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Flashcards in general anesthesia overview Deck (44)
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1
Q

what are the “4 A’s” of general anesthesia?

A
A controlled reversible state of:
– Amnesia (with loss of consciousness) 
– Analgesia
– Akinesia (skeletal muscle relaxation) 
– Autonomic and sensory areflexia
2
Q
define:
A) Balanced anesthesia
B) Regional anesthesia
C) combined technique
D) conscious sedation
A

A) Balanced Anesthesia- GA with several Agents

B) Regional Anesthesia- using LA’s to anesthetize a
body region

C) Combined Technique- regional plus “light” GA

D) Conscious Sedation- IV agents for analgesia/anxiolysis maintaining consciousness

3
Q

what is the definition of Minimum Alveolar Concentration (MAC)?

A

The steady state minimum alveolar concentration (percent) of an inhalational agent that is required for immobility of 50% of the subjects exposed to a noxious stimulus (e.g., surgical incision)

4
Q

what are the stages of surgical anesthesia?

A
  • Recurrence of regular respiration –> cessation
  • Loss of corneal, swallowing, eyelid reflexes
  • Skeletal muscle relaxation
  • Decreased blood pressure
5
Q

T/F: intravenous and inhaled anesthetics are often used alone

A

FALSE- often used combined

6
Q

T/F: Anesthetics are MORE hazardous than analgesia

A

true

7
Q

what are the most common inhaled anesthetics?

A

halothane, isoflurane, desflurane and sevoflurane

8
Q

The rate of partial pressure of inhaled anesthetics increase in the brain depending on:

A
  • Solubility
  • Inspired anesthetic concentration
  • Pulmonary ventilation
  • Arteriovenous concentration gradients
  • Pulmonary and cerebral blood flow
9
Q

what does the blood-gas partition coefficient describe?

A

describes an anesthetic’s relative affinity for the blood compared to air

– # molecules in blood / # molecules in gas at SS

10
Q

T/F: Agents with high solubility require relatively

few molecules to dissolve into the blood to raise partial pressure to equilibrium

A

FALSE

its LOW solubility

11
Q

The rate of induction of anesthesia by an inhalational agent can be increased by increasing what?

A

the inspired concentration of the agent

12
Q

Increasing ____________ generally increases the speed of induction

A

ventilation

13
Q

Increased __________________ decreases the rate of rise of the arterial anesthetic gas tension

A

pulmonary blood flow (increased cardiac output)

14
Q

T/F: Patients with low cardiac output would have a relatively quick induction

A

true

15
Q

what anesthetic will sensitize the myocardium to catechol- amines, predisposing to ventricular arrhythmias

A

Halothane

16
Q

what are the respiratory effects of inhaled agents?

A

A) Decreased tidal volume with an increased respiratory rate (drop in minute ventilation)

B) All inhalational agents decrease the ventilatory response to increases in PaCO2

C) Decreased ventilatory response to hypoxia

17
Q

what are the risks associated with Halothane?

A

A) Malignant hyperthermia

B) 20% metabolism “toxic” products causing hepatic damage with repeated exposure

C) spontaneous abortion in pregnant Operating Room staff

18
Q

what is malignant hyperthermia?

A

1) Rare, inherited, potentially lethal syndrome
2) hypermetabolic activity, marked CO2 production, altered skeletal muscle tone and metabolic acidosis
3) probably due to altered calcium metabolism?

19
Q

how is malignant hyperthermia treated?

A

Treatment = Dantrolene (CA++ blocker)

20
Q

how does Enflurane compare to halothane?

list pros/cons of the drug

A

A) Less soluble than halothane (Faster induction)

B) Less chance of dysrhythmia

C) more hypotension and respiratory depression

D) More neuromuscular depression

E) Less liver damage

21
Q

__________ is the most commonly used inhaled agent in the United States

A

Isoflurane

22
Q

how does Isoflurane compare to the other inhaled agents?

