lOMoARcPSD|5734770
Critical Care Calculations Study Guide
lOMoARcPSD|5734770
Critical Care Calculations
Study Guide
Example #1
Your 65 kg patient has dopamine ordered at 6 mcg/kg/min. The IV has 400 mg of
dopamine in 250 mL. What IV rate is correct?
1. Always determine the dose of medication per mL (Drug Concentration)
400 mg dopamine = 1.6 mg dopamine/mL fluid
250 mL fluid
2. Do you need to convert your dose from mg to mcg? mcg to mg? grams to mcg?
1.6 mg = 1600 mcg dopamine/mL fluid
3. Use a streamlined equation where you only need 4 items:
A. Ordered amount of drug
B. Pt. weight (most of the time)
C. Number of minutes in an hour (always the same!!)
D. Dose/mL (calculated in #1)
Ordered amount of drug x pt’s weight x 60 (minutes/hr)
Drug concentration
6 (rate) x 65 (pt weight) x 60 (minutes/hr) = 23400 = 14.6; round to 15; set rate at 15 mL/hour
1600 (mcg dopamine/mL) 1600
4. If the drug is not weight based, simply exclude the weight from the equation
Example #2
Your patient has a nitroprusside drip at 0.4 mcg/kg/min. The concentration is 50 mg
nitroprusside in 250 mL fluid. The patient weighs 80 kg. What rate will you set the IV at?
Remember the equation
Ordered amount of drug x pt’s weight x 60 (minutes/hr)
Drug concentration
1. What is the dose/mL? (Drug Concentration) 50 mg/250 mL = 0.2 mg/mL
2. Do you need to convert from mg to mcg? YES! 0.2 x 1000 = 200 mcg/mL
3. Input information into the equation:
0.4 (ordered amt of drug) x 80 (pt weight) x 60 (min/hr) = 9.6 mL/hour; round to 10 mL/hour
200 mcg/mL (dose)
, lOMoARcPSD|5734770
Critical Care Calculations
Study Guide
Ordered amount of drug x pt’s weight x 60 (minutes/hr)
Drug concentration
Example #3
Lidocaine is ordered a 1 mg/min. Your IV has 2 grams of Lidocaine in 500 mL. What
rate will your IV run at?
1. Always begin by determining the amount of medication in each mL.
2 grams = 0.004 gm/mL ;
500 mL
2. Do you need to convert your dose?
Multiply by 1000 to convert to mg = 4 mg/mL
3. Use your streamlined equation
Ordered amount of drug x pt’s weight (NA in this example) x 60
(minutes/hr) Drug concentration
1 mg (ordered amount) x weight (NA) x 60 (minutes/hour) = 15 mL/hour
4 mg/ml (drug concentration)
What if you have the rate and need to calculate the dose:
Example #4
Your 70 kg patient has dopamine (400 mg in 250 mL) running at 26 mL/hour. How many
mcg/kg/min is the patient receiving?
You can use your same formula
1. Determine the amount of medication per mL.
400/250 = 1.6 mg/mL
2. Do you need to convert your dose?
Yes 1.6 mg x 1000 = 1600 mcg)
3. Use your streamlined equation, but you will have an “X” to solve for
“X”(Ordered amount of drug) x 70 (pt’s weight) x 60 (minutes/hr) = 26
1600 (Drug concentration)
Solve for “X” by cross multiplying; X = 26 x 1600 = 41600 = 9.9; round to 10 mcg/kg/min
70 x 60 4200
Critical Care Calculations Study Guide
lOMoARcPSD|5734770
Critical Care Calculations
Study Guide
Example #1
Your 65 kg patient has dopamine ordered at 6 mcg/kg/min. The IV has 400 mg of
dopamine in 250 mL. What IV rate is correct?
1. Always determine the dose of medication per mL (Drug Concentration)
400 mg dopamine = 1.6 mg dopamine/mL fluid
250 mL fluid
2. Do you need to convert your dose from mg to mcg? mcg to mg? grams to mcg?
1.6 mg = 1600 mcg dopamine/mL fluid
3. Use a streamlined equation where you only need 4 items:
A. Ordered amount of drug
B. Pt. weight (most of the time)
C. Number of minutes in an hour (always the same!!)
D. Dose/mL (calculated in #1)
Ordered amount of drug x pt’s weight x 60 (minutes/hr)
Drug concentration
6 (rate) x 65 (pt weight) x 60 (minutes/hr) = 23400 = 14.6; round to 15; set rate at 15 mL/hour
1600 (mcg dopamine/mL) 1600
4. If the drug is not weight based, simply exclude the weight from the equation
Example #2
Your patient has a nitroprusside drip at 0.4 mcg/kg/min. The concentration is 50 mg
nitroprusside in 250 mL fluid. The patient weighs 80 kg. What rate will you set the IV at?
Remember the equation
Ordered amount of drug x pt’s weight x 60 (minutes/hr)
Drug concentration
1. What is the dose/mL? (Drug Concentration) 50 mg/250 mL = 0.2 mg/mL
2. Do you need to convert from mg to mcg? YES! 0.2 x 1000 = 200 mcg/mL
3. Input information into the equation:
0.4 (ordered amt of drug) x 80 (pt weight) x 60 (min/hr) = 9.6 mL/hour; round to 10 mL/hour
200 mcg/mL (dose)
, lOMoARcPSD|5734770
Critical Care Calculations
Study Guide
Ordered amount of drug x pt’s weight x 60 (minutes/hr)
Drug concentration
Example #3
Lidocaine is ordered a 1 mg/min. Your IV has 2 grams of Lidocaine in 500 mL. What
rate will your IV run at?
1. Always begin by determining the amount of medication in each mL.
2 grams = 0.004 gm/mL ;
500 mL
2. Do you need to convert your dose?
Multiply by 1000 to convert to mg = 4 mg/mL
3. Use your streamlined equation
Ordered amount of drug x pt’s weight (NA in this example) x 60
(minutes/hr) Drug concentration
1 mg (ordered amount) x weight (NA) x 60 (minutes/hour) = 15 mL/hour
4 mg/ml (drug concentration)
What if you have the rate and need to calculate the dose:
Example #4
Your 70 kg patient has dopamine (400 mg in 250 mL) running at 26 mL/hour. How many
mcg/kg/min is the patient receiving?
You can use your same formula
1. Determine the amount of medication per mL.
400/250 = 1.6 mg/mL
2. Do you need to convert your dose?
Yes 1.6 mg x 1000 = 1600 mcg)
3. Use your streamlined equation, but you will have an “X” to solve for
“X”(Ordered amount of drug) x 70 (pt’s weight) x 60 (minutes/hr) = 26
1600 (Drug concentration)
Solve for “X” by cross multiplying; X = 26 x 1600 = 41600 = 9.9; round to 10 mcg/kg/min
70 x 60 4200
