Lidocaine

• Also known as Xylocaine and sometimes Lignocaine
• Local Anesthetic
• Antiarrhythmic drug – for ventricular arrhythmias (but Amiodarone is mostly used for this)
• The first Amino-Amide local anesthetic
• First marketed in 1949
• Alters signal conduction in neurons by blocking the fast voltage gated sodium channels in the neuronal cell membrane.  Thus prevents depolarization of the postsynaptic neuron.

Esters and Amide local anesthetics – way to remember which

• Esters have only one “i” in the name: Procaine, Cocaine
• Amides have over two “i”s in the name:  Lidocaine, Bupivicaine, Prilocaine.

Contraindications to using Lidocaine

• Porphyria – rare inherited or aquired disorders of enzymes which produce porphyrins and heme resulting in neurological complications (abdominal pain, vomiting, neuropathy)  or skin problems.
• Heme is one the best known porphyrin the pigment in red blood cells and cofactor of the protein hemoglobin.
• Porphyrin means purple

Lidocaine overdose

• can occur with topical creams
• Treatment with IV lipid emulsions can reverse the effects of lidocaine toxicity.

Adverse Effects

• Rare
• Allergic reactions rare.
• CNS (central nervous system) and cardiovascular effects
• CNS at lower doses, cardiac at higher doses
• CNS: nervousness, tingling around mouth, tinnitus, tremor, dizziness, blurred vision, seizures, depression, loss of consciousness
• Cardiovascular effects: hypotension, bradycardia, arrhythmias

Insensitivity to Lidocaine

• Genetic
• Exists in some patients with ADHD and Ehlers-Danlos syndrome

Lidocaine Safety and Toxic doses

• Particular care in calculating maximum safe dose for young children
• Peak blood levels of lidocaine usually occur 10-25 minutes after injection – the point at which toxic effects are likely to be seen.
• Maximum safe dose of lidocaine without vasoconstrictor (ie. epinephrine) is 3-4.5 mg/kg (duration of action 1 hour).  No more than 300 mg (30 cc’s of 1% Lidocaine) at once.
• Maximum safe dose of lidocaine with vasoconstrictor is 5-7 mg/kg (duration of action 2-6 hours)

How to calculate Maximum safe doseage of Lidocaine

• You need to know that 1% Lidocaine solution is 10 mg/mL
• Example Calculation for a 70 Kg man:  Lido 1% with Epi:  keep under 7 mg/Kg.  7×70 = 490 mg for 70 kg man.  Divide 490 mg by 10 mg/ML = 49 ml.

How is this important to our Plastic Surgical and Acupuncture practice?

• We use lidocaine in plastic surgical procedures – topical and subcutaneous – for removal of moles, injection of fillers such as Juvederm, and sometimes for Botox.
• I also use injected  lidocaine as part of some trigger point deactivation practices in acupuncture.

Cosmetic Procedures at Surgical Artistry which may use Lidocaine

• Liposuction – tumescent lidocaine
• Mole removal – injected subcutaneous local lidocaine
• Fillers – Juvederm – some formulations have lidocaine within the product
• Fillers and Botox – sometimes we use topical lidocaine
• Face Veins – sometimes we use topical lidocaine
• Minor office surgeries – we use injected lidocaine in the subcutaneous level