Pharm Block 3- General Anesthetics

Front 1

components of an anesthetic state

Back 1

-amnesia
-unconsciousness
-analgesia
-immobility in response to noxious stimuli
-attenuation of autonomic responses to noxious stimuli

Front 2

minimal alveolar concentration (MAC)

Back 2

-potency measurement for inhaled anesthetics
-minimum alveolar conc that prevents movement in response to pain in 50% of subjects

Front 3

advantages of MAC

Back 3

-can be continuously monitored
-provides a direct correlate to anesthetic conc at site of action in CNS
-simple to measure end point (lack of movement)

Front 4

IV drugs potency measure

Back 4

-usually use free plasma concentration that produces loss of response to surgical incision in 50% of patients

Front 5

Meyer-Overton Rule

Back 5

-previous belief that anesthetics used a common mech (bc potency correlates with lipophilicity)
-emantioselective properties and others have led to abandonment of this

Front 6

GABA-a receptor

Back 6

-GABA-regulated Cl- channel
-function is enhanced by most, but not all anesthetics
-anesthetics produce allosteric interactions (no direct effect on GABA binding)

Front 7

NMDA receptors

Back 7

-glutamate-regulated cation channel
-decrease Na+/Ca2+ influx

Front 8

parenterally administered anesthetics

Back 8

-all hydrophobic
-single IV bolus --> high conc in brain within a single circulation time = rapid induction
-redistribution back to blood and into adipose --> half-life and duration of action NOT the same

Front 9

barbiturate

Back 9

-sodium thiopentol
-INDUCER (10-30s, lasts 10 min)
-long t1/2 (12 hrs) = hangover

Front 10

intra-arterial injection of sodium thiophate

Back 10

-can produce severe inflamm
-can be necrotic
-is NOT performed

Front 11

sodium thiopental and peds pts

Back 11

-can be administered rectally if needed

Front 12

barbiturate s/e

Back 12

-sodium thiopental
-dec cerebral O2 utilization --> dec cerebral blood flow and intracranial pressure (good!)
-venous dilation --> severe BP drops
-respiratory depression

Front 13

sodium thiopentate c/i

Back 13

-hypovolemia and cardiomyopathy (causes venous dilation and bp drops)
-NOT c/i in pts with coronary artery dz bc demand is reduced and no arrythmogenic effects

Front 14

propofol uses

Back 14

-induce/maintain anesthesia
-out-pt surgery (shorter t1/2 than thiopental)
-antiemetic

Front 15

propofol s/e

Back 15

-hypoTN (more severe than tiopental)
-resp depression (more than thiopental)
-pain on injection
-can produce excitation during induction
-vasodilation and depression of myocardial contractility
-blunts baroreceptor reflexes

Front 16

propofol c/i

Back 16

-used with caution in patients that are intolerant of decreases in blood pressure

Front 17

etomidate uses

Back 17

-induction in pts at risk for hypoTN

Front 18

etomidate s/e

Back 18

-high incidence of pain on injection (lidocaine) with myoclonus (benzodiazapines or opiates)
-more nausea/vomiting
-adrenocortical stress response suppression
-CNS like thiopental
-small inc in HR, little/no change bp

Front 19

dissociative anesthesia

Back 19

-produced by Ketamine
-profound analgesia
-unresponsive to commands, but eyes can be open
-amnesia
-spontaneous respiration (no effect on resp, is a bronchodilator)

Front 20

ketamine s/e

Back 20

-nystagmus, salivation, lacrimation, spontaneous limb movements, inc muscle tone
-INC intracranial pressure
-emergence delirium
-inc bp dt sympathomimetic activity

