10
2. Question
Your first dose for a full arrest of Lidocaine calls for 1.5mg/kg. Your patient weights 176 Lbs. Lidocaine comes packaged as 100mg/5ml. How many mls are you giving your patient?
Correct
Incorrect
First, find your desired dose: Desired dose is 1.5mg/kg and your patient weighs 176lbs. Change 176lbs to 80kg, then multiply 80 x 1.5 = 120mg.
So, 120mg is your desired dose.Then, find your concentration per ml.
So, 100mg/5ml = 20mg/mlThen divide your desired dose by the concentration.
120mg divided by 20mg/ml = 6mlHint
First, find your desired dose: Desired dose is 1.5mg/kg and your patient weighs 176lbs. Change 176lbs to 80kg, then multiply 80 x 1.5 = 120mg.
So, 120mg is your desired dose.Then, find your concentration per ml.
So, 100mg/5ml = 20mg/mlThen divide your desired dose by the concentration.

Question 3 of 10
3. Question
Your patient is requiring morphine sulfate. Medical control wants you to 5 mg IV. Morphine sulfate comes in a vial 8 mg/2ml. How many mls do you draw up?
Correct
Incorrect
First, find the concentration in 1ml:
8mg/2ml = 4mg/ml
Then, divide your desired dose by the concentration.
5mg divided by 4mg/ml = 1.25mlSo, you draw up 1.25ml to administer 5mg.
Hint
First, find the concentration in 1ml:
Then, divide your desired dose by the concentration. 
Question 4 of 10
4. Question
You need to give 4 mg of Diazepam to your seizing patient. It is packed in as 5 mg/ml. How many mls will you be giving?
Correct
Incorrect
Your desired dose is 4mg.
The concentration is already calculated per milliliter, so you just divide your desired dose by the concentration:4mg divided by 5mg/ml = 0.8ml

Question 5 of 10
5. Question
You are ordered to give 100mg of succinylcholine prior to RSI. The drug comes in a vial that has 200mg/10ml. How many ml do you draw up?
Correct
Incorrect
Your desired dose is 100mg.
Find the concentration per ml: 200mg/10ml = 20mg/ml
Then divide desired dose by concentration:
100mg divided by 20mg/ml = 5mlSo you draw up 5ml to administer 100mg.

Question 6 of 10
6. Question
You are ordered to administer 40mg of Lasix. The vial has 100mg/10ml. How many ml do you draw up to give the desired dose?
Correct
Incorrect
Your desired dose is 40mg
Find the concentration per ml : 100mg/10ml = 10mg per mlThen, divide the desired dose by the concentration: 40mg divided by 10mg/ml = 4ml

Question 7 of 10
7. Question
You are ordered to give 2mg/kg of a drug to your 132lb patient. The drug is supplied in a vial with 200mg/10ml. How many ml should you draw up to administer the desired dose?
Correct
Incorrect
First, find the desired dose. Convert pounds to kilograms and then multiply:
1. 132lbs /2.2 = 60kg
2. 2mg x 60kg = 120mg
Then, solve your concentration per milliliter:
3. 200mg/10ml = 20mg/ml
Finally, divide your desired dose by the concentration:
4. 120/20 
Question 8 of 10
8. Question
You are ordered to give 0.25mg/kg of Cardizem to your 132lb patient. Cardizem comes in a vial that has 25mg/5ml. How many ml do you draw up to administer the desired dose?
Correct
Incorrect
First, find the desired dose… convert 132lbs to 60kg, and then multiply 0.25 by 60, to get 15mg as your desired dose.
Then solve the concentration per milliliter: 25mg/5ml = 5mg/ml
Finally, divide the desired dose by the concentration: 15mg divided by 5mg/ml = 3ml

Question 9 of 10
9. Question
You are ordered to give 200mcg of a drug. The drug comes in a vial with 1mg/1ml. How many ml should you draw up to administer the desired dose?
Correct
Incorrect
You already have your desired dose: 200mcg.
You already have your concentration: 1mg/ml.
Looks easy right? YES! But dont forget to change your mg to micrograms FIRST!
So, your concentration is actually 1000mcg/ml.
Divide 200mcg by 1000mg/ml to get 0.2ml 
Question 10 of 10
10. Question
You are ordered to give 250mg of a drug. Your vial has 1g/10ml. How many ml do you draw up to administer the correct dose?
Correct
Incorrect
Desired dose: 250mg
Concentration: Change your grams to milligrams, then solve per ml : 1000mg/10ml = 100mg/mlDivide desired dose by concentration:
250mg divided by 100mg/ml = 2.5 ml
Leave A Comment
You must be logged in to post a comment.