General Anesthetics Flashcards

1
Q

INHALED ANESTHETICS

A
• Gases
 N2O
• Volatile halogenated hydrocarbons
 Halothane
 Enflurane 
 Isoflurane
 Desflurane
 Sevoflurane
 Methoxyflurane
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2
Q

IV anesthetics include:

A
  • Barbiturates
  • Propofol
  • Ketamine
  • Etomidate
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3
Q

MOA INHALED ANESTHETICS

A
  • The actions of inhaled anesthetics are the consequence of direct interactions with ligand-gated ion channels.
  • Positive modulation of GABAA and glycine receptors.
  • Inhibition of nicotinic receptors
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4
Q

MAC?

POTENCY OF MAC?

A

• MAC is the concentration that results in immobility in 50% of patients when exposed to a noxious stimulus such as surgical incision.

  • MAC is low for potent anesthetics and large for less potent agents.
  • MAC values are additive
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5
Q

WHAT IS THE MEYER–OVERTON CORRELATION

A
  • The potency of an anesthetic can be predicted from its liposolubility.
  • The oil:gas partition coefficient is a good measure of the liposolubility.
  • The potency of an anesthetic increases as its solubility in oil increases.
  • As uλ(oil:gas) increases, the MAC decreases
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6
Q

ULTRA-SHORT ACTING BARBITURATES

A

Thiopental and Methohexital:

• Used for induction of anesthesia and for short surgical procedures.

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7
Q

ULTRA-SHORT ACTING BARBITURATES

USE?

A
  • They decrease intracranial pressure.
  • They do not produce analgesia.
  • They may cause hyperalgesia.
  • May cause apnea, coughing, chest wall spasm, laryngospasm and bronchospasm: a concern for asthmatic patients.
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8
Q

PROPOFOL

A
  • Most popular IV anesthetic.
  • Postoperative vomiting is uncommon. Antiemetic.
  • Used for induction and maintenance of anesthesia.
  • Produces no analgesia.
  • Rapidly metabolized in the liver.
  • Potent respiratory depressant.
  • Reduces intracranial pressure.
  • Causes hypotension, through decreased PVR.
  • Fospropofol: prodrug converted to propofol in vivo.
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9
Q

ETOMIDATE

A
  • Primarily used for anesthetic induction of patients at risk for hypotension.
  • Causes minimal cardiovascular and respiratory depression.
  • No analgesic effects.
  • Reduces intracranial pressure.
  • Associated with nausea and vomiting.
  • May inhibit steroidogenesis, with decreased plasma levels of hydrocortisone.
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10
Q

KETAMINE

A

• Produces dissociative anesthesia, characterized by catatonia, amnesia and analgesia, with or without loss of consciousness.
• Mechanism of action may involve blockade of NMDA receptors.
• Only IV anesthetic that possesses both analgesic properties and the ability to produce CV stimulation.
- Causes sensory and perceptual illusions, and vivid dreams (‘emergence phenomena’).
• Diazepam, midazolam, or propofol reduce the incidence of these phenomena.

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11
Q

NEUROLEPTIC-OPIOID COMBINATIONS

A
  • When a potent opioid analgesic, such as fentanyl, is combined with a neuroleptic such as droperidol, neurolept analgesia is established.
  • Neurolept analgesia can be converted to neurolept anesthesia by the concurrent administration of 65% N2O in O2.
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12
Q

Respiratory Effects:

What anesthetics are not suitable in patients with bronchospasm?

A

Isoflurane and desflurane

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13
Q

which anesthetics are a better choice for pt.s with impaired Myocardial function.

A

Isoflurane
Desflurane
Sevoflurane

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14
Q

Respiratory effects:

What anesthetics are nonpungent

A

Halothane
sevoflurane
N2O

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15
Q

What anesthetic is the least respiratory depressant?

Most depressant?

A

N2O

  • only volatile anesthetics are respiratory depressants.
  • Isoflurane and enflurane are the most depressant
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16
Q

CNS AE effects

  • Least?
  • Enflurane at high concentrations causes?
A

Inhaled anesthetics increase intracranial pressure

  • N2O increases pressure the least
  • Enflurane at high concs can cause tonic-clonic movements
17
Q

N2O should be avoided in patients with?

Why?

A
  • Pneumothorax
  • obstructed middle ear
  • Air embolus
  • Obstructed loop of bowel
  • Intraocular air bubble
  • Pulmonary bulla
    because it enter cavities faster than other gases leave!!!
  • Intracranial air
18
Q

Hepatoxocity (HH)

A

Halothane

  • severe and life threatening in some individuals
  • No specific tx.
  • Liver transplantation!!
19
Q

Nephrotoxicity (MN)

A

Methoxyflurane

- Due to fluoride released during metabolism.

20
Q

malignant hyperthermia

A

Genetic disorder of skeletal mm

  • Halothane and sucks (succinylcholine)-depolarizing mm relaxant
  • One of the main causes of death in anesthesia!!!!
21
Q

Hematotoxicity

A

prolonged exposure to N2O decreases methionine synthase activity and causes megaloblastic anemia

  • staff working in poorly ventilated dental operating suits!
22
Q

What causes emergence phenomena?

what drugs reduce the incidence?

A

Ketamine

- diazepam, midazolam or propofol reduce the incidence