A

1) Less CV or respiratory depression than enflurane but moreso than halothane
2) Cardiac output maintained through increase in HR.
3) Minimal liver toxicity

23
Q

what are the risks associated with Isoflurane?

A

A) Risk of malignant hyperpyrexia

B) No convulsant EEG pattern

C) Mildly pungent; bronchial irritation and
secretion.

24
Q

what inhaled agent has the fastest induction time?

A

Desflurane

Least blood soluble of all the anesthetics -
most rapid induction

25
Q

when would Desflurane be contraindicated as the sole anesthetic?

A

Contraindicated as sole anesthetic agent in

cases of coronary artery disease or where rise in heart rate or blood pressure is undesirable.

26
Q

what is the most common side effect of Desflurane?

A

Very pungent- causes severe laryngospasm, secretion, apnea.

27
Q

T/F: Sevoflurane is non-pungent, poorly soluble, and has few real problems associated with it

A

True

28
Q

how do intravenous anesthetics work?

A

– a) potentiating the action of an inhibitory
ionophore (the GABAA receptor).

– b) blocking the action of excitatory
ionophores (Nicotinic Ach & NMDA receptors).

29
Q

what are the advantages/disadvantages of intravenous anesthetics?

A

■ ADVANTAGES - Rapid onset, controlled dosage, ease of administration.

■ DISADVANTAGES - Overdose not readily corrected, no antagonists or antidotes, prolonged after effects (hangover).

30
Q

what are the classes of intravenous anesthetics?

A
• Sedative-hypnotics
– Barbiturates
– Imidazoles (Etomidate)
– Alkylphenols (Propofol)
– Benzodiazepines 
  • Opioids
  • Dissociative anesthetics – Ketamine
31
Q

T/F: Barbiturates have an ultra-short acting life, and are very lipid soluble

A

True

32
Q

what drugs are given to combat the initial side effects of Barbiturates?

what are these side effects?

A
  • give atropine or SCOPOLAMINE

- stops coughing/sneezing or laryngospasms

33
Q

what are the contraindications for Barbiturates?

A

Porphyria, status asthmaticus

34
Q

what are the risks of barbiturates?

A

■ Barbiturate solutions VERY ALKALINE → avoid extravasation

■ Thrombophlebitis a risk with i.v. injection

■ Respiratory depression marked →
mechanical ventilation should be available.

35
Q

give the characteristics of Thiopental:

A

Thiopental = barbiturate

– Crosses BBB rapidly

– Short effect due to redistribution (t1/2a)

– Dose dependent decreases in SV, MAP, CO

– Potent respiratory depressant

36
Q

T/F: Etomidate has minimal CV effects

A

true

37
Q

_____________ is a newer class of drugs that behaves similar to Thiopental, but gives less of a “hangover” after its effects wear off

A

Alkylphenols

38
Q

when would you NOT use Alkylphenols?

A

Contraindicated for sedation in children due to acidosis and possible neurological sequelae.

39
Q

List the characteristics of Propofol (an Alkylphenol)

A
  • Effects similar to barbiturates
  • Amnestic and anti-emetic effects
  • Useful as sedation agent
  • Most popular ambulatory surgery induction agent –> least residual sedation
40
Q

___________ have a rapid onset (seconds) BUT NO ANALGESIA or Areflexia.

A

Imidazoles

41
Q

what is the primary use of Benzodiazepines?

A

Primarily for anxiolytic/amnestic effects – Preop/intraop sedation

42
Q

Ketamine is in what class of drugs? how does it function?

A

Cyclohexylamines

  • Blocks both nicotinic ACh and NMDA (glutamic acid) receptor channels
43
Q

T/F: Ketamine gives dissociative anesthesia, but not true surgical anesthesia

A

true

44
Q

what class of drug is Etomidate in?

list its side-effects

A

Etomidate = Imidazole

S.E.’s:

1) nausea/vomiting or pain on injection
2) inhibits steroidogenesis- surpasses adrenocortical production