Charolotte Cooper & Jean Montgomery, Austin Community College
Practice Problems
- Example 1
- Example 2
- Example 3
- Example 4
- Example 5
- Example 6
- Example 7
- Example 8
- Example 9
- Example 10
- Review
A patient is to receive Lidocaine at 3mg/min. Supplied is a one liter bag of D5W containing Lidocaine 4g. Calculate the infusion rate in mL/hr.
First, identify the doctor's order. Doctor's orders
This is also known as the dose. Second, identify the dose on hand (DOH).
Dose on hand = | 4g
1000mL
|
Supplied is Lidocaine 4g in a one liter (1000mL) bag of D5W. This can be written as
Now solve for the infusion rate in mL/hr using dimensional analysis.
Doctor's order | Conversion | DOH | Conversion | Wanted Quantity | |||||
3mg
min
|
X | 1g
1000mg
|
X | 1000mL
4g
|
X | 60min
1hr
|
= | 45 | mL
hr
|
The infusion rate would be 45mL/hr.
Remember to set up your problem so that the proper units cancel.
A diabetic is to receive an infusion of insulin at 12 units/hr. The nurse prepares a 250mL bag of NS with 100 units of regular insulin. What is the infusion rate in mL/hr?
First, identify the doctor's order.
Doctor's order = | 12units
hr
|
This is also known as the dose.Second, identify the dose on hand (DOH).
Dose on hand = | 100units
250mL
|
Supplied is 100 units of regular insulin in a 250mL bag of NS. This can be written as
Doctor's order | DOH | Wanted Quantity | |||
12units
hr
|
X | 250mL
100units
|
= | 30 |
mL
hr
|
The infusion rate would be 30mL/hr.
Remember to set up your problem so that the proper units cancel.
The doctor orders Heparin at 1800 units/hr. Available is 25,000 units in 250mL of solution. Calculate the infusion rate in mL/hr.
First, identify the doctor's order.
Doctor's order = | 1800units
hr
|
This is also known as the dose. Second, identify the dose on hand (DOH).
Dose on hand = | 25,000units
250mL
|
Supplied, are 25,000 units in 250mL of solution. This can be written as
Now solve for the infusion rate in mL/hr using dimensional analysis.
Doctor's order | DOH | Wanted Quantity | |||
1800units
hr
|
X | 250mL
25,000units
|
= | 18 |
mL
hr
|
The infusion rate would be 18mL/hr.
Remember to set up your problem so that the proper units cancel.
Calculating a dose based on weight.
The doctor orders Nipride 3mcg/kg/min to keep SBP < 140mmHg. The pharmacy supplies this in a 250mL bag of D5W that contains 50mg of the drug. The patient weighs 56kg. Compute the dosage in mcg/min and the infusion rate in mL/hr.
First, identify the doctor's order.
Doctor's order = | 3mcg
kgmin
|
The doctor's order is given as 3mcg/kg/min. This can be written as
Second, identify the dose on hand (DOH).
Dose on hand = | 50mg
250mL
|
Supplied is a 250mL bag of D5W that contains 50mg of the drug. This can be written as
Third, identify the patient's weight.
Patient's weight = | 56kg
1
|
The patient's weight given is 56kg. This can be written as
Now let's first solve for mcg/min using dimensional analysis.
Doctor's order | Patient's weight | Wanted Quantity | ||
3mcg
kgmin
|
X | 56kg
1
|
= | 168mcg
min
|
The dose for this patient would be 168mcg/min. Remember to set up your problem so that the proper units cancel.
Now that you know the dose for the patient, calculate the infusion rate in mL/hr using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
168mcg
1min
|
X | 1mg
1000mcg
|
X | 250mL
50mg
|
X | 60min
1hr
|
= | 50.4 | mL
hr
|
= 50 | mL
hr
|
The infusion rate would be 50 mL/hr.
Remember to set up your problem so that the proper units cancel.
To check your answer, back solve. You can do this by first solving for mg/hr using the dose calculated for the patient.
