IV Sedatives and Hypnotics Flashcards
What does GABA stand for?
Gamma Aminobutyric Acid
There are three phases that occur after a bolus injection of propofol:
- Rapid distribution (moves into tissues until they equilibrate with plasma)
- Slow distribution phase (return of drug to the plasma)
- Terminal Phase (removed from the body)
What is context sensitive half time?
Time required to acheive a 50% reduction in concentration after stopping a continuous infusion in drugs that are not limited to the blood (i.e. all IV anesthetics)
Where is propofol metabolized?
The liver
Excreted by the kidneys
How does reduced liver function effect propofol metabolism?
Interestingly, it doesn’t
This suggests there must be other forms of metabolism at work, but we’re not sure what they are
Propofol Classification
GABA Agonist
How does propofol effect ICP?
It lowers ICP by lowering CBF
Generally considered neuroprotective
It’s also a free radical scavenger
What are the characteristic hemodynamic effects of a propofol bolus?
Drop in SBP and DBP WITHOUT the expected increase in HR
What is the drug dose of propofol in healthy adults?
1-2.5 mg/kg
How do elderly patients respond to propofol?
Prolonged effects and increased sensitivity
BECAUSE of decreased CO and clearance
How do pediatric patients respond to propofol?
larger than average volume of distribution and quicker clearance, resulting in creased propofol requirement per kg
When calculating the appropriate propofol amount for a morbidly obese patient, what weight should be used?
LBW, not actual weight
Maintenance of general anesthesia can commonly be acheived with prop infusion of:
100-200 mcg/kg/min
What is the recommended maximum propofol dose?
4 mg/kg/hr
Why isn’t etomidate used as an infusion?
It’s associated with adrenal suppression
Etomidate classification
GABA - A receptor agonist
Is etomidate a good choice for neuro patients?
It reduces ICP, but it’s often associated with EEF spikes
Used frequently for ECT
proconvulsant and lowers the seizure threshold
Why does etomidate cause adrenal suppression?
It inhibits the enzyme that converts cholesterol into cortisol
Ketamine Classification
NMDA receptor Antagonist
Why is ketamine analgesic?
Believed to be in the prevention of developing hyperalgesia
preventing wind up at NMDA receptors
Which patients should not receive ketamine?
CAD patients (if they can’t tolerate the increased BP and HR)
R sided HF patients (increases PVR)
How is ketamine useful in post op pain?
It reduced opiate requirements, but it cannot replace opiates altogether
Most useful in patients who will require high does of opiates
Should ketamine be used in patients with increased ICP?
Historically, no. But studies are showing that ICPs remain normal with ketamine even though it has an excitatory CNS effect
It may even be neuroprotective
Dexmedetomidine Classification
Alpha 2 Adrenergic Agonist
What are the main side effects of ketamine?
emergence delirium
hallucinations
nystagmus
increased salivation
What effect does ketamine have on bronchioles?
Bronchodilator
Precedex provides analgesia at the ______ level
spinal cord
What are the cardiovascular effects of precedex?
bradycardia and hypotension
What do alpha 2 receptors do?
Peripherally, they are located on presynaptic nerve terminals and regulate transmitter release
Centrally,
Benzodiazepine classification
GABA-A receptor agonist