Veterinary Calculations
Posted: Tuesday June 30th, 2020 | Updated: Sunday July 11th, 2021
Posted: Tuesday June 30th, 2020 | Updated: Sunday July 11th, 2021
Understanding The Math Behind Dilutions: Aminocaproic Acid Part 1 of 2
Patient and History:
An older male canine presents to your clinic with pale mm, lethargy, tachypnea, and tachycardia. Bloodwork reveals that he is anemic and needs blood. AFAST reveals that he has a large splenic mass. The patient weighs roughly 23.0 kg. It’s requested that you give 50 mg/kg of aminocaproic acid diluted down to a 20 mg/ml solution with 0.9% NaCl over 30 minutes
Relevant Patient Details:
Weight – 23.0 kg
Supply Details:
Drug – Aminocaproic Acid 250 mg/ml
Diluent – 0.9% NaCl
Calculations:
How much Aminocaproic Acid will the patient receive?
(50 mg/kg)(23.0 kg) = 1,150 mg Aminocaproic Acid
What is your total volume of drug and diluent?
(1,150 mg) / (1 ml / 20 mg) --> You will need 57.5 ml total volume
How much of the total volume will be the aminocaproic acid?
(1,150 mg) / (1 ml / 250 mg) --> You will need 4.6 ml of Aminocaproic Acid
How much of the total volume will be the 0.9% NaCl?
57.5 ml total volume – 4.6 ml aminocaproic acid = 52.9 ml 0.9% NaCl
What will the rate of administration be in ml/hr?
((57.5 ml) / (30 minutes))(60 minutes / 1 hr) = 115 ml/hr administration rate
Patient and History:
An older male canine presents to your clinic with pale mm, lethargy, tachypnea, and tachycardia. Bloodwork reveals that he is anemic and needs blood. AFAST reveals that he has a large splenic mass. The patient weighs roughly 23.0 kg. It’s requested that you give 50 mg/kg of aminocaproic acid diluted down to a 20 mg/ml solution with 0.9% NaCl over 30 minutes
Relevant Patient Details:
Weight – 23.0 kg
Supply Details:
Drug – Aminocaproic Acid 250 mg/ml
Diluent – 0.9% NaCl
Calculations:
How much Aminocaproic Acid will the patient receive?
(50 mg/kg)(23.0 kg) = 1,150 mg Aminocaproic Acid
What is your total volume of drug and diluent?
(1,150 mg) / (1 ml / 20 mg) --> You will need 57.5 ml total volume
How much of the total volume will be the aminocaproic acid?
(1,150 mg) / (1 ml / 250 mg) --> You will need 4.6 ml of Aminocaproic Acid
How much of the total volume will be the 0.9% NaCl?
57.5 ml total volume – 4.6 ml aminocaproic acid = 52.9 ml 0.9% NaCl
What will the rate of administration be in ml/hr?
((57.5 ml) / (30 minutes))(60 minutes / 1 hr) = 115 ml/hr administration rate
Understanding The Math Behind Dilutions: Aminocaproic Acid Part 2 of 2
Patient and History:
An older male canine presents to your clinic with pale mm, lethargy, tachypnea, and tachycardia. Bloodwork reveals that he is anemic and needs blood. AFAST reveals that he has a large splenic mass. The patient weighs roughly 23.0 kg. It’s requested that you give 50 mg/kg of aminocaproic acid diluted down to a 20 mg/ml solution with 0.9% NaCl over 30 minutes
Relevant Patient Details:
Weight – 23.0 kg
Supply Details:
Drug – Aminocaproic Acid 250 mg/ml
Diluent – 0.9% NaCl
Calculations:
Using the formula V1C1 = V2C2 calculate how much 0.9% NaCl you will need to make a 20 mg/ml solution of aminocaproic acid
V1 = (50 mg/kg)(23 kg)(1 ml / 250 mg) = 4.6 ml aminocaproic acid
C1 = 250 mg/ml
V2 = x
C2 = 20 mg/ml
Plug the values into the equation and solve for x:
V1C1 = V2C2
(4.6 ml)(250 mg/ml) = x(20 mg/ml)
1,150 mg = x(20 mg/ml)
1,150 mg(1 ml / 20 mg) = x
57.5 ml = x (this is the total volume of drug and diluent)
57.5 ml total volume – 4.6 ml aminocaproic acid = 52.9 ml 0.9% NaCl
Patient and History:
An older male canine presents to your clinic with pale mm, lethargy, tachypnea, and tachycardia. Bloodwork reveals that he is anemic and needs blood. AFAST reveals that he has a large splenic mass. The patient weighs roughly 23.0 kg. It’s requested that you give 50 mg/kg of aminocaproic acid diluted down to a 20 mg/ml solution with 0.9% NaCl over 30 minutes
Relevant Patient Details:
Weight – 23.0 kg
Supply Details:
Drug – Aminocaproic Acid 250 mg/ml
Diluent – 0.9% NaCl
Calculations:
Using the formula V1C1 = V2C2 calculate how much 0.9% NaCl you will need to make a 20 mg/ml solution of aminocaproic acid
V1 = (50 mg/kg)(23 kg)(1 ml / 250 mg) = 4.6 ml aminocaproic acid
C1 = 250 mg/ml
V2 = x
C2 = 20 mg/ml
Plug the values into the equation and solve for x:
V1C1 = V2C2
(4.6 ml)(250 mg/ml) = x(20 mg/ml)
1,150 mg = x(20 mg/ml)
1,150 mg(1 ml / 20 mg) = x
57.5 ml = x (this is the total volume of drug and diluent)
57.5 ml total volume – 4.6 ml aminocaproic acid = 52.9 ml 0.9% NaCl
Understanding The Math Behind Dilutions:
Example: Canine Lyophilized Albumin 5 gram vial diluted to 16%
The manufacturer states to rehydrate the vial to a concentration of 16% using 30 ml of 0.9% NaCl. How did they arrive at a volume for dilution of 30 ml?
