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Induction: Prop/Etom/Ket Flashcards

1
Q

For Propofol, what are the doses for:
1. Induction
2. Maintenance
3. Conscious sedation

A
  1. Induction = 1.5 - 2.5 mg/kg IV
  2. Maintenance = 100 - 300 μg/kg/min
  3. Conscious sedation = 25 - 100 μg/kg/min
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2
Q

What are the inactive ingredients in propofol? Why is one particularly important?

A
  • 1.2% Lecithin (from egg yolks) can cause anaphylaxis with egg allergies.
  • 2.25% glycerol
  • 10% soybean oil
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3
Q

What are the disadvantages of propofol’s inactive ingredient composition?

A
  • ↑ bacterial growth
  • ↑ plasma triglycerides with prolonged infusions
  • Pain on injection
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4
Q

What is the mechanism of action of propofol?

A
  • GABA receptor modulator that increases Cl⁻ conductance.
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5
Q

How does propofol cause immobility through spinal cord-depression?

A
  • Trick question. Immobility from propofol is not from drug-induced spinal cord depression.
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6
Q

What are the clearance characteristics of propofol?

A

The clearance of propofol is primarily through hepatic metabolism, with minor contributions from renal clearance and pulmonary elimination.

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7
Q

What metabolizes propofol?

A
  • CYP450 and UGT1A9
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8
Q

What is the E ½ time of propofol?

A
  • 30 - 90 minutes
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9
Q

What is the context-sensitive half-time of propofol? Is this a relatively low or high context half-time?

A
  • 40 minutes (for an 8 hours infusion)
  • Low CS ½ time.
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10
Q

What are the following characteristics of propofol:
1. Elimination ½ time.
2. Volume of distribution
3. Clearance (mL/kg/min)

A
  1. E ½ time = 30 - 90 minutes
  2. Vd = 3.5 - 4.5
  3. Clearance = 30 - 60 mL/kg/min
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11
Q

Differentiate blood pressure and heart rate changes that occur with propofol vs thiopental.

A
  • Propofol: ↓BP & ↓HR
  • Thiopental: ↓BP & ↑HR
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12
Q

Does propofol cross the placenta? What are the consequences of this?

A
  • Yes but is rapidly cleared from neonatal circulation.
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13
Q

Do cirrhosis and renal dysfunction have significant effects on propofol metabolism?

A

No

(Induction drugs 1, slide 43)

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14
Q

What is the induction dose of propofol in adults? Children?

A
  • Adults: 1.5-2.5 mg/kg IV
  • Pediatrics: higher doses due to larger central volume and clearance rate.
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15
Q

What is the induction dose of propofol in the elderly?

A
  • 1 mg/kg IV (25 - 50% lower than regular adult)
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16
Q

What plasma propofol levels would correlate with unconsciousness?
What about awakening?

A
  • Unconscious: 2 - 6 μg/mL
  • Awake: 1 - 1.5 μg/mL
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17
Q

What are the characteristics of propofol in the context of conscious sedation?

A
  • Minimal analgesia but has anti-convulsive and amnestic properties.
  • Prompt recovery w/ low residual sedation
  • ↓ risk of PONV
  • Midazolam or opioids as adjuncts.
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18
Q

What are the anti-emetic properties of propofol?
Why is this thought to occur?

A
  • Very anti-emetic (more effective than ondansetron)
  • Direct depressant of vomiting center
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19
Q

What is the sub-hypnotic dosing for propofol?

A
  • 10 - 15 mg IV, followed by 10 mcg/kg/min
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20
Q

What is the anti-pruritic dosing of propofol?

A
  • 10 mg IV
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21
Q

What is the anti-convulsant dosing of propofol?

A

1mg/kg IV

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22
Q

What are “other” category benefits of propofol?

A
  • Bronchodilation
  • Anti-emetic
  • Anti-pruritic
  • Anti-convulsant
  • Low dose analgesia
  • Antioxidant
  • Does not trigger MH
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23
Q

What are propofol’s effects on CMRO₂, CBF, and ICP?

A
  • ↓ CMRO₂, CBF, and ICP
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24
Q

Large doses of propofol may ______ cerebral perfusion pressure.

