From the Guidelines
For a 15kg child, the maximum safe dose of 2% lidocaine with adrenaline is 105mg, which translates to 5.25ml maximum volume (105mg ÷ 20mg/ml = 5.25ml). The calculation is based on the maximum recommended dose of 7mg/kg for lidocaine with adrenaline, as stated in the most recent guidelines 1. When administering, it's crucial to inject slowly and aspirate before injection to avoid intravascular administration. Monitoring the child for signs of toxicity, including central nervous system effects (agitation, confusion, seizures) and cardiovascular effects (hypotension, arrhythmias), is also essential. The addition of adrenaline (epinephrine) to lidocaine prolongs the anesthetic effect and reduces systemic absorption by causing local vasoconstriction, which allows for a higher maximum dose compared to plain lidocaine. Some key points to consider when using local anesthetics in pediatric patients include:
- Using the minimum effective dose needed for the procedure
- Avoiding excessive doses on mucosal surfaces where systemic uptake and possible toxicity could result
- Staying within the manufacturer’s recommendations regarding allowable surface area application
- Being aware of the potential for enhanced sedative effects when local anesthetic drugs are used in combination with other sedatives or opioids, as noted in the guidelines 1. It's also important to note that the guidelines recommend lower doses when injecting into vascular tissues and that doses of amides should be decreased by 30% in infants younger than 6 months, as stated in the guidelines 1.
From the Research
Maximum Dose of 2% Lidocaine with Adrenaline for a 15kg Child
- The maximum safe dose of lidocaine for children is not explicitly stated in the provided studies, but we can look at the recommended doses for children in general.
- A study on tumescent lidocaine anesthesia 2 suggests that the maximum safe dosage of lidocaine is 28 mg/kg without liposuction and 45 mg/kg with liposuction, but this is for subcutaneous injection of dilute lidocaine and may not be directly applicable to a 15kg child.
- Another study on plasma lidocaine levels following airway topicalisation for paediatric microlaryngobronchoscopy 3 suggests that a dose of 5 mg/kg lidocaine is considered appropriate for paediatric airway topicalisation.
- Based on this information, the maximum dose of 2% lidocaine with adrenaline that can be administered to a 15kg child would be approximately 75mg (5mg/kg x 15kg), assuming a dose of 5mg/kg is used.
Considerations for Administration
- It is essential to note that the dose of lidocaine should be carefully calculated and administered, taking into account the child's weight, age, and medical history.
- The presence of adrenaline (epinephrine) can affect the systemic absorption of lidocaine, as shown in a study on the pharmacokinetics of single-dose lidocaine and epinephrine following iontophoretic administration to the tympanic membrane 4.
- The studies provided do not give a clear answer to the maximum dose of 2% lidocaine with adrenaline for a 15kg child, and it is crucial to consult with a medical professional for specific guidance on administering local anesthetics to children 5, 6.