Use a common unit of measurement throughout your calculations
Start by converting the 5 gram vial of albumin to mg:
5 grams albumin = 5000 mg albumin
(5 grams)(1000 mg / 1 gram)
Find the final concentration we need in mg/ml:
16% = (16 grams / 100 ml) = (0.16 grams / 1 ml)(1000 mg / 1 gram) = 160 mg/ml
Find the amount of diluent we need to make 5000 mg of albumin into 160 mg/ml:
(5000 mg)(1 ml / 160 mg) = 31.25 ml total volume needed
16% = (16 grams / 100 ml) / (16 / 16) = (1 / 6.25) = 1:6.25 = 0.16 = 16%
1:6.25 --> 1 part solute to 6.25 total parts --> (5)(6.25) = 31.25 ml
Notice the diluent volume of 30 ml and the total volume of 31.25 ml does not match. The extra 1.25 ml is known as the drug volume
In order to make this concentration, the drug volume is too significant to ignore. Therefore, when 30 ml of 0.9% NaCl is added to the vial of albumin, the total volume is 31.25 ml in the end
Find the amount of 0.9% NaCl needed to rehydrate the 5 gram vial of albumin to make a 16% concentration using the formula V1C1 = V2C2:
Volume 1 = in this case we do not have a starting volume because the albumin needs to be rehydrated
Concentration 1 = 5000 mg
Volume 2 = x
Concentration 2 = 160 mg/ml
(5000 mg) = (x)(160 mg / 1 ml)
(5000 mg)(1 ml / 160 mg) = x
31.25 ml = x (Subtract the drug volume of 1.25 ml and you get the 30 ml of diluent the manufacturer recommends)
Example: Canine Lyophilized Albumin 5 gram vial diluted to 16%
The manufacturer states to rehydrate the vial to a concentration of 16% using 30 ml of 0.9% NaCl. How did they arrive at a volume for dilution of 30 ml?
Use a common unit of measurement throughout your calculations
Start by converting the 5 gram vial of albumin to mg:
5 grams albumin = 5000 mg albumin
(5 grams)(1000 mg / 1 gram)
Find the final concentration we need in mg/ml:
16% = (16 grams / 100 ml) = (0.16 grams / 1 ml)(1000 mg / 1 gram) = 160 mg/ml
Find the amount of diluent we need to make 5000 mg of albumin into 160 mg/ml:
(5000 mg)(1 ml / 160 mg) = 31.25 ml total volume needed
16% = (16 grams / 100 ml) / (16 / 16) = (1 / 6.25) = 1:6.25 = 0.16 = 16%
1:6.25 --> 1 part solute to 6.25 total parts --> (5)(6.25) = 31.25 ml
Notice the diluent volume of 30 ml and the total volume of 31.25 ml does not match. The extra 1.25 ml is known as the drug volume
In order to make this concentration, the drug volume is too significant to ignore. Therefore, when 30 ml of 0.9% NaCl is added to the vial of albumin, the total volume is 31.25 ml in the end
Find the amount of 0.9% NaCl needed to rehydrate the 5 gram vial of albumin to make a 16% concentration using the formula V1C1 = V2C2:
Volume 1 = in this case we do not have a starting volume because the albumin needs to be rehydrated
Concentration 1 = 5000 mg
Volume 2 = x
Concentration 2 = 160 mg/ml
(5000 mg) = (x)(160 mg / 1 ml)
(5000 mg)(1 ml / 160 mg) = x
31.25 ml = x (Subtract the drug volume of 1.25 ml and you get the 30 ml of diluent the manufacturer recommends)
Understanding The Math Behind Dilutions:
Example: Canine Lyophilized Albumin 5 gram vial diluted to 5%
The manufacturer states to rehydrate the vial to a concentration of 5% using 100 ml of 0.9% NaCl. How did they arrive at a volume for dilution of 100 ml?
