math help

Double-Helix, BSN, RN · May 7, 2011

Please, help me with these two math problems. I know the answers ( I have the answer key), but I need to figure out how to do the math so I can do well on a math test. Any help is appreciated.
1) You have an order for 5,000units of heparin in 250ml MS to infuse at 500 units/hr. The drop factor is calibrated to infuse 60gtt/ml. What is the flow rate?
2)Your pt went to the GI lab at 1030 with 200ml of NS infusing at 25gtt/min. The pt's order states: discontinue IV fluids upon returning to floor. The pt returns to his room at 1130. How many mL of NS should be remainin? The drop factor is 15gtts/ml.

Here goes...

Problem 1.

1. Calculate the number of units in one ml of solution by dividing the total units by the total volume (5000units/250ml= X units per ml)

2. Calculate the number of mls given per hour by dividing the units/hour by the units/ml (X from step 1). Units cancel out, leaving you with ml/hr (500units per hour/ X units per ml= Y ml/hr)

3. Calculate the gtt/hr by multiplying the drop factor (gtt/ml) by the ml/hr (Y from step 2). Mls cancel out, leaving gtt/hr) (60gtt/ml times Y= Zgtt/hr)

4. Calculate the flow rate, gtt/min, by dividing the gtt/hr (Z from step 3) by 60minutes/hr. Hours cancel out, leaving gtt/min. (Z gtt per hour / 60 minutes per hour = final answer gtt/min

Problem 2.

1. Calculate the gtt that have infused during the time the patient was gone (1 hour or 60 minutes). Find this by multiplying the gtt/min by 60 mins. (25gtt/min times 60 minutes = Xgtt.

2. Calculate the mls that have infused by dividing the gtts infused (X from step 1) by the drop factor. (Xgtts / 15 gtt/ml = Y mls infused)

3. Calculate the volume remaining in the bag by subtracting the mls infused (Y from step 2) by the initial volume in the bag when the patient left. (200ml-Yml = remaining ml, final answer)

I hope this helps! Private message me or respond if you want me to check your work. Always write out the units when doing calculations- it really helps make sense of the question. Also, check to make sure your answer makes sense. For example, is a flow rate of 2000gtt/min realistic? Does is make sense that the patient would receive 500 ml of fluid in one hour, when they started out with 200? If you are having problems with the calculations, ask your instructor for help, since he/she knows exactly what formula you are supposed to use.