General and Local Anesthetic Drugs Flashcards
Anesthetics primarily act on the… (2)
Synapse:
- presynaptic: release of NTs.
- postsynaptic: frequency/amplitude of impulses exciting the synapse.
What inhibitory channels do general anesthetics activate? (2)
Cl- channels (GABA-A and glycine receptors).
K+ channels.
What excitatory channels do general anesthetics inhibit? (3)
AChR (mAChR and nAChR)
EAA (AMPA, kainite, NMDA)
Serotonin
What is the “driving force” for uptake of inhaled anesthetics?
Alveolar concentration, which is driven by inspired air concentration and alveolar ventilation.
What is the blood:gas coefficient?
What is the relationship between the coefficient and rate of anesthetia onset?
It defines the relative affinity of an anesthetic for the blood compared with that of inspired gas (i.e. blood solubility).
Inverse - agents with low blood solubility reach high arterial pressure very quickly, and vice-versa.
What is the blood:brain coefficient?
Does this vary much between drugs?
It defines the relative affinity of an anesthetic for the brain compared to blood.
It is relatively similar for all inhaled anesthetics; anesthetics are more soluble in the brain.
What is the blood:gas partition coefficient, brain:blood partition coefficient and MAC for NO?
Blood:gas - 0.47 (low)
Brain:blood - 1.1 (low)
MAC - >100% (high)
Incomplete anesthetic; rapid onset and recovery.
What is the blood:gas partition coefficient, brain:blood partition coefficient and MAC for Halothane?
Blood:gas - 2.3 (high)
Brain:blood - 2.9 (high)
MAC = 0.75% (low)
Medium rate of onset and recovery.
What is MAC?
What is meant by a MAC >100%?
How much MAC in NO is sufficient for surgical anesthesia for most people?
Minimal Alveolar Concentration = measurement of anesthetic potency.
MAC >100% = if 100% of inspired air is the anesthetic, less than 50% of subjects would be anesthetize and other agents are needed to achieve full surgical anesthesia.
Using NO to produce 40% MAC in combo with 70% of a volatile agent’s MAC would equal 110% MAC and is sufficient in most people.
What are the common side-effects of inhaled anesthetics?
What side-effect is specific to Halothane?
Which agents may cause renal toxicity?
Nausea and vomiting.
Hepatitis: symptoms onset within 2 days to 3 weeks after exposure (nausea, myalgia, rash, eosinophilia, jaundice and elevated LFTs).
Agents that are metabolized to products including fluoride ions (enflurane and sevoflurane).
What causes malignant hyperthermia?
What is the antidote?
Succinylcholine in combo with volatile anesthetics may cause malignant hyperthermia.
Dantrolene.
IV anesthetics are the preferred mechanism of anesthesia is most cases because…
They are highly lipophilic and preferentially partition into highly perf used lipophilic tissues (brain and spinal cord) - quick onset of action.
What are the important IV anesthetic drugs? (5)
Etomidate Ketamine Midazolam Propofol Fentanyl
Which IV anesthetics are known to have a slow onset? (2)
Midazolam
Fentanyl
Which IV anesthetics are considered to have a rapid onset? (2)
Etomidate
Propofol