Use a common unit of measurement throughout your calculations
Start by converting the 5 gram vial of albumin to mg
5 grams albumin = 5000 mg albumin
(5 grams)(1000 mg / 1 gram)
Find the final concentration we need in mg/ml
5% = (5 grams / 100 ml) = (0.05 grams / 1 ml)(1000 mg / 1 gram) = 50 mg/ml
Find the amount of diluent we need to make 5000 mg of albumin into 50 mg/ml
(5000 mg)(1 ml / 50 mg) = 100 ml total volume needed
5% = (5 grams / 100 ml) / (5 / 5) = (1 / 20) = 1:20 = 0.05 = 5%
1:20 --> 1 part solute to 20 total parts --> (5)(20) = 100 ml
Notice the diluent volume of 100 ml and the total volume of 100 ml matches. The drug volume in this case is not significant with this high of a dilution
Find the amount of 0.9% NaCl needed to rehydrate the 5 gram vial of albumin to make a 5% concentration using the formula V1C1 = V2C2
Volume 1 = in this case we do not have a starting volume because the albumin needs to be rehydrated
Concentration 1 = 5000 mg
Volume 2 = x
Concentration 2 = 50 mg/ml
(5000 mg) = (x)(50 mg / 1 ml)
(5000 mg)(1 ml / 50 mg) = x
100 ml = x (The drug volume is not significant with this high of a dilution)
Example: Canine Lyophilized Albumin 5 gram vial diluted to 5%
The manufacturer states to rehydrate the vial to a concentration of 5% using 100 ml of 0.9% NaCl. How did they arrive at a volume for dilution of 100 ml?
Use a common unit of measurement throughout your calculations
Start by converting the 5 gram vial of albumin to mg
5 grams albumin = 5000 mg albumin
(5 grams)(1000 mg / 1 gram)
Find the final concentration we need in mg/ml
5% = (5 grams / 100 ml) = (0.05 grams / 1 ml)(1000 mg / 1 gram) = 50 mg/ml
Find the amount of diluent we need to make 5000 mg of albumin into 50 mg/ml
(5000 mg)(1 ml / 50 mg) = 100 ml total volume needed
5% = (5 grams / 100 ml) / (5 / 5) = (1 / 20) = 1:20 = 0.05 = 5%
1:20 --> 1 part solute to 20 total parts --> (5)(20) = 100 ml
Notice the diluent volume of 100 ml and the total volume of 100 ml matches. The drug volume in this case is not significant with this high of a dilution
Find the amount of 0.9% NaCl needed to rehydrate the 5 gram vial of albumin to make a 5% concentration using the formula V1C1 = V2C2
Volume 1 = in this case we do not have a starting volume because the albumin needs to be rehydrated
Concentration 1 = 5000 mg
Volume 2 = x
Concentration 2 = 50 mg/ml
(5000 mg) = (x)(50 mg / 1 ml)
(5000 mg)(1 ml / 50 mg) = x
100 ml = x (The drug volume is not significant with this high of a dilution)
Understanding The Math Behind Dilutions:
Example: Canine Lyophilized Albumin 5 gram vial diluted from 16% to 5%
We have rehydrated a vial of albumin to the 16% concentration. We need to dilute it further to make a 5% concentration. How much diluent must we now add to the vial if we’re starting out with 31.25 ml?
Use a common unit of measurement throughout your calculations
Convert the concentrations in mg/ml
16% = (16 grams / 100 ml) = (0.16 grams / 1 ml)(1000 mg / 1 gram) = 160 mg/ml
5% = (5 grams / 100 ml) = (0.05 grams / 1 ml)(1000 mg / 1 gram) = 50 mg/ml
Find how many total mg we are starting with
We have a rehydrated vial of 16% albumin with 31.25 ml total volume
We know the concentration of that vial is 16% or 160 mg/ml
(160 mg / 1 ml)(31.25 ml) = 5000 mg total of albumin
Find the amount of diluent we need to make 31.25 ml of 16% albumin into 5% albumin
Method #1 Using the final concentration we are looking for and total grams in the vial
Method #2 Using two concentrations we are working with and the volume we already have
Method #3 Using the formula V1C1 = V2C2
Volume 1 = 31.25 ml
Concentration 1 = 16%
Volume 2 = x
Concentration 2 = 5%
(31.25 ml)(16%) = x(5%)
((31.25 ml)(16%)) / (5%) = x
100 ml = x --> 100 ml total volume needed – 31.25 ml starting out with = 68.75 ml
Example: Canine Lyophilized Albumin 5 gram vial diluted from 16% to 5%
We have rehydrated a vial of albumin to the 16% concentration. We need to dilute it further to make a 5% concentration. How much diluent must we now add to the vial if we’re starting out with 31.25 ml?
