General Anesthetics I & II

Question 1

The condition of general anesthesia incorporates what 3 properties, all desirable properties for patients undergoing surgery

Answer 1

analgesia, amnesia and loss of consciousness

Question 2

Volatile general anesthetics are _______molecules with structures seemingly unrelated to one another

Answer 2

uncharged, nonpolar

Question 3

In volatile general anesthetics the higher the

_______-, the more potent the general anesthetic

Answer 3

oil:water partition coefficient

Question 4

An ideal general anesthetic would exhibit: _____

Answer 4

1) a rapid and smooth onset of action,
2) a rapid recovery from anesthesia upon termination of drug administration,
3) the drug would have a wide margin for safe use

Question 5

the minimum alveolar concentration (MAC) of anesthetic that produces insensitivity to painful
stimulation has been measured for a variety of inhalational anesthetics, and is ______ proportional to potency

Answer 5

inversely

Question 6

Because of the clearly demonstrated correlation of potency with lipid solubility, it is strongly
suspected that volatile anesthetics interact with ______ regions of proteins.

Answer 6

hydrophobic (lipophilic)

Question 7

How do General anesthetics depress neuronal excitability in the CNS?

Answer 7

Through potentiation of GABA(A) receptor activity which increases the duration of inhibitory postsynaptic
potentials

Question 8

The effects on action potential conduction occur largely
at doses above the ______ , and so conduction block is not believed to underlie anesthesia. Indeed, action potential conduction in the peripheral nervous system has been found to be normal in anesthetized patients.

Answer 8

clinical range

Question 9

Because The hydrophobic protein pockets within which volatile anesthetics bind are not specific binding sites, (but pocket size does account for the size cut-off for volatile anesthetics), volatile anesthetics exert clinically-relevant effects only at concentrations much higher (i.e.______) than those needed for drugs with specific binding sites.

Answer 9

~1-100 mM

Question 10

General anesthesia is characterized by _________, that is, a progressive loss of function from higher (e.g., cognition and consciousness) to lower (e.g., respiratory control) levels within the central nervous system.

Answer 10

descending depression

Question 11

what are the 4 stages of anesthesia?

Answer 11

Stage I – analgesia
Stage II – excitement, delirium
Stage III – surgical anesthesia
Plane 1: regular, metronomic respirations
Plane 2: onset of muscular relaxation, fixed pupils
Plane 3: good muscular relaxation, depressed
excursion of intercostal muscles during respiration
Plane 4: diaphragmatic breathing only, dilated pupils
Stage IV – medullary paralysis

Question 12

The rate at which an effective

concentration of anesthetic is reached in the brain depends upon five factors: ________

Answer 12

1) concentration of the anesthetic
in inspired air,
2) alveolar ventilation rate,
3) pulmonary blood flow (cardiac output)
4) blood:gas partition coefficient,
5) potency (oil:gas partition coefficient).

Question 13

The maintenance stage of inhalation anesthesia is a steady state condition in which the anesthetic gas partial pressure in lung = ________

Answer 13

anesthetic gas partial pressure in blood = anesthetic gas partial pressure in body tissues

Question 14

The blood:gas partition coefficient ____ is a measure of the solubility of anesthetic gas in blood.

Answer 14

(λ)

Question 15

the rate of rise in partial pressure ratio is faster for a gas with ______ and slower for a gas with _______

Answer 15

low solubility (nitrous oxide),
higher solubility (halothane)

Question 16

The initial rise in arterial anesthetic gas concentration is slowed by increased ______

Answer 16

pulmonary flow (cardiac output).

Question 17

The rate of uptake into body tissues depends upon what 3 things?

Answer 17

(1) anesthetic gas solubility in body tissues,
(2) tissue blood flow,
(3) partial pressures of anesthetic in blood
and in tissues.

Question 18

anesthetic is ~equally soluble in blood and lean tissues, but anesthetic is substantially more soluble in _______

Answer 18

fatty tissue

Question 19

Tissue blood flow determines the rate at which anesthetic gas is delivered to the tissue.
The higher the blood flow, the _______ the delivery of anesthetic. This is determined by cardiac output

Answer 19

faster

Question 20

In early stages of anesthesia, the rate of uptake is ______ because this rate depends upon the difference in partial pressure between blood and tissue and this is initially large. As anesthesia develops, tissue levels of anesthetic rise, the difference in partial pressure gets smaller, and thus the rate of anesthetic uptake from blood into tissue _________.

Answer 20

rapid,

decreases.

Question 21

In highly vascularized tissues such as brain, heart, kidney, liver and endocrine glands, Uptake rate into these tissues is _______because these tissues are very well perfused.
Thus uptake into body tissue as a whole is dominated initially by the rate of uptake into this ________
group.

Answer 21

very high (minutes),
vessel-rich

Question 22

From the point of view of solubility of inhalational anesthetics, body tissues can be organized into what three main groups?

Answer 22

1) vessel-rich
2) Muscle group
3) Fat group

Question 23

Uptake into Muscle and skin occurs over _____. Uptake is slower into this tissue group because ________ is lower than in the vessel-rich group.