Dose | Conversion | Conversion | Wanted Quantity | ||||||
168mcg
1min
|
X | 1mg
1000mcg
|
X | 60min
1hr
|
= | 10.08 | mg
hr
|
= 10 | mg
hr
|
Using the dose for the patient based on their weight, they should receive 10 mg/hr.
Using the DOH and the infusion, the patient should receive 10 mg/hr.
Since both answers are equal to each other, your calculation is correct.
Remember to set up your problem so that the proper units cancel.
DOH | Infusion Rate | Wanted Quantity | |||
50mg
250mL
|
X | 50mL
hr
|
= | 10 | mg
hr
|
Calculating a dose based on weight.
A patient weighing 252 pounds is to begin an infusion of dopamine at 5mcg/kg/min. The drug is supplied in a 250mL bag of NS that contains 400mg. What is the dosage in mcg/min and the infusion rate in mL/hr?
First, identify the doctor's order.
Doctor's order = | 5mcg
kgmin
|
The doctor'ss order is given as 5mcg/kg/min. This can be written as
Second, identify the dose on hand (DOH).
Dose on hand = | 400mg
250mL
|
Supplied is a 250mL bag of NS that contains 400mg. This can be written as
Third, identify the patient's weight.
The patient's weight given is 252lb. This can be written as
Let's first convert the patient's weight from pounds to kilograms.
Patient's weight | Conversion | Wanted Quantity | ||
252lb
1
|
X | 1kg
2.2lb
|
= | 114.5kg |
Now let's solve for mcg/min using dimensional analysis.
The dose for this patient would be 573 mcg/min.
Remember to set up your problem so that the proper units cancel.
Now that you know the dose for the patient, calculate the infusion rate in mL/hr using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
573mcg
min
|
X | 1mg
1000mcg
|
X | 250mL
400mg
|
X | 60min
1hr
|
= | 21.48 | mL
hr
|
= 21 | mL
hr
|
The infusion rate would be 21 mL/hr.
Remember to set up your problem so that the proper units cancel.
To check your answer, back solve. You can do this by first solving for mg/hr using the dose calculated for the patient.
Dose | Conversion | Conversion | Wanted Quantity | ||||||
573mcg
min
|
X | 1mg
1000mcg
|
X | 60min
1hr
|
= | 34.38 | mg
hr
|
= 34 | mg
hr
|
Using the DOH and the infusion, the patient should receive 34 mg/hr.
Since both answers are equal to each other, your calculation is correct.
To finish back solving, solve for mg/hr using the calculated infusion rate and the DOH.
DOH | Infusion Rate | Wanted Quantity | |||||
400mg
250mL
|
X | 21mL
hr
|
= | 33.6 | mg
hr
|
= 34 | mg
hr
|
Using the DOH and the infusion, the patient should receive 34 mg/hr.
Since both answers are equal to each other, your calculation is correct.
Remember to set up your problem so that the proper units cancel.
A patient weighing 98 kg is to receive an infusion of dobutamine at 5mcg/kg/min. Available is 500mg in 250mL of solution. What is the dosage in mcg/min and the infusion rate in mL/hr?
First, identify the doctor's order.
Doctor's order = | 5mcg
kgmin
|
The doctor's order is given as 5mcg/kg/min. This can be written as
Second, identify the dose on hand (DOH).
Dose on hand = | 500mg
250mL
|
Supplied is 500mg in 250mL of solution. This can be written as
Third, identify the patient's weight.
Patient's weight = | 98kg
1
|
The patient's weight given is 98kg. This can be written as
Now let's first solve for mcg/min using dimensional analysis.
Doctor's order | Patient's weight | Wanted Quantity | ||
5mcg
kgmin
|
X | 98kg
1
|
= | 490mcg
min
|
The dose for this patient would be 490mcg/min. Remember to set up your problem so that the proper units cancel.
