Calculation of IV Fluids- Flow Rate (with or without electronic pump), Drop Factor, Examples of calculation

1. DRUG DILUTION
AND FREQUENCY
CHANGES
BY
DR. RACHANA SHETTY (PharmD)
DR. BEEGUM SHEENA KARIM (PharmD)
DR. ANAM SOHAIL (PharmD)

2. IV Components
Abbreviation Solution Component
D Dextrose
W Water
S Saline
NS Normal Saline (0.9% NaCl)
NaCl Sodium Chloride
RL Ringer’s Lactate
LR Lactated Ringer’s
2

3. Normal Serum Osmolarity
Hypotonic
◦Used to dilute excess serum electrolytes
◦ e.g.: 0.45% Saline
Isotonic
◦Used to expand volume and maintain normal tonicity
◦ e.g.: 0.9% Saline, Lactated Ringer’s, 5% Dextrose
Hypertonic
◦Used to correct electrolyte imbalances
◦ e.g.: 10% Dextrose and 3% Saline; 5% Dextrose and Lactated Ringer’s
3

4. IV Solution Label
4

5. Standard Straight Gravity Flow
IV
5

6. IV with Piggyback (IV PB)
6

7. 7

8. Terms & ConceptsTerms & Concepts
What is the IV flow rate?
The speed at which intravenous fluid
infuses into the body
What is the drop factor?
The number of drops (abbreviated
“gtt”) required to deliver 1mL of fluid
What determines gtt/mL?
The size of the IV
administration set (tubing)
What are the tubing sizes?
10, 15, or 20 gtt/mL (Macrodrip
tubing)
60 gtt/mL (Microdrip tubing)
How do you calculate the IV flow rate?
Using the IV flow rate formula

9. IV Flow Rate FormulaIV Flow Rate Formula
IV Flow Rate Formula is used when calculating an infusion by gravity
(without an IV pump).
Volume to be Infused (in mL) x Drop Factor = Flow Rate
Total Infusion Time (in minutes) (in gtt/min)
Electronic Flow Rate Formula is used when calculating an infusion by
IV pump (electronic infusion device, or EID).
Volume to be Infused (in mL) = Flow Rate
Total Infusion Time (in hours) (in mL/h)
*Round all rates to the nearest whole number

10. IV Flow Rate: mL per hour
Regulate an IV volume by electronic infusion pump or controller calibrated in
mL per hour
10
Total mL
Total hours
=
X mL
1 hour
= mL per hour
(rounded to a whole number)

11. Calculation of IV Flow Rate:
mL per hour
Order reads: D5W 250 mL IV over the next 2 hours by infusion pump
11

12. Calculation of IV Flow Rate:
mL per hour
•Step 1 - Think
–Pump is set by the rate of mL per hour.
–So, if 250 mL is to be infused in two hours, how
much will be infused in one hour?
•125 mL will be infused in one hour
•You would set the pump at 125 mL per hour
12

13. IV Flow Rate: mL per hour
•Step2 - Use ratio-proportion formula:
13
Total mL
Total h
=
X mL
1 h
= mL/h
250 mL
2 h
=
X mL
1 h
X = 125 mL
Therefore, set pump at 125 mL per hour (125 mL per
hour)

14. IV Flow Rate in mL per hour:
Infusion Rate is less than 1 hour
Total mL ordered
Total min ordered
=
X mL/h
60 min/h
X = mL/h
14
(rounded to a whole number)

15. Calculation of mL per hour:
Infusion Rate is less than 1 hour
Order:
◦ Ampicillin 500 mg IV in 50 mL D5½NS in 30 min by controller
15

16. Calculation of mL per hour:
Infusion Rate is less than 1 hour
Step 1 – Think
Controller is set by the rate of mL per hour
If 50 mL is to be infused in 30 minutes
 100 mL will be infused in 60 minutes
Because 100 mL is twice as much as 50 mL and 60 minutes is twice as much as 30
minutes
 Set rate of controller at 100 mL per hour to infuse 50 mL per 30 min
16

17. Calculation of mL per hour:
Infusion Rate is less than 1 hour
Step 2
17
Total mL ordered
Total min ordered
=
XmL/h
60 min/h
50 mL
30 min
=
XmL/h
60min/ h
30 X = 3000
X = 100 mL/h
Total volume ordered(ml) X 60 min = X ml/hr
Total time ordered (min) hr

18. IV Flow Rate: drops per
min
Formula for IV flow rate for manually regulated IVs ordered in mL per
hour or for minutes
18
RC
T
V
=×
Volume (mL)
Time (min)
Calibration or drop factor (drops per mL)
gtt per min

19. IV Flow Rate: drops per
min
 Carry calculations to one decimal.
 Round drops per min to the nearest whole number.
 Watch - count only whole drops
19

20. Calculation of drops per
min
Physician orders:
◦ D5W IV at 125 mL per hour
STEP 1: Infusion set is calibrated for a drop factor of 10 drops per mL
Calculate IV flow rate in drops per min
Notice that the mL cancel out, leaving drops per min
20

21. Calculation of drops per
min
21
mL1
gtt10
min60
mL125
gtt/mL10
min60
mL125
×=×
gtt/min820.=
6
1
• Use your watch to count drops and adjust
roller clamp to deliver 21 drops per min
STEP 2:

22. Calculation of drops per min:
Microdrip Drop Factor
Order:
◦ D5W NS IV at 50 mL per h
Drop factor is 60 drops per mL
Notice order, 50 mL per hour, is the same as the flow rate of 50 drops per min
when drop factor is 60 drops per mL
22

23. Calculation of gtt per min:
Microdrip Drop Factor
23
mLpergtt
min60
mL
60
50
×
= 50 drops per min

24. IV Flow Rate Shortcut
Method
Shortcut to calculate IV flow rate is:
24
mL per hour
Drop factor constant
= gtt per min

25. Drop Factor Constants
Drop Factor Drop Factor Constant
10 drops per mL
15 drops per mL
20 drops per mL
60 drops per mL
25
6
10
60
=
4
15
60
=
3
20
60
=
1
60
60
=
MACRO
DRIP
MICRO
DRIP

26. Drop Factor Constants
Administer 125 mL per hour IV with 20 drops per mL infusion set
26
min3
gtt125
=gtt/mL20
min60
mL125
×
3
1
gtt/min42gtt/min641 == .