Use a common unit of measurement throughout your calculations
Convert the concentrations in mg/ml
16% = (16 grams / 100 ml) = (0.16 grams / 1 ml)(1000 mg / 1 gram) = 160 mg/ml
5% = (5 grams / 100 ml) = (0.05 grams / 1 ml)(1000 mg / 1 gram) = 50 mg/ml
Find how many total mg we are starting with
We have a rehydrated vial of 16% albumin with 31.25 ml total volume
We know the concentration of that vial is 16% or 160 mg/ml
(160 mg / 1 ml)(31.25 ml) = 5000 mg total of albumin
Find the amount of diluent we need to make 31.25 ml of 16% albumin into 5% albumin
Method #1 Using the final concentration we are looking for and total grams in the vial
- 1:20 --> 1 part solute to 20 total parts solute and solvent --> (5)(20) = 100 ml
- 100 ml total volume – 31.25 ml volume of what we started with = 68.75 ml
Method #2 Using two concentrations we are working with and the volume we already have
- (160 mg / 1ml)(1 ml / 50 mg) = (1 / 3.2) = 1:3.2
- 1:3.2 --> 1 part solute to 3.2 total parts solute and solvent (31.25)(3.2) = 100 ml
- 100 ml total volume – 31.25 ml volume of what we started with = 68.75 ml
Method #3 Using the formula V1C1 = V2C2
Volume 1 = 31.25 ml
Concentration 1 = 16%
Volume 2 = x
Concentration 2 = 5%
(31.25 ml)(16%) = x(5%)
((31.25 ml)(16%)) / (5%) = x
100 ml = x --> 100 ml total volume needed – 31.25 ml starting out with = 68.75 ml
Understanding The Math Behind Dilutions (Dilution Factor vs Dilution Ratio):
Example: Doctor requests you to dilute 5 ml of Dextrose 50% 1:1 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:1 = 1 part volume drug to 1 part equal volume of diluent = 2 total parts drug and diluent
5 ml Dextrose 50% : 5 ml 0.9% NaCl
You’ll need 5 ml of 0.9% NaCl for a total volume of 10 ml drug and diluent
In the dilution ratio method:
1:1 = 1:2 = (1/2) = 0.50 = 50% --> you will dilute the initial drug concentration by 1/2
You’ll go from a 500 mg/ml solution to a 250 mg/ml solution
Check your work:
(50%)(50%) = 25% or 250 mg/ml and (2,500 mg) / (10 ml) = 250 mg/ml or 25%
Dilution Factor Method:
How much diluent will you need?
1:1 = 1 part drug to 1 total part drug and diluent
5 ml Dextrose 50% : 5 ml total volume
You’ll need 0 ml of 0.9% NaCl for a total of 5 ml drug only
In the dilution factor method, 1:1 ultimately is not a dilution:
1:1 = 1/1 = 1 = 100% --> 100% --> This is 100% drug concentration. No dilution is necessary
Your solution concentration of 500 mg/ml won’t change because no diluent was added
Check your work:
(50%)(100%) = 50% or 500 mg/ml and (2,500 mg) / (5 ml) = 500 mg/ml or 50%
Example: Doctor requests you to dilute 5 ml of Dextrose 50% 1:1 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:1 = 1 part volume drug to 1 part equal volume of diluent = 2 total parts drug and diluent
5 ml Dextrose 50% : 5 ml 0.9% NaCl
You’ll need 5 ml of 0.9% NaCl for a total volume of 10 ml drug and diluent
In the dilution ratio method:
1:1 = 1:2 = (1/2) = 0.50 = 50% --> you will dilute the initial drug concentration by 1/2
You’ll go from a 500 mg/ml solution to a 250 mg/ml solution
Check your work:
(50%)(50%) = 25% or 250 mg/ml and (2,500 mg) / (10 ml) = 250 mg/ml or 25%
Dilution Factor Method:
How much diluent will you need?
1:1 = 1 part drug to 1 total part drug and diluent
5 ml Dextrose 50% : 5 ml total volume
You’ll need 0 ml of 0.9% NaCl for a total of 5 ml drug only
In the dilution factor method, 1:1 ultimately is not a dilution:
1:1 = 1/1 = 1 = 100% --> 100% --> This is 100% drug concentration. No dilution is necessary
Your solution concentration of 500 mg/ml won’t change because no diluent was added
Check your work:
(50%)(100%) = 50% or 500 mg/ml and (2,500 mg) / (5 ml) = 500 mg/ml or 50%
Understanding The Math Behind Dilutions (Dilution Factor vs Dilution Ratio):
Example: Doctor requests you to dilute 1 ml of Dextrose 50% 1:2 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:2 = 1 part volume drug to 2 parts equal volume diluent = 3 total parts drug and diluent
1 ml Dextrose 50% : 2 ml 0.9% NaCl
You will need 2 ml of 0.9% NaCl for a total volume of 3 ml drug and diluent
In the dilution ratio method:
1:2 = 1:3 = (1/3) = 0.3333 = 33.33% --> you will dilute the initial drug concentration by 1/3
You’ll go from a 500 mg/ml solution to a 166.67 mg/ml solution
Check your work:
(50%)(33.33%) = 16.67 % or 166.67 mg/ml and (500 mg) / (3 ml) = 166.67 mg/ml or 16.67%
Dilution Factor Method:
How much diluent will you need?
