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Flashcards in General Anesthetics Deck (29)
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1
Q

What are 5 major effects of GAs?

A

Unconsciousness, amnesia, analgesia, attenuation of autonomic reflexes, skeletal muscle relaxation

2
Q

What are 3 characteristics of an ideal GA?

A

(1) Rapid, smooth loss of consciousness
(2) Quick on, quick off
(3) Wide safety margin

3
Q

What is balanced anesthesia?

A
Using small doses of multiple agents:
IV anesthetics --> induction
Inhaled --> maintenance
Opioids --> analgesia
BZs --> amnesia
Neuromuscular blocking drugs --> allows less use of inhaled
4
Q

What is the difference between sedation & general anesthesia?

A

Patients under general anesthesia have lost their ability to protect the airway while sedated patients can protect their airway and also respond to stimuli and commands.

5
Q

What are the differences between a gaseous and volatile anesthetic?

A

Gaseous - gas at room temperature (NO)

Volatile - liquid at room temperature; used mostly for maintenance (other inhaled GAs)

6
Q

What is alveolar fraction?

A

Alveolar partial pressure; driving force for inhaled anesthetics to be uptake by CNS

7
Q

How does inspired fraction influence anesthetic onset?

A

Higher the inspired fraction (amount of anesthetic flowing through airway), faster the anesthetic onset

8
Q

How does alveolar ventilation influence anesthetic onset?

A

The greater the alveolar ventilation, the faster the anesthetic onset

9
Q

How does blood solubility influence the onset of the GA?

A

More insoluble agents have a faster onset.

ISO (most soluble, longest) > SEVO > DES > N2O (fast but cannot be used alone)

10
Q

What is the most important factor in emergence?

A

Alveolar ventilation

11
Q

What is MAC?

A

Minimal Alveolar Concentration; 1/MAC measures potency!
Partial pressure of inhalational anesthetic in alveoli at which 50% of non-relaxed patients remain immobile in response to noxious stimulus (skin incision)

12
Q

How do inhaled anesthetics impact cardiovascular, respiratory, hepatic systems and uterine smooth muscle?

A

CV: decrease in BP
Respiratory: increased RR, decreased minute volume (panting)
Hepatic: decrease in portal vein flow
USM: decrease in uterine tone

13
Q

Which inhaled anesthetic can lead to hepatotoxicity

A

Halothane

14
Q

Which inhaled anesthetic can lead to nephrotoxicity?

A

Methoxyflurane

15
Q

Which inhaled anesthetic is proconvulsant?

A

Enflurane

16
Q

Which inhaled anesthetic can cause expansion of trapped gas in a body cavity?

A

Nitrous oxide

17
Q

What is malignant hyperthermia and what is it caused by?

A

Rare, life-threatening, hereditary condition; caused by decrease in Ca reuptake –> prolonged muscle contraction –> hyperthermia, hypercapnia, hypoxia, hyperkalemia, myoglobinuria
Induced by inhaled anesthetics (except NO) & succinylcholine

18
Q

How is malignant hyperthermia treated?

A

Dantrolene

19
Q

What are some features of the onset of IV anesthetics?

A

Lipophilic —> preferential partitioning into lipophilic tissues (brain & spinal cord) –> rapid onset

20
Q

What are some features of the elimination of IV anesthetics?

A

Rapid redistribution from rapidly perfused tissues into lean tissues –> rapid offset
Liver metabolism too

21
Q

What is context sensitive 1/2 time?

A

Describes the elimination 1/2 time after a continuous infusion

22
Q

Propofol: type of GA; mechanism of action; clinical uses; features

A

IV anesthetic; GABA agonist; used for induction & maintenance of GA + sedation; non-analgesic but amnestic

23
Q

What are some side effects of propofol use?

A

CV: vasodilation and decreased BP
Respiratory: decreased Vt, RR, minute volume
Anti-emetic

24
Q

Etomidate: type of GA; clinical uses; features

A

IV anesthetic; Induction & short sedation; non-analgesic

25
Q

What are some side effects of etomidate use?

A

Minimal hemodynamic effects, adrenal effects, increased PONV (feeling puky), respiratory depression

26
Q

Ketamine: type of GA; mechanism of action; features

A

IV anesthetic; NMDA receptor antagonist; analgesic, dissociative anesthesia with nystagmus

27
Q

What are some side effects of ketamine use?

A

Increases in HR, BP, CO, hallucinations (co-administere BZ), lacrimation & secretions
*Preserved airway reflexes

28
Q

Dexmedetomidine: type of GA; mechanism of action; clinical uses; features

A

IV anesthetic; alpha 2 agonist; sedation or GA adjunct; sedative & analgesic

29
Q

What are some side effects of dexmedetomidine use?

A

Decreases in BP and HR; but preserves respiratory drive