General Anesthetics I and II Flashcards
Characteristics of General Anesthesia?
Hypnosis, amnesia, analgesia, muscle relaxation, attenuation of autonomic reflexes
Is there one anatomic site responsible for producing general anesthesia?
No, but certain anesthetic effects can be attributed to certain locations.
Theory for how unconsciousness is produced?
Depression of thalamic neurons and blocking thalamo-cortical communication.
Where is immobility in response to noxious stimuli mediated?
Spinal Cord
Likely mechanisms of anesthetic drugs?
Inhibit excitatory and enhance inhibitory synaptic transmission.
Volatile anesthetics effects on Glutamate and GABA?
Glutamate- inhibit release
GABA- both increased and decreased release
Post-synaptic effects of anesthetics?
variable effects on EXCITATORY NTs receptors
enhance receptor response to INHIBITORY NTs
Volatile anesthetic effects on Na+ channels
Inhibit activity, reduce nt release at synapse
Neurotransmitters serve as what in ligand-gated ion channels?
Ligands, mediate fast excitatory or inhibitory neurotransmission
3 categories of Glutamate ion channels
NMDA (modulate long term synaptic response)
AMPA, Kainate (involve fast excitatory transmission)
Drug effects on GABAa receptors at clinical concentrations and high concentrations
Clinical: increase Cl current produced by low GABA
High:
1) Direct gating ability to activate receptor w/o GABA
2) Prevention of GABA from initiating Cl current
Barbitiuate, Propofol and Volatile anesthetics effect on GABAa receptor?
Create conformational change in GABAa receptor to increase affinity for GABA
Where do anesthetics likely bind?
Hydrophobic pockets on proteins
What must be used in conjunction with anesthetics in order to conduct surgery?
Opioids or Neuromuscular blocking agents to produce analgesia or muscle relaxation.
How are inhaled anesthetics delivered?
By agent specific vaporizers attached to anesthesia machine.
Equilibration implies what for anesthetic gas in twophases (ie alveoli and blood, blood and brain)
same partial pressures in both phases (does not mean they have same concentration)
What is MAC?
Age dependent concentration of an inhaled anesthetic at which 50% of patients will not move.
Additive when 2 agents given together
What propels anesthetics to brain?
partial pressure gradients
P (Alv), Pa, P(brain)
In comparison to the other volatile anesthetics what is different about Desflurane?
has a low bp, low potency, least soluble
MOA of Nitrous Oxide?
NMDA receptor antagonist
Use of N2O?
mask induction in children (no smell, can flavor)
SE of N2O?
Post-surgical N/V
adverse effects on embryonic development
accumulates in closed air spaces (bowel, middle ear, pneumothorax, air emboli)
Name three volatile anesthetics
Isoflurane, Desflurane, Sevoflurane
What is Isoflurane used for?
Gold Std of anesthesia maintenance
SE of isoflurane, desflurane, and sevoflurane?
Dose Dependent CNS depression
Increased cerebral blood flow, ICP
DD decrease in BP, resp fx, relaxes skeletal muscle
Increase in HR, malignant hyperthermia
What volatile anesthetic is the most pungent?
Desflurane
MOA of methohexital?
GABAa receptor binding; produce hypnosis/ sedation
NMDA glutamate receptor antagonist
MOA of propofol?
GABAa receptor agonist, antagonist of NMDA- glutamate receptor
Use of propofol?
induction/ maintenance of general anesthesia
SE of propofol?
Propofol infusion syndrome (seen in pts given for several days)
Metabolic acidosis, myocardial failure, rhabodomyolysis, hyperkalemia, renal failure
MOA of etomidate?
GABAa receptor agonist
Use of etomidate?
Hypnosis; no analgesia
good for pts w/ minimal cardiac reserve
SE of etomidate?
involuntary myoclonic movements
post-op N/V
single dose inhibits cortisol synthesis
MOA of ketamine?
NMDA receptor antagonist
kappa opiate agonist
DD unconsciousness, amnesia, analgesia
SE of ketamine?
Stim sympathetics
Increased Cerebral blood flow–> ICP
emergence delirium, salivation, lacrimation, nystagmus
Ketamine treats?
sedative anethestic- children or Developmentally Disbled
Induction agent- Reactive airway disease, trauma patients (hypovalemia), cardiac disease
Adjuvant- to decrease opioid use
Name three Acetyl cholinesterase inhibitors used to reverse neuromuscular blockade?
Neostigmine, Edrophonium, Pyridostigmine
Of Neostigmine, Edrophonium, Pyridostigmine what has the longest duration of action?
Pyridostigmine
MOA of dexmedetomidine?
Binds a2a and a2b in LC and SC–> sedation, sympatholysis, analgesia
Use of dexmedetomidine?
awake intubations, craniatomies, adjunct to general anesthesia (in pts susceptible to narcotic induced resp depression)
Name three amino steroid non-depolarizing NMB.
Pancuronium, Vecuronium, Rocuronium
MOA of Pancuronium, Vecuronium, Rocuronium?
competitive blockade of Ach (no depolarization)
What Amino steroid non-depolarizing blocker causes increased HR?
Pancuronium
Length of action of Pancuronium, Vecuronium, Rocuronium?
P- long
V-intermediate
R- intermediate
What are Pancuronium, Vecuronium, Rocuronium used for?
Skeletal muscle relaxation
Name a depolarizing NMB?
Succinlycholine
MOA of succinylcholine?
attaches to Ach receptors and overstimulates
first seen as disorganized contractions then paralysis
What is unique about succinylcholine related to its duration of action?
Rapid onset, ultra-short Duration of action
CAN NOT be reversed
SE of succinylcholine?
malignant hyperthermia, cardiac dysrhythmias, hyperkalemia, increased ICP and intraocular pressure
myalgias, masseter spasm
Use of succinylcholine
skeletal muscle relaxation (intubation)
MOA of sugammadex?
complexes w/ rocuronium, rendering it inactive
SE of sugammadex?
decrease in BP, N/V, dry mouth
Name two isoquinoline NMBs.
Atracurium and Cisatracurium
MOA of Atracurium and Cisatracurium?
competitive blockade of Ach (no depolarization)
Use of isoquinoline NMBs?
skeletal muscle relaxant (pts w/ liver or renal dysfunction)
SE of Atracurium?
histamine release w/ resultant hypotension and tachycardia
