## Med Math: Drop Factors Question #15

### Question

Order for 500 mL D5W to infuse over the next 12 hours. Microdrip tubing will be used. What is the drop per minute rate?

1. 38 gtt/min
• Rationale:
2. 42 gtt/min
• Rationale:
3. 22 gtt/min
• Rationale:
4. 52 gtt/min
• Rationale:

### Explanation

D5W is ordered at 500 ml. You would need to know how much volume per hour you needed in order to solve. The volume is 500 ml over 12 hour. It should be noted that the hour is not converted to minutes in this type of problem. The second step of the problem involves the drop factor. The Drop factor is also noted to be the gtt factor and is 60 gtt if not stated within the problem. There is a simple formula below for calculating the gtt/min. The final answer should have gtt/min within and rounded to the nearest whole number.

Total ML

—– = ____ml/hr

Hr

Answer multiplied by 60 gtt divided by 60 min = ___gtt/min
See the formula in action belowâ€¦.

500 ml

——— x = __42____ml/hr

12 hours

42 ml/hr x 60 gtt / 60 min = _41.6__round to the whole number = 42 gtt/min

500 ml/12 hrs = 42 mL/hr (rate per hour) THEN 42 mL/hr x 60 gtt factor / 60 min = 42 gtts/min

OR 500 mL/720 min x 60 gtt factor/1 = 360000/720 = 41.6 or 42 gtt/min