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Flashcards in General Anesthesia Deck (51)
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1
Q

Name the 4 Inhaled Anesthetic Agents.

A

1) NITROUS OXIDE
2) DESFLURANE
3) SEVOFLURANE
4) ISOFLURANE

2
Q

Name the 4 Intravenous Anesthetic Agents.

A

1) PROPOFOL
2) ETOMIDATE
3) KETAMINE
4) DEXMEDETOMIDINE

3
Q

What are the 5 Major effects of a general anesthetic?

A

1) Unconsciousness
2) Amnesia
3) Analgesia
4) Attenuation of Autonomic Reflexes
5) Skeletal Muscle Relaxation

4
Q

What are the 3 conditions of the IDEAL general anesthetic?

A

1) RAPID smooth loss of consciousness
2) RAPID reversal on discontinuation
3) WIDE margin of safety

5
Q

What is CONSCIOUS SEDATION?

A

CONSCIOUS SEDATION (3 glasses of wine analogy)

1) AMOUNT - MINIMAL amount of amnestic and opioid
2) PATIENT INTERACTION - Still able to converse, respond to stimlui and commands
3) ABC - Able to protect airway and maintain ventilation

6
Q

What is the continuum of conscious sedation -> General anesthesia?

A

Decrease in any of the 3 conditions of conscious sedation (Low amount, pt still able to interact and respond to stimuli, maintain airway and ventilation)

7
Q

What condition distinctly differentiates SEDATION from GENERAL ANESTHESIA?

A

When the pt has LOST the ability to protect the airway and maintain normal ventilation
General anesthesia is actually PREFERRED by operators bec immobility/unresponsiveness to protecting the airway (e.g. aspirating, vomiting) is desired [Prevents potential pneumonitis]

8
Q

What is BALANCED ANESTHESIA?

A

Utilizing SMALL doses of multiple agents (Inhaled, IV, Opioids, Benzodiazepines, Neuromuscular blocking drugs) to MINIMIZE side effects and MAXIMIZE efficacy

9
Q

GASEOUS vs VOLATILE: What is the one commonly used gaseous anesthetic?

A

NITROUS OXIDE - Gaseous inhaled anesthetic (Gas at room temperature) Has GOOD Amnestic, and analgesic actions

10
Q

GASEOUS vs VOLATILE: Is N2O inhaled agent used alone?

A

NO, almost ALWAYS used in addition to other agents

10
Q

GASEOUS vs VOLATILE: What are the 3 volatile inhaled agents used?

A

VOLATILE - Liquid at room temperature

1) Desflurane
2) Isoflurane
3) Sevoflurane

11
Q

GASEOUS vs VOLATILE: What is the chemical structure of volatile inhaled agents? What is its importance?

A

D,I,S are FLUORINATED ethers - Fluoride addition stabilizes the ether -> Prevents ether flammability

12
Q

INHALED ANESTHETIC ONSET: What is the major factor determining the ONSET of an INHALED anesthetic?

A

1) HIGH Fa - Alveolar fraction of anesthetic to its target organ (CNS) or Alveolar partial pressure

13
Q

INHALED ANESTHETIC ONSET: How does the anesthesiologist control for a HIGH Fa (alveolar fraction) to CNS? (2)

A

1) HIGH Fi - Inspired fraction or partial pressure (vaporizer reading)
2) HIGH ALVEOLAR VENTILATION - High respiration rate of the pt

14
Q

INHALED ANESTHETIC ONSET: What is the other factor that the anesthesiologist can NOT control for but still contributes to a HIGH Fa?

A
LOW SOLUBILITY (INSOLUBLE) of Inhaled Agent (Blood: Gas partition coefficient) 
*Solubility is INVERSELY proportional to onset*
15
Q

INHALED ANESTHETIC ONSET: Rank the onset of the inhaled anesthetics based on solubility.

