## Med Math: Drop Factors Question #18

### Question

Order is for 2 L of D10W to infuse over 16 hours and infusion administration set delivers 100 gtt/mL. What is the flow rate gtt/min?
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1. 21 gtt/min
• Rationale:
2. 42 gtt/min
• Rationale:
3. 50 gtt/min
• Rationale:
4. 100 gtt/min
• Rationale:

### Explanation

D10W is to be infused for 2 bags or aka 2 Liters of IV fluid. You would need to know how much volume you need per ml/hr in order to solve. The volume is set at 100 gtt/ml. It should be noted that it is not necessary to calculate the total volume in this problem as it is already stated at 2L or 2000 ml. The 2000 ml to be infused is divided by 16 hours. Then the ml per hour is multiplied by the drop factor and divided by 60 mins. The drop factor has either 60, 15 or 10 available in IV tubing administration kits for IV’s. Since 100 gtt/ml divides into 1 liter over 10 times, the drop factor would be 10.There is a simple formula below for calculating the drop factor. The final answer should have gtt/min within.

Total ML

—– = ____ml/hr

Hr

Ml/hr

—– x gtt ( aka drop factor) = ___gtt/min

60 min

2000 mL/16hr = 125 mL/hr then 125 mL/hr x 10 gtt factor / 60 min =

1250/60 min = 20.8 or 21 gtt/min

OR 2000 mL/960 min (16 hr x 60) x 10 gtt factor/1 = 20000/960 = 20.8 = 21 gtt/min