L22 General anesthetics

Question 1

characteristics of general anesthesia

Answer 1

amnesia
analgesia
unconsciousness
inhibition of sensory and autonomic reflexes
skeletal muscle relaxation

Question 2

how do inhaled anesthetics work

Answer 2

we don’t know but something with GABA chloride channel IPSP.

chloride ions enter the cell making it more negative and therefore less likely to reach threshold

Question 3

what happens if too much is given

Answer 3

stop breathing, stop circulating

no antidote

Question 4

MAC

Answer 4

Minimum Alveolar Concentration @ 1ATM that prevents movement during a skin incision in 50%.

at 1.3 MAC ATM 95% will not move

Question 5

differences with inhalation anesthetics as opposed to normal drugs

Answer 5

High CO decreases induction

gas

Question 6

how do you measure how much med is getting to the brain

Answer 6

measure what is returned to the lung via exhalation

Question 7

FA/FI

Answer 7

alveolar concentration/inhalation concentration how much drug concentration you give a patient

Question 8

3 factors determining how fast the drug will be taken up into blood

Answer 8

1. solubility
2. partial pressure difference
3. cardiac output

Question 9

order of uptake of gases into tissues

Answer 9

1. vessel rich (BHLK)
2. muscle
3. fat (very soluble but not much vasculature)
4. very poorly perfused

the partial pressure determines movement (as opposed to concentration)

Question 10

cardiac outputs affect on anesthetic uptake

Answer 10

Arterial Blood → Brain
Increased blood flow near alveolus slows equilibrium because it increases uptake
Therefore, it also slows FA/FI
Cerebral blood flow is regulated - increase CO should not bring extra agent to the brain

with a higher CO - someone will fall asleep slower

Question 11

Propofol

Answer 11

IV anesthetic agent

Uses:
Induction, Maintenance, sedation – OR, procedures, ICU

most common induction agent

causes vasodilation decreasing BP
can produce apnea
Decreases O2 consumption by brain and ICP
wake up time is not extended by the concentration

Question 12

Thiopental

Answer 12

Barbiturate - GABA
Was most-used induction Rx until propofol
Not available in U.S.
Arterial vasoconstrictor - can cause ischemia or can be helpful to prevent excess bleeding
Put brain to sleep
Vasoconstrictor and ↓ CMRO2

Question 13

Ketamine

Answer 13

NMDA N-Methyl-D-aspartate receptor antagonist
Dissociative anesthesia
Induction & short procedures, gtt for pain
Keep breathing, BRONCHODILATOR
↑ CMRO2, cerebral blood flow & ICP
↑BP, HR
Bad dreams, salivation, twitchy

Question 14

Etomidate

Answer 14

Least cardiovascular side effects
GABA again
Vasoconstrictor and ↓ CMRO2
Adrenal suppression