1:2 = 1 part drug to 2 total parts drug and diluent
1 ml Dextrose 50% : 2 ml total volume
You will need 1 ml of 0.9% NaCl for a total volume of 2 ml drug and diluent
In the dilution factor method:
1:2 = (1/2) = 0.50 = 50% --> you will dilute the initial drug concentration by 1/2
You’ll go from a 500 mg/ml solution to a 250 mg/ml solution
Check your work:
(50%)(50%) = 25% or 250 mg/ml and (500 mg) / (2 ml) = 250 mg/ml or 25%
Example: Doctor requests you to dilute 1 ml of Dextrose 50% 1:2 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:2 = 1 part volume drug to 2 parts equal volume diluent = 3 total parts drug and diluent
1 ml Dextrose 50% : 2 ml 0.9% NaCl
You will need 2 ml of 0.9% NaCl for a total volume of 3 ml drug and diluent
In the dilution ratio method:
1:2 = 1:3 = (1/3) = 0.3333 = 33.33% --> you will dilute the initial drug concentration by 1/3
You’ll go from a 500 mg/ml solution to a 166.67 mg/ml solution
Check your work:
(50%)(33.33%) = 16.67 % or 166.67 mg/ml and (500 mg) / (3 ml) = 166.67 mg/ml or 16.67%
Dilution Factor Method:
How much diluent will you need?
1:2 = 1 part drug to 2 total parts drug and diluent
1 ml Dextrose 50% : 2 ml total volume
You will need 1 ml of 0.9% NaCl for a total volume of 2 ml drug and diluent
In the dilution factor method:
1:2 = (1/2) = 0.50 = 50% --> you will dilute the initial drug concentration by 1/2
You’ll go from a 500 mg/ml solution to a 250 mg/ml solution
Check your work:
(50%)(50%) = 25% or 250 mg/ml and (500 mg) / (2 ml) = 250 mg/ml or 25%
Understanding The Math Behind Dilutions (Dilution Factor vs Dilution Ratio):
Example: Doctor requests you to dilute 2 ml of Dextrose 50% 1:2 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:2 = 1 part volume drug to 2 parts equal volume of diluent = 3 total parts drug and diluent
2 ml Dextrose 50% : 4 ml 0.9% NaCl
You will need 4 ml of 0.9% NaCl for a total fluid volume of 6 ml drug and diluent
In the dilution ratio method:
1:2 = 1:3 = (1/3) = 0.3333 = 33.33% --> you will dilute the initial drug concentration by 1/3
You’ll go from a 500 mg/ml solution to a 166.67 mg/ml solution
Check your work:
(50%)(33.33%) = 16.67 % or 166.67 mg/ml and (1000 mg) / (6 ml) = 166.67 mg/ml or 16.67%
Dilution Factor Method:
How much diluent will you need?
1:2 = 1 part drug to 2 total parts drug and diluent
2 ml Dextrose 50% : 4 ml total volume
You will need 2 ml of 0.9% NaCl for a total fluid volume of 4 ml drug and diluent
In the dilution factor method:
1:2 = (1/2) = 0.50 = 50% --> you will dilute the initial drug concentration by 1/2
You’ll go from a 500 mg/ml solution to a 250 mg/ml solution
Check your work:
(50%)(50%) = 25% or 250 mg/ml and (1000 mg) / (4 ml) = 250 mg/ml or 25%
Example: Doctor requests you to dilute 2 ml of Dextrose 50% 1:2 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:2 = 1 part volume drug to 2 parts equal volume of diluent = 3 total parts drug and diluent
2 ml Dextrose 50% : 4 ml 0.9% NaCl
You will need 4 ml of 0.9% NaCl for a total fluid volume of 6 ml drug and diluent
In the dilution ratio method:
1:2 = 1:3 = (1/3) = 0.3333 = 33.33% --> you will dilute the initial drug concentration by 1/3
You’ll go from a 500 mg/ml solution to a 166.67 mg/ml solution
Check your work:
(50%)(33.33%) = 16.67 % or 166.67 mg/ml and (1000 mg) / (6 ml) = 166.67 mg/ml or 16.67%
Dilution Factor Method:
How much diluent will you need?