A

N2O (Least soluble) > DESFLURANE > SEVOFLURANE > ISOFLURANE (Most soluble)
“No doctor sounds ill”

16
Q

INHALED ANESTHETIC EMERGENCE: What is the Fi during emergence

A

ZERO - No more of the anesthetic is being delivered to the pt

17
Q

INHALED ANESTHETIC EMERGENCE: What is the major determining factor of an inhaled anesthetic’s emergence? What is a minor factor?

A

1) MAJOR: Alveolar Ventilation - The quicker the pt breathes, the more the gas can be removed from the lungs
2) MINOR: Metabolism

18
Q

What is MAC? What does it measure?

A

Minimal Alveolar Concentration - Measures potency

Ex: 1MAC&raquo_space; 10MAC in potency

19
Q

How is MAC experimentally determined?

A

Basically P50 - ALVEOLAR partial pressure of the inhaled anesthetic at which 50% of the population of non-muscle relaxed pts remain immobile at skin incision

20
Q

What is the effect of inhaled agents on major organ systems (CV, Respiratory, Hepatic, Uterine SM)

A

1) CV: DECREASE BP (Due to decreased SVR and negative inotropy)
2) Respiratory: Very shallow rapid breathing, INCREASED RR, DECREASED Vt = Decrease in minute ventilation (Respiratory Minute Volume)
* *Respiratory minute volume (minute ventilation) = Vt * RR
3) Hepatic: DECREASED Portal Vein flow but increase in liver enzymes are rarely seen
4) Uterine SM: DECREASED Uterine tone (Helpful for C section- can deliver baby via small incision) BUT potential painful risk due to INCREASED Uterine bleeding

21
Q

What is malignant hyperthermia (MH)?

A

Rare hypermetabolic syndrome that presents in GENETICALLY susceptible pts after toxicity due to exposure of triggering agents (Volatile inhaled agents + Succinylcholine)

22
Q

What are the top 4 triggering agents that induce MH?

A

1-3) VOLATILE AGENTS - Desflurane + Sevoflurane + Isoflurane

4) Succinylcholine

23
Q

What is the physiological event of MH?

A

Decrease in Ca2+ reuptake from the sarcoplasmic reticulum -> Excess Ca2+ buildup -> Prolonged muscle contraction

24
Q

What are the 4 resulting events of MH? (4 H’s)

A

1) HYPOXIA - Increased BMR
2) HYPERCAPNIA - Increased metabolism
3) HYPERTHERMIA - Feverish
4) HYPERKALEMIA - Rupture of constantly contracting cells

25
Q

What is the antidote of MH? What is its mechanism of action?

A

DANTROLENE - Inhibits Ca2+ release from the sarcoplasmic reticulum (Very work intensive and time intensive, very short shelf-life)

26
Q

What is the PREFERRED method of ANESTHETIC INDUCTION?

A

IV

27
Q

IV (PROPOFOL/ ETOMIDATE/ KETAMINE): What is the nature of the onset of these IV anesthetics?

A

RAPID ONSET OF ACTION
These three IV agents are LIPOPHILIC -> Preferentially partitions into highly perfused lipophilic tissues (Brain + Spinal cord)

28
Q

IV (PROPOFOL/ ETOMIDATE/ KETAMINE): What is the nature of emergence of these three IV anesthetics?

A

RAPID EMERGENCE - Based on concentration gradient
IV anesthetics will rapidly redistribute from highly perfused tissues (e.g. brain) -> Lean tissues = Quick offset of action

RAPID LIVER METABOLISM (occurs later)

29
Q

What is context sensitive half time? Is a high or low context sensitive half time desired?

A

Elimination half time after a prolonged continuous infusion

LOW Context sensitive half time is desired

30
Q

IV AGENTS: What is the mechanism of action of PROPOFOL and ETOMIDATE?

A

GABA Agonist - Promote synaptic inhibitory neurotransmission

31
Q

IV AGENTS: What are the amnestic and analgesic properties of PROPOFOL?

A

Non-analgesic

AMNESTIC

32
Q

IV AGENTS: What is the effect of PROPOFOL on CV, Respiratory, and Nausea?