Now that you know the dose for the patient, calculate the infusion rate in mL/hr using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
490mcg
min
|
X | 1mg
1000mcg
|
X | 250mL
500mg
|
X | 60min
1hr
|
= | 14.7 | mL
hr
|
= 15 | mL
hr
|
The infusion rate would be 15 mL/hr. Remember to set up your problem so that the proper units cancel.
To check your answer, back solve. You can do this by first solving for mg/hr using the dose calculated for the patient.
Patient's dose | Conversion | Conversion | Wanted Quantity | ||||||
490mcg
min
|
X | 1mg
1000mcg
|
X | 60min
1hr
|
= | 29.4 | mg
hr
|
= 29 | mg
hr
|
Using the dose for the patient based on their weight, they should receive 29 mg/hr.
To finish back solving, solve for mg/hr using the calculated infusion rate and the DOH.
DOH | Infusion Rate | Wanted Quantity | |||
500mg
250mL
|
X | 15mL
hr
|
= | 30 | mg
hr
|
Using the DOH and the infusion, the patient should receive 30 mg/hr.
A dose of 6mcg/kg/min is ordered to infuse IV to sustain the blood pressure of an adult weighing 75 kg. The supplied solution contains 500mg in 250mL of D5W. Calculate the dose in mcg/min and the infusion rate in mL/hr.
First, identify the doctor's order.
Doctor's order = | 6mcg
kgmin
|
The doctor's order is given as 6mcg/kg/min. This can be written as
Second, identify the dose on hand (DOH).
Dose on hand = | 500mg
250mL
|
The supplied solution contains 500mg in 250mL of D5W. This can be written as
Third, identify the patients weight.
Patient's weight = | 75kg
1
|
Now let’s first solve for mcg/min using dimensional analysis.
Doctor's order | Patient's weight | Wanted Quantity | |||
6mcg
kgmin
|
X | 75kg
1
|
= | 450 | mcg
min
|
The dose for this patient would be 450 mcg/min. Remember to set up your problem so that the proper units cancel.
Now that you know the dose for the patient, calculate the infusion rate in mL/hr using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
450mcg
min
|
X | 1mg
1000mcg
|
X | 250mL
500mg
|
X | 60min
1hr
|
= | 13.6 | mL
hr
|
= 14 | mL
hr
|
The infusion rate would be 14 mL/hr.
Remember to set up your problem so that the proper units cancel.
To check your answer, back solve. You can do this by first solving for mg/hr using the dose calculated for the patient.
Dose | Conversion | Conversion | Wanted Quantity | ||||
450mcg
min
|
X | 1mg
1000mcg
|
X | 60min
1hr
|
= | 27 | mg
hr
|
Using the dose for the patient based on their weight, they should receive 27mg/hr.
To finish back solving, solve for mg/hr using the calculated infusion rate and the DOH.
DOH | Infusion Rate | Wanted Quantity | |||
500mg
250mL
|
X | 14mL
hr
|
= | 28 | mg
hr
|
Using the DOH and the infusion, the patient should receive 28 mg/hr.
The order is to infuse a solution of 50mg in 250mL D5W at 0.8mcg/kg/min. Calculate the dose in mcg/min and the flow rate in mL/hr of a patient weighing 66 kg.
First, identify the doctor's order
Doctor's order = | 0.8mcg
kgmin
|
The doctor's order is given as 0.8mcg/kg/min. This can be written as
Second, identify the dose on hand (DOH).
Dose on hand = | 50mg
250mL
|
The supplied solution contains 50mg in 250mL D5W. This can be written as
Third, identify the patient's weight.
Patient's weight = | 66kg
1
|
Now let's first solve for mcg/min using dimensional analysis.
Doctor's order | Patient's weight | Wanted Quantity | ||||
0.8mcg
kgmin
|
X | 66kg
1
|
= | 52.8mcg
min
|
= | 53mcg
min
|
The dose for this patient would be 53 mcg/min. Remember to set up your problem so that the proper units cancel.
