Slides 6 Flashcards
What is general anesthesia?
A state of:
1) Analgesia
2) Amnesia
3) Loss of consciousness
4) Inhibition of sensory and autonomic reflexes
5) Skeletal muscle relaxation
How is general anesthesia achieved?
By a combination of
intravenous and inhaled drugs.
What are IV general anesthetic agents used for?
To achieve an anesthetic state or sedation.
What are the IV general anesthetic agents?
1) Barbiturates: Thiopental, methohexital
2) Benzodiazepines: Midazolam, diazepam
3) Propofol
4) Ketamine
5) Opioid analgesics: Morphine, fentanyl,
sufentanil, alfentanil, remifentanil.
6) Miscellaneous sedative-hypnotics: Etomidate,
dexmedetomidine.
What are the inhaled general anesthetic agents?
1) Volatile liquids: Halothane, isoflurane, desflurane, enflurane, methoxyflurane, and sevoflurane.
2) Gases: Nitrous oxide
What is balanced anesthesia?
Employs multiple drugs
(inhaled anesthetics, sedative-hypnotics, opioids,
neuromuscular blocking drugs) to minimize unwanted effects
Modern anesthesia typically involves a combination
of:
1) IV agents for induction of anesthesia.
2) Inhaled agents for maintenance of anesthesia.
3) Muscle relaxants.
4) Analgesics.
5) Cardiovascular drugs to control autonomic
responses.
What are IV anesthetics commonly used for?
1) Induction of general anesthesia because of more rapid onset than inhaled agents.
2) Provide sedation for
patients in ICU settings.
What causes the rapid onset of IV anesthetics?
Their lipophilicity = preferentially partition into highly perfused lipophilic tissues (brain, spinal cord).
IV anesthetics recovery is __ and they are used for __ procedures.
Rapid; short
What is the termination of the effect of a single IV bolus determined by?
Redistribution of the drug into less perfused and inactive tissues such as
skeletal muscle and fat. (NOT related to their metabolism)
What is the most popular IV anesthetic? Which drugs did it replace?
Propofol; barbiturates
How does Propofol exert its effects?
1) Interacts with GABAA receptor-chloride channels 2) Potentiates glycine-gated currents
Propofol acts as a __ but does not have __.
Hypnotic; analgesic properties
What is the rate of onset and recovery of Propofol?
Its rate of onset of action is similar to IV barbiturates, but recovery is more rapid and
patient ambulation is earlier.
What is the agent of choice for ambulatory surgery?
Propofol
What can Propofol be used for?
Both induction and maintenance of anesthesia
What does Propofol reduce?
The required concentration of inhaled anesthetics
When used during maintenance of anesthesia,
Propofol infusion can be combined with __ to completely avoid the use of inhaled anesthetics.
IV opioids and neuromuscular blockers
Propofol is effective in producing __ in patients in critical care setting, but
cumulative effect can lead to __.
Prolonged sedation; delayed arousal
Which recovery is more complete (with less “hangover” effects):
Propofol or Thiopental?
Propofol
What can raise serum lipids?
Prolonged administration of conventional emulsion formulation
What happens if you give Propofol to critically ill young children?
1) Severe acidosis in the
presence of respiratory infection
2) Neurologic sequelae upon withdrawal