A

CV: Vasodilatory, negatively inotropic - Do NOT want to use on a pt who has cardiac myopathy
Respiratory: Decreased RR, Decreased Vt, Decreased Minute Volume, DECREASED upper airway reflexes - can intraoperatively vomit -> risk for aspirative pneumonitis
Antiemetic: Reduces nausea

33
Q

IV AGENTS: What is the use of ETOMIDATE?

A

Induction

Short Sedation

34
Q

IV AGENTS: Which pt pool is it most beneficial to use ETOMIDATE?

A

Pts who have heart pathology OR can go into shock

Reason: ETOMIDATE has minimal hemodynamic effect (HR, BP, inotropy)

35
Q

IV AGENTS: **Why can you NOT use ETOMIDATE for PROLONGED SEDATION?

A

Because Etomidate has a dose-dependent inhibition of 11-b-hydroxylase (important for cholesterol -> cortisol) = INHIBITION OF CORTISOL PRODUCTION

36
Q

IV AGENTS: What are two distinct uncomfortable factors of using ETOMIDATE?

A

1) Burns on injection

2) Post-operative nausea/vomiting (Also known as “vomidate”)

37
Q

IV AGENTS: What is the mechanism of action of KETAMINE?

A

NMDA Receptor ANTAGONIST

38
Q

IV AGENTS: What is the anesthesia state after administering KETAMINE?

A

Dissociative Anesthesia (Cataleptic State) With HORIZONTAL NYSTAGMUS - Not complete unconsciousness

39
Q

IV AGENTS: What is the analgesic property of KETAMINE?

A

YES, ANALGESIC - Very helpful to treat burns

40
Q

IV AGENTS: What is the effect of KETAMINE on CV, Respiratory, and upper airway reflexes

A

CV: INCREASED HR, Inotropy, and CO
Respiratory: MINIMAL if any respiratory depression
Upper Airway Reflexes: Preserved

41
Q

IV AGENTS: What are the negative effects of using KETAMINE?

A

1) Hallucinations and unpleasant emergence may occur -> Therefore, coadminstration of benzodiazepine is recommended
2) INCREASED Lacrimations and Secretions (saliva)

42
Q

IV AGENTS: What is KETAMINE’S potential drug interaction that can be utilized with regards to opioids?

A

Ketamine in SUBANALGESIC doses can LIMIT or REVERSE opioid tolerance

43
Q

IV AGENTS: What is the use of DEXMEDETOMIDINE?

A

Sedation

Adjunct to General Anesthesia

44
Q

IV AGENTS: What is the mechanism of action of DEXMEDETOMIDINE?

A

Alpha-2 agonist receptors located in the locus ceruleus and spinal cord

45
Q

IV AGENTS: What are the sedative and analgesic properties of DEXMEDETOMIDINE?

A

Yes, sedative

Yes, analgesic

46
Q

IV AGENTS: Which two IV agents are analgesic, and which two are NON-analgesic

A

NON-analgesic: Propofol + Etomidate

Analgesic: Ketamine + Dexmedetomidine

47
Q

IV AGENTS: What is the effect of DEXMEDETOMIDINE on CV and respiratory?

A

CV: DECREASED BP, HR, CO
Respiratory: Preserved respiratory drive

48
Q

IV AGENTS: Does the context sensitive half time of DEXMEDETOMIDINE make it a preferable drug or non-preferred?

A

NON-PREFERRED

Context sensitive time of dexmedetomidine is SIGNIFICANTLY INCREASED after 8hrs of infusion

50
Q

IV AGENTS: What are the respiratory effects of all the inhaled agents PROPOFOL, ETOMIDATE, KETAMINE, DEXMEDETOMIDIINE?

A

Propofol + Etomidate = Respiratory Depressants

Ketamine + Dexmedetomidine = Preserved Respiratory Drive

58
Q

IV AGENTS: What is the CV effect of PROPOFOL, DEXMEDETOMIDINE, ETOMIDATE, and KETAMINE?

A

Propofol + Dexmedetomidine - DECREASE CO
Etomidate - Neutral, no hemodynamic effect
Ketamine - INCREASE CO