Download Nur201AdvancedAdultIntravenousCalulations

Advanced Adult Intravenous
Calculations
IV Flow Rate: mL/h
• To regulate an IV volume by electronic
infusion pump or controller calibrated in
mL/h, calculate:
Total mL ordered
 mL/h (rounded to a whole number)
Total h ordered
Calculation of IV Flow Rate:
mL/h (continues)
• Order reads: D5W 250 mL IV over the
next 2 h by infusion pump
– Step 1
• Think. The 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.
Calculation of IV Flow Rate:
mL/h (continued)
– Step 2
• Use the formula:
Total mL ordered
 mL/h
Total h ordered
250 mL 125 mL

2h
1h
Therefore, set the pump at 125 mL per hour
(125 mL/h).
Calculation of IV Flow Rate:
mL/h (continued)
– Step 2
• Use the formula:
Total mL ordered
 mL/h
Total h ordered
250 mL 125 mL

2h
1h
Therefore, set the pump at 125 mL per hour
(125 mL/h).
Calculation of IV Flow Rate:
mL/h (continued)
– Step 2
• Use the formula:
Total mL ordered
 mL/h
Total h ordered
250 mL 125 mL

2h
1h
Therefore, set the pump at 125 mL per hour
(125 mL/h).
Calculation of mL/h:
Infusion Rate is < 1 h (continued)
– Step 2
Total mL ordered
 60 min/h  mL/h
Total min ordered
2
50 mL 60 min

 100 mL/h
30 min
1h
1
IV Flow Rate: gtt/min
• The formula method to calculate IV flow
rate for manually regulated IVs ordered in
mL/h or for a prescribed number of
minutes is:
Calibration or drop factor (gtt/mL)
Volume (mL)
Time (min)
V
CR
T
gtt/min
IV Flow Rate: gtt/min
• Carry calculations to one decimal. Round
gtt/min to the nearest whole number,
because you can watch-count only whole
drops.
Calculation of gtt/min
• The physician orders D5W IV @ 125
mL/h. The infusion set is calibrated for a
drop factor of 10 gtt/mL. Calculate the IV
flow rate in gtt/min. Notice that the mL
cancel out, leaving gtt/min. 1
125 mL
125 mL 10 gtt
 20.8 gtt/min
 10 gtt/mL 

60 min
60 min 1mL
6
Use your watch to count the drops and adjust the roller
clamp to deliver 21 gtt/min.
Calculation of gtt/min: Microdrip
Drop Factor
• When the IV drop factor is 60 gtt/mL
(microdrip sets), then the flow rate in
gtt/min is the same as the volume ordered
in mL/h.
Calculation of gtt/min: Microdrip
Drop Factor
• Order: D5W NS IV @ 50 mL/h. The drop
factor is 60 gtt/mL. Notice that the order,
50 mL/h, is the same as the flow rate of 50
gtt/min when the drop factor is 60 gtt/mL.
50 mL
 60 gtt/mL  50 gtt/min
60 min
Drop Factor Constants
Drop Factor
10 gtt/mL
15 gtt/mL
20 gtt/mL
60 gtt/mL
Drop Factor Constant
60
6
10
60
4
15
60
3
20
60
1
60
Adjusting IV Flow Rate (continued)
• Step 1
Remaining volume
 Recalculated mL/h
Remaining hours
• Step 2
V
 C  gtt/min
T
• Step 3
Adjusted gtt/min  Ordered gtt/min
 % variation
Ordered gtt/min
• The % variation will be positive (+) if the
administration is slow and the rate has to be
increased, and negative () if the administration
is too fast and the rate has to be decreased.
Calculation of IV Flow Rate
Adjustment (continued)
Remaining volume 300 mL

 40 mL/h
7.5 h
Remaining hours
V
40 mL 1
C
 60 gtt/mL 40 gtt/min
T
60 min
1
Adjusted gtt/min  Ordered gtt/min
 % variation
Ordered gtt/min
40  50  10

