Pharma 8: General Anaesthetics Flashcards

1
Q

General anesthesia

Definition

Stages

A

The absence of sensation, which is associated with a reversible loss of consciousness

Stages:
Stage 1: Analgesia
Stage 2: Excitement
Stage 3: Surgical Anesthesia
Stage 4: Medullary Paralysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Thiopental

Type

A

Barbiturate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Thiopental

MOA

A

GABA-A modulator—> enhance GABA-A mediated synaptic inhibition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Thiopental

Adv

A

Fast and potent anesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Thiopental

Disadv

A

Weak analgesia, muscle relaxation]

Laryngospasm

Cardio, resp depression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Thiopental

Metabolism

A

Slowly metabolized and accumulates in body fat—> prolonged effect if given repeatedly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Benzodiazepines

A

Lorazepam

Midazolam

Etomidate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Benzodiazepines

MOA

A

Enhance GABA-A mediated synaptic inhibition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Common use of Lorazepam and Midazolam

A

Premedication given ORALLY to reduce anxiety and ease amnesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Midazolam use

A

For endoscopy where full anesthesia not required

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Entomidate use

A

IV

An induction agent preferable to Thiopental in pt with circulatory failure and also cuz its metabolized faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Opioids

A

Morphine

Fentanyl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Opioids MOA

A

uReceptor agonists that are used with other anesthetics to cause analgesia

U receptor activation—> inhibit AC—> reduce cAMP—> increase K conductance, decrease Ca conductance—> reduce transmitter release and synaptic transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Opioids (morphine, fentanyl) cause

A

Hypotension

Respiratory depression

Muscle rigidity

Postanesthetic N/V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Opioids as amnesiacs

A

NOT GOOD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Propofol

Use

A

Anxiolytic/hypnotic

Induces and maintains anesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Propofol

Recovery, onset

A

Both rapid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Propofol effect of intracranial pressure

A

Reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Propofol as anelgesic

A

Weak

20
Q

Propofol as amnesiac

A

Good

21
Q

Propofol

Side effects

A

Hypotension

Transient apnea on induction

22
Q

Propofol MOA

A

Potentiates GABA via GABA-A receptor—>affects endocannabinoids system

23
Q

Ketamine

MOA

A

NMDA receptor ANTAGONIST

24
Q

Ketamine

Uses

A
  1. Dissociate anesthesia ie pt appears awake but is unconscious(even unconscious )and pain free ie it causes sedation, amnesia, immobility.
  2. Analgesia
25
Q

What limits use of KETAMINE

A

Postoperative hallucinations—> used as an animal tranquilizer

26
Q

INNOVAR preparation

Combination of

A

Droperidol—>neuroleptic, D2 antagonist)

Fentanyl—> opioid

27
Q

INNOVAR preparation

Use

A

NEUROLEPT ANALGESIA

Pt remains responsive to simple commands/question, BUT in deep state of sedation/analgesia

—> used for minor surgical procedure as endoscopy

28
Q

Route of inhaled drugs

A

Introduced to blood via lungs—>alveolar blood—>brain, other tissues

29
Q

Potency of inhaled drugs measured by

A

MEAN ALVEOLAR CONCENTRATION

Low MAC—> more potent

Eg isolfurane (1.2) more potent than nitrous oxide (100)

30
Q

Concentration of inhaled anesthetic (gas) is proportional to

A

Partial pressure (tension)

31
Q

Partition coefficient

A

Ratio of the concentration of the agents in 2 phases at equilibrium

!solubility of gas in media—>P.C

32
Q

Speed of induction and recovery depend on

A
  1. Anesthetic properties
    i. blood gas partition coefficient
    ii. oil gas partition coefficient
  2. Physiological factors
    i. alveolar ventilation rate
    ii. cardiac output
33
Q

Blood gas partition coefficient

A

Lower solubility of drug—> less drug transferred vis lung to blood to achieve partial pressure—> equilibrium reached faster→low Bg partition

Ie. Blood gas partition coefficient is INVERSELY related to induction and recover speed ie DIRECTLY proportional to time

Eg. NO (0.5) faster than halthone (2.4)

34
Q

Different scenarios of blood gas coefficient ie high and low

A

High BG coefficient:
more soluble agent →more drug needed to saturate blood→ more time to raise partial pressure and depth of anesthesia

Low BG coefficient:
less soluble agent→less drug needed to saturate blood→less time it takes to raise partial pressure and depth of anesthesia

35
Q

Oil gas partition coefficient considers

A

solubility in fat with high lipid solubility→delaying recovery from anesthesia because t accumulates in body fat HALTHONE

36
Q

Oil gas partition coefficient directly related to

A

potency

37
Q

The MOA of general anesthetics on a molecular level

A

acts through modulatory sites

  1. enhance activity of inhibitory GABA-A
  2. enhance activity of inhibitory GLYCINE
  3. INHIBIT excitatory recpeotrs like intotropic Glu and nAChR
  4. Act on TREK→K channel→activated to reduce membrane excitability
38
Q

Halthone advantages

A

Prototype

  1. best for pediatric use
  2. good for asthmatics because it relaxes sm
39
Q

Halthone disadvantages

A
  1. reduces hepatic and renal blood flow
  2. arrhythmia
  3. Sensitizes heart to CA via B1-AR
  4. hypotension
  5. MALIGNANT HYPERTHERMIA
  6. potentially FATAL hepatotocxicity
40
Q

Isolfurane advantages

A

Most widely used

  1. low organ toxicity
  2. rapid recovery
  3. muscle relaxation
  4. DOES NOT sensitize heart to CA
  5. NO INCREASE IN ICP
  6. Cardiac output stable
41
Q

Isolfurane disadvantages

A

Irritates resp tract

Strong coronary vasodilator→worsen cardiac ischemia in pt with cor disease

42
Q

NO

advantages

A
  1. good analgesic
  2. SAFEST INHALATION ANESTHETIC→no resp depression and least hepatotoxic
  3. rapid onset, recovery
  4. non irritating
43
Q

NO disadvantages

A
  1. weak ANESTHESIA→must be used with others for surgery
  2. no muscle relaxation
  3. Prolonged and repeated administration (<6hrs)→Bone marrow supression ie anemia and leucopenia
  4. enters gaseous cavities→expansion
44
Q

How to reach balanced anesthesia

A
  1. To reach unconscious state rapidly→ THIOPENTAL/PROPOFOL (IV administration)
  2. To maintain unconsciousness→ NO +/- ISOFLURANE (at least one inhalation agent)
  3. To produce analgesia→MORPHINE (IV analgesic)
  4. To relax skeletal muscles for tracheal intubation or thoracic surgery→PANCRONIUM (!must use mechanical ventilator)
45
Q

IV anesthetics

A
thiopental
midazolam
fentanyl
propofol
kentamine
INNOVAR
46
Q

Inhaled anesthetics

A

HALOTHANE

NO

ISOFLURANE