general anesthetics Flashcards
MAC
minimum alveolar concentration. the minimum concentration of gas at which 50% of all pts. do not respond to surgical stimulus.
diethyl ether
complete anesthetic with significant drawbacks
7 characteristics of ideal anestisia
- smooth and rapid induction
- produce unconsciousness
- produce amnesia
- maintain essential physiologic fnxs while blocking undesired reflexes
- skeletal muscle relaxation
- block perception of sensory stimuli
- smooth, rapid and uneventful recovery with no lasting adverse affects
Meyer-Overton correlation
strong correlation between solubility in olive oil and anestetic potency
lipid-based theory
direct action on lipids leads to indirect action on proteins
protein-based theory
direct action (at the hydrophobic sites that affect fxn) on proteins leads to alteration in protein fxn
general anesthetic protein targets
ligand-gated ion channels (GABA)
CNS proteins
neurophysio studies indicate that __________ is more sensitive to anesthetics than __________.
synaptic transmission, action potentials
___________ is the major center for consciousness and alertness in the brain.
RAS (recticular activating system)
___________ loop is essential to maintaining consciousness.
thalamocortical
inhibition of the __________ system, which is involved with memory, is likely involved in anesthetic-induced amnesia.
limbic
4 stages of general anesthesia
- analgesia (induction)
- excitement
- surgical anesthesia
- medullary paralysis
the solubility of an anesthetic in the blood is quantified as _____________.
blood:gas partition coefficient
a low blood:gas PC means_________.
quicker onset and faster recovery
2 major characteristics of a good volatile anesthetic are__________.
high potency (low MAC) and low blood solubility (low B:G)
nitrous oxide: B:G, MAC, concentration used in dentistry
low, high, 20-50%
t/f: nitrous oxide is not a strong cardiac and respiratory depressant
true
why is NO used with more potent drugs?
to reduce stronger drug’s concentration and achieve faster onset and recovery
rank from highest to lowest B:G- NO, isofluorane, halothane, sevofluorane, desfluorane
halothane, isoflurane, sevoflurane, desflurane, NO
when is desflurane contraindicated?
pts. susceptible to malignant hyperthemia
intravenous anesthetic barbituate mechansim
- potentiate GABA-A receptor
- activates Cl- channels (hyperpolarization of post synaptic membrane)
- synaptic transmission inhibited
4 reasons why IV agents have become more popular
- rapid distribution
- reduced cardiac depression
- no risk of malignant hyperthermia
- eliminate risk of occupational exposure to volatile anesthetics
major adverse affect of IV anestetics
respiratory depression
thiopental (sodium pental)
- ultra short acting barbituate
- unconsciousness w/in a minute
- at 1 minute, 60% of total dose in the brain
- after 5-10 mins, consciousness returns
- largely replaced by propofol
methoxhexital
- 2.5x more potent, faster and shorter duration than thiopental
- sleeptime 5-7 minutes
- 3x faster clearing than thiopental
- clearance makes for favorable use in dental procedures
propofol
- MOST popular anesthetic agent
- rapid recovery and clearance
- induction dose: 2-2.5mg/ kg
- maintenance infusion: 50ug/kg/min to 300ug/kg/min
ketmine
- dissociative anesthesia (pt. awake, but not processing info)
- PCP- like affects
- blocks Glu (NMDA) receptors
- minimal affect on respiratory fxn
- IV: 1 minute onset
- intramuscularly: 5-15min
- orally: 30 mins