1:2 = 1 part drug to 2 total parts drug and diluent
2 ml Dextrose 50% : 4 ml total volume
You will need 2 ml of 0.9% NaCl for a total fluid volume of 4 ml drug and diluent
In the dilution factor method:
1:2 = (1/2) = 0.50 = 50% --> you will dilute the initial drug concentration by 1/2
You’ll go from a 500 mg/ml solution to a 250 mg/ml solution
Check your work:
(50%)(50%) = 25% or 250 mg/ml and (1000 mg) / (4 ml) = 250 mg/ml or 25%
Understanding The Math Behind Dilutions (Dilution Factor vs Dilution Ratio):
Example: Doctor requests you to dilute 2 ml of Dextrose 50% 1:3 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:3 = 1 part volume drug to 3 parts equal volume of diluent = 4 total parts drug and diluent
2 ml Dextrose 50% : 6 ml 0.9% NaCl
You will need 6 ml of 0.9% NaCl for a total fluid volume of 8 ml drug and diluent
In the dilution ratio method:
1:3 = 1:4 = (1/4) = 0.25 = 25% --> you will dilute the initial drug concentration by 1/4
You’ll go from a 500 mg/ml solution to a 125 mg/ml solution
Check your work:
(50%)(25%) = 12.5% or 125 mg/ml and (1000 mg) / (8 ml) = 125 mg/ml or 12.5%
Dilution Factor Method:
How much diluent will you need?
1:3 = 1 part drug to 3 total parts drug and diluent
2 ml Dextrose 50% : 6 ml total volume
You will need 4 ml of 0.9% NaCl for a total fluid volume of 6 ml drug and diluent
In the dilution factor method:
1:3 = (1/3) = 0.3333 = 33.33% --> you will dilute the initial drug concentration by 1/3
You’ll go from a 500 mg/ml solution to a 166.67 mg/ml solution
Check your work:
(50%)(33.33%) = 16.667% or 166.67 mg/ml and (1000 mg) / (6 ml) = 166.67 mg/ml or 16.667%
Example: Doctor requests you to dilute 2 ml of Dextrose 50% 1:3 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:3 = 1 part volume drug to 3 parts equal volume of diluent = 4 total parts drug and diluent
2 ml Dextrose 50% : 6 ml 0.9% NaCl
You will need 6 ml of 0.9% NaCl for a total fluid volume of 8 ml drug and diluent
In the dilution ratio method:
1:3 = 1:4 = (1/4) = 0.25 = 25% --> you will dilute the initial drug concentration by 1/4
You’ll go from a 500 mg/ml solution to a 125 mg/ml solution
Check your work:
(50%)(25%) = 12.5% or 125 mg/ml and (1000 mg) / (8 ml) = 125 mg/ml or 12.5%
Dilution Factor Method:
How much diluent will you need?
1:3 = 1 part drug to 3 total parts drug and diluent
2 ml Dextrose 50% : 6 ml total volume
You will need 4 ml of 0.9% NaCl for a total fluid volume of 6 ml drug and diluent
In the dilution factor method:
1:3 = (1/3) = 0.3333 = 33.33% --> you will dilute the initial drug concentration by 1/3
You’ll go from a 500 mg/ml solution to a 166.67 mg/ml solution
Check your work:
(50%)(33.33%) = 16.667% or 166.67 mg/ml and (1000 mg) / (6 ml) = 166.67 mg/ml or 16.667%
Understanding The Math Behind Dilutions (Dilution Factor vs Dilution Ratio):
Example: Doctor requests you to dilute 10 ml of Baytril 2.27% 1:5 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:5 = 1 part volume drug to 5 parts equal volume of diluent = 6 total parts drug and diluent
10 ml Baytril 2.27%: 50 ml 0.9% NaCl
You will need 50 ml of 0.9% NaCl for a total fluid volume of 60 ml drug and diluent
In the dilution ratio method:
1:5 = 1:6 = (1/6) = 0.1667 = 16.67% --> you will dilute the initial drug concentration by 1/6
You’ll go from a 22.7 mg/ml solution to a 3.78 mg/ml solution
Check your work:
(2.27%)(16.67%) = 0.378% or 3.78 mg/ml and (227 mg) / (60 ml) = 3.78 mg/ml or 0.378%
Dilution Factor Method:
How much diluent will you need?
1:5 = 1 part drug to 5 total part drug and diluent
10 ml Baytril 2.27% : 50 ml total volume
You will need 40 ml of 0.9% NaCl for a total fluid volume of 50 ml drug and diluent
In the dilution factor method:
1:5 = (1/5) = 0.20 = 20% --> you will dilute the initial drug concentration by 1/5
You’ll go from a 22.7 mg/ml solution to a 4.54 mg/ml solution
Check your work:
(2.27%)(20%) = 0.454% or 4.54 mg/ml and (227 mg) / (50 ml) = 4.54 mg/ml or 0.454%
Example: Doctor requests you to dilute 10 ml of Baytril 2.27% 1:5 with 0.9% NaCl
Dilution Ratio Method:
How much diluent will you need?
