Top Banner
IV Administration – Dosage Calculation Keith Rischer, RN
30
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: IV Administration – Dosage Calculation Keith Rischer, RN.

IV Administration – Dosage Calculation

Keith Rischer, RN

Page 2: IV Administration – Dosage Calculation Keith Rischer, RN.

Alternate Methods Dosage Calc.

Formula Ratio proportion Dimensional analysis

Page 3: IV Administration – Dosage Calculation Keith Rischer, RN.

IV solutions

Administered in plastic bags/bottles Administered continuously and/or

intermittently Components:

Water Glucose(dextrose) Saline Electrolytes Salts

Page 4: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 5: IV Administration – Dosage Calculation Keith Rischer, RN.

IV Solution Label

Calculate components: D5 0.45% NS in 1000

mL

D10 ¼ NS in 500 mL

Page 6: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 7: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 8: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Total mL ordered X 60 min/hr = mL/hrTotal 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

Page 9: IV Administration – Dosage Calculation Keith Rischer, RN.

Setting Flow Rates for Manually Regulated IVs

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

Page 10: IV Administration – Dosage Calculation Keith Rischer, RN.

Calculating flow rates - ManuallyFormula 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

Page 11: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 12: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 13: IV Administration – Dosage Calculation Keith Rischer, RN.

Drop Factor Constants

Drop Factor Drop Factor Constant

10 drops per mL

15 drops per mL

20 drops per mL

60 drops per mL

610

60

415

60

320

60

160

60

Page 14: IV Administration – Dosage Calculation Keith Rischer, RN.

Drop Factor Constants

Physician orders: D5W IV at 125 mL/hr 10 gtts/mL manual infusion set 125 mL=20.8 gtt/minute or 21 gtts

6 Physician orders: 0.9 NS IV at 75 mL/hr.

75mL=

6

Page 15: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 16: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 17: IV Administration – Dosage Calculation Keith Rischer, RN.

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 21

Page 18: IV Administration – Dosage Calculation Keith Rischer, RN.

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

21

Page 19: IV Administration – Dosage Calculation Keith Rischer, RN.

Calculation of IV Flow Rate Adjustment

Remaining volume

Remaining hours

V

TC

40 mL

60 min60 gtt per mL

300 mL

7.5 h40 mL per hour

1

1

40 gtt per min

Adjusted flow rate

Page 20: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 21: IV Administration – Dosage Calculation Keith Rischer, RN.

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 seconds…1 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?

Page 22: IV Administration – Dosage Calculation Keith Rischer, RN.

IV Push Injections

Use same calculations as other parenteral injections

IMPORTANT – Follow manufacturer or hospital guidelines for rate of administration

Page 23: IV Administration – Dosage Calculation Keith Rischer, RN.

IV Push Rate Calculation

XQH

D

Dosage Desired

Supply Dosage Recommended

Quantity (available form)

IV Push Rate Time

Page 24: IV Administration – Dosage Calculation Keith Rischer, RN.

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”

Page 25: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 26: IV Administration – Dosage Calculation Keith Rischer, RN.

Calculation of IV Push Rate

How much Furosemide should you prepare?Step 3. Calculate

mL 4 mL 1mg 10

mg 40Q

H

D

Page 27: IV Administration – Dosage Calculation Keith Rischer, RN.

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

Page 28: IV Administration – Dosage Calculation Keith Rischer, RN.

Calculation of IV Push Rate

How much should you infuse every 15 seconds? Push Factor Constant

4 per minute15 seconds = 1/4

60 seconds

4 mL over 2” Push factor is 8 (4x2”=8)

Volume 4 mL=0.5 mL push every 15 seconds

Push Factor 8

Page 29: IV Administration – Dosage Calculation Keith Rischer, RN.

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?

Page 30: IV Administration – Dosage Calculation Keith Rischer, RN.