Front 21

ketamine advantages

Back 21

-prfound analgesia
-very little resp depression
-bronchodilator

Front 22

ketamine uses

Back 22

-pts with bronchospasm
-children undergoing short, painful procedures

Front 23

short-acting benzodiazipine anesthesia

Back 23

-midazolam
-GABA-a activator
-used for conscious sedation

Front 24

midazolam uses

Back 24

-conscious sedation
-induction
-adjunct during regional anesthesia
-anti-anxiety

Front 25

midazolam s/e

Back 25

-slow induction and long duration
-metabolized to active metabolite
-resp depression --> arrest
-CV like thiopental

Front 26

midazolam c/i

Back 26

-use with cautin in pts wtih neuromuscular dz, Parkinson's, bipolar

Front 27

inhaled anesthetics

Back 27

-very low therapeutic indices (2-4)
-partial pressure of the anesthetic determines transmembrane movement
-equil occurs when partial pressures, not concentrations, are equal

Front 28

partition coefficients important for inhaled anesthetics

Back 28

-blood:gas --> determines absorption in lung
-brain:blood --> det distribution to brain
-fat:blood --> det redistribution and recovery

Front 29

low blood:gas partition coefficient

Back 29

-rapid equilibrium in blood
-relatively few molecules are required to raise partial pressure
-emerge quickly

Front 30

relationship btw rate of induction and blood:gas partition coefficient

Back 30

-inversely related
-low blood:gas pc means rapid induction

Front 31

pulmonary ventilation effect on induction

Back 31

-affects moderately blood soluble anesthetics more than low soluble agents

Front 32

pulm blood flow effect on induction

Back 32

-increased blood flow slows the rate of rise in arterial partial pressure
-effect is most dramatic for moderately soluble anesthetics

Front 33

elimination of anesthetics

Back 33

-blood:gas partition coefficient is the most important determinant
-low solubility anesthetics are eliminated fastest

Front 34

when is anesthesia acheived

Back 34

-when the brain partial pressure si equal to MAC
-brain is well perfused so partial press in alveolar gas and brain become equal very quickly

Front 35

agents with with blood and fat solubility

Back 35

-recovery is a function of the duration of anesthetic administration
-bc anesthetic accumulates in fat

Front 36

isoflurane pharmacokinetics

Back 36

-moderate blood:gas partition coeff
-99% excreted unchanged from lungs

Front 37

isoflurane uses

Back 37

-commonly used inhalation anesthetic in US
-induce and maintain (inpatient)
-use with nitrous oxide to reduce dose

Front 38

isoflurane s/e

Back 38

-airway irritant: coughing, dec tidal vol, inc RR, resp depression
-myocardial dpression --> dec bp
-arrhythmias (sensitizes heart to catecholamines)
-INC intracranial pressure

Front 39

desflurane pharmacokinetics

Back 39

-very volatile at room temp
-very low blood:gas part coeff --> rapid induction and recovery

Front 40

desflurane uses

Back 40

-outpt surgeries
-maintenance only bc of coughing/bronchospasm in awake pts

Front 41

desflurane s/e

Back 41

-coughing and bronchospasm in awake pts
-direct skel m relaxation
-resp irritant
-myocardial depression

Front 42

sevoflurane pharmacokinetics

Back 42

-very low blood:gas part coeff
-5% metab in liver; renal damage

Front 43

sevoflurane uses

Back 43

-inpt and outpt
-induction and maintenance
-kids and adults
-no resp irritation

Front 44

sevoflurane s/e

Back 44

-CV: like isoflurane (dec myocardial contractility, dec bp, arryth)
-resp: like isoflurance (no irritation and less depression)

Front 45

nitrous oxide pharmacokinetics

Back 45

-very insolbule in blood --> very rapid induction and recovery
-can dilute oxygen in lungs because it comes out of blood so fast (put pts on 100% O2 during emergence)

Front 46

nitrous oxide uses

Back 46

-weak anesthetic
-sedation and analgesia in outpt dentistry
-adjunct to other inhaled anesthetics to reduce their dose

Front 47

nitrous oxide s/e

Back 47

-c/i in pneumothorax
-neg inotrope but also sympatho-stimulant
-oxygen dilution
-abuse liability