Induction Agents Flashcards by Serena Tan

What organs utilize the most blood supply?
What organs utilize the least?
What organs are in between these two groups?

Vessel-rich group = 75% CP (brain, heart, liver, kidneys)
Skeletal muscles & skin = 18% CO
Fat = 5% CO
Bone, tendons, & cartilage = 2% CO

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What are the one-word (ish) summaries of the four stages of anesthesia?

Analgesia
Delirium
Surgical Anesthesia
Medullary paralysis (death)

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What reflexes are we suppressing during stage 1 anesthesia?
If stage 1 anesthesia is maintained, what is it called?

Coughing, swallowing, and gagging reflexes (lower airway reflexes)
Conscious sedation

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During induction, when would one most likely see laryngospasm?

Stage 2

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During emergence, when would one most likely need to be re-intubated?

Stage 2

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

Induction = 1.5 - 2.5 mg/kg IV
Maintenance = 100 - 300 μg/kg/min
Conscious sedation = 25 - 100 μg/kg/min

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What is the most common concentration of a 1% solution?

10mg/mL

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

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

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

↑ bacterial growth
↑ plasma triglycerides with prolonged infusions
Pain on injection

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What is the mechanism of action of propofol?

GABA receptor modulator that increases Cl⁻ conductance.

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How does propofol cause immobility through spinal cord-depression?

Trick question. Immobility from propofol is not from drug-induced spinal cord depression.

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What are the clearance characteristics of propofol?

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

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What metabolizes propofol?

CYP450 and UGT1A9

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What drug is the induction drug of choice?

Propofol

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

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

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

Unconscious: 2 - 6 μg/mL
Awake: 1 - 1.5 μg/mL

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What is the conscious sedation dose of propofol?

25 - 100 μg/kg/min

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What is the sub-hypnotic dosing for propofol?

10 - 15 mg IV, followed by 10 mcg/kg/min

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What is the anti-pruritic dosing of propofol?

10 mg IV

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

↓ CMRO₂, CBF, and ICP

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Large doses of propofol may ______ cerebral perfusion pressure.

decrease

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Though propofol will not produce seizures, it will produce _______.

myoclonus

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Between thiopental, propofol, and isoflurane, which is the least EEG suppressive?

Propofol

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What severe condition(s) can occur with prolonged propofol infusions?

Hepatocellular injury or Propofol Infusion Syndrome.

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What is the worst side effect in children who have propofol infusion syndrome?

- Severe, refractory, fatal bradycardia

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.*

What is Propofol Infusion Syndrome?

- **Metabolic acidosis** thought to occur from poisoning of electron transport chain and impaired oxidation of fatty acids.

What percentage of etomidate is propylene glycol? What is the result of this?

- 35% propylene glycol resulting in pain on injection.

Which induction agent can be given without an IV? How is this?

Etomidate - can be given sub-lingual.

Why does etomidate have a low incidence of myoclonus?

- Trick Question. **Etomidate has a high incidence of myoclonus**, just like all other induction agents.

What is the induction dosage for etomidate?

- 0.3 mg/kg

What is the best use for etomidate?

- Induction for **unstable cardiac patients**.

What needs to be used concurrently with etomidate when performing a laryngoscopy? Why?

- Opioids, etomidate has **no analgesic effects**.

What is Etomidate's most common side effect? How often does this occur?

- Involuntary Myoclonic Movements ( 50 - 80 %) of administrations. - Also PONV (30%)

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.)

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).

Though etomidate is great for cardiac patients, what condition can result in significant hypotension if not treated prior to induction?

- Hypovolemia

Histamine release via etomidate is mediated through what?

- Trick question. **Etomidate does not release histamine**.

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

What are ketamine's two greatest advantages over propofol or etomidate?

- No pain at injection (no propylene glycol) - Profound analgesia at sub-anesthetic doses.

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".

What are the two greatest disadvantages of ketamine?

- Emergence delirium - Abuse potential

What is Benzethonium Chloride? What is it's relevance?

- Ketamine preservative that inhibits ACh receptors

Differentiate S(+)Ketamine vs R(-)Ketamine.

S-Ketamine (left-handed isomer) is essentially better. - More intense analgesia - ↑metabolism & recovery - Less salivation - Lower emergence delirium

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.**

What is Ketamine's time of onset? (IV & IM) When would this drug be utilized IM?

- IV: 1 min - IM: 5 min (mostly for pediatric patients)

In what patient population is ketamine tolerance most often seen?

Burn patients

What is the induction dose of ketamine IV?

- 1.5 mg/kg IV

What is the maintenance dosing of ketamine? *Give both IM and IV dosings*.

- 0.2 - 0.5 mg/kg IV - 4 - 8 mg/kg IM

What is the subanesthetic/analgesic dose of ketamine?

- 0.2 - 0.5 mg/kg IV

Ketamine is a potent sialagogue. What does this mean for your clinical practice?

- Manage excessive secretions during intubation & watch for coughing/laryngospasm. - Give Glycopyrrolate prior

What "other systems" effects does ketamine have?

- **Non-depolarizing NMBs enhancement.** - **Succinylcholine prolongation via plasma cholinesterase inhibition.** - PLT aggregation inhibition

Which induction agent has the highest analgesic properties?

- Ketamine

Why would ketamine be a decent induction drug for an OSA patient? Why not?

- Preservation of upper airway reflexes & ventilatory function. - Sialagogue.

What should be administered with etomidate to prevent involuntary myoclonic movements?

Fentanyl 1-2 μg/kg IV

What drug and dosing of said drug should be used to treat excessive salivary secretions from ketamine administration?

**Glycopyrrolate: 0.2mg**

Why does ketamine prolong succinylcholine's effects?

Ketamine is a plasma cholinesterase inhibitor.

What is the induction dose of succinylcholine?

1 - 1.5 mg/kg

What is the induction dose of rocuronium?

0.6 - 1.2 mg/kg

What is the induction dose of cisatracurium, vecuronium, and pancuronium?

0.1 mg/kg

What is the induction dose of Fentanyl?

1.5 - 3 mcg/kg

What is the induction dose of Lidocaine?

1 mg/kg (100 mg max)