# The Nursing Math Thread - page 12

A member pm'd me the following question highlighted below. We created this thread for you guys to talk about math, solve math problems, and post math websites that you have found helpful. I was... Read More

1. Quote from moncj66
Help!!
Order: Tetracycline Elixir qid for a child weighing 50 lb at a dosage of 8 mg/kg/day in equally divided doses.
How many mg would one does contain? Tetracycline is supplied at 50 mg per 7 mL. How many mL should be administered?

I did 5ml/50mg * 181.6mg/dose = 18.16ml/dose

The answer is Patient weight 22.7 kg
Daily dose 181.6 mg
Each dose 45.4 mg
Give 6.4 mL

From this site: http://www.msumedcalc.com/quiz6.html
These answers are correct. Are you looking for the way to get them?
8 mg/kg (dose desired) x 50 pounds/1 (weight of child) x 1 kg/2.2 pounds (conversion factor) x 7 mL/50 mg (dose on hand) x 1 day/4 doses = 6.36 mL/dose, rounded up to 6.4 mL/dose

mg per dose = 6.36 mL (dose desired)/7 mL (dose on hand) x 50 mg (amount in dose on hand) = 45.4 mg
2. Quote from moncj66
Order: Tylenol suspension 1/2 tsp po q4h prn for fever for a child weighing 32 lb.
The medication is supplied as 325 mg per 10 mL
The recommended dose is 25 - 35 mg/kg/day q4h prn
Is the ordered dose in the safe range?

Each dose ordered 81.25 mg
Daily possible dose 487.5 mg/day
Safe range 363.6 mg/d - 507.5 mg/d
Yes, the dose ordered is within the safe range

Im not getting the right answer..I can get the safe range, but Im not understanding the dose ordered? Can someone please show me how to do this? I already failed the exam once, I only have one more try on tuesday...
Ordered: 1/2 teaspoon of 325 mg/10 mL for a 32 pound child
Safe dose: 25-35 mg/kg/day q4h (q4h is 6 doses in a 24 hour day)
Determine Safe Dose Range:
25 mg/kg x kg/2.2 pounds x 32 pounds/1 x 1/6 doses = 60.6060 mg
35 mg/kg x kg/2.2 pounds x 32 pounds/1 x 1/6 doses = 84.8484 mg
Determine Dose Ordered:
0.5 teaspoon (dose desired)/10 mL (solution on hand) x 325 mg/1 (amount of drug in solution on hand) x 5 mL/1 teaspoon (conversion factor) = 81.25 mg (amount of drug in dose you will give)
Question: Is the ordered dose in the safe range? YES. The 81.25 mg falls between tha safe range of 60.6060 mg to 84.8484 mg.
3. yes, I was looking for how they got those answer because I got completely different answers..THANKS SO MUCH..I will practice some more ur a lifesaver!

Physician orders 300 ml NS over 1 hour. Tubing has gtts of 60. After the first hour, the physicial wants the rest of the solution to infuse at 125 ml per hour.

What is the flow rate in drops per minute during the first hour?

What is the flow rate in ml/hr during the first hour?

How much fluid had the patient recieved after 6 hours?
5. Quote from Evil Cactus

Physician orders 300 ml NS over 1 hour. Tubing has gtts of 60. After the first hour, the physicial wants the rest of the solution to infuse at 125 ml per hour.

What is the flow rate in drops per minute during the first hour?

What is the flow rate in ml/hr during the first hour?

How much fluid had the patient recieved after 6 hours?
I'm a little confused by this...is 300ml the total solution to be infused? If it is I wouldn't think there would be any left if the Dr wants it infused over 1 hour. Are we talking about a bag of NS which could be 1000ml?

If so it would be ; 60gtts/min and 330ml/hr
1000-300=700ml remaining after 1st hour
700ml to infuse at 125ml per hr x 5 hrs= 625ml given in next 5 hours.
625 + 300 (from first hour)= 925ml given in 6 hours
Sorry if this isn't what you meant... Daytonite? Any thoughts?
6. I need more help!
QUestion: calculate IV fluids 1 1/4 fluid maintenance for a child weighing 21 kgs?
7. Quote from evil cactus

physician orders 300 ml ns over 1 hour. tubing has gtts of 60. after the first hour, the physician wants the rest of the solution to infuse at 125 ml per hour.

what is the flow rate in drops per minute during the first hour?

what is the flow rate in ml/hr during the first hour?

physician orders 300 ml ns over 1 hour. tubing has gtts of 60. after the first hour, the physician wants the rest of the solution to infuse at 125 ml per hour.

what is the flow rate in drops per minute during the first hour?
300 ml/1 hour (amount to infuse) x 60 gtts/ml (drop factor of iv tubing to be used) x 1 hour/60 minutes (conversion factor of hours to minutes) = 300 gtts/minutes (flow rate in drops per minute during the first hour of the infusion)
what is the flow rate in ml/hr during the first hour?
this is information that is given to you in the problem: 300 ml/hour
(1 x 300 ml) fluid received first hour + (5 x 125 ml) fluid received in next 5 hours = 925 ml
8. Quote from moncj66
I need more help!
QUestion: calculate IV fluids 1 1/4 fluid maintenance for a child weighing 21 kgs?
What replacement formula are you supposed to use? The one I have for a 21 kg child is 1000 mL for the first 10 kg + 50mL/kg/24 hours for each kg over 10 kg. If 1 and 1/4 fluid maintenenace is ordered then that needs to be considered in the calculations.
9. I just wanted to say thanks daytonite, u helped me sooo much! I got a 100 on my retest thanks to u!! UR DEFINITELY A LIFESAVER and angel on this site..would love to meet u one day..hehe!!
10. Quote from moncj66
i just wanted to say thanks daytonite, u helped me sooo much! i got a 100 on my retest thanks to u!! ur definitely a lifesaver and angel on this site..would love to meet u one day..hehe!!
congratulations!!!:d:d
11. Bleh, I just found out that I failed my first medcalc exam! All rounding errors, stupid me. 2 more chances to fix it.

A Heparin solution with a strength of 20,000 U in 500 mL of D5W is ordered to infuse at a rate of 1000 U/hr IV with an administration set that delivers 60 drops/mL. Calculate the drip rate in drops/minute.

13. Quote from onlyfaith