CALCULATE FLOW RATES IN DROPS PER MINUTE:
Order: Zosyn 1.3 g in 100 mL D5W IVPB q8h to infuse over 30 min. Drop factor: 60 gtt/mL
Determine rate in gtt/min.
A.
150 gtt/min
B.
100 gtt/min
C.
200 gtt/min
D.
400 gtt/min
The Correct answer and Explanation is:
To calculate the flow rate in drops per minute (gtt/min) for an intravenous (IV) infusion, we need to use the following formula:
Flow rate (gtt/min)=(Total volume (mL)Total time (min))×Drop factor (gtt/mL)\text{Flow rate (gtt/min)} = \left(\frac{\text{Total volume (mL)}}{\text{Total time (min)}}\right) \times \text{Drop factor (gtt/mL)}Flow rate (gtt/min)=(Total time (min)Total volume (mL))×Drop factor (gtt/mL)
Here’s how we can determine the correct flow rate:
- Determine the total volume of the IV infusion:
- The order is for 100 mL of D5W (5% dextrose in water).
- Determine the total infusion time:
- The infusion time is 30 minutes.
- Identify the drop factor:
- The drop factor given is 60 gtt/mL.
Now, apply these values to the formula:Flow rate (gtt/min)=(Total volume (100 mL)Total time (30 min))×Drop factor (60 gtt/mL)\text{Flow rate (gtt/min)} = \left(\frac{\text{Total volume (100 mL)}}{\text{Total time (30 min)}}\right) \times \text{Drop factor (60 gtt/mL)}Flow rate (gtt/min)=(Total time (30 min)Total volume (100 mL))×Drop factor (60 gtt/mL)
First, calculate the volume per minute:100 mL30 min=3.33 mL/min\frac{100 \text{ mL}}{30 \text{ min}} = 3.33 \text{ mL/min}30 min100 mL=3.33 mL/min
Next, multiply this by the drop factor:3.33 mL/min×60 gtt/mL=200 gtt/min3.33 \text{ mL/min} \times 60 \text{ gtt/mL} = 200 \text{ gtt/min}3.33 mL/min×60 gtt/mL=200 gtt/min
Thus, the correct flow rate is 200 drops per minute (gtt/min).
Explanation
- Volume to Infuse: We start by noting the total volume of fluid to be infused, which is 100 mL in this case. This is the amount of medication (Zosyn) to be delivered through the IV.
- Infusion Time: The prescribed infusion time is 30 minutes. This is the duration over which the 100 mL of fluid will be delivered.
- Drop Factor: The drop factor provided is 60 gtt/mL. This factor determines how many drops are delivered per milliliter of fluid. It helps in converting the infusion rate from milliliters per minute to drops per minute.
- Calculation: By dividing the total volume by the total time, we get the flow rate in milliliters per minute. Multiplying this rate by the drop factor converts it to drops per minute.
Thus, using the formula correctly, the flow rate for this infusion is determined to be 200 gtt/min, which matches option C.