Local Anesthetic Calculator
Table of contents
What is local anesthetic and how does it work?How to calculate the max dose of local anestheticLocal anesthetic maximum doses chartHow does the local anesthetic calculator workFAQsWelcome to the Omni local anesthetic calculator, a simple and convenient tool that can help you to determine the maximum allowable subcutaneous dose of amide-type local anesthetic without epinephrine.
Local anesthetics are a significant part of medical and dental practices, mainly due to their efficacy and good safety margin; however, it is essential to be cautious about the maximum allowable subcutaneous dose to avoid adverse health consequences. Come along to refresh your memory regarding the local anesthetic maximum doses chart and some of the anesthetic-related questions, such as:
- What is local anesthetic?
- How do I calculate the maximum dose of local anesthetic (e.g., bupivacaine max dose)?
- How does the maximum local anesthetic dose calculator work? And more!
❗ The maximum local anesthetic dose calculator cannot be used as a substitute for clinical knowledge and consultation with a medical specialist. If any health condition bothers you, consult a physician. Also, note that the calculator is not a primary guide for dosing; it only helps you determine the maximum allowable subcutaneous dose of anesthetic without epinephrine.
We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice, diagnosis, or treatment. All information on this website is for informational purposes only and is not intended to and should not serve as a substitute for medical consultation. Always seek the advice of a health provider.
What is local anesthetic and how does it work?
Let's start from the beginning to refresh your memory – what is local anesthetic? Local anesthetic is a medication used to prevent neural conductions, in other words, to stop the nerves in the affected area from sending signals to the brain. Hence, local anesthetics are mainly used for treating painful conditions, and alleviating pain and discomfort during uncomfortable medical procedures (e.g., biopsy, removal of warts, tooth extraction, etc.).
Local anesthetics have various potency (with concentrations ranging from 0.25 to 4%) and the duration of action – the greater protein binding is correlated with a longer period of anesthesia, i.e., the neural blockade. For instance, compared to bupivacaine, mepivacaine exhibits a lower percentage of protein binding and, therefore, has a shorter duration of action.
It is also important to note that local anesthetics can lead to both systemic toxicity (which is dose-dependent) and local toxicity (which could be caused by the irritating nature of a solution). Consequently, it is paramount to be cautious of the maximum allowable dose to avoid serious health complications.
Keep reading to learn how to calculate the max dose of local anesthetic!
How to calculate the max dose of local anesthetic
To calculate the maximum allowable dose in mg, use the formula below:
dose(mg) = subQ dose, mg/kg × weight
where:
dose(mg)— Maximum allowable subcutaneous anesthetic dose according to your weight in mg;subQ dose, mg/kg— Expresses the maximum allowable subcutaneous dose of anesthetic per kg (i.e., mg/kg), as presented in the table below; andweight— Your weight in kg.
For calculating the maximum allowable dose in ml, use the following formula:
dose(ml) = subQ dose, mg/kg × (weight / 10) × (1 / concentration)
where:
dose(ml)— Maximum allowable subcutaneous anesthetic dose according to your weight in ml; andconcentration— Anesthetic concentration percentage.
For example, let's calculate the lidocaine dose.
💡 Do you think the local anesthetic calculator is helpful? Check out other health-related calculators, such as the injury severity score calculator to assess the trauma severity of your patient and Aldrete score calculator to evaluate your patient's recovery from anesthesia.
Local anesthetic maximum doses chart
You can find the maximum allowable subcutaneous dose per kg for each local anesthetic below:
Drug | mg/kg | Should not exceed |
|---|---|---|
Bupivacaine | 2 | 175 mg |
Lidocaine | 4.5 | 300 mg |
Mepivacaine | 4.4 | 400 mg |
Ropivacaine | 3 | 225 mg |
How does the local anesthetic calculator work
Using the maximum local anesthetic calculator is relatively straightforward; all you have to do is:
- Enter a patient's weight in the unit of your convenience.
- Choose the anesthetic (i.e., bupivacaine, lidocaine, mepivacaine, and ropivacaine).
- Chose the concentration of drug (0.25%, 0.5%, 0.75, 1%, 1.5%, 2%, 3%, or 4%).
- That's all! The calculator will determine the maximum allowable subcutaneous dose of lidocaine without epinephrine in mg and ml.
How do I calculate the maximum allowable dose of subcutaneous ropivacaine in mg?
To calculate the maximum allowable subcutaneous ropivacaine dose in mg without epinephrine:
- Determine the weight of a patient in kg.
- Multiply the value in kg by the maximum allowable subcutaneous dose per kg, in this case: 3. For instance, if the patient weighs 60 kg, multiply the value by 3.
- Voila! For a patient weighing 60 kg, the maximum allowable subcutaneous dose of ropivacaine is 180mg.
What is the maximum allowable volume of subcutaneous mepivacaine based on weight?
The maximum allowable volume of subcutaneous mepivacaine per kg (i.e., mg/kg) without epinephrine is 4.4. However, a single subcutaneous dose of mepivacaine that a patient can receive should not exceed 400 mg.
What is the difference between bupivacaine, lidocaine, mepivacaine and ropivacaine?
Some differences between Bupivacaine, Lidocaine, Mepivacaine, and Ropivacaine lie in their relative potency and duration of action. For instance, Bupivacaine and Ropivacaine have a more prolonged action duration than Lidocaine and Mepivacaine. Additionally, of the four, Lidocaine has the lowest potency.
Which anesthetic is preferable for lengthy medical procedures?
Although bupivacaine is a long-acting amide local anesthetic with high efficacy for lengthy procedures, research shows it is one of the most painful anesthetics during injection (after etidocaine). A solution to this could be to first utilize a less irritating agent (e.g., lidocaine), then provide an anesthetized location with bupivacaine to extend analgesia for a longer period.