anesthesia

Question 1

what is the MAC

Answer 1

concentration of inhaled anesthetic as a percent of air at which 50% of patients do not respond to surgical stimulus. MACs are additive and typically lower in the elderly.

Question 2

what does lipid solubility have to do with MAC

Answer 2

the more lipid soluble the lower the MAC and thus the more potent

Question 3

what is the blood: gas ratio

Answer 3

the smaller the ratio the more drug that gets into the CNS

Question 4

what to remember about blood:gas

Answer 4

the more soluble in the blood, the less action the anesthetic will have. the gaseous form is the free drug and thus the active drug. also determines the recovery period.

• high blood:gas = slow onset and recovery
• low blood:gas = fast onset and recovery

Question 5

thiopental characteristics and uses

Answer 5

barbiturate used for induction. highly lipid soluble, fast onset and recovery. short acting due to redistribution

Question 6

midazolam characteristics and uses

Answer 6

benzo used for preop sedation. induction for outpatient. causes anterograde amnesia. can depress the respiratory system.

Question 7

what is the antidote for midazolam

Answer 7

flumazenil

Question 8

propofol characteristics and uses

Answer 8

induction and maintenance of anesthesia. antiemetic, CNS and cardiac depressant.

Question 9

fentanyl characteristics and uses

Answer 9

opiate used for induction and maintenance. depresses respiratory function. central analgesics.

Question 10

ketamine class and mechanism

Answer 10

dissociative anesthetic. NMDA receptor antagonist. analogue of phencyclidine

Question 11

ketamine uses

Answer 11

induction.

Question 12

what are the SE of ketamine

Answer 12

cardiovascular stimulation, increased intracranial pressure. emergent delirium, hallucinations, nightmares the night after use

Question 13

what is the mechanism for local anesthetics

Answer 13

target is the inactivated sodium channels. slows recovery and prevents propagation of AP

Question 14

discuss the fact that local anesthetics are weak bases

Answer 14

they need to be in the unionized form to get into the target tissue. this means they need to be in a basic environment and deprotonated. when they get through the membrane they need to be protonated for action.

Question 15

what are the two types of local anathetics

Answer 15

ester and amides

Question 16

esters

Answer 16

procaine, cocaine, benzocaine. metabolized through the esterases and thus depend on genetic polymorphisms.

Question 17

amides

Answer 17

lidocaine, bupivacaine, mepivacaine. they are metabolized through the liver amidases and thus if poor liver function then they cannot be used.

Question 18

what is the rule in locals to know use

Answer 18

if I before caine then amide and watch for liver function

Question 19

SE of the local

Answer 19

neurotoxic, cardiotoxic, allergies (PABA)

Question 20

what are locals always administered with to keep them local

Answer 20

alpha-1 agonists for vasoconstriction