1:5 = 1 part volume drug to 5 parts equal volume of diluent = 6 total parts drug and diluent
10 ml Baytril 2.27%: 50 ml 0.9% NaCl
You will need 50 ml of 0.9% NaCl for a total fluid volume of 60 ml drug and diluent
In the dilution ratio method:
1:5 = 1:6 = (1/6) = 0.1667 = 16.67% --> you will dilute the initial drug concentration by 1/6
You’ll go from a 22.7 mg/ml solution to a 3.78 mg/ml solution
Check your work:
(2.27%)(16.67%) = 0.378% or 3.78 mg/ml and (227 mg) / (60 ml) = 3.78 mg/ml or 0.378%
Dilution Factor Method:
How much diluent will you need?
1:5 = 1 part drug to 5 total part drug and diluent
10 ml Baytril 2.27% : 50 ml total volume
You will need 40 ml of 0.9% NaCl for a total fluid volume of 50 ml drug and diluent
In the dilution factor method:
1:5 = (1/5) = 0.20 = 20% --> you will dilute the initial drug concentration by 1/5
You’ll go from a 22.7 mg/ml solution to a 4.54 mg/ml solution
Check your work:
(2.27%)(20%) = 0.454% or 4.54 mg/ml and (227 mg) / (50 ml) = 4.54 mg/ml or 0.454%
Understanding The Math Behind Dilutions (Dilution Ratio Method):
Patient and History:
A younger F canine presents to your clinic dull. Bloodwork reveals hypoglycemia. The patient weighs roughly 3.0 kg. It’s requested that you give a 0.5 ml/kg dextrose 50% bolus diluted 1:2 with 0.9% NaCl IV slowly
Relevant Patient Details:
Weight – 3.0 kg
Supply Details:
Drug – Dextrose 50%
Diluent – 0.9% NaCl
Calculations:
How much Dextrose will the patient receive?
(0.5 ml/kg)(3.0 kg) = 1.5 ml Dextrose 50%
How much diluent will you need?
1:1 = 1 part volume drug to 1 part equal volume of diluent = 2 total parts
1.5 ml Dextrose 50% : 1.5 ml 0.9% NaCl
You will need 1.5 ml 0.9% NaCl
What is your total volume of drug and diluent?
1.5 ml Dextrose 50% + 1.5 ml 0.9% NaCl = 3.0 ml total fluid volume
Patient and History:
A younger F canine presents to your clinic dull. Bloodwork reveals hypoglycemia. The patient weighs roughly 3.0 kg. It’s requested that you give a 0.5 ml/kg dextrose 50% bolus diluted 1:2 with 0.9% NaCl IV slowly
Relevant Patient Details:
Weight – 3.0 kg
Supply Details:
Drug – Dextrose 50%
Diluent – 0.9% NaCl
Calculations:
How much Dextrose will the patient receive?
(0.5 ml/kg)(3.0 kg) = 1.5 ml Dextrose 50%
How much diluent will you need?
1:1 = 1 part volume drug to 1 part equal volume of diluent = 2 total parts
1.5 ml Dextrose 50% : 1.5 ml 0.9% NaCl
You will need 1.5 ml 0.9% NaCl
What is your total volume of drug and diluent?
1.5 ml Dextrose 50% + 1.5 ml 0.9% NaCl = 3.0 ml total fluid volume
Fentanyl/Lidocaine/Ketamine CRI
Patient and History:
A middle-aged MN canine presents to your clinic very painful. The patient weighs 25 kg. It’s requested to start the patient on a fentanyl/lidocaine/ketamine CRI. The doctor requests that fentanyl run at 3 mcg/kg/hr, lidocaine at 30 mcg/kg/min, and ketamine at 0.5 mg/kg/hr.
Supply Details:
Fentanyl – 50 mcg/ml concentration. Lidocaine – 20 mg/ml concentration. Ketamine – 100 mg/ml concentration
Calculations:
What volume of each drug do we need to combine in one syringe for a 10 hour CRI?
Fentanyl
(3 mcg/kg/hr)(25 kg) = 75 mcg/hr
(75 mcg/hr)(1 ml/50 mcg) = 1.5 ml/hr
(1.5 ml/hr)(10 hr) = 15 ml Fentanyl
Lidocaine
(30 mcg/kg/min)(25 kg) = 750 mcg/min
(750 mcg/min)(60 min/1 hr) = 45,000 mcg/hr
(45,000 mcg/hr)(1 mg / 1000 mcg) = 45 mg/hr
(45 mg/hr)(1 ml/20 mg) = 2.25 ml/hr
(2.25 ml)(10 hr) = 22.5 ml Lidocaine
Ketamine
(0.5 mg/kg/hr)(25 kg) = 12.5 mg/hr
(12.5 mg/hr)(1 ml/100 mg) = 0.125 ml/hr
(0.125 ml/hr)(10 hr) = 1.25 ml Ketamine
What will be the FLK CRI rate?