 0.2  20%
50
50
IV Push Rate Calculation
Dosage Desired
Quantity of Time Recommended
D
Q  X
H
IV Push Rate Time
Supply Dosage Recommended
Calculation of IV Push Incremental
Rate (continues)
• Order: Ativan 3 mg IV Push 20 min
preoperatively
• Supply: Ativan 4 mg/mL with drug
literature guidelines of “IV infusion not to
exceed 2 mg/min.”
Calculation of IV Push Incremental
Rate (continues)
• Order: Ativan 3 mg IV Push 20 min
preoperatively
• Supply: Ativan 4 mg/mL with drug
literature guidelines of “IV infusion not to
exceed 2 mg/min.”
Calculation of IV Push Incremental
Rate (continued)
• What is a safe infusion time?
– Use Formula
D
3 mg
3
1
Q 
1 min  min  1 min
H
2 mg
2
2
• Or, ratio-proportion
2 mg
3 mg

1 min
X min
2X  3
2X 3

2
2
1
X  1 min
2
Calculation of IV Push Incremental
Rate (continued)
• How much should you infuse every 15
seconds?
– 1 min = 60 sec; 1½ min = 1½ × 60 = 90 sec
0.75 mL
X mL

90 sec
15 sec
90 X  11.25
90X 11.25

90
90
• X = 0.125 mL = 0.13 mL of Ativan 4 mg/mL
infused IV push every 15 seconds will deliver 3
mg of Ativan.
IV Fluid Volume
• To calculate total infusion volume; mL is
known:
Total hours  mL/h  Total volume
mL X total mL