A

decrease

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25
Though propofol will not produce seizures, it will produce _______.
myoclonus
26
What is the mechanism for propofol-induced hypotension? What conditions will exaggerate this effect?
- SNS inhibition causing ↓SVR and ↓ ICF Ca⁺⁺. - Hypovolemia, elderly, and LV compromise
27
How is propofol-induced hypotension from induction usually counteracted?
- Intubation (from laryngeal stimulation).
28
Why is bradycardia seen with propofol? What would occur with propofol overdose?
- ↓SNS response & baroreceptor reflex depression. - Profound bradycardia & eventual asystole.
29
What are the pulmonary effects of propofol? How does this change with opioids?
- Dose-dependent depression of respiratory drive. - Synergistic resp depression with opioids
30
What severe condition(s) can occur with prolonged propofol infusions?
- Hepatocellular injury or Propofol Infusion Syndrome.
31
What is Propofol Infusion Syndrome?
- **Metabolic acidosis** thought to occur from poisoning of electron transport chain and impaired oxidation of fatty acids.
32
What relatively benign condition(s) can occur from prolonged propofol infusions? Why does this happen?
**Green and cloudy urine** from phenols and uric acid crystals. *Neither alters renal function.*
33
What sort of infusion dosing can result in propofol infusion syndrome?
- >75 μg/kg/min for longer than 24 hours
34
What is the worst side effect in children who have propofol infusion syndrome?
- Severe, refractory, fatal bradycardia
35
What are the symptoms of propofol infusion syndrome? How is propofol infusion syndrome diagnosed?
- Urine changes, lactic acidosis, brady-dysrhythmias, and rhabdomyolysis. - ABG & serum lactate concentrations.
36
What are the "other" organ system side effects of propofol?
- Injection pain (lido before) - ↓ IOP - Plt aggregation inhibition - Allergic reactions (lecithin) - Prolonged myoclonus - Abuse/misuse
37
Which induction agent can be given without an IV? How is this?
Etomidate - can be given sub-lingual.
38
What is the onset of etomidate? How much of it is protein bound? What protein does it bind to?
- Onset: 1 minute - 76% albumin bound
39
What is etomidate's Vd? How does clearance compare to thiopental? What is the result of this clearance?
- Large Vd - 5x faster clearance than thiopental resulting in a **prompt awakening**.
40
What metabolizes etomidate? What is the elimination profile?
- CYP450's & plasma esterases - Elimination ½ time = 2-5 hours with 85% via urine and 10 - 13% via bile.
41
What is the best use for etomidate?
- Induction for **unstable cardiac patients**.
42
What needs to be used concurrently with etomidate when performing a laryngoscopy? Why?
- Opioids, etomidate has **no analgesic effects**.
43
What is Etomidate's most common side effect? How often does this occur?
- Involuntary Myoclonic Movements ( 50 - 80 %) of administrations.
44
What should be administered with etomidate to prevent involuntary myoclonic movements?
Fentanyl 1-2 μg/kg IV
45
Etomidate has a dose dependent inhibition of the conversion of cholesterol to _________. What does this mean clinically?
- Cortisol - Etomidate **decreases SNS capability to respond to stress** (longer vent times, hypotension, etc.)
46
How long does adrenocortical suppression with etomidate last? What two pathologies would cause you to hesitate before giving etomidate?
- 4-8 hours. - **Sepsis & hemorrhage** (anything where you need an intact cortisol response).
47
What are etomidate's effects on CBF & CMRO₂ ? Why is this and what does it do?
- Etomidate = ↓CBF & ↓CMRO₂ due to being a direct **cerebral vasoconstrictor**. - Will also ↓ICP.
48
What is the EEG profile of etomidate?
- More excitatory than thiopental - May activate seizure foci - Augments SSEP amplitude.
49
Though etomidate is great for cardiac patients, what condition can result in significant hypotension if not treated prior to induction?
- Hypovolemia
50
Histamine release via etomidate is mediated through what?
- Trick question. **Etomidate does not release histamine**.
51
What is the pulmonary profile of etomidate?
- **No change in minute ventilation**. - Less respiratory depression than barbiturates - Rapid IV produces apnea - Stimulates CO₂ medullary centers
52
What type of drug is ketamine? What type of anesthesia does it produce? What two properties does it possess?
- Phenycyclidine derivative; NMDA receptor antagonist (PCP; "angel dust") - Dissociative anesthesia - Amnestic & intense analgesia
53
What signs and symptoms does dissociative anesthesia (ketamine) produce?
**"Zonked" state** - Non-communicative but awake - Hyptonus & purposeful movements - Eyes open but "no one's home".
54
What are ketamine's two greatest advantages over propofol or etomidate?
