IV Administration

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IV Administration Dosage Calculation

• Keith Rischer, RN

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Alternate Methods Dosage Calc.

• Formula
• Ratio proportion
• Dimensional analysis

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IV solutions

• Administered in plastic bags/bottles
• Administered continuously and/or intermittently
• Components
• Water
• Glucose(dextrose)
• Saline
• Electrolytes
• Salts

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IV solutions

• Labeled
• Letters solution components
• Numbers concentration
• LR Lactated Ringers
• NS Normal Saline 0.9 NaCl
• D5W 5 Dextrose in water
• 5 g dextrose / 100 ml solution
• D5 NS with 20 mEq KCL

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IV Solution Label

• Calculate components
• D5 0.45 NS in 1000 mL
• D10 ¼ NS in 500 mL

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Tonicity of IV Solutions

• Hypotonic
• Isotonic
• Hypertonic

• 0.9 NS
• D5W
• LR
• ½ (0.45) NS
• ¼ (0.225) NS
• D5 ½ NS
• D5 NS
• D5 LR
• 3 NS

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Calculating Flow Rates IV Pumps

• Total mL ordered mL per hour
• Total hours ordered
• Vancomycin 1000 mg (250 mL) IV over 2 hours by
  infusion pump
• Vancomycin 750 mg (250 mL) IV over 1.5 hours

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IV Flow Rate in mL per hour Infusion Rate is
less than 1 hour

• Total mL ordered X 60 min/hr mL/hr
• Total min ordered
• Order
• Ampicillin 500 mg IV in 50 mL NS over 30 minutes
• Order
• Give Amiodarone 150mg in 100 ml of D5W over 10
  minutes

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Setting Flow Rates for Manually Regulated IVs

• Adjusting the rate by hand
• Counts drops per minute
• Use the roller clamp to adjust rate

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Calculating flow rates - Manually

• Formula method
• V X C (gtt factor) R
• T
• Volume (mL) X drop factor (gtt per mL) Rate
  (gtt/min)
• Time (min)
• Physician orders D5W IV at 125 mL/hr.
• The IV infusion set is calibrated with a drop
  factor of 10 gtt/mL.
• Calculate the IV flow rate
• Physician orders 0.9 NS IV at 75 mL/hr.
• The IV infusion set is calibrated with a drop
  factor of 10 gtt/mL.
• Calculate the IV flow rate

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Calculating gtts per/minute

• Once gtts/minute determined...
• Divide this total by a factor of 4
• 20 gtts/minute 5 gtts every 15 seconds
• 12 gtts/minute 3 gtts every 15 seconds
• How many gtts every 15 seconds?...
• Divide the gtts determined by 15 (seconds)
• This will be the seconds between each gtt
• 5 gtts every 15 seconds
• 15/5 x seconds
• 3 gtts every 15 seconds
• 15/3 x seconds

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Calculation of Drops per min Microdrip Drop
Factor

• Volume (mL) X drop factor (gtt per mL) Rate
  Time (min)
• Order
• D5 NS IV at 50 mL per h
• Drop factor is 60 drops per mL
• Calculate gtt/min

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Drop Factor Constants
Drop Factor Drop Factor Constant
10 drops per mL
15 drops per mL
20 drops per mL
60 drops per mL
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Drop Factor Constants

• Physician orders D5W IV at 125 mL/hr
• 10 gtts/mL manual infusion set
• 125 mL20.8 gtt/minute or 21 gtts
• 6
• Physician orders 0.9 NS IV at 75 mL/hr.
• 75mL
• 6

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Adjusting IV Flow Rate

• Check for institutional policy regarding
  correcting off-schedule IV rates and the
  percentage of variation allowed
• Variation should not exceed 25 percent
• 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

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Adjusting IV flow rates

• Follow three steps
• Remaining volume recalculated mL/h
• Remaining hours
• V X C (gtt factor) R
• T
• Adjusted gtt per min ordered gtt per min
  variation
• Ordered gtt per min

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Calculation of IV Flow Rate Adjustment

• Order 500 mL LR to run over 10 hours at 50 mL
  per hour
• Drop factor is 60 drops per mL and IV is
  correctly infusing at 50 drops per min
• After 2 hours, 300 mL is remaining
• Almost half of total volume infused in
  one-quarter the time

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Calculation of IV Flow Rate Adjustment

• IV infusion is ahead of schedule
• Compute a new rate of 300 mL to complete IV fluid
  order in remaining 7 hours
• Patient would require close assessment for fluid
  overload

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Calculation of IV Flow Rate Adjustment
Adjusted flow rate
1
1
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Calculation of IV Flow Rate Adjustment

• Adjusted gtt per min ordered gtt per min
• Ordered gtt per min
• 40 50 -10 -0.2 - 20
• 50 50

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Adjusting IV flow rates

• The physician orders 1000 mL of D5 0.45 NS at
  100 mL per hour over 10 hours. Drop factor-10 gtt
  per mL
• What is the initial correct gtt/minute
• How many gtts/15 seconds1 gtt every __ secs.
• After 5 hours only 300 mL has infused. The IV is
  behind schedule. Calculate the new flow rate.
  Is this new rate acceptable?

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IV Push Injections

• Use same calculations as other parenteral
  injections
• IMPORTANT Follow manufacturer or hospital
  guidelines for rate of administration

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IV Push Rate Calculation
Dosage Desired
Quantity (available form)
IV Push Rate Time
Supply Dosage Recommended
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Calculation of IV Push Rate

• Order Furosemide (Lasix) 40 mg IV Push stat x1
• Supply Furosemide 10 mg per mL with drug
  literature guidelines of IV infusion not to
  exceed 20 mg over 1 minute

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Calculation of IV Push Rate

• How much Furosemide should you prepare?
• Step 1. Convert
• No conversion is necessary
• Step 2. Think
• You want to give more than 1 mL

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Calculation of IV Push Rate

• How much Furosemide should you prepare?
• Step 3. Calculate

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Calculation of IV Push Rate

• What is a safe infusion time?
• Use the formula
• D X Q X
• H
• 40 mg X 1 min 2 minutes
• 20 mg

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Calculation of IV Push Rate

• How much should you infuse every 15 seconds?
• Push Factor Constant
• 4 per minute
• 15 seconds 1/4
• 60 seconds
• 4 mL over 2
• Push factor is 8 (4x28)
• Volume 4 mL0.5 mL push every 15
  seconds
• Push Factor 8

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Calculation of IV Push Rate

• Order Dilantin 100 mg IV now
• Supply Dilantin 50 mg per mL with drug
  literature guidelines of the infusion rate
  should not exceed 50 mg per min.
• How much should you prepare?
• What is safe infusion time?
• How much should you infuse every 15 seconds?

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