Now that you know the dose for the patient, calculate the infusion rate in mL/hr using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
53mcg
min
|
X | 1mg
1000mcg
|
X | 250mL
50mg
|
X | 60min
1hr
|
= | 15.9 | mL
hr
|
= 16 | mL
hr
|
The infusion rate would be 16 mL/hr.
Remember to set up your problem so that the proper units cancel.
To check your answer, back solve. You can do this by first solving for mg/hr using the dose calculated for the patient.
Patient's dose | Conversion | Conversion | Wanted Quantity | ||||||
53mcg
min
|
X | 1mg
1000mcg
|
X | 60min
1hr
|
= | 3.18 | mg
hr
|
= 3 | mg
hr
|
Using the dose for the patient based on their weight, they should receive 3 mg/hr.
Since both answers are equal to each other, your calculation is correct.
Titrations
A medication is ordered at a rate of 1-4mg/min. The solution strength is 2g in 500mL D5W. What is the infusion rate range in mL/hr? What would the manual infusion rate be in gtt/min for a microdrip IV set (60gtt/mL)?
First, identify the doctor's order.
Doctor's order = | 1 - 4mg
min
|
This is also known as the dose.
NOTE: The healthcare provider must change the flow rate of the drug from time to time depending on how the patient is responding and thus must constantly monitor the patient's vital signs in order to titrate the dose (rate of administration) of a drug correctly.
To do this, infusion rate must be calculated at the lower end of the range and then again at the higher end of the range to determine the rate of administration.
Second, identify the dose on hand (DOH).
Dose on hand = | 2g
500mL
|
The solution strength is 2g in 500mL D5W. This can be written as
Now solve for the infusion rate at the lower end of the range in mL/hr using dimensional analysis.
Doctor's order | Conversion | DOH | Conversion | Wanted Quantity | |||||
1mg
min
|
X | 1g
1000mcg
|
X | 500mL
2g
|
X | 60min
1hr
|
= | 15 | mL
hr
|
The infusion rate at the lower end of the range would be 15mL/hr. Remember to set up your problem so that the proper units cancel.
Now solve for the infusion rate at the higher end of the range in mL/hr using dimensional analysis.
Doctor's order | Conversion | DOH | Conversion | Wanted Quantity | |||||
4mg
min
|
X | 1g
1000mcg
|
X | 500mL
2g
|
X | 60min
1hr
|
= | 60 | mL
hr
|
The infusion rate at the higher end of the range would be 60mL/hr. Remember to set up your problem so that the proper units cancel.
The range is 15-60mL/hr.
Now let's calculate the drip rate (gtt/min) for the lower end of the infusion rate.
Infusion Rate | Drop Factor | Conversion | Wanted Quantity | |||
15mL
hr
|
X | 60gtt
1mL
|
X | 1hr
60min
|
= | 15gtt
min
|
The drip rate for the lower end of the infusion rate is
Now let's calculate the drip rate (gtt/min) for the higher end of the infusion rate.
Infusion Rate | Drop Factor | Conversion | Wanted Quantity | |||
60mL
hr
|
X | 60gtt
1mL
|
X | 1hr
60min
|
= | 60gtt
min
|
The drip rate for the lower end of the infusion rate is
The drip rate range is also 15-60 gtt/min.
Calculate dosages using mg/kg and mcg/kg
A patient weighing 160 pounds is to receive a titrated infusion of a medication between 5-10mcg/kg/min. The supplied solution contains 100mg in 40mL of NS. What is the dose range in mcg/min? What is the manual infusion rate range in gtt/min for a microdrip IV set (60gtt/min)? The client stabilizes at 16mL/hr. What is the stabilizing dose in mcg/min?
First, identify the doctor's order.
Doctor's order = | 5 - 10mcg
kgmin
|
This is also known as the dose.
NOTE: The healthcare provider must change the flow rate of the drug from time to time depending on how the patient is responding and thus must constantly monitor the patient's vital signs in order to titrate the dose (rate of administration) of a drug correctly.