- No pain at injection (no propylene glycol) - Profound analgesia at sub-anesthetic doses.
55
What are the two greatest disadvantages of ketamine?
- Emergence delirium - Abuse potential
56
What is Benzethonium Chloride? What is it's relevance?
- Ketamine preservative that inhibits ACh receptors
57
Differentiate S(+)Ketamine vs R(-)Ketamine.
S-Ketamine (left-handed isomer) is essentially better. - More intense analgesia - ↑metabolism & recovery - Less salivation - Lower emergence delirium
58
What benefits does a racemic ketamine mixture offer?
- Less fatigue & cognitive impairment - Inhibits catecholamine reuptake at nerve endings (like cocaine).
59
What is Ketamine's main mechanism of action?
- Non-competitive inhibition of NMDA (N-methyl-D-aspartate) receptors by inhibiting pre-synaptic release of **glutamate.**
60
What are Ketamine's secondary receptor sites?
- Weak GABAA effects. - Opioid (μ, δ, and κ)
61
What is Ketamine's duration of action? What about its lipid solubility? What is the result of this?
- 10-20 min - Highly lipid soluble (5-10x greater than thiopental). - Results: Brain → non plasma bound → peripheral tissue.
62
What is the Vd and E½ time of ketamine?
- Vd = 3L/kg - E ½ = 2-3 hours
63
Name the pharmacokinetic profile of ketamine: - Clearance: - Metabolism: - Excretion:
- Clearance: high hepatic clearance (1L/min) - Metabolism: CYP450's. - Excretion: kidneys
64
What is the primary metabolite of ketamine and what its its significance?
Norketamine is metabolite (⅓ potency and prolongs analgesia).
65
What is the induction dose of ketamine IV? What if it is given intramuscularly?
- 0.5 - 1.5 mg/kg IV - 4 - 8 mg/kg IM
66
What is the maintenance dosing of ketamine?
- 0.2 - 0.5 mg/kg IV - 4 - 8 mg/kg IM
67
What is the subanesthetic/analgesic dose of ketamine?
- 0.2 - 0.5 mg/kg IV
68
What is the post-operative sedation and analgesia dosing for ketamine in pediatric cardiac surgery cases?
1-2 mg/kg/**hour**
69
What is the neuraxial epidural analgesia dosing of ketamine? What about intrathecal route?
- 30mg epidural - 5 - 50 mg via intrathecal/spinal/subarachnoid
70
What drug and dosing of said drug should be used to treat excessive salivary secretions from ketamine administration?
**Glycopyrrolate: 0.2mg**
71
You gave ketamine and the patient fell asleep within 30 seconds. If you gave no more doses when would you expect the patient to: - Wake up? - Be fully conscious? - Start remembering things?
- Wake up in 10-20 minutes - Full consciousness in 60 - 90 min - Amnestic effects should also wear off in 60 - 90 min.
72
Though ketamine has many indications, when should it be avoided?
- Patients with **pulmonary HTN and ↑ICP**.
73
What are Ketamine's effects on ICP? Why?
- ↑ICP via ↑CBF by 60% - **Potent cerebral vasodilator**.
74
At what dosing will the ICP increasing effects of ketamine plateau?
- 2mg/kg IV
75
What does the cardiovascular profile of ketamine look like? How can this side effect profile be blunted?
- SNS stimulation ( ↑ in sBP, PAP, HR, CO, etc.) - Blunted via pre-med with benzo's, volatiles, or nitrous.
76
Say you just gave ketamine and you have an unexpected drop in systolic BP and CO. What happened? How do you treat it?
- Depleted catecholamine stores - **Treat with direct-acting SNS agents (ex. phenylephrine)** vs indirect (ex. ephedrine).
77
What is the Pulmonary profile of ketamine?
- No depression of ventilation with CO₂ response maintained. - ↑ salivary excretion - **Intact upper airway tone & reflexes**. - **Bronchodilator with no histamine release**.
78
What does emergence delirium present like with ketamine?
- Visual, auditory, proprioceptive illusions. Morbid & vivid dreams up to 24 hours.
79
What is the proposed physiologic mechanism of action for emergence delirium occurrence with ketamine?
Depression of inferior colliculus & medial geniculate nucleus.
80
What percentage of patients will develop ketamine induced emergence delirium? How can it be prevented?
- Psychedelic effects in **5 - 30%** of patients. - **Pre-med with midazolam & glycopyrrolate**.
81
What "other systems" effects does ketamine have?
- **Non-depolarizing NMBs enhancement.** - **Succinylcholine prolongation via plasma cholinesterase inhibition.** - PLT aggregation inhibition
82
What are ketamine's most common drug interactions?
- Volatiles → hypotension - Non-depolarizing NMBs → enhancement - Succinylcholine → prolongation
83
Why does ketamine prolong succinylcholine's effects?
Ketamine is a plasma cholinesterase inhibitor.
84
Why would ketamine be a decent induction drug for an OSA patient? Why not?
- Preservation of upper airway reflexes & ventilatory function. - Sialagogue.

Clinical Meds (5 decks)

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