general anesthetics

Question 1

IV anesthetics

Answer 1

• Barbiturates
• Propofol
• Ketamine
• Etomidate

Question 2

use of inhaled anesthetics

Answer 2

maintenance of anesthesia after admin of an IV agent

Question 3

inhaled anesthestic common features

Answer 3

inc perfusion of brain
bronchodilation
dec minute ventilation
rate of onset inversely correlates to blood solubility

Question 4

inhaled anesthetics MOA

Answer 4

ligand gated ion channels

positive modulation of GABA(a) and glycine receptors

inhibition of nicotinic receptors

Question 5

minimum alveolar concentration

Answer 5

concentration that results in immobility in 50% of pt when exposed to noxious stimulus

% of alveolar gas mixture

low for potent anesthestics

Question 6

MAC values

Answer 6

NO = high MAC, therefore needs to be added with something else for effect

methoxyflurane = low MAC - very potent

Question 7

meyer-overton correlation

Answer 7

potency - predict from liposolubility

high oil:gas partition = MAC decreases = high potency

Question 8

rate at which concentration in anesthetic in brain is reach depends on

Answer 8

• Solubility of the anesthetic
• Its concentration in the inspired air
• Pulmonary ventilation rate
• Pulmonary blood flow
• Arteriovenous concentration gradient

Question 9

anesthestic solubility in blood

Answer 9

low solubility in blood - reaches arterial blood - the anesthetic rises quickly

the more insoluble in blood, the more will be as gas

if has high blood solubility, need more anesthetic before partial pressure of anesthetic increases = arterial tension increases less rapidly

Question 10

low blood:gas partition, fast or slow onset?

Answer 10

fast onset of anesthesia

Question 11

blood:gas partition values

Answer 11

nitrous oxide = low ratio (low solubility in blood - fast onset)

methoxyflurane: high ratio (highly soluble in blood - slow onset)

Question 12

compare oil:gas to blood:gas ratio and their potency

Answer 12

high potency = slow onset

high oil:gas and high blood:gas ratios - are also very potent

therefore, high potency also has slower onset

Question 13

rate of induction vs anesthetic concentration vs ventilation rate vs pulmonary blood flow

Answer 13

inc anesthetic concentration = inc rate of induction

inc ventilation = inc rate of induction

inc pulmonary blood flow = dec rate of induction (larger volume exposed to anesthetic)

Question 14

arteriovenous concentration gradient

Answer 14

difference reflects solubility in tissues = uptake by tissues slows onset and recovery

Question 15

elimination of anesthetics

Answer 15

low blood and tissue solubility - recovery mirrors induction (REGARDLESS OF DURATION OF ADMIN)

high blood/tissue solubility - recovery depends on duration of administration because of fat accumulation**

Question 16

anesthetic effects on CV

Answer 16

dec cardiac contractility = dec BP

Question 17

halothane and enflurane on CV effects

Answer 17

dec MAP via depression on myocardium - little effect on PVR

Question 18

isoflurane, desflurane, sevoflurane CV effects

Answer 18

vasodilation - little effect on CO

**better for pt with impaired myocardial fxn

Question 19

which anesthetics to give pt w/impaired mycardial function

Answer 19

isoflurane
desflurane
sevoflurane

Question 20

halothane CV effects with catecholamines

Answer 20

sensitizes myocardium to catecholamines – ventricular arrhythmias

Question 21

anesthetic respiratory effects

Answer 21

bronchodilators and respiratory depressants

isoflurane, desflurane = pungent - not good for pt with bronchospasm

halothane, sevoflurane, NO = nonpungent

isoflurane and enflurane are most resp depressant

N2O least depressant

Question 22

which anesthetics are not good for people with bronchospasms

Answer 22

isoflurane
desflurane

use halothane, sevoflurane, NO

Question 23

anesthetics CNS effects

Answer 23

inc ICP
not good for pt with brain tumor or head injury

N2O inc blood flow the least

enflurane can cause tonic-clonic movements

Question 24

N2O on air containing cavities

Answer 24

N2O exchanges with nitrogen - N2O escapes faster than nitrogen escapes

= inc volume/pressure of cavity

Question 25

when should N2O be avoided

Answer 25

• Pneumothorax
• Obstructed middle ear
• Air embolus
• Obstructed loop of bowel
• Intraocular air bubble
• Pulmonary bulla
• Intracranial air

Question 26

hepatotoxicity from anesthetics

Answer 26

halothane

Question 27

nephrotoxicity from anesthetics

Answer 27

methoxyflurane - fluoride released during metabolism

Question 28

malignant hyperthermia with anesthetics

Answer 28

• Tachycardia
• Hypertension
• Severe muscle rigidity
• Hyperthermia
• Hyperkalemia
• Acidosis

halothane and succinylcholine

AD trait = ryanodine receptor gene 1 affected (uncontrolled Ca2+ release = hyperthermia release) - depletion of O2 and ATP b/c aerobic metabolism – leads to anaerobic metabolism = lactate – hyperkalemia and myoglobinuria

main COD d/t anesthesia

Question 29

dantrolene

Answer 29

blocks Ca2+ from sarcoplasmic reticulum

Question 30

caffeine halothane muscle contracture test

Answer 30

establish susceptibility to malignant hyperthermia

Question 31

hematotoxicity

Answer 31

chronic exposure to N2O dec methionine synthase = megaloblastic anemia

hazard for dentists

Question 32

ultra short barbituates

Answer 32

thiopental
methohexital

induction of anesthesia and for short surgical procedures

dec ICP
no analgesia = may cause hyperalgesia

coughing, chest wall spasm, laryngospasm = concern for asthmatic pt

Question 33

propofol

Answer 33

induction and maintence of anesthesia

• produces no analgesia
• metabolized in liver
• potent resp depressant
• dec ICP
• hypotension through dec PVR

fospropofol = prodrug converted to propofol in vivo

Question 34

etomidate

Answer 34

used for anesthetic induction of pt at risk for hypotension

minimal CV/respiratory depression

• no analgesic effects
• dec ICP
• n/v

Question 35

ketamine

Answer 35

dissociative anesthesia = catatonia, amnesia, analgesia w/w/o LOC

may involve blockade of NMDA receptors

only IV anesthetic that is both analgesic and ability to produce CV stimulation

“emergence phenomena” - sensory and perceptual illusions and vivid dreams
- reduced by incidence diazepam, midazolam, propofol

Question 36

neuroleptic opioid combinations

Answer 36

potent opioid analgesic + neuroleptic = neurolept analgesia is established

neurolept anesthesia = addition of 65% N2O in O2

Question 37

anesthetics adjuvants

Answer 37

benzodiazepines = anxiolytic and anterograde amnesic properties

opioids = analgesia

NM blockers = muscle relaxation

anti-emetics

anti-muscarinics = amnesic effects, prevent salivation, protect heart from bradycaria