CONSIDER THIS SCENARIO: A nurse working in a rural long-term care facility needs to complete a time tape for a patient needing basic rehydration. A 1,000 mL I.V. bag of 0.9% sodium chloride is to infuse by gravity drip with a tubing drip factor of 15 gtt/mL. The provider wants this fluid to infuse over the next 8 hours. How will the nurse complete the needed calculations and time taping? (Remember to round to nearest whole milliliter, drop, and minute.)
The start time is 2310. The I.V. infusion bag information includes the patient's name, the nurse's initials, the infusion rate in mL/hr and gtt/min, the start time, the date, infusion time, and completion time. The measurement of mL/hr is calculated as the total amount of fluid divided by the total number of hours, per provider order. This calculation reads:
mL/hr = 1,000 mL ÷ 8 hr = 125 mL/hr
The number of drops per minute is calculated using the tubing drip factor (number of drops per milliliter), the number of milliliters per hour, and a conversion factor of 60 minutes per hour. Using dimensional analysis, the gtt/min calculation (rounded to the nearest whole drop) would look like this:
gtt/min = 15 gtt/1 mL X 1,000 mL/8 hr X 1 hr/ 60 min = 15,000/480 = 31.25 or 31 gtt/min
The completion time can be calculated using military time and adding 8 hours to the start time. Make a quick graph to do this. When calculating, it is important to understand that simple metric math cannot be applied here because there are 60 minutes in an hour and 24 hours in a day. Therefore, hours and minutes need to be clearly separated. Then, add 8 hours to the current time of 2310, with two numbers for each hour notation and two numbers for each minute notation. The result would be 3110 hours. Because there are only 24 hours in a day, subtract 24 from 31 in the hours column to move the time into the next day. Hence, the completion time for this task is estimated to be 0710 hours the next day.
Before time taping the inverted I.V. infusion bag, handwrite hourly numbers on lined paper. After placing the time tape onto the bag, the time tape is documented by placing a mark (transferred from the paper calculations) at the estimated remaining fluid level and writing the corresponding time. Start and completion times are circled. (See How to calculate remaining I.V. fluid.)
For this scenario, the amount of fluid remaining is identified by subtracting 125 mL (the calculated hourly rate) from each preceding level. For example, after one hour, at the time of 0010, 125 mL will have infused with 875 mL remaining in the bag (1,000 – 125 = 875). Calculating fluid remaining can also be done by calculating the amount of fluid, in milliliters, infused at each hourly point and subtracting that number from the total amount of fluid at the start of the infusion. For example, if 375 mL have been infused from a 1,000 mL bag after 3 hours (3 × 125), subtract 375 from 1,000 for an answer of 625 mL of remaining fluid.