Evolve HESI Practice Exam

How should the nurse calculate the flow rate for an IV infusion of 1,000 ml of Ringer's lactate over 4 hours using a 20 gtt/ml set?

1. 100 gtt/min

2. 83 gtt/min

3. 125 gtt/min

4. 60 gtt/min

The correct answer is: 83 gtt/min

To determine the correct flow rate for the IV infusion, it's essential to follow the steps to calculate the drops per minute required for the infusion. First, we need to establish the total volume to be infused and the total time for the infusion. In this case, the nurse is administering 1,000 ml of Ringer's lactate over a period of 4 hours. Next, we convert the time from hours to minutes since the flow rate calculation is typically done per minute. There are 60 minutes in an hour, so 4 hours equals 240 minutes (4 hours x 60 minutes/hour = 240 minutes). Now, to find the flow rate in ml per minute, we divide the total volume by the total time: 1,000 ml ÷ 240 minutes = approximately 4.17 ml/min. Since the IV set has a drop factor of 20 gtt/ml, we must convert the flow rate from ml/min to gtt/min. This is done by multiplying the flow rate in ml/min by the drop factor: 4.17 ml/min x 20 gtt/ml = 83.4 gtt/min. When rounding to the nearest whole number, this results in an approximate flow rate of 83 g