General Anesthetics Flashcards

0
Q

Intravenous Anesthetics: Barbiturates and Non-Barbiturates

A

Barbiturate: Methohexital

Non Barbiturate: Propofol, Etomidate, Ketamine

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1
Q

Inhalation anesthetics

A
  • Nitrous Oxide (gas)
  • Deflurane
  • Halothane
  • Isoflurane
  • Sevoflurane
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2
Q

Inhalation anesthetics have a broad or narrow therapeutic index?

A

Narrow (2-4)

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3
Q

Sevoflurane is the least ____________ ether for anesthetics.

A

Pungent- least irritating so used in children.

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4
Q

T/F: Inhalation anesthetics require special equipment and monitoring while IV anesthetics require monitoring but no special equipment.

A

True

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5
Q

Current theory of the MOA of inhalation anesthetics

A

Anesthetics reversibly interact with hydrophobic sites specific membrane proteins, altering signal transduction pathways.

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6
Q

Targets for inhalation anesthetics

A

1) Enhancement of inhibitory GABA-A, glycine receptor activity
2) Inhibition of excitatory glutamate, nicotinic, 5-HT3 receptors.
3) Voltage gated ion channels (Na, K)-inhibits action potential propagation
4) GPCRs

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7
Q

What are 3 factors that affect rate of anesthetic uptake

A

1) Blood solubility
2) Alveolar blood flow
3) Difference in “partial pressure” of agent in alveolar gas vs. venous blood

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8
Q

T/F: Most important determinant of rate of induction; counter-intuitively, agents with LOW blood solubility have more RAPID induction.

A

True

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9
Q

The concentration of inhaled anesthetics is expressed as _______________ (% of total atmospheric pressure) rather than concentration.

A

Partial pressure

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10
Q

T/F: Partial pressure exerted by any gas in a mixture of gases is proportional to the concentration of each gas (vol%). Give an example as of how to find partial pressure.

A

True: 7L nitrous oxide +3L oxygen= 70% NO

-Partial pressure of NO=70%x760mm hg= 532mm

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11
Q

T/F: The more soluble an anesthetic agent is in blood, the less that must be taken up before partial pressure in brain can reach equilibrium.

A

False: the more that must be taken up

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12
Q

Explain concentration gradient and “second gas” effects on uptake

A

If a second gas is delivered along with nitrous, the concentration gradient effect of nitrous accelerates uptake of the 2nd drug.

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13
Q

Tissue solubility of anesthetics: The ________ is highly lipophilic and receives 3X the blood flow of other tissues; other tissues will equilibrate more slowly.

A

Brain- equilibrium is reached when the partial pressure among various tissues are equivalent.

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14
Q

Potency of inhalation anesthetics is defined by the

A

Minimum alveolar concentration.

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15
Q

T/F: A high MAC in inhalation anesthetics correlates with high solubility.

A

False: correlates with low solubility

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16
Q

What maintains alveolar tension and hastens induction; more important for agents with high blood solubility.

A

Pulmonary Ventilation rate

17
Q

Rank order of liver metabolism of Inhaled anesthetics

A

Halothene> enflurane>sevoflurane>isoflurane>deflurane>NO

18
Q

Recovery is __________ with more blood soluble anesthetic agents.

A

Prolonged

19
Q

T/F: If potency is low and drug is not very soluble (NO), then the alveolar concentration necessary to establish anesthesia cannot be reached while providing adequate oxygenation.

A

True

20
Q

Factors that increase MAC (decrease potency)

A
  • Infancy
  • Chronic alcohol intake
  • Hypernaturemia
  • Sympathomimetics
21
Q

Factors that decrease MAC (increase potency)

A
  • Elderly
  • Acute alcohol intake
  • Pregnancy
  • Opoids,sedatives
  • Hypothermia
22
Q

What is a rare but life-threatening, hypermetabolic syndrome in genetically predisposed individuals exposed to a volatile anesthetic or muscle relaxant.

A

Malignant Hyperthermia

23
Q

A patient was administered halothane and know shows unexplained tachycardia, hypercarbia, tachypnea, acidosis, muscle rigidity, hypoxemia, ventricular arrhythymias, hyperkalemia, and elevated body temp. What does this patient have

A

Malignant hyperthermia- death if untreated

24
Q

Treatment for Malignant hyperthermia

A

-Stop trigger
-Cool, iced normal saline
-100% Oxygen 10L/min
etc.

25
Q

Cause of Malignant Hyperthermia

A

Mutation in skeletal ryanodine receptor calcium release channel

26
Q

What is the main contributor to duration of action in intravenous anesthetics

A

Redistribution out of CNS

27
Q

Methohexital is a ___________ acting barbiturate whose mechanism activates barbiturate binding site on _________receptors. Onset is 30 sec and duration is _______ min. The use is…

A

1) Short-acting
2) GABA-A
3) 10 min
4) induction of anesthesia and procedural sedation

28
Q

Most commonly used IV agent in US.

A

Propofol

29
Q

Mechanism of propofol

A

GABA-A agonist: Sedative and amnestic but not analgesic

30
Q

Onset and duration of propofol

A

40 sec, 6 min

31
Q

Use of propofol

A

General anesthesia induction and maintenance.

  • Procedural sedation
  • Post-op anti-emetic
32
Q

Side effects of propofol

A
  • Hypotension, resp. depression

- Pain at injection site potential for inducing hypertriglyceridemia

33
Q

Mechanism of Etomidate

A

Potentiation of GABA-A currents

  • Minimal CV and resp effects
  • Not analgesic
34
Q

Use of Etomidate

A

Induction and maintenance of general anesthesia.

  • Procedural sedation (off label)
  • Patients with hypotension
35
Q

SE of etomidate

A
  • Injection site pain
  • Myoclonic movements
  • Some post op nausea and vomiting
  • Adrenal insufficiency with continuous infusion
36
Q

Intravenous anesthetic that is a derivative of PCP

A

Ketamine

37
Q

What anesthetic is this: NMDA receptor antagonist (blocks glutamate).

1) Produces dissociative sedation.
2) Produces significant analgesia and bronchodilation.
3) Minimal cardiovascular effects

A

Ketamine

38
Q

Use of Ketamine

A
  • Less often due to unpleasant emergence phenomenon.
  • Induction and maintenance of pediatric anesthesia; children are less prone to unpleasant emergence.
  • Procedural analgesia/sedation (off label); for brief painful procedures like fracture.
  • Patients with airway disease.
39
Q

Side effects of Ketamine

A

CNS psychotomimetic- vivid dreams; hallucinations; distorted visual and auditory sensitivity; associated with fear and confusion but may also produce euphoria; counteracted in adults with benzodiazepines.
-Some nausea/vomiting, tachycardia and hyper-salivation.