Advanced Adult
Intravenous Calculations
Chapter 16
Revised KBurger1108
IV Heparin
• Anticoagulant – prevention of clot formation
• High alert medication
• All heparin orders, dosage, vial, amount
and calculations should be checked by
another nurse
• Available in various dosage strengths
• See figure 16-1 page 406 in Pickar
2
Heparin Flow Rate
• Set up a ratio-proportion with:
- supply dosage strength [units per ml]
- ordered infusion dose [units/hr per units/ml]
• Example:
Order: 500 mL D5W with Heparin 25,000 units
to infuse @ 850 units / hr
25,000units
=
500 mL
25,000X = 425,000
25,000
25,000
850units/hr
X mL/hr
= 17 mL/hr
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Heparin Flow Rates
Try these…
1. The doctor orders heparin to infuse at 800 unit
per hour. The pre-mixed intravenous solution
available is 250mL D5W with 25000 units
heparin added. Calculate the infusion rate for
delivery with an infusion pump. 8 mL / hr
2. The doctor orders heparin to infuse at 750 unit
per hour. The pre-mixed intravenous solution
available is 500mL D5W with 25000 units
heparin added. Calculate the infusion rate for
delivery with an infusion pump. 15 mL / hr
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See p.408 Pickar
Standard Weight-Based Heparin Protocol
4.
5.
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7.
8.
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10.
Weight in kilograms. Required for order to be processed ______kg
Heparin 25,000 units in 250mL 1/2NS.
Bolus dosage strength 1000units/mL.
APTT q6hrs or 6 hrs after rate change; daily for 2 consecutive
therapeutic APTTs.
CBC initially and repeat every ______day[s]
Obtain APTT and PT/INR on day one prior to initiation of therapy
Guaiac stool initially then every _____day[s] until heparin d/c
Neuro checks every _____hrs while on heparin
Discontinue APTT and CBC once heparin is discontinued
Notify physician of any bleeding problems
Bolus with 80 units/kg. Start drip at 18 units/kg/hr
11.
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If APTT is less than 35 seconds
If APTT is 36-44 seconds
If APTT is 45-75 seconds
If APTT is 76-90 seconds
If APTT is greater than 90 seconds
1.
2.
3.
Rebolus with 80units/kg and increase rate by 4 units/kg/hr
Rebolus with 40units/kg and increase rate by 2 units/kg/hr
Continue current rate
Decrease rate by 2 units/kg/hr
Hold heparin for 1 hour and decrease rate by 3 units/kg/hr
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Using the Heparin Protocol
• Patient weight = 110 lbs
Convert to kilograms = 50 kg
• Calculate the heparin bolus
Protocol states: Bolus with 80 units/kg
80 units X 50 kg = 4000 units
• Calculate the bolus in milliliters
Protocol states: Bolus dosage strength 1000 units/mL
1000 Units
1 mL
= 4000 Units
X mL
= 4 mL
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Using the Heparin Protocol
• Calculate the starting infusion rate
Protocol states: Start drip at 18 units/kg/hr
Multiply by pt weight of 50 kg: 18units X 50 kg = 900units/hr
Protocol states: Heparin 25,000 Units in 250 mL of ½ NS.
25000 Units = 900 Units/hr
250 mL
X mL/hr
X = 9 mL/hr
• Adjust infusion rate according to APTT results.
Follow protocol guidelines.
Examples: Client has APTT of:
Rebolus with 40units/kg/hr & increase rate by 2 units/kg/hr
40
70
Continue current rate
88
Decrease rate by 2units/kg/hr
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IV Flow Rate Ordered “Per Minute”
• Critical Care IV calculations
• Determine electronic IV infusion rate
(mL per hour) for IV medications ordered
per minute (such as mg per min)
• Step 1: Calculate dosage in mL per min
• Step 2: Calculate flow rate in mL per hour
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2000 mg
EXAMPLE: Ordered lidocaine 2g IV
in 500 mL D5W @ 2 mg/min
Step 1
Calculate ml/min:
2000mg = 2mg/min
500mL
X mL/min
X = 0.5mL/min
Step 2
Calculate ml/hr:
0.5mL
1 min
=
X mL/hr
60 min/hr
X = 30ml//hr
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IV Flow Rate Ordered by
Kilogram per minute
• Calculate electronic IV infusion rate
(mL per hour) for IV medications ordered by
weight per minute (such as mg per kg per min):
Step 1- Calculate desired dosage per minute
Step 2- Calculate desired dosage in mL per minute
Step 3- Calculate flow rate in mL per hour
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EXAMPLE: 250mL of D5W with 225 mg of
0.003 mg
dobutamine to infuse @ 3mcg/kg/min.
Client weighs 50 kg
Step 1- Calculate desired dosage per minute
0.003mg X 50 kg = 0.15mg/minute
Step 2- Calculate desired dosage in mL per minute
225mg
=
0.15mg/min
250mL
X mL/min
X = 0.17 ml/min
Step 3- Calculate flow rate in mL per hour
0.17mL =
X mL/hr
1 min
60min/hr
X = 10ml/hr
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Titrating IV Drugs
•
•
•
•
Mostly seen in Critical care and/or OB
Started with bolus
Then increased to produce desired effect
Started at lowest dosage and increased or
decreased as needed
• Examples:
Dopamine, Pitocin
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Example:
RL 1000mL with Magnesium Sulfate
20g. Start with bolus of 4g for 30 min, then
maintain continuous infusion @ 2g/hr.
Step 1:Calculate bolus in g/mL:
20g
=
1000mL
4g
X mL
X = 200mL
should infuse over 30 min
Step 2:Calculate bolus in mL/hr
200mL =
30 min
XmL/hr
60 min/hr
X = 400mL/hr
Step 3:Calculate continuous infusion rate by
repeating steps 1 and 2 using 2 g instead of 4g.
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