Aesthetics 2 Flashcards

Question

Local Anesthetics: Ester type drugs

Answer 1

Benzocaine Chloroprocaine Cocaine Procaine

Answer 2

``` Bupivacaine Etidocaine Lidocaine Mepivacaine Prilocaine Ropivacaine ```

Answer 3

Amine, weak base Ionized form predominates at low pH Inflammation/acidosis decrease tissue pH

Answer 4

``` • Reversible inhibition of axonal nerve conduction by binding to Na+ channel • Bind on internal site of Na+ channel • Ionized anesthetic has more affinity for channel • Prolongs inactivation state of channel • Once bound, drugs greatly restrict conformational changes that underlie activation ``` ``` Small, unmyelinated fibers more easily anesthetized: autonomic and sensory nerves blocked easier than motor neurons: – Pain – Temperature – Touch – Sympathetic vasomotor activity inhibited before proprioception – Muscle tone – Somatic motor activity – Nerves recover in reverse order ```

Answer 5

``` • Duration of action – Determined by rate of diffusion/absorption (determined by chemical properties, local pH, blood flow) • Metabolism – Ester type drugs: Esterases, plasma cholinesterases – Amide type drugs: Amidases, liver – Urinary excretion of metabolites ```

Answer 6

• If absorbed into systemic circulation, local anesthetics can have: – CNS effects • CNS stimulation (restlessness, tremor, euphoria, clonic convulsions) [inhibition of inhibitory neurons] followed by CNS inhibition (sedation, drowsiness) • Headache, paresthesias, nausea, seizures followed by coma • Death occurs by respiratory failure – CV effects • Hypotension • Cardiac depression – Hypersensitivity reactions • Allergic dermatitis or asthmatic attack • Usually due to ester anesthetics due to metabolism to PABA (allergic)

Answer 7

• Vasoconstrictors prolong effects of local anesthetics • Epinephrine, phenylephrine • Slows rate of absorption; decreases drug plasma concentration • Less likelihood of side effects • Should not be used in anesthetizing tissues with end arteries (fingers, toes, ears, nose, penis). Sympathomimetic amines increase oxygen consumption of tissue-coupled with vasoconstriction-hypoxia results-potential tissue damage. Gangrene could occur. • Should not be used in patients in whom adrenergic stimulation may have an adverse effect (hypertensive, ventricular arrhythmias)

Answer 8

Topical Anesthesia – Skin (Benzocaine) – Mucous membranes, cornea (Tetracaine, lidocaine, cocaine) – Epinephrine – no significant local effect; can’t penetrate mucous membranes Mixtures of Anesthetics: – LET: Lidocaine, Epinephrine, Tetracaine – EMLA: Eutectic mixture of lidocaine and others

Answer 9

– Anesthetic injected directly into tissues – Dental procedures, minor surgical procedures – Epinephrine doubles duration of anesthesia – Disadvantage: Large amounts of drug used to anesthetize small areas

Answer 10

– Small electrical current forces anesthetic into a tissue – Used in dentistry

Answer 11

``` • Administered in a series of injections to form a wall of anesthesia encircling operative field • Advantage: Less drug for greater area of anesthesia than infiltration ```

Answer 12

• Injected into or adjacent to a nerve or nerve plexus • Example: (Brachial plexus – upper extremity; Intercostals – anterior abdominal wall; Cervical plexus – neck) • Produces large area of anesthesia with small amount of drug; even better than field block or infiltration

Answer 13

``` • Injection into lumbar subarachnoid space below the level at which the cord terminates • Spread of anesthetic in CSF controlled by horizontal tilt of patient and specific gravity of anesthetic. Hyperbaric solutions used (density > CSF) • Can be used for people contraindicated for general, for lower body (knee etc) surgery ```

Answer 14

``` • Injection into lumbar or caudal epidural space • Bupivacaine used for labor/delivery • Absorbed into systemic circulation; has to be monitored closely to prevent cardiac depression and neurotoxicity in mother/neonate ```

Answer 15

• Ester type local anesthetic • Only local anesthetic that causes vasoconstriction • Controlled substance; subject to abuse • Used topically to anesthetize the internal structures of the nose, ear, throat

Answer 16

* 1st synthetic local anesthetic - Ester * Short duration (20-45 min) * Parenteral administration * Metabolized to PABA

Answer 17

``` • Ester • Pruritus • Eardrops • Teething/gum pain • Supplied as lozenges for pharyngitis • Treatment of sunburn ```

Answer 18

• Amide – Metabolized in liver – Monoethylglycinexylidide & glycinexylidine • Topical/parenteral administration • Infiltration, nerve block, epidural, spinal anesthesia • Intermediate duration (60-120 min)

Answer 19

``` • Lidocaine congener • Metabolized to O-toluidine Can cause methemoglobinemia • Limited to topical/infiltration anesthesia • Half life > Lidocaine ```

Answer 20

• Obstetrical anesthesia • Cardiotoxic – Decreases threshold for tachycardia • Half life ~ 300 minutes