To do this, infusion rate must be calculated at the lower end of the range and then again at the higher end of the range to determine the rate of administration.
Second, identify the dose on hand (DOH).
Dose on hand = | 100mg
40mL
|
The supplied solution contains 100mg in 40mL of NS. This can be written as
Third, identify the patient's weight.
Patient's weight = | 160lb
1
|
The patient's weight given is 252lb. This can be written as
Let's first convert the patient's weight from pounds to kilograms.
Patient's weight | Conversion | Wanted Quantity | ||
160 lb
1
|
X | 1kg
2.2lb
|
= | 72.7 kg |
Using the conversion 1 kg = 2.2 lb we can determine the patients weight to be 72.7 kg.
Now let's solve for the dose at the lower end of the range in mcg/min using dimensional analysis.
Doctor's order | Patient's weight | Wanted Quantity | |||||
5 mcg
kgmin
|
X | 72.7kg
1
|
= | 363.5 | mcg
min
|
= 364 | mcg
min
|
The dose for this patient at the lower end of the range would be 364mcg/min.
Remember to set up your problem so that the proper units cancel.
Now let's solve for the dose at the higher end of the range in mcg/min using dimensional analysis.
Doctor's order | Patient's weight | Wanted Quantity | ||
10 mcg
kgmin
|
X | 72.7kg
1
|
= | 727mcg
min
|
The dose for this patient at the higher end of the range would be 727mcg/min.
Remember to set up your problem so that the proper units cancel.
Dose range 364-727 mcg/min
Now that you know the dose range for the patient, calculate the infusion rate in mL/hr at the lower end of the range using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
364mcg
min
|
X | 1mg
1000mcg
|
X | 40mL
100mg
|
X | 60min
1hr
|
= | 8.7 | mL
hr
|
= 9 | mL
hr
|
The infusion rate would be 9 mL/hr at the lower end of the dose range.
Remember to set up your problem so that the proper units cancel.
Now that you know the dose range for the patient, calculate the infusion rate in mL/hr at the higher end of the range using dimensional analysis.
Patient's dose | Conversion | DOH | Conversion | Wanted Quantity | |||||||
727mcg
min
|
X | 1mg
1000mcg
|
X | 40mL
100mg
|
X | 60min
1hr
|
= | 17.4 | mL
hr
|
= 17 | mL
hr
|
The infusion rate would be 17 mL/hr at the higher end of the dose range.
Remember to set up your problem so that the proper units cancel.
The infusion rate range is 9-17 mL/hr.
Now let,s calculate the manual infusion rate (gtt/min) for the lower end of the infusion rate.
Infusion Rate | Drop Factor | Conversion | Wanted Quantity | ||||
9mL
hr
|
X | 60gtt
1mL
|
X | 1hr
60min
|
= | 9 | gtt
min
|
The drip rate for the lower end of the infusion rate is
Now let's calculate the manual infusion rate (gtt/min) for the higher end of the infusion rate.
Infusion Rate | Drop Factor | Conversion | Wanted Quantity | ||||
17mL
hr
|
X | 60gtt
1mL
|
X | 1hr
60min
|
= | 17 | gtt
min
|
The drip rate for the lower end of the infusion rate is
The manual infusion rate range is also 9-17 gtt/min
Lastly, let's determine the stabilizing dose in mcg/min using the patient's stabilizing rate of 16mL/hr.
Stabilizing Rate | DOH | Conversion | Conversion | Wanted Quantity | |||||||
16mL
hr
|
X | 100mg
40mL
|
X | X | 1hr
60min
|
= | 667.67mcg
min
|
= | 667mcg
min
|
1000mcg
1mg
|
The stabilizing dose for this patient would be 667mcg/min.
Remember to set up your problem so that the proper units cancel.
Answers and step-by-step explanations.
Now that you have completed the practice problems,please take the time to review your answers for each problem. Please click here to view/print the document to check your answers. You can also view our video click here.