Induction Drugs - Propofol Exam 2 Flashcards
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/min1.5 - 2.5 mg/kg IV
What is the most common concentration of a 1% solution?
10mg/mL
What are the inactive ingredients in Propofol?
- 1.2% Lecithin (from egg yolks) Lecithin can cause anaphylaxis in individuals with egg allergies.
- 2.25% glycerol
- 10% soybean oil
What are the disadvantages of Propofol’s inactive ingredient composition? (3)
- ↑ bacterial growth
- ↑ plasma triglycerides with prolonged infusions
- Pain on injection
Differentiate Ampofol and Aquavan.
- Ampofol - low-lipid, no preservative, burns on injection more often.
- Aquavan - prodrug with less injection pain, causes dysesthesias, slower onset, larger Vd, and high potency.
What is the mechanism of action of Propofol?
GABA receptor modulator that increases Cl⁻ conductance.
Does Propofol cause immobility through spinal cord-depression?
No, immobility from Propofol is not from drug-induced spinal cord depression.
How is propofol metabolized?
How is it excreted?
How is it cleared?
- plasma clearance (lungs) > hepatic blood flow
- Lungs and liver CYP450
- excreted by kidneys
Hepatic metabolism of propofol produces?
- Water-soluble sulfate
- glucuronic acid
What metabolizes Propofol?
CYP450 and UGT1A9
What is the elimination half-time (E ½ time) of Propofol?
30 - 90 minutes
What is the context-sensitive half-time of Propofol?
Is this considered a low context-sensitive half-time?
- 40 minutes (for an 8 hours infusion)
- Low CS half-time
What are the characteristics of Propofol regarding
1. elimination half-time
2. volume of distribution
3. clearance
- E ½ time = 30 - 90 minutes
- Vd = 3.5 - 4.5
- Clearance = 30 - 60 mL/kg/min
Differentiate blood pressure and heart rate changes that occur with Propofol vs thiopental.
- Propofol: ↓BP & ↓HR
- Thiopental: ↓BP & ↑HR
Does propofol cross the placenta? What are the consequences of this?
Yes, but is rapidly cleared from neonatal circulation.
Do cirrhosis and renal dysfunction have significant effects on Propofol metabolism?
No
What is the induction drug of choice?
Propofol
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.
What is the induction dose of Propofol in the elderly?
1 mg/kg IV (25 - 50% lower than regular adult)
What plasma Propofol levels correlate with unconsciousness?
Unconscious: 2 - 6 μg/mL
Awake: 1 - 1.5 μg/mL
What is the conscious sedation dose of Propofol?
25 - 100 μg/kg/min
What are the characteristics of Propofol in conscious sedation?
- Minimal analgesia
- Anti-convulsive and amnestic properties
- Prompt recovery with low residual sedation
- ↓ risk of PONV
- Midazolam or opioids as adjuncts.
What are the anti-emetic properties of propofol?
Why is this thought to occur?
- Very anti-emetic (more effective than ondansetron)
- Direct depressant of vomiting center and subcortical pathways
What is the sub-hypnotic dosing for Propofol?
- 10 - 15 mg IV
- followed by 10 mcg/kg/min
What is the anti-pruritic dosing of Propofol?
10 mg IV
What is the anti-convulsant dosing of Propofol?
1mg/kg IV
What are the other benefits of Propofol?
- Bronchodilation
- Anti-emetic
- Anti-pruritic
- Anti-convulsant
- Low dose analgesia
- Antioxidant
- Does not trigger MH
What are Propofol’s effects on CMRO₂, CBF, and ICP?
↓ CMRO₂, CBF, and ICP
What does large doses of propofol do to cerebral perfusion pressure?
- decrease CPF
- support MAP
Although it does not produce seizure, what can happen during induction/emergence?
myoclonus (muscle jerking)
Between thiopental, Propofol, and isoflurane, which is the least EEG suppressive?
Propofol
Which would decrease blood pressure more, thiopental or Propofol?
Propofol
What is the mechanism for propofol-induced hypotension?
What conditions will exaggerate this effect?
- SNS inhibition (smooth muscle relaxation)
- ↓SVR and ↓ ICF Ca⁺⁺
- exaggerated with hypovolemia, elderly, and LV compromise
How is Propofol-induced hypotension from induction modulated?
Intubation (from laryngoscopy stimulation)
Why is bradycardia seen with propofol?
What would occur with propofol overdose?
- ↓SNS response & baroreceptor reflex depression.
- Profound bradycardia & eventual asystole.
What are the pulmonary effects of propofol?
How does this change with opioids?
- Dose-dependent depression of respiratory drive.
- Synergistic resp depression with opioids
How does propofol affect hypoxic pulmonary vasoconstriction?
- Does not affect it
- Pulmonary vessels constrict to redirect blood flow from
poorly ventilated areas of the lung to better-ventilated regions
What severe condition(s) can occur with prolonged Propofol infusions?
- Hepatocellular injury
- Propofol Infusion Syndrome
What is Propofol Infusion Syndrome?
Metabolic acidosis thought to occur from poisoning of electron transport chain and impaired oxidation of fatty acids.
How does propofol affect the renal and heptaic system?
No effect on renal and hepatic function but;
* Green and cloudy urine
* Phenols and uric acid crystals
What sort of infusion dosing can result in Propofol infusion syndrome?
> 75 μg/kg/min for longer than 24 hours
What is the worst side effect in children who have Propofol infusion syndrome?
Severe, refractory, fatal bradycardia
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.
- Reversible in early stage
What are the other organ system effects of Propofol?
- Injection pain (lido before)
- ↓ IOP
- Plt aggregation inhibition
- Allergic reactions (lecithin)
- Prolonged myoclonus
- Abuse/misuse
