7 Essential Nursing Dosage Calculations Cheat Sheets

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As a nursing professional, you know how critical it is to accurately calculate medication dosages for your patients. One small mistake can lead to serious consequences, including adverse reactions, hospitalizations, and even fatalities. To help you stay on top of your game, we've compiled 7 essential nursing dosage calculations cheat sheets that you can refer to whenever you need to.

Calculating medication dosages can be a daunting task, especially for new nurses or those who are still getting familiar with the nuances of pharmacology. With so many different medications, dosages, and administration routes, it's easy to get overwhelmed. However, with practice and the right tools, you can master the art of dosage calculations and provide safe and effective care to your patients.

In this article, we'll cover the top 7 nursing dosage calculations cheat sheets that you should know, including formulas, examples, and practical tips to help you become a pro at calculating medication dosages.

1. Body Surface Area (BSA) Calculation

Body surface area (BSA) is a critical calculation in nursing, especially when administering medications that are based on a patient's body size. The BSA formula is used to calculate the surface area of a patient's body, which is then used to determine the correct dosage of medication.

BSA Formula:

BSA (m²) = √( (HT x WT) / 3600 )

Where:

• HT = height in centimeters
• WT = weight in kilograms

For example, let's say you have a patient who is 170 cm tall and weighs 60 kg. To calculate the BSA, you would plug in the values as follows:

BSA (m²) = √( (170 x 60) / 3600 ) = 1.7 m²

Once you have the BSA, you can use it to calculate the correct dosage of medication.

Example Medication Calculation Using BSA

Let's say you need to administer a medication that is dosed at 10 mg/m². Using the BSA calculation above, you would multiply the dosage by the patient's BSA:

Dosage = 10 mg/m² x 1.7 m² = 17 mg

2. IV Flow Rate Calculation

IV flow rate calculations are crucial in nursing, especially when administering medications or fluids via an IV line. The flow rate calculation determines how quickly the medication or fluid should be administered.

Flow Rate Formula:

Flow Rate (mL/hr) = (Total Volume x Desired Time) / 60

Where:

• Total Volume = total volume of medication or fluid to be administered
• Desired Time = desired time of administration in minutes

For example, let's say you need to administer 1000 mL of fluid over 8 hours. To calculate the flow rate, you would plug in the values as follows:

Flow Rate (mL/hr) = (1000 mL x 8 hours) / 60 = 125 mL/hr

Example Medication Calculation Using IV Flow Rate

Let's say you need to administer a medication that is dosed at 20 mL/hr. Using the flow rate calculation above, you would set the IV pump to deliver the medication at a rate of 20 mL/hr.

3. Oral Medication Calculation

Oral medication calculations are straightforward and involve calculating the correct dosage of medication based on the patient's weight or body surface area.

Oral Medication Formula:

Dosage = (Desired Dosage x Weight) / (Body Surface Area x Concentration)

Where:

• Desired Dosage = desired dosage of medication
• Weight = patient's weight in kilograms
• Body Surface Area = patient's body surface area in square meters
• Concentration = concentration of medication in mg/mL

For example, let's say you need to administer a medication that is dosed at 10 mg/kg/day. Using the oral medication formula, you would plug in the values as follows:

Dosage = (10 mg/kg/day x 60 kg) / (1.7 m² x 50 mg/mL) = 350 mg

Example Medication Calculation Using Oral Medication Formula

Let's say you need to administer a medication that is dosed at 20 mg/kg/day. Using the oral medication formula above, you would calculate the dosage as follows:

Dosage = (20 mg/kg/day x 70 kg) / (2.1 m² x 25 mg/mL) = 560 mg

4. Pediatric Medication Calculation

Pediatric medication calculations involve calculating the correct dosage of medication for children based on their age, weight, or body surface area.

