Calculator not permitted?!


Aug 11, '06All I have to say is I'm terrible at math so I really feel for you. I hope my school allows calculators...

Aug 11, '06Geez....what did we do without the things? My dad made it through College using a slide rule. I know calculators make things easier, but we should be able to figure things out when we don't have the bloody thing handy.
Suebird 
Aug 11, '06I think that is really silly. You should be able to use them because it reduces error. We get to use them at our school.

Aug 11, '06Well I usually make littly tiny errors with division and whatnot without a calculator.
Now that I know I can't use one........
What type of math is involved in the dosage calculations that would possibly require the aide of a calculator?
I mean....is it pretty comprehensible to the point where a calculator isn't needed much anyway?
God I'm upset about this. 
Aug 11, '06I'm in block 3 of nursing school. We get to use calculators. Some of the students depend on them for really simple calculations such as this. Dosage ordered 500mg PO. Available are 250mg tablets. How many tabs do you give?
I find them helpful when converting weights from pounds to kilograms or on heparin drip calculations but I could do it with a pencil if I needed to. 
Aug 11, '06I did a lot of mine w/out a calculator just because I wanted to know I could do it. It is division and multiplication. If you take small parts of an equation instead of getting overwhelmed by the big picture, it's not so bad. Go back and review decimal places when converted things like L to mL, etc. You can do this without a calculator and then think how much easier it will all be when you can use a calculator later!

Aug 11, '06I have to preach about the Dimensional Analysis for meds book i am using right now to self teach dosage calculations. I was freaking out about how am i going to learn how to do that, and i heard that alot of schools(nursing)(including mine) do not really "TEACH" dosage calculations, they expect self study. So i took the initiative and decided to tech myself, i picked up the book by ANNA CURREN, Dimensional analysis for meds, and it has helped me so much i cant even begin to explain. Its teaches you how to do the dosages without a calculator, and with a calculator.
So if it is dosages in general that you are afraid of, or maybe your math skills need brushed up, get this book. I promise you wont be afraid to do dosages without a calculator anymore. I know i am not. 

Aug 11, '06Quote from FinallyyDon't student nurses have enough to worry about:: ....even docs and nurses use calculators where I work. I always check my calculations on calculator twice just to make sure of no errors.The school I'm going to doesn't allow its students to use calculators for dosage calculations. This scares me.
are dosage calculations possible, and comprehensible without calculators?
they are not all as easy as one thread's example but very doable w/calculator
some examples:
Order: Atropine 0.3 mg IM now
Label: Atropine 400 mcg/mL
How many mL would be administered?
Order: TheoDur 0.45 g
Label: TheoDur 300 mg
How many tablets should be given?
Order: Nitroglycerine gr. 1/150 SL for chest pain
Label reads: Nitroglycerine 0.4 mg tabs
How many tabs would you give?
Order reads: Morphine sulfate gr. 1/8
Label reads: Morphine sulfate 10 mg per mL.
How many mL will you give?
Order: 2000 mL Ringer's Lactate (RL) to run for 16 hours.
Drop factor 10 gtt/mL
Flow rate _____ gtt/min _____ mL/hr
more of this on: http://home.sc.rr.com/nurdosagecal/ 
Aug 11, '06Most calculations you don't need a calculator. In real life nursing we never have to deal with horendous calculations. In school.. probably. A nursing student on a BMW forum that I am a member of submitted this question on one of the posts. Which I eagerly answered for him but with the use of a calculator. Otherwise, I would have taken all day to answer this for him.
The question was:
"Mr. norm has been admitted to your unit with a diagnosis of pulmoary embolism. He must be started on a heparin drip. The physician has ordered him to receive an 80 unit/kg bolus. The heparin bolus will be given from a vial containg 10000 units/ml. He will receive 15 units/kg/hr heparin drip. The heparin drip is mixed in 25000 units/250 mls. He weighs 245lbs. What is the mls for the bolus and what will the pump be set on for the drip
#5 mr norm from prob #4 has a ptt result of 104.6. The doctors order reads to decrease the drip by 4 units/kg/hr for this ptt. The heparin drip is now indfusing at 14.2 ml/hr. What will the nurse set the pump on after making the decrease?__________
This was my reply to his query:
To answer the 1st paragraph, there are 2 questions: 1. How many mls (milliliters) is in the bolus infusion. 2. What is the drip rate for the infusion pump.
To answer #1 you need to first get the weight of the Mr. Norm in kilograms. so 245lbs = 111.36kg (1kg = 2.2lbs)
The doctor wants 80units/kg so you multiply 80units x 111.36kg = 8,908.8 units total. This is how much units the doctor wants for a bolus dose.
How many ml's is 8,908.8 units?
The given drug is prepared in stock form above as 10,000units / 1ml. So you just divide 8,908.8units from 10,000units/ml and it will give you .89ml.
#2. Again get weight of patient in Kg's. which is 111.36kg.
The doctor wants the drip to be given 15units/kg/hr. So multiply 111.36kg (Mr. Norms weight)x 15 units/hr = 1670.4units/hour.
How many ml/hr is this?? Stock preparation is 25000units/250ml. << this must be simplified which would equal 100units/1ml.
So divide: the MD want's 1670.4units/hour divide by what you have on hand which is 100units/1ml which would = 16.7ml/hour.
The last question:
The doctor wants to decrease the current drip rate (14.2ml/hour) by 4 units/kg/hour.
You already know the weight. Now you must determine first what the patient is already getting which is 14.2ml/hour. Now determine how many units is that? Based on above stock which is 25000units/250mls which in simplified form is 100units/1ml, multiply 14.2ml/hour x 100units/1ml = 1420units/hour
1420units/hour is what the guy is currently getting. The MD wants to decrease this by 4 units/kg. Now get the weight which we know by now is 111.36kg. Multiply this by 4units = 445.44units. So the MD wants to decrease 445.44 units from the 1420units/hour that he is already getting.
Your answer would be 974.56units/hour  this is what the doctor ordered. Now how much ml/hour would this drip factor translate to? Based on the prepared stock which was 25000units/250ml or 100units/1ml, simply divide 974.56units/hour by 100units/1ml which will give you 9.7ml/hour.
Now that wasn't hard now was it?Last edit by Pheebz777 on Aug 11, '06 
Aug 11, '06First a lot of nursing schools are making sure that you know what you are doing when you get out there on your own. What if you are on the floor and your batteries fail on your calculator. You're working night shift there is only one other nurse on the floor and she is at lunch. That med needs to be given/hung now not when she gets back after you borrow her calculator. So you need to have the knowledge of setting up the problem and being able to work it through. If you are that stressed out about it, substitute your answer back into the equation and see if it works. My LPN program you could not use calculators and you had to pass the math test 100% you were given 3 chances. And the last two were given when it was convenient for them, not in class. This weeded out a good 40% of our class. When I did the RN program, they would pass out calculators when they chose to let you use them. You had to pass the math test 100% for each clinical. If you did not pass you could not pass meds. If you could not pass meds, you failed clinical. If you failed clinical you failed the rotation.Last edit by LauraF, RN on Aug 12, '06

Aug 11, '06When I was in school, we couldn't use calculators for testing until 3rd semester, and only if you passed the dosage criticals. It was only to make sure we understood medical math concepts. In clinicals we would do both and of course it was always checked by instructor @ med checks. I feel comfortable with the math either way. (but of course, it made us all anxious on testing days when we had to show our work!)