Calculate the mg/mL concentration quickly from the percentage by moving the decimal point 1 place to the right. In this example, 0.5% bupivacaine = 5 mg/ml buipivacaine.

Epinephrine induced vasoconstriction reduces systemic side effects of lidocaine and allows a greater dose of lidocaine to be given.

Yes. "Supplementing a local anesthetic with epinephrine in penis operations has many advantages, including high patient satisfaction, relatively painless infiltration, low complication rates, improved view of the operating field, and an extended effect of anesthetics with a prolonged reduction in pain. Because of the anatomy of the organ, there is no risk of necrosis related to using a subcutaneous penile ring block. Thus the view that epinephrine should not be used in penis procedures is obsolete." – See Schnabl et al. 2014

Max dose of bupivacaine with epinephrine = 3 mg/kg x 70 = 210 mg.

Concentration of 0.5% bupivacaine = 5 mg/ml; 210 mg / (5 mg/ml)= 42 ml

Amide. You can tell because it has 2 "i"s in its name.

CASE (cont.) 3 Minutes after injecting 20 ml of local anesthetic, the surgeon tests the operative site and patient flinches.

• Speed of onset is related to pKa (i.e. degree of ionization)

• Potency is related to lipid solubility.
• Duration of action is related to protein binding.

CASE (cont.) The surgeon decides to use some 2% lidocaine. Shortly afterward, patient reports feeling ill.

CNS: Lightheadedness, tinnitus, tongue numbness (CNS Excitation) → CNS depression, seizure → coma

Cardiovascular (Requires much greater doses): Dose dependent blockage of Na Channels → disruption of cardiac conduction system → bradycardia, ventricular dysrhythmias, decreased contractility, cardiovascular collapse/circulatory arrest.

Bupivacaine is more cardiotoxic than lidocaine.

Extremely rare.

Lidocaine requires an alkaline environment to function. This is because the basic environment creates the non-acidic form lidocaine must take in order to cross the neuronal membrane. Infections create an acidic environment, which neutralizes local anesthetics.