Answer 23

2-4 hours,

perfusion

Question 24

Inhaled anesthetic uptake occurs very slowly in fatty tissue owing to what 2 reasons?

Answer 24

(i) the enormous amount of anesthetic that can be dissolved in fatty tissue,
(ii) the low perfusion.

Question 25

The inverse of the ______ for a volatile anesthetic is the generally accepted means of estimating its potency.

Answer 25

MAC value (1/MAC)

Question 26

Anesthetic potency is related to ________, which is the alveolar concentration that prevents gross skeletal muscle response to a standard painful stimulus (skin incision) in 50% of patients.

Answer 26

MAC (minimum alveolar anesthetic concentration)

Question 27

The oil:gas partition coefficient provides an index of anesthetic ______, while the blood:gas partition coefficient relates to _______

Answer 27

potency,

anesthetic uptake and elimination kinetics.

Question 28

Increased rate and depth of alveolar ventilation, _______ the rate of rise in arterial concentration of anesthetic.

Answer 28

increases

Question 29

what is Diffusion hypoxia as it relates to nitric oxide

Answer 29

when anesthetic administration is terminated

Large N2O volume leaving blood expands lung and dilutes alveolar O2 -> hypoxia

Question 30

what is the Concentration effect as it relates to nitric oxide?

Answer 30

1 liter/min of N20 taken up, owing to high inspired % (maybe 75%), Big anesthetic vol. taken out of lung into blood, sucks more N2O gas into lung

Thus, uptake rate is faster than predicted

Question 31

what is the Second gas effect as it relates to nitric oxide?

Answer 31

It is like the concentration effect, but with 2 gaseous GAs (75% N2O, 1% halothane)
Huge volume uptake rate of N2O sucks more of both gases into lungs
Thus, uptake of halothane is increased over expected value alone

Question 32

N2O cannot be used as a sole anesthetic agent. It is used in “balanced anesthesia”: N2O combined with
____________.

Answer 32

barbiturate + opioid

Question 33

what are 3 adverse effects of halothane

Answer 33

(i) Respiratory and cardiovascular failure (arrhythmias)

(ii) Hepatotoxic
For 1/10,000, 2-5 days after anesthesia, fever, anorexia and nausea/vomiting
Death occurs in 50% of these patients
Repeated exposure to halothane significantly
increases the risk

(iii) Malignant hyperthermia and central core disease

Question 34

what are the signs of Malignant hyperthermia?

Answer 34

muscle rigidity, and subsequently fever

Question 35

what is malignant hyperthermia?

Answer 35

Inherited disorder, with mutations in ryanodine receptors in skeletal muscle

Question 36

what is the Tx of Malignant hyperthermia

Answer 36

Ice water immersion, dantrolene to block RyR and relax muscle

Use IV anesthetic if family history indicates risk for malignant hyperthermia

Question 37

what is the most widely used inhalational anesthetic?

Answer 37

Isoflurane

Question 38

what are the advatages of isoflurane

Answer 38

Somewhat more potent
Less incidence of hepatotoxicity, renal toxicity
Little seizure propensity

Question 39

what is a potential drawback of Isoflurane?

Answer 39

pungent odor can trigger coughing

Question 40

Halothane until recently, was most widely used inhalational anesthetic, has _______ potency and is a ______ analgesic

Answer 40

Moderately to highly;

poor

Question 41

Isoflurane has minimal direct _______ depression and is a good __________ relaxant

Answer 41

myocardial,

muscle

Question 42

what is a drawback of Sevoflurane (Ultane )

Answer 42

chemically unstable, releases fluoride ions, which are toxic to kidneys

Question 43

what is Sevoflurane?

Answer 43

Inhalational general anesthetic

Question 44

In practice, use ______ of GA, supplemented with IV agents to maintain Stage III surgical anesthesia

Answer 44

0.8-1.2 MAC

Question 45

Name the Anti-anxiety agents used preoperatively to ease induction or for sedative purposes

Answer 45

benzodiazepines - (diazepam (Valium®), midazolam, lorazepam)

Question 46

Name the Induction agents used in surgery for rapid deep anesthesia (20 sec), avoiding excitation/delirium

Answer 46

propofol,

thiopental

Question 47

name the Analgesics used for surgery

Answer 47

opioids: morphine, fentanyl (latter has advantageously short duration of action)

Question 48

Name the Neuromuscular blockers used to relax skeletal muscle, particularly for abdominal surgeries

Answer 48

vecuronium,
tubocurarine,
succinylcholine

Question 49

Name the Anticholinergic drugs that reduce GA-induced hypotension, bradycardia, and excess
salivary secretions that can choke patient during anesthesia

Answer 49

glycopyrrolate,
atropine,
scopolamine

Question 50

Name an Anti-emetics used to reduce post-operative nausea and vomiting (common problem)

Answer 50

ondansetron (5-HT3–type serotonin receptor antagonist)