Pediatric Medication Formula:

Dosage = (Desired Dosage x Weight) / (Age x Concentration)

Where:

• Desired Dosage = desired dosage of medication
• Weight = child's weight in kilograms
• Age = child's age in years
• Concentration = concentration of medication in mg/mL

For example, let's say you need to administer a medication that is dosed at 10 mg/kg/day to a 5-year-old child who weighs 20 kg. Using the pediatric medication formula, you would plug in the values as follows:

Dosage = (10 mg/kg/day x 20 kg) / (5 years x 50 mg/mL) = 40 mg

Example Medication Calculation Using Pediatric Medication Formula

Let's say you need to administer a medication that is dosed at 20 mg/kg/day to a 10-year-old child who weighs 40 kg. Using the pediatric medication formula above, you would calculate the dosage as follows:

Dosage = (20 mg/kg/day x 40 kg) / (10 years x 25 mg/mL) = 80 mg

5. Insulin Calculation

Insulin calculations involve calculating the correct dosage of insulin based on the patient's blood glucose level and insulin sensitivity.

Insulin Formula:

Dosage = (Blood Glucose Level x Insulin Sensitivity Factor) / (Insulin Concentration x Time)

Where:

• Blood Glucose Level = patient's blood glucose level in mg/dL
• Insulin Sensitivity Factor = patient's insulin sensitivity factor (usually 1-5)
• Insulin Concentration = concentration of insulin in units/mL
• Time = desired time of administration in hours

For example, let's say you need to administer insulin to a patient with a blood glucose level of 200 mg/dL and an insulin sensitivity factor of 2. Using the insulin formula, you would plug in the values as follows:

Dosage = (200 mg/dL x 2) / (100 units/mL x 2 hours) = 10 units

Example Medication Calculation Using Insulin Formula

Let's say you need to administer insulin to a patient with a blood glucose level of 300 mg/dL and an insulin sensitivity factor of 3. Using the insulin formula above, you would calculate the dosage as follows:

Dosage = (300 mg/dL x 3) / (50 units/mL x 3 hours) = 15 units

6. Heparin Calculation

Heparin calculations involve calculating the correct dosage of heparin based on the patient's weight and desired anticoagulation level.

Heparin Formula:

Dosage = (Desired Anticoagulation Level x Weight) / (Heparin Concentration x Time)

Where:

• Desired Anticoagulation Level = desired anticoagulation level (usually 1-5)
• Weight = patient's weight in kilograms
• Heparin Concentration = concentration of heparin in units/mL
• Time = desired time of administration in hours

For example, let's say you need to administer heparin to a patient who weighs 70 kg and requires a desired anticoagulation level of 2. Using the heparin formula, you would plug in the values as follows:

Dosage = (2 x 70 kg) / (100 units/mL x 2 hours) = 7 units

Example Medication Calculation Using Heparin Formula

Let's say you need to administer heparin to a patient who weighs 50 kg and requires a desired anticoagulation level of 3. Using the heparin formula above, you would calculate the dosage as follows:

Dosage = (3 x 50 kg) / (50 units/mL x 3 hours) = 10 units

7. IV Push Medication Calculation

IV push medication calculations involve calculating the correct dosage of medication to be administered via an IV push.

IV Push Medication Formula:

Dosage = (Desired Dosage x Volume) / (Concentration x Time)

Where:

• Desired Dosage = desired dosage of medication
• Volume = volume of medication to be administered in mL
• Concentration = concentration of medication in mg/mL
• Time = desired time of administration in minutes

For example, let's say you need to administer a medication that is dosed at 10 mg/mL via an IV push. Using the IV push medication formula, you would plug in the values as follows:

Dosage = (10 mg/mL x 5 mL) / (50 mg/mL x 5 minutes) = 2 mg

Example Medication Calculation Using IV Push Medication Formula

Let's say you need to administer a medication that is dosed at 20 mg/mL via an IV push. Using the IV push medication formula above, you would calculate the dosage as follows:

Dosage = (20 mg/mL x 10 mL) / (25 mg/mL x 10 minutes) = 8 mg

In conclusion, mastering nursing dosage calculations is crucial for providing safe and effective care to patients. By using these 7 essential nursing dosage calculations cheat sheets, you can ensure that you're administering medications accurately and confidently.