General anesthetics

Question 1

3 components of general anesthesia

Answer 1

induction (loss of consciousness)
maintenance
recovery (elimination of anesthetics)

Question 2

TIVA stands for

Answer 2

total intravenous anesthesia

refers to the combination of intravenous infusions of anesthetics and analgesics

Question 3

PIVA stands for

Answer 3

partial intravenous anesthesia

usually to reduce the inspired concentration of inhalational anesthetic by using intravenous as well.

PIVA is very common in vet med.

Question 4

injectable anesthetics can be divided into 4 broad groups:

Answer 4

dissociative
barbiturates (pentobarbital)

phenols (propofol)
steroid anesthesia (alfaxalone)

Question 5

cyclohexylamines are

Answer 5

group of injectable dissociative anesthetics: ketamine, tiletamine

are antagonists of NMDA, interact with opioid receptors.

used in combination with tranqs and sedatives

Question 6

describe dissociative anesthesia

Answer 6

complete analgesia with catalepsy(trance), immobility and superficial sleep, hypertonus

hallucinations in ppl

Question 7

NMDA stands for

Answer 7

N-methyl-D-aspartate

a type of cellular receptor which are found in the reticular formation of the brain and in the spinal cord

Question 8

ketamine effect on the heart? (3)

Answer 8

inotropic
vasodilatory of vascular smooth muscle
HR and BP usually increase

Question 9

ketamine half-life

Answer 9

fairly short circa 30 min

Question 10

what is zoletil

Answer 10

a tiletamine + zolazepam combo. med

the benzo reduces potential convulsions from the tiletamine but can cause resp. depression from the benzo.

Question 11

propofol acts on what receptors?

Answer 11

activates GABA receptors.

very short acting, recovery quick too.

Question 12

alfaxalone acts on what receptors?

Answer 12

GABA in CNS

Question 13

The potency of an inhalant anesthetic agent is expressed as

Answer 13

the minimum alveolar concentration (MAC)

meaning, the min. alveolar concentration that prevents muscular movement in response to noxious stimuli in 50% of animals (so the potency)

a MAC of 1 will allow 50% of animals to move.
1.3 multiplied by a given MAC value will prevent movement in approx. 95% of animals.

Question 14

An anesthetic with a lower MAC value is

Answer 14

more potent, meaning it requires a lower concentration to achieve the desired effect compared to an anesthetic with a higher MAC value.

For example, if one anesthetic has a MAC of 1% and another has a MAC of 2%, it means that the second anesthetic is less potent, as it requires a higher concentration to achieve the same level of anesthesia.

Question 15

Factors that increase MAC (so increased the amount of anesthetic required) (4)

Answer 15

hyperthermia
catecholamines
hyperthyroidism
hypernatremia

Question 16

why use ketamine and propofol combo? (5)

Answer 16

synergism: ket. antagonizes NMDA, prop. agonizes GABA
lower doses of each
rapid induction
hemodynamic stability(ket improves)
anterograde amnesia form both

Question 17

The blood:gas solubility coefficient (or partition coefficient) is

Answer 17

a measure of the distribution of the inhalation agent between blood and gas in the body.

Question 18

The blood:gas solubility coefficient indicates

Answer 18

the speed of induction and recovery.

low blood:gas coefficient means less soluble - more effect on the brain with fast induction and recovery.

high blood:gas coefficient means more soluble - less effect on the brain with slower induction and recovery.

Question 19

low blood:gas coefficient means

Answer 19

less soluble - more effect on the brain with fast induction and recovery.

A low blood:gas coefficient means that these gases are less soluble in blood and thus are rapidly taken up and eliminated by the body.

For gases with lower solubility, even though they’re less soluble in blood, their uptake is still relatively efficient due to the concentration gradient. When these less soluble gases enter the alveoli during inhalation, they create a high partial pressure in the alveoli compared to the blood. This steep concentration gradient drives the gas into the bloodstream, despite its lower solubility.

Question 20

high blood:gas coefficient means

Answer 20

more soluble - less effect on the brain with slower induction and recovery.

they dissolve more extensively in the blood, leading to slower changes in the partial pressure of the gas in the blood.

the high solubility of the gas means it takes longer for the concentration of the gas in the bloodstream to decrease. This slower elimination from the bloodstream prolongs the time it takes for the patient to wake up

Question 21

isoflurane causes what physiological changes (4)

Answer 21

in addition to loss of consciousness; decrease in blood pressure and systemic vascular resistance.

depresses respiration too
induces muscle relaxation

Question 22

which volatile anesthetic vapor is least irritating to the resp. tract?

Answer 22

sevoflurane

Question 23

isoflurane blood:gas solubility is

Answer 23

low which results in rapid induction and recovery.

Question 24

what is malignant hyperthermia

Answer 24

a rare but serious condition where body temperature rapidly rises to dangerously high levels, triggered by certain anesthetics.

It’s caused by an abnormal reaction in the muscles, leading to increased metabolism and heat production.

This can result in muscle rigidity, high fever, and if not treated promptly, it can be life-threatening.

Question 25

which volatile anesthetic vapor has the lowest solubility coefficient and what does that mean for it?

Answer 25

desflurane

“single breath” induction, fastest induction and recovery

Question 26

Difference between potency and efficacy

Answer 26

Potency relates to the amount of drug needed for a specific effect, while efficacy describes the maximum effect the drug can produce.

e.g. buprenorphine is more potent than morphine (requires a smaller dose for full effect) but bupe is a partial agonist in comparison to morphine which is full, so morphine is more efficacious in that it can produce a stronger response.

Question 27

rule for rewarming patients

Answer 27

basic rule of thumb to avoid sudden extreme vasodilation 1’C per 1 hour

Question 28

main 3 side effects of inhalatory anesthetics

Answer 28

hypotension
negative inotropic effect on heart
airway irritation

Question 29

which gas anesthetic would you choose in head injury cases?

Answer 29

sevoflurane does not increase intracranial pressure thus it is suited to head trauma and cranial vault tumor patients

avoid isoflurane if posssible

Question 30

What substances act on NMDA receptors?

Answer 30

ketamine, tiletamine
ethanol
nitrous oxide

Question 31

NMDA receptors require what mineral ions

Answer 31

Ca2+
Mg2+

The influx of calcium through activated NMDA receptors plays a significant role in neurotransmission.

Magnesium ions are known to block the NMDA receptor channel at resting membrane potentials. This magnesium block prevents excessive influx of calcium ions.

However, when the membrane is depolarized, such as during synaptic activity, magnesium is displaced from the channel, allowing calcium influx and NMDA receptor activation.

Question 32

why can ketamine cause hypersalivation since it is actually a sympathomimetic?

Answer 32

due to laryngeal spasm the individual may not swallow its own saliva as frequently

plus central effects may override or counteract the sympathomimetic effects of ketamine, leading to increased parasympathetic activity, which can manifest as hypersalivation.

Question 33

how do you avoid convulsions with ketamine?

Answer 33

combine with alfa2 or benzo sedatives/tranqs