1. Hourly Flow Rates – DOSAGE PER HOUR
Rule 19-1 Converting dosage/h to mL/h
Determine the following:
D = rate of desired dose
Q = dosage unit
H = dose on hand
A = amount to administer
Use preferred method to calculate.
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
Rate of desired dose = mcg/h, mg/h, g/h, units/h
dosage unit = mL
dose on hand = total number of mcg or mg
amount to administer = mL/h
Methods of calculation
Proportion method
Dimensional analysis
Formula method

2. Hourly Flow Rates – DOSAGE PER HOUR (cont.)
Find the hourly flow rate. Ordered: morphine sulfate 4 mg/h On hand: morphine sulfate 10 mg/100 mL D5W Step A No conversion is needed.
Example
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).

3. Hourly Flow Rates – DOSAGE PER HOUR (cont.)
Step B Calculate
H = 10 mg; Q = 100 mL; D = 4 mg/hr
10 mg: 100 mL = 4 mg/h : A
100 mL x 4/h = 10 x A
400 mL/h/10 = 10A / 10
A = 40 mL/h
Example
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
Set up proportion.
H:Q = D:A or H/Q = D/A

4. Hourly Flow Rates – DOSAGE PER HOUR (cont.)
Example
Step C Dosage strength is 1mg to 10 mL and 4 mL x 10 is 40 mL, so it is reasonable.
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
Problem can also be done using dimensional analysis and the formula method.
See text for examples of these.

5. Hourly Flow Rates – DOSAGE PER MINUTE (cont.)
Rule 19-2 To convert a per minute order to an hourly rate:
Convert the order to mL/min. Determine:
D Q
H A
Calculate using your chosen calculation method.
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
D = rate of desired dose = mg or mcg/min
Q = dosage unit = mL
H = dose on hand = mg or mcg
A = amount to administer = mL/min
Calculate using proportion method, dimensional analysis, or formula method.

6. Hourly Flow Rates – DOSAGE PER MINUTE (cont.)
Rule 19-2 (cont.)
Convert mL/min to mL/h
Proportion and formula methods – multiply by 60
Dimensional analysis use the factor 60/1 as part of your equation
Hourly flow rate = mL/h
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).

7. Hourly Flow Rates – DOSAGE PER MINUTE (cont.)
Find the hourly flow rate.
Ordered: 5000 mg Esmolol in 500 mL D5W at 8 mg/min via infusion pump
Step A Convert mg/min to mg/h.
A conversion factor or 60 min/1 hr is needed.
Example
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).

8. Hourly Flow Rates – DOSAGE PER MINUTE (cont.)
Step B Calculate using dimensional analysis.
H = 5000 mg; Q = 500 mL; D = 8 mg/min
A mL/h = 500 mL/5000 mg x 8 mg/1 min x 60 min/1 h
A mL/h = 2400 mL/50 h
A mL/h = 48 mL/h
Example
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
Using dimensional analysis
Looking for amount to administer in mL/h so A mL/ hr goes on one side of the equation
First factor is dosage unit over dose on hand = 500 mL/5000 mg
Second factor is desired dose = 8 mg/ min
Third factor is the conversion factor for minutes to hour = 60 min/1 h
Cancel units and solve the equation

9. Hourly Flow Rates – DOSAGE PER MINUTE (cont.)
Step C Think!...Is It Reasonable? The concentration of 5000 mg/ 500 mL = 10 mg / mL, 8 mg/min x 60 min/h = 480 mg/h and 480  10 = 48 mL It is reasonable.
Example
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
This problem can also be calculated using the proportion or formula method.
See examples in text.

10. Practice
Ordered: Procainamide 4 mg/min IV On hand: Procainamide hydrochloride 1 g/ 250 mL D5W Calculate hourly flow rate:
ANSWER: 60 mL/h
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h).
Step A convert mg to grams.
1 g : 1000 mg = D : 4mg
1000 D = 4 g
D = g / min
Step B
A mL/h = 250 mL/ 1 g x g/1 min x 60min/1 hr [cancel units: g and min]
A mL/h = 60 mL/h
Step C Since dose on hand is 1 g = 1000mg / 250 mL = 4 mg/mL, and 4 mg x 60 min = 240 and 60 mL x 4 mg/mL = 240 It is reasonable.

11. Apply Your Knowledge
True or False: Vasoactive medications regulate the heart rate and rhythm. Medications can be titrated to achieve a specific effect. To be administered by electronic infusion pump, IVs must be calculated in mL/min. F
They are administered to keep blood pressure within normal range T
Learning Outcome: 19.1 Calculate the hourly flow rate for IV infusions ordered in dosage per time (e.g. mcg/ min, mg/h). F
mL/h