lecture 14

Question 1

what is MAC

Answer 1

minimum alveolar concentration

the alveolar concentration of gas at which 50% of patients do not respond to a surgical stimulus

the MAC for NO is 1.04 atm or 104% - so patients would need to breathe pure NO for 50% of them to fail to respond to a surgical stimulus

Question 2

a complete _ produces:
unconsciousness
unresponsiveness
amnesia
immobility
autonomic stability 

Diethyl ether is example but has drawback of being very flamable

Answer 2

anesthetic

modern general anesthesia tends toward using a combo of drugs, taking advantage of the best aspects of each

Question 3

general anesthetics contain other drugs

_ minimize salivation, laryngospasm (block vagal stim) reflex bradycarda

Answer 3

antimuscarinics

Question 4

general anesthetics contain other drugs

preop pain relief, sedation, amnesia, anxiety

Answer 4

various analgesics

Question 5

general anesthetics contain other drugs

reduce anesthetic requirement, provide analgesia

Answer 5

NO and/or opioids

Question 6

general anesthetics contain other drugs

paralyze skeletal muscle - not diaphragm

Answer 6

anti-nicotinics

Question 7

there is a very strong correlation between solubility in olive oil and anestheic potency

Answer 7

anesthesia begins when the anesthetic reaches a critical concentration in membrane lipids

Question 8

MOA of general anesthesia

Answer 8

membrane lipid based theories of anesthesia

direction action on lipids leads to indirect actions on proteins tickness, volume, curve, etc

Question 9

General anesthetics block _ better than blocking axonal

Local - block axonal Na channels

Answer 9

synaptic transmission

block many different ligand activated ion channels

LA- voltage-gated

Question 10

what sort of proteins are the likely targets of general anesthesia

Answer 10

GABA receptors - ligand activated ion channel

and non ligand gated CNS ion channels

big hyperpolarization receptor

bottom line - they interfere with the fxn of many proteins of neurochemical interest - definitive target unknown

Question 11

GABA receptor is in neuronal membrane - Cl-

4 bindings sites for _ _ _ and one for GABA binding

Answer 11

ethanol
barbiturate
benzodiazepine

Question 12

GA binds to proteins, _ is target

Answer 12

unknown target forsure

many proteins

Question 13

are APs or synaptic transmission generally more sesitive to GA

Answer 13

synaptic transmission

pre and post have both been seen

Question 14

Have to produce sedation but keep doing brain functions

Consciousness seems to be more affected than like the heart

Produces the sedation effect - but heart keeps going and organs keep fxn regularly

_ part of the brainstem - deals with consciousness and we block it with anesthesai - sedatio

Answer 14

Reticular activating formation

major center for consciousness and alertness

we are depressing its activity - unconsciousnes ensues

Question 15

Neurophysiological mechanisms of GA

reicular formatuion is depressed
anesthetics exert _ effects on other structures, such as the thalamus/hippcampus

this loop essential to maintain conscious

Answer 15

direct effects

many believe the thalamocortical loop is essential to maintain conscoious

Question 16

_ system affected by GA
involved in memory
anesthetic-induced amensia - can’t sense the lost of time - lost sense of tiem

Answer 16

limbic system

Question 17

depth of GA

1. analgesia (induction) - loss of pain sensation
2. excitement
3. surgical anesthesia - unconsciousness
4. medullary paralysis - death

Answer 17

4 stages

we want state 3 as rapidly as possible

Question 18

IV drug
Binds at the PCP site blocking NMDA- angle dust - cyclopine

Produces a different kind of anesthesia - called dissocaitive anesthesia - analgesia and amensia with minial resp effect

Quick

Might use with cardiac arrest patients, eldery, low BP very unstable hypotension

Some people have hard time coming out of the effects

Answer 18

ketamine

Question 19

Barbiturate IV
similar to thiopental but 2.5x more potent, faster acting, shorter duration of action

sleep time 5-7 min

Answer 19

methoxhexital - barb

good for dentist

Question 20

IV barbiturate
ultra short acting, induction phase
causes unconsiousnce 30sec-1min (60% to brain)
then distrubutes 5-10 min and come back

Answer 20

thiopental - truth serum 5-10min

replaced by propofol - also a barb

Question 21

what class
single injection can induce anesthesia
also used as maintenance (total IV anesthesia)
respiratory depression major adverse effect

Answer 21

IV barbiturates

rapid distribution vein to brain

reduced cardiac depression - adverse affect

no risk of maligant hyperthemia

no risk of doctor exposure to volatile anesthetics

Question 22

which class

act as CNS depressants
by potentiating the activitiy of the GABA-A
activating Cl channels (hyperpolarizing post synaptic membrane)-thus providing an inhib influence on synaptic channel

Answer 22

barbituates

pre and post synaptic

makes gaba work better

Barbs act by binding to GABA receptors - potentiate GABA make it work a little better
They are not inhibitors - they bind to the GABA receptors (inhib influece, have a postive effect on a negative receptor)

Question 23

volatile anesthetics

we want low _ and low _

Answer 23

low MAC and low blood:gas coefficient

bloodgas - determines onset and revocery time

MAC - olive oil - little of drug to produce effect

NO has low bloodgas - induction and recovery fast, but high MAC - not potent, does not produce full surgical anesthesia

Question 24

MOA
Volative
BARB
Ketamine

Answer 24

volative - unknown
BARB- potential GABA
ketamin - PCP dissociative anesthesia