Anesthesia Pharmacology: General Anesthesia
Practice Questions
Therapeutics-index range -- general anesthetics:
0.5-1
2-4
5-10
> 10
Concerning measurement of anesthetic potency:
anesthetic potency is determined by measuring brain anesthetic concentration
anesthetic potency is determined based on alveolar gas concentration
both
neither
MAC:
Alveolar gas concentration that will produce retrograde amnesia in at least 20% of patients:
Alveolar gas concentration that will produce immobility in 50% of patients exposed to Led Zeppelin
Alveolar gas concentration that will produce immobility in 50% of patients exposed to painful stimuli
Anesthetic potency --
At equilibrium the partial pressure of the anesthetic gas in the lung is usually significantly higher than the partial pressure of the gas in the brain.
Concerning anesthetic gases -- there is a rapid equilibrium between blood and brain partial pressures
MAC values are highly dependent on the nature of the painful stimulus
MAC values are relatively sensitive to patient gender, height, weight, and anesthesia duration
Guedel's four stages of general anesthesia:
medullary depression
surgical anesthesia
delirium
analgesia/amnesia
all of the above
Apnea, non-reacted dilated pupils, circulatory failure, and hypertension are most likely associated with this stage of general anesthesia:
amnesia/analgesia
delirium
surgical anesthesia
medullary depression
Central gaze, constricted pupils, regular aspirations, and the anesthetic depth is sufficient that noxious stimuli does not cause reflexes or excessive autonomic effects
analgesia/amnesia
delirium
surgical anesthesia
medullary depression
Halothane (Fluothane) --
usually adequate analgesia
Likely to provide adequate muscle relaxation
commonly used in adults; less likely to be used in children
reversible reduction of GFR
Enflurane (Ethrane)--
Widely used in pediatric cases
may cause concern if patient has a seizure-disorder history
skeletal muscle relaxation:inadequate for surgery
Difficult adjustment of anesthesia depth due to significant effects on pulse and respiration
Considering enflurane (Ethrane), halothane (Fluothane), and isoflurane (Forane) -- cardiac output is well maintained --
enflurane (Ethrane)
halothane (Fluothane)
isoflurane (Forane)
Isoflurane (Forane):
minimal muscle relaxation
promotes uterine muscle contraction; desirable if uterine contraction is required to limit blood loss
stimulates airway reflexes -- increasing secretions, coughing, and laryngospasm
convulsive activity is associated with isoflurane (Forane), similar to enflurane (Ethrane)
Isoflurane (Forane) anesthesia --
rapid, smooth adjustment of depth of anesthesia with limited effects on pulse or respiration
easily controlled depth of anesthesia
significant renal toxicity
A & B
A,B & C
Associated with malignant hyperthermia
halothane (Fluothane)
isoflurane (Forane)
both
neither
Probably isoflurane (Forane) is the most widely used inhalation agent (USA):
true
false
Desflurane (Suprane) anesthesia:
associated with laryngospasm and coughing
relatively high solubility
typically provides adequate muscle relaxation
malignant hyperthermia may be a problem, as with enflurane (Ethrane)
Sevoflurane (Sevorane, Ultane):
low blood solubility
resembles desflurane (Suprane) in pharmacological properties
very commonly used
A & C
A, B & C
Nitrous oxide anesthesia:
relativity solubility of nitrous oxide prevents rapid absorption of significant quantities of gas
may be associated with diffusional hypoxia
nitrous oxide is typically used in combination with the inducing agent (e.g. thiopental (Pentothal), the skeletal muscle relaxant, and hyperventilation
B & C
A & B
Nitrous oxide:
effective muscle relaxation
should not be used in the patient has occluded middle ear
significant depression of myocardial contractility