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Flashcards in General Anaestics Deck (30)
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1
Q

What are the 5 goals of Anesthesia?

A

1) Unconsciousness
2) Amnesia
3) Analgesia
4) Inhibition of Autonomic reflexes
5) Skeletal Muscle relaxation

2
Q

MOA - unknown but may include

A
  • GABA chloride channels (inhibitor)
  • Potassium channels (inhibitory)
  • Ach (excitatory)
  • Glutamate (excitatory
3
Q
Types of (inhaled) Anesthetics: 
Volatile - they have high boiling points and liquid at RT (all the ranes)
A

halothane
enflurane
isoflurane
sevoflurane

4
Q

Gaseous Anesthetics:

Low bowling points and gas at Rt

A
Nitrous Oxide (blue cylinder)
Xenon
5
Q

Guedal’s Stages of Anesthesia

A

(a) Stage I Analgesia, initially analgesia without amnesia (decrease awareness of pain but fully awake)
(b) Stage II Excitement (Disinhibition), delirious and vocalizing but amnesic [we want to get through this phase as fast as possible]
(c) Stage III Surgical Anesthesia, pupil size used to determine plane of this stage - unconscious, no reflexes, loss response to stimuli [where you want to keep the pt]
(d) Stage IV Medullary Depression, CNS depression, death ensues

6
Q

Pharmacokinetics:

A

the concentration of inhaled anesthetic gas is proportional to its partial pressure (also called tension) - concentration at the site of action is a critical parameter

7
Q

Factors Controlling Gas Uptake into the CNS

A

1) Alveolar concentration of the gas.
***(2) Solubility in the blood, high blood
solubility, slow induction. Poor solubility,
rapid induction. The blood: gas partition
coefficient. Nitrous oxide 0.47 rapid (prefers the fat of the brain), halothane 2.3 slow.
**(3) Cardiac Output. Changes in pulmonary
blood flow.
4) Alveolar-Venous Blood Partial Pressure Difference: change rate of ventilation, increase the concentration in the blood.

8
Q

what is the induction of anesthesia by gas control? 1

A

1) solubility of gas in the blood is called the blood: gas partition coefficient – slow onset stays in blood longer and enters the brain like Halothane

9
Q

what is the induction of anesthesia by gas control? 2

A
2) Inspired gas partial pressure. Increase the partial pressure (%) in inspired
air of gas to increase rate of transfer into
the brain (overcome solubility issues).
10
Q

Elimination of the drugs

A

Is limited by biotransformation in the lover (varies with gas)
- limited biotransformation in the kidneys

11
Q
  • MAC - Minimum Alveolar Anesthetic Concentration - measurement for potency
A

Alveolar concentration required to eliminate the response of surgical incision in 50% of the patient population
- derived from quantal dose-response curve

  1. 5 MAC = mild amnesia
  2. 0 MAC = obtundation deepens
  3. 3 MAC = no response to the surgery 99% patients immobile at 1.3 MAC
12
Q

Pharmacodynamics: what is the primary target of gas anesthetics?

A

GABAa chloride channel

  • most inhaled gas anesthetics enhance GABA mediated chloride neuron inhibition
  • the gases may also hyperpolarize neurons through activation of potassium channels
  • gases may also block the excitatory actions of Ach at nicotinic receptors
13
Q

major sites of action for inhalation anesthetics?

A

1) GABAa receptors (Cl- influx, hyperpolarization)
2) glycine receptors (ligan gated channel, influx of Cl-)
3) Potassium channels

14
Q

what is malignant hyperthermia?

A

a disease that causes a fast rise in body temperature and severe muscle contractions when someone with the MH gets general anesthesia. MH is passed down through families. an autosomal dominant genetic disorder
- occurs with sime pts on gas plus succinylcholine

15
Q

what are some results of malignant hyperthermia?

A

hyperthermia, HTN, muscle rigidit, hyperkalemia, acidosis - causes by too much release Ca from the SR of the muscle

16
Q

how do you treat malignant hyperthermia?

A

dantrolene (Dantrium®)

which blocks the release of calcium from SR.

17
Q

What are the gas anesthetics?

A
Desflurane 
• Enflurane 
• Halothane 
• Isoflurane 
• Nitrous oxide (blue cylinder)
 • Sevoflurane
18
Q

IV anesthetics

A
  • used in addition to inhaled anesthetics and alone
  • faster induction of anesthesia compared to inhaled agents
  • rapid recovery
  • potency adequate for use in short surgical procedures
19
Q

Barbiturates - not used that often act by blocking GABA channels and Na channels

A

(a) thiopental, methohexital

(b) readily cross BBB (lipid soluble) and rapidly induce anesthesia

20
Q

Thipoental - what is it used for?

A
  • induction of anesthesia, induce unconsciousness in less than 30 seconds.
  • Actions through GABAa receptors and Na+ gated ion channels.
  • Contraindicated in acute intermittent porphyria (genetic disorder of heme metabolism)
21
Q

Benzodiazepines

A

(a) diazepam, lorazepam, midazolam used for preanesthesia medication
(b) sedative, anxiolytic, amnestic inducing
(c) medazolam drug of choice for iv administration

22
Q

Opioid Analgesics

A
  • used with benzos to induce anesthesia
    IV morphine
    Fentanyl (and derivitaves)
23
Q

PROPOFOL (Diprivan®) - gas + iv drug

A

(a) most popular iv anesthetic (think Michael Jackson)
(b) reduced incidence of nausea and vomiting with rapid recovery at termination of iv infusion
(c) used for both induction and maintenance of anesthesia
(d) fospropofol, prodrug that reduces the incidence of injection site pain

24
Q

Ketamine (Ketalar®)

A

(a) sold on the streets by junkies as “Special K”
(b) drug produces dissociative anesthetic state, which includes catatonia, amnesia, analgesia with or without loss of consciousness
(hypnosis) .
(c) drug blocks excitatory neurotransmitter glutamic acid at NMDA receptors
(d) only iv anesthetic with both analgesic and anesthetic properties
(e) drug often induces emergence phenomena following use as an anesthetic (perceptual illusions, vivid dreams)
(f) diazepam or midazolam reduces incidence of emergence phenomena
(g) useful in low dose because of lack of respiratory depression

25
Q

Katamine is AKA

A

special k

26
Q

Phencyclidine (PCP)

A

angel dust

27
Q

Fosproprofol

A
  • this is a prodrug of propofol
  • phosphorus added - alk phos removed in the blood to release propofol
  • onset and recovery is prolonged bc conversion is required
    injection site pain is reduced
28
Q

Ketamin – what does it induce

A

vivid dreams and hallucination

29
Q

what drugs are hypnotic but not analgesic?

A
  • etomidate hypnotic but not analgesic, GABAA agonist
  • propofol (PROE po fole)
  • fospropofol prodrug of propofol, converted by alkaline phosphatase, reduces injection site pain
30
Q

Dexmedetomidine

A

binds to presynaptic adrenetic (alpha agonist) receptor

  • (deks MED e toe mi deen)
  • analgesic actions in the spinal cord
  • hypnosis in locus caeruleus actions
  • reduced output of excitatory norepinephrine