9. General Anaesthetics

Question 1

general anaesthesia

Answer 1

-a medically induced reversible condition
-unconscious state
-can tolerate painful stimuli
-there is a loss of vegetative or muscular reactions

Question 2

what are the modes of action of general anaesthesia

Answer 2

Biophysical theory - influences the neuronal membrane fluidity and neuronal function

Biochemical theory- multi receptor activity of GA leads to CNS depression

Question 3

What are the phases of GA

Answer 3

1)Preanesthetic
2)Excitatory
3) Surgical
4)Paralytic

Question 4

how are GA classified ?

Answer 4

-via route of admin (inhaled vs injectable)

-via type of anaesthesia induced (associative vs dissociative)

Question 5

what are the types of GA

Answer 5

-inhalational
-combined (inhaled vs injectable)
-supplemented (GA with other drugs (opioids, anxiolytics, hypnosedatives)

Question 6

what are the alternatives for GA

Answer 6

neuroleptanalgesia (opioid analgesics and antipsychotics)

analgosedation (analgesics and benzos)

Question 7

inhaled anaesthetics

Answer 7

-all cause associative type of anesthesia
-pk is influenced by partition coefficient
toxicity - biotransformation and exhalation (pt and staff)
-easy and fast control of level of anesthesia

Question 8

how are inhaled anesthetics divided

Answer 8

volatile liquids vs anaesthetic gasses

Question 9

MAC (minimum alveolar concentration)

Answer 9

plasma conc in CNS depends on blood conc which is directly relate to alveolar concentration
-parameter of clinical efficacy
- conc which induces stadium of tolerance in 50% of patients

Question 10

what are the volatile anaesthetic liquids

Answer 10

-ethers
(halogenated hydrocarbons)
-> ISOFLURANE
->SEVOFLURANE
->DESFLURANE

Question 11

ISOFLURANE

Answer 11

-weak muscle relaxing activity ,
-highest decrease of peripheral resistance
-Low metabolization
-Strong smell bad in pediatrics

Question 12

SEVOFLURANE

Answer 12

• Pleasant smell
• Without analgesic effect

Question 13

DESFLURANE

Answer 13

• PUNGENT SMELL
• Greenhouse gas
• Fast onset and recovery
• Only used for maintenance of anesthesia

Question 14

what are the anesthetic gases ?

Answer 14

-Nitrous oxide
-Xenon

Question 15

Nitrous oxide

Answer 15

• Low solubility in plasma
• Increasing conc -> euphoric-> analgesic->anesthetic
• Carrier gas for other inhaled anesthetics
• Can be used for breast feeding females and delivery

Question 16

Xenon

Answer 16

• NMDA RECEP INHIBITOR
• Minimal influence on CVS
• COSTLY

Question 17

IV anaesthetics

Answer 17

-can also be given i.m, p.o.intranasally , per rectally
-used for INDUCTION TO GA
-short performances it is used as monanesthesia
-

Question 18

what are IV anesthetics used for

Answer 18

serious seizures
ICU
C sections
analgesy in refractory pain in oncology

Question 19

how IV anesthesias classified

Answer 19

barbiturates vs non barbiturates

Question 20

what are the barbiturates ?

Answer 20

THIOPENTAL

Question 21

thiopental

Answer 21

-ultra short acting
-used in induction
-used in combo with inhaled GA
-effect onset is no later than 20s -> tissue redistribution
metabolised in liver
-BP and heart output is decreased in HIGH DOSES

Question 22

what are the non barbiturates?

Answer 22

 KETAMINE
 PROPOFOL
 ETOMIDATE

Question 23

KETAMINE moa and type

Answer 23

nmda antagonists
dissociative anesthetic

Question 24

indications of ketamine

Answer 24

GA
resistant bronchospasms

Question 25

routes of admin of ketamine

Answer 25

iv im transnasally and transbuccaly

Question 26

pk of ketamine

Answer 26

f depends on route of admin
low plasma protein binding
fast liver metabolism

Question 27

what are the ae of ketamine

Answer 27

confusion
hallucinations
increased muscle tone
PD -with other GA and muscle relaxants

Question 28

CI of ketamine

Answer 28

serious hypertension
hyperthyreoisis
acute psychosis

Question 29

PROPOFOL

Answer 29

moa -alsoteric modulation of gabaa

ind- GA , ICU sedation,

admin route 0IV

Pk -plasma protein binding , rapid CYP metabolism

AE- myoclonus , cough during GA intro , hypotension, hypertriglyceridemia

Interactions- BZD , opioids, analgesics and other GA

CI - hypersensitivity, chronic sedation in pt <16y old

Question 30

ETOMIDATE

Answer 30

short effect without analgesy
-minimal influence on CVS and respiration

• introduction to GA, diagnostic p. and examinations

Question 31

opioids used in anesthesiology

Answer 31

 ALFENTANIL
 SULFENTANIL
 REMIFENTANIL

-used for maintenance of anesthesia

Question 32

Benzos used in anaesthesiology

Answer 32

MIDAZOLAM
DIAZEPAM

used for preperation

Question 33

what is the course of anesthesia

Answer 33

1) Premedication
2) Induction of GA
3) Maintenance of GA
4) Termination of GA

Question 34

premedication

Answer 34

anxiolytics – benzodiazepines (midazolam)
* sedatives – benzodiazepines, H1 antihistamines
* analgesics – NSAID, opioids
* reduction of vagus nerve activity- atropine + scopolamine
* prokinetics – metoclopramide
* ↓ gastric acidity – PPI/H2 antagonists

Question 35

induction of anesthesia

Answer 35

• short acting injectable GA
  -can be i.m., p.o. p rect
  -rarely in children
  -Muscle relaxation-neeeded for INTUBATION (depolarising muscle relaxant suxamethonium )

Question 36

Maintenance of anesthesia

Answer 36

• inhalational anesthetic (combo of anesthetic, analgesic and muscle relaxant)
  e.g. N2O2 +O2 + sevoflurane/isoflurane +opioid +suxamethonium

-TIVA (total IV anesthesia )
- premed- benzos
Induction- fentanyl , propofil
Maintenance – Bristol regime -10-8-6 scheme ( 10 for 10 then 8 for 10 then 6 for rest
-artificial ventilation

Question 37

Termination of anesthesia

Answer 37

• neostigmine, physostigmine – antagonists of non-depolarizing muscle relaxants
• naloxone – recovery of respiration and vigility (opioid antagonist)

*flumazenil – recvery of vigility (benzodiazepine antagonist)

-Sugammadex- selectively coats muscle relaxants -> fast inhibitor of rocuronium

*! ensuring quality postoperative care

Question 38

RISKS AND COMPLICATIONS OF GA

Answer 38

• MALIGNANT HYPERTHERMIA -> DANTROLENE