Or, use ratio-proportion:
h
Total h
• To calculate IV volume; flow rate (gtt/min),
drop factor, and time are known:
V
 C  R; “V” is the unknown
T
Standard Weight Based Heparin
Protocol
Standard Weight Based Heparin Protocol
For all patients on heparin drips:
1. Weight in KILOGRAMS. Required for order to be processed:
kg
2. Heparin 25,000 U in 250 mL of ½ NS. Boluses to be given as 1000 U/mL.
3. APTT q.6h or 6 hours after rate change; q.d. after two consecutive therapeutic APTTs.
4. CBC initially and repeat every
day(s).
5. Obtain APTT and PT/INR on day one prior to initiation of therapy.
6. Guaiac stool initially then every
7. Neuro checks every
day(s) until heparin discontinued. Notify if positive.
hours while on heparin. Notify physician of any changes.
8. D/C APTT and CBC once heparin drip is discontinued, unless otherwise ordered.
9. Notify physician of any bleeding problems.
10. Bolus with 80 U/kg. Start drip at 18 U/kg/h.
11. If APTT is < 35 secs:
Rebolus with 80 U/kg and increase rate by 4 U/kg/h
12. If APTT is 36–44 secs:
Rebolus with 40 U/kg and increase rate by 2 U/kg/h
13. If APTT is 45–75 secs:
Continue current rate
14. If APTT is 76–90 secs:
Decrease rate by 2 U/kg/h
15. If APTT is > 90 secs:
Hold heparin for 1 hour and decrease rate by 3 U/kg/h
Standard Weight Based Heparin
Protocol Worksheet (continues)
Standard Weight Based Heparin Protocol Worksheet
Round Patient’s Total Body Weight to Nearest 10 kg
kg
DO NOT Change the Weight Based on Daily Measurements
FOUND ON THE ORDER FORM
Initial Bolus (80 U/kg)
U
Initial Infusion Rate (18 U/kg/h)
mL
U/h
mL/h
Make adjustments to the heparin drip rate as directed by the order form.
ALL DOSES ARE ROUNDED TO THE NEAREST 100 UNITS
Date
Time
APTT
Bolus
Rate Change
U/h
mL/h
New Rate
RN 1
RN 2
Standard Weight Based Heparin
Protocol Worksheet (continued)
If APTT is
Then
< 35 secs:
Rebolus with 80 U/kg and increase rate by 4 U/kg/h
36–44 secs:
Rebolus with 40 U/kg and increase rate by 2 U/kg/h
45–75 secs:
Continue current rate
76–90 secs:
Decrease rate by 2 U/kg/h
> 90 secs:
Signatures
Hold heparin for one hour and decrease rate by 3 U/kg/h
Initials
IV Heparin Protocol
• Bolus patient with heparin 80 U/kg body
weight and start drip at 18 U/kg/h
• Patient’s weight 110 lb
• How many units of heparin should the patient
receive?
• Step 1: Calculate pt.s wt. in kg ( 1kg=2.2 lb)
• Step 2: Calculate the heparin bolus dosage.
• 80 U/kg X 50 kg = 4000 U
• This pt should receive 4000 U IV hep. As a
bolus
Calculate the number of milliliters
to admin. For the bolus
• Supply: heparin 1000 U/mL
• Think: You want to give 4000 U, which is 4
times 1000 U/mL, so you want to give 4
times 1 mL or 4 mL.
•
4
• D
4000 U
• H X Q = 1000 U X 1 mL = 4 mL
• Admin. 4 mL of heparin for the bolus
Calculate the infusion rate for
the heparin IV drip
•
•
•
•
•
•
•
•
Protocol: Start drip at 18 U/kg/h
Supply: heparin 25,000 U/250 mL or 100 U/ml
18 U/kg/h X 50 kg = 900 u/h
Think, you want to admin. 9 times 1 mL or 9mL
for the heparin infusion
9
D
900 U/h
H X Q 100 U X 1 mL/h = 9 mL/h
1
To calculate IV heparin flow rate
in mL/h
• D (U/h desired)
• H (U have on hand) X Q (mL you have on
hand)=R (mL/h)
Or ratio or supply is equiv. to ratio of desired
dosage rate
Supply U
Desired U/h
Supply mL
X mL/h
Order: D5W 500 mL w/ heparing
25,000 U IV at 1000 U/h
• D
1000 U/h
• H X Q = 25,000 U X 500 mL = R (mL/h
• 1000 U/h
1
20
• 25,000 U X 500 mL= 1000mL/h = 20 mL/h
•
50
50
•
1
Order: D5W 500 mL w/ hep 25,000
U IV at 850 U/h
• Calculate the flow rate in mL/h
• D
1
17
• H X Q = 850 U/h X 500mL = 850 mL/h = 17
•
25,000 U
50
•
50
1
IV Flow Rate Ordered “Per
Minute”
• To determine the flow rate (mL/h) for IV
medications ordered per minute (such as
mg/min):
– Step 1
– Step 2
Calculate the dosage in mL/min:
D
 Q  R (mL/min)
H
Calculate the flow rate of the
quantity to administer in mL/h:
mL/min  60 min/h  mL/h
Ratio/Proportion
• 25,000 U = 850 U/h
• 500 mL
X mL/h
•
•
•
•
25,000 X = 425,000
25,000 X = 425,000
25,000
25,000
X = 17 mL/h
IV Flow Rate Ordered by “kg/min”
• To calculate flow rate (mL/h) for IV medications
ordered by weight per minute (such as
mg/kg/min):
– Step 1
Convert to like units, such as mg to
mcg or lb to kg.
– Step 2 Calculate desired dosage per minute.
– Step 3 Calculate the desired dosage in
mL/min.
– Step 4 Calculate the flow rate of the quantity
to administer in mL/h.
Verifying Safe Drug Dosage
Recommended “Per Minute”
• To check safe dosage of IV medications
ordered in mL/h:
– Step 1
– Step 2
– Step 3
Calculate mg/h.
Calculate mg/min.
Compare recommended dosage
and ordered dosage to decide if the
dosage is safe.
Verifying Safe Drug Dosage
Recommended by “kg/min”
• To check safe dosage of IV medications
recommended in mg/kg/min and ordered in
mL/h:
– Step 1
– Step 2
– Step 3
– Step 4
– Step 5
Convert to like units, such as mg to
mcg or lb to kg.
Calculate recommended mg/min.
Calculate ordered mg/h.
Calculate ordered mg/min.
Compare ordered and
recommended dosages; decide if safe.
IV and IV PB Flow Rates with Fluid
Volume Restrictions (continues)
• Follow these six steps to calculate the flow
rate of an IV, which includes IV PB.
Calculate:
V
– Step 1
IV PB flow rate:
T
CR
or use
mL/h
R
Drop factor constant
IV and IV PB Flow Rates with Fluid
Volume Restrictions (continued)
– Step 2
Total IV PB time:
Time for one dose × # of doses in 24 h
– Step 3
Total IV PB volume:
Volume of one dose × # of doses in 24 h
– Step 4
Total regular IV volume:
Total volume – IV PB volume
– Step 5
Total regular IV time:
Total time – IV PB time
IV and IV PB Flow Rates with Fluid
Volume Restrictions (continued)
– Step 6
Regular IV flow rate:
V
CR
T
or use
mL/h
R
Drop factor constant
THE END