27. DO WE NEED TO
ADJUST THE FLOW
RATE???
YES, to correct off-schedule IV rates
Check for institutional policy regarding correcting the off-
schedule IV rates and the percentage of variation allowed.
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28. Adjusting IV Flow Rate
% variation will be
 Positive (+) if administration is slow and rate has to be increased
 Negative (−) if administration is too fast and rate has to be decreased
Variation should NOT exceed 25 percent!!!
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29. If adjustment is permitted
Step 1:
Step 2:
Step 3: variation%
minpergttOrdered
minpergttOrderedminpergttAdjusted
=
−
29
minpergttC
T
V
=×
hourpermLedRecalculat
hoursRemaining
volumeRemaining
=
Use following formula to recalculate the mL per hour and gtt per min for
the time remaining and the percentage of variation

30. Calculation of IV Flow Rate
Adjustment
Order: 500 mL LR to run over 10 hour at 50 mL per hour
o Drop factor is 60 drops per mL and IV is correctly infusing at 50 drops per min
o After 2½ hours, 300 mL is remaining
o Almost half of total volume infused in one-quarter the time
o IV infusion is ahead of schedule
o Compute a new rate of 300 mL to complete IV fluid order in remaining 7½ hours.
o Patient would require close assessment for fluid overload
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31. Calculation of IV Flow Rate
Adjustment
31
Remaining volume
Remaining hours
V
T
× C =
40 mL
60 min
× 60 gtt per mL
=
300 mL
7.5 h
= 40 mL per hour
1
1
= 40 gtt per min
Adjustedflow rate

32. Calculation of IV Flow Rate
Adjustment
Adjusted gtt per min − Ordered gtt per min
Ordered gtt per min
= % variation
32
%. 2020
50
10
50
5040
−=−=
−
=
−

33.  The physician orders 1000 mL of D5 0.45% NS at 100 mL per
hour over 10 hours. Drop factor is 10 gtt per mL
 What is the initial correct gtt/minute
 How many gtts/15 seconds…1 gtt every __ secs.
 After 5 hours only 300 mL has been infused. The IV is behind
schedule. Calculate the new flow rate. Is this new rate acceptable?
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34. IV Push Rate Calculation
desiredAmountX
desiredDosage
handonAmount
handonDose
=
34

35. IV Push Rate Calculation
35
• Caution:
– IV drugs are potent and rapid acting.
– Never infuse IV push drugs more rapidly than
recommended.
– Some drugs require further dilution after
reconstitution.
– Read package inserts and drug resources for
administration guidelines.

36. Calculation of IV Push
Incremental Rate
 Order: Ativan 3 mg IV Push 20 min preoperatively
 Supply: Ativan 4 mg per mL with drug literature guidelines of “IV infusion
not to exceed 2 mg/min”
 How much Ativan should you prepare?
◦Step 1. Convert
◦ No conversion is necessary
◦Step 2. Think
◦ You want to give less than 1 mL
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37. Calculation of IV Push Incremental
Rate
◦Step 3. Calculate amount to be infused
37
4 mg
1 mL
=
3 mg
X mL
4 X = 3
X = 0.75 mL

38. Calculation of IV Push
Incremental Rate
STEP 4. Calculate safe infusion time
38
3X2
minX
mg3
min1
mg2
=
=
2X
2
=
3
2
X =1
1
2
min

39. Calculation of IV Push
Incremental Rate
How much should you infuse every 15 seconds?
◦1 min = 60 seconds
◦1½ min = 60 + 30 = 90 seconds
39

40. Calculation of IV Push
Incremental Rate
40
0.75 mL
90 sec
=
X mL
15 sec
90X = 11.25
90X
90
=
11.25
90
• X = 0.125 mL = 0.13 mL of Ativan 4 mg per mL infused
IV push every 15 seconds will deliver 3 mg of Ativan

41. IV Infusion Time
To calculate IV infusion time
◦Total volume (ml) and flow rate (ml/hr) is known:
41
hoursTotal
hourperml
volumeTotal
=
Or, use ratio-proportion:
mL
h
=
Total mL
X total h

42. IV Infusion Time
To calculate IV infusion time
When Flow rate in drops per min, Drop factor and volume are known
“T” is the unknown
42
V
T
× C = R;

43. IV Fluid Volume
To calculate IV volume
◦ Flow rate (drops per min), drop factor, and time are known:
43
“V” is the unknown
V
T
× C = R;

44. REMEMBER!!!
 While preparing for any type of IV flow rate calculation,
be sure to determine what, if any, conversions need to take
place first.
 Once you have completed all necessary conversions,
decide which among the two IV flow rate formulas is to be
used (discussed in this tutorial).
 Remember, it is always best to be consistent with the
dosage calculation method you choose to use when
completing this type of problem.
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