1.5 ml/hr Fentanyl + 2.25 ml/hr Lidocaine + 0.125 ml/hr Ketamine = 3.875 ml/hr
Patient and History:
A middle-aged MN canine presents to your clinic very painful. The patient weighs 25 kg. It’s requested to start the patient on a fentanyl/lidocaine/ketamine CRI. The doctor requests that fentanyl run at 3 mcg/kg/hr, lidocaine at 30 mcg/kg/min, and ketamine at 0.5 mg/kg/hr.
Supply Details:
Fentanyl – 50 mcg/ml concentration. Lidocaine – 20 mg/ml concentration. Ketamine – 100 mg/ml concentration
Calculations:
What volume of each drug do we need to combine in one syringe for a 10 hour CRI?
Fentanyl
(3 mcg/kg/hr)(25 kg) = 75 mcg/hr
(75 mcg/hr)(1 ml/50 mcg) = 1.5 ml/hr
(1.5 ml/hr)(10 hr) = 15 ml Fentanyl
Lidocaine
(30 mcg/kg/min)(25 kg) = 750 mcg/min
(750 mcg/min)(60 min/1 hr) = 45,000 mcg/hr
(45,000 mcg/hr)(1 mg / 1000 mcg) = 45 mg/hr
(45 mg/hr)(1 ml/20 mg) = 2.25 ml/hr
(2.25 ml)(10 hr) = 22.5 ml Lidocaine
Ketamine
(0.5 mg/kg/hr)(25 kg) = 12.5 mg/hr
(12.5 mg/hr)(1 ml/100 mg) = 0.125 ml/hr
(0.125 ml/hr)(10 hr) = 1.25 ml Ketamine
What will be the FLK CRI rate?
1.5 ml/hr Fentanyl + 2.25 ml/hr Lidocaine + 0.125 ml/hr Ketamine = 3.875 ml/hr
Potassium Supplementation
Patient and History:
An older MN canine patient presents to your clinic febrile, tachycardic, tachypneic, hypotensive, dehydrated, and dull. He weighs 7.5 kg. No murmurs, crackles, or wheezes were ausculted. His bloodwork reveals a high lactate and hypokalemia. It’s requested that you to start the patient on intravenous fluid therapy at 80 ml/kg/day of LRS with 0.2 meq/kg/hour of KCL supplementation
Relevant Patient Details:
Weight – 7.5 kg
Supply Details:
Fluids – LRS 1000 ml bag
KCL – 2 meq/ml concentration
Calculations:
What fluid rate in ml/hr will the patient be on?
(80 ml/kg/day)(7.5 kg) = 600 ml/day
(600 ml/day)(1 day/24 hr) = 25 ml/hr
How many hours will a 1000 ml bag of LRS last the patient at that fluid rate?
(1000 ml)(1 hr/25 ml) = 40 hours
How much KCL will you need for supplementation?
(0.2 meq/kg/hr)(7.5 kg) = 1.5 meq/hr
(1.5 meq/hr)(40 hr) = 60 meq of KCL per liter
(60 meq)( 1 ml/2 meq) = 30 ml of KCL
Final fluid amounts (remember to remove 30 ml of LRS out of the bag first)
970 ml LRS and 30 ml (60 meq) of KCL
Patient and History:
An older MN canine patient presents to your clinic febrile, tachycardic, tachypneic, hypotensive, dehydrated, and dull. He weighs 7.5 kg. No murmurs, crackles, or wheezes were ausculted. His bloodwork reveals a high lactate and hypokalemia. It’s requested that you to start the patient on intravenous fluid therapy at 80 ml/kg/day of LRS with 0.2 meq/kg/hour of KCL supplementation
Relevant Patient Details:
Weight – 7.5 kg
Supply Details:
Fluids – LRS 1000 ml bag
KCL – 2 meq/ml concentration
Calculations:
What fluid rate in ml/hr will the patient be on?
(80 ml/kg/day)(7.5 kg) = 600 ml/day
(600 ml/day)(1 day/24 hr) = 25 ml/hr
How many hours will a 1000 ml bag of LRS last the patient at that fluid rate?
(1000 ml)(1 hr/25 ml) = 40 hours
How much KCL will you need for supplementation?
(0.2 meq/kg/hr)(7.5 kg) = 1.5 meq/hr
(1.5 meq/hr)(40 hr) = 60 meq of KCL per liter
(60 meq)( 1 ml/2 meq) = 30 ml of KCL
Final fluid amounts (remember to remove 30 ml of LRS out of the bag first)
970 ml LRS and 30 ml (60 meq) of KCL