FLUID THERAPY
IVF COMPUTATION
TERMS & TERMINOLOGY
FLOW RATE:
• is the volume per unit time usually expressed
as ml/hr. can be ml/min or ml/sec
DRIP RATE:
• is the number of drops per unit time usually
expressed as drops/min(gtts/min)
DOSE:
• amount of drug per unit time given to the
patient expressed as mg/min, g/hr or IU/min
TERMS & TERMINOLOGY
DROP FACTOR:
• is the number of drops per unit volume.
Expressed as drops/ml
NUMERATOR:
• the top portion of the fraction
DENOMINATOR:
• the bottom portion of the fraction
UNIT:
• a dimension that is given to a number
• Microdrip tubing is
narrower and so produces
smaller drops. It is used for
children and infants, or to
infuse sensitive medications
where precision in the flow
rate is essential.
• Microdrip tubing
(sometimes called minidrip)
comes in only one size: 60
gtt/mL.
ROUNDING
• not all calculations used to compute IV fluid
administration rates divide out evenly; it is
necessary to have a uniform way to round the
answers to whole numbers.
• Examples:
167.57 = 167.6 = 168
32.15 = 32.2 = 32
Calculation of Drip Rates (gtt/min)
• The nurse must calculate drops per minute
whenever a drug infusion is given with the use
of a secondary administration set.
• Formula:
Total volume (ml) to infuse x drop factor
_____________________________________
= gtt/min
Time (min)
❖Remember that the answer, drops, cannot be given as a fraction ;
the answer must be rounded to a whole number.
Example:
• 1,500 mL IV saline is ordered over 12 hours.
Using a drop factor of 15 drops/mL, how many
drops per minute need to be delivered?
1,500 (mL) x 15 (gtt /mL)
________________________
12 x 60
= 22,500
___________
= 720
= 31 or 31-32 gtts/min
= 31.25
Exercises:
• Calculate the rate of drip in gtts/min:
1. Infuse 1 L of D5LRS to run for 24 hours.
2. Infuse 500 ml of 0.3NaCl for 8 hours using
microset. (60 gtt/factor)
3. Infuse 100 ml of PLR for a duration of 60
minutes.
Calculation of Flow Rates (mL/hr)
• Milliliters per Hour (ml/hr)
• Divide the total volume in ml of fluid ordered
for infusion by the total number of hours the
infusion to run.
• Formula:
Number of ml
_____________________
Number of hours
= mL/hr
Calculation of Flow Rates (mL/hr)
Example:
• Infuse 1000 ml Lactated Ringer’s (LR) solution
over 10 hours.
# of ml =
______________
# of hours =
1000 ml
____________
10 hr
= 100 ml/hr
Exercises:
• Calculate the rate of flow in mL/h:
1. Infuse 1L of 5% dextrose in water for 12
hours.
2. Infuse 1000 ml of lactated Ringer’s to run for
6 hours.
3. Hook 500 ml of 0.9% sodium chloride for 4
hours.
Calculating rates of Infusion rather
than 1 hour
• The nurse must be able to convert infusion
rates given in minutes to milliliters per hour
because volumetric pumps are calibrated in
milliliters.
Formula:
Total volume (mL) to infuse x 60 min/hr
_____________________________________
Time
= mL/hr
Example:
• Infuse 50 ml of 0.9% NaCl with ampicillin
1 g for 20 minutes.
50 ml x 60 min/hr
3000 min/hr
____________
_____________________ =
20 min
20 min
= 150 mL/hr
Exercises:
• Calculate the following problems:
1. Infuse 150 mL D5W with gentamicin 80 mg to
run for 30 minutes.
2. Infuse 50 ml 0.9% NaCl with Oxacillin to run
for 15 minutes
Determining Infusion Duration
• If the order states 1L q8h, it is obvious that the
infusion will require replacement in 8 hours.
If the order states mL/hr such as 120 mL/hr, and a liter
(1000 ml) will be supplied:
1. Determine the hours of duration first
(total mL ÷ mL per hr)
2. Convert any remainder of hours to minutes using
conversion formula:
60 minutes = 1 hour (60xhr = minutes)
❑
Solution:
Hr =
1 hr
________
x 1000 mL
= 8.3 hr
120 ml
Minutes = 60 minutes x 0.3 hr
____________
= 18 min
1 hr
Total expected duration of 1000 mL flowing at
120/hr = 8 hr and 18 min
Exercise:
• Infuse 500 mL of D5LR at 40 mL/hr.
• What is the infusion time? (hours and minutes
if applicable)
Solution:
1 hr x 500 mL
______
40 mL
60
minutes
_________
x 0.5
= 12.5 hr
= 30
1 hr
Total expected duration of 500 mL flowing at 40/hr =
12 hr and 30 min