Pharm - Neuro - Anesthetic Agents

Front 1

Characteristics of general anesthesia

Back 1

Global but reversible.

Can induce...
amnesia
analgesia
immobility in response to a surgical incision
control of unwanted autonomic reflexes
unconsciousness.

Front 2

Can an unconscious/amnestic pt under general anesthesia be experiencing pain?

Back 2

No, technically.

Pain requires an emotional experience of the sensation of actual/potential tissue damage.

Unconscious people can't have an unpleasant emotional experience.

Front 3

5 steps of general anesthesia

Back 3

induction
maintenance/monitoring
supplementation
emergence
postoperative pain management

Front 4

Induction

Back 4

first stage of general anes
fat sol drugs (thiopental or propofol)
fast unconsciousness and rapid emergence.
also given non-depol muscle relaxants to facilitate stillness and tracheal intubation.

Front 5

examples of agents that can do induction

Back 5

thiopental, propofol - fat sol

Front 6

Where does general anes deviate from lethal injection?

Back 6

same drugs, but no attempt to maintain airway support and protection from aspiration.

Front 7

When does awareness under anes occur?

Back 7

Amnesia component of the general ANES fails but the muscle relaxants still work.

Front 8

Maintenance component of general anes

Back 8

Inhalation agents (hydrocarbons)
Desflurane, isoflurane, sevoflurane, NO (weak potency)
Efficacy is measured via end title - which is the percentage of drug measured when the pt exhales.

Front 9

Inhalation agents

Back 9

Desflurane, isoflurane, sevoflurane.
NO too - but it is weak. Need 104% end title to get anes effects. In contrast, sevoflurane needs only 2%.

Death from NO due to hypoxia.

Front 10

Supplementation

Back 10

third part of general anes

Bc high dose inhalation agents gives bad SE, must give IV of opioids, alpha 2 agonists, or benzos.

Fentanyl is the most common one used (lipid sol quick acting opioid).

Dexmedetomidine also used - alpha 2 agonist.

Midazolam - best benzo sedative.

Front 11

Max time a pt can lay idle in an ER

Back 11

45 minutes is really pushing it. Want the pt out after surgery ASAP.

Front 12

Regional anes

Back 12

Note - can be used to keep pt comfortable in recovery room.

So it can be used as the sole anesthetic or in conjunction with sedation or full general anes.

Front 13

Regional anes - mech of action

Back 13

Block Na channels usually (basically stop nerve conduction)

Front 14

Common peripheral ergional anes techniques

Back 14

Brachial plexus block, femoral nerve block, ankle block, sciatic nerve block.

Front 15

Common neuraxial blocks

Back 15

Spinal and epidiral.

Front 16

Mechanism of spinal anesthesia

Back 16

A type of regional

Injected into CSF so you need very small amt.

Front 17

SE of local anes

Back 17

Systemic toxicity causing sz and cardiac arrest.

Front 18

Structure of local anes

Back 18

Weak bases with aromatic ring and hydrocarbon chain. The linkage of these two is what determines if it is an amide or ester.

Front 19

Commmon amides

Back 19

Lidocaine and bupivacaine

Front 20

Common esters

Back 20

Tetracaine and chloroprocaine.

Metab in blood by plasma esterases.

***esther kim, on all 4s (tetra), cleaning with chlorox.

Front 21

Local anes agents in order of toxicity (highest to lowest)

Back 21

Bupivacaine (cardiac arrest) --> lidocaine (sz) --> chloroprocaine

Trade-off toxicity with duration of action

Chloroprocaine is metab by plasma cholinesterases in the blood.

Front 22

Where in the nerve membrane do local anes agents bind?

Back 22

Near the Na+ channel on the inside part of the membrane.

Duration of action is dependent on strength of protein binding in the membrane,

With inflammation, the environement is acidic, so the weak base anes agent will be ionized and unable to penetrate membrane. So you need to do a nerve block in this case.

Front 23

Reasons to use a good regional anesthetic

Back 23

Can keep the pt awake.

Or even if combining with general, you will need less for the general (less change of morbidity and SE of opioids) and will help with postop analgesia.

Front 24

For ACL repair, this is the regimen:

Back 24

Preoperative sedation, anxiolysis with 2 mg of midazolam.

Performance of a femoral nerve block with 25 ml of 0.5% bupivacaine (125 mg).

Induction with 3-5 mg/kg of propofol, 100 ug of fentanyl (you are now completely asleep).

Maintenance of general anesthesia with 1.5% end tidal sevoflurane (duration approximately 3 hours).

Administration of 30 mg of toradol (NSAID) at the end of the case.