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Questions and Answers
Which statement accurately contrasts the effects of barbiturates and benzodiazepines on GABA receptors?
Which statement accurately contrasts the effects of barbiturates and benzodiazepines on GABA receptors?
- Benzodiazepines directly open GABA channels, while barbiturates require GABA for channel opening.
- Benzodiazepines can open GABA channels in the absence of GABA, while barbiturates cannot.
- Barbiturates prolong the duration of GABA channel opening, whereas benzodiazepines increase the frequency of channel opening. (correct)
- Barbiturates enhance GABA effects, while benzodiazepines block GABA binding.
A patient with acute intermittent porphyria requires anesthesia. Which intravenous anesthetic should be avoided due to its potential to exacerbate this condition?
A patient with acute intermittent porphyria requires anesthesia. Which intravenous anesthetic should be avoided due to its potential to exacerbate this condition?
- Ketamine
- Thiopental (correct)
- Midazolam
- Propofol
Which characteristic of thiopental's distribution contributes most significantly to its short duration of action following a single IV dose?
Which characteristic of thiopental's distribution contributes most significantly to its short duration of action following a single IV dose?
- Rapid redistribution from the CNS to other tissues (correct)
- High protein binding in plasma
- Active transport out of the brain
- Rapid hepatic metabolism
A patient undergoing a brief surgical procedure receives an intravenous anesthetic. Postoperatively, the patient experiences vivid dreams and hallucinations. Which anesthetic is most likely responsible?
A patient undergoing a brief surgical procedure receives an intravenous anesthetic. Postoperatively, the patient experiences vivid dreams and hallucinations. Which anesthetic is most likely responsible?
Which intravenous anesthetic is LEAST likely to cause hypotension in a patient with compromised cardiovascular function?
Which intravenous anesthetic is LEAST likely to cause hypotension in a patient with compromised cardiovascular function?
Which intravenous anesthetic agent is most likely to increase cerebral blood flow and intracranial pressure?
Which intravenous anesthetic agent is most likely to increase cerebral blood flow and intracranial pressure?
A patient is undergoing a surgical procedure, and the anesthesia team wants to use an intravenous anesthetic with antiemetic properties to reduce the risk of postoperative nausea and vomiting. Which agent would be most appropriate?
A patient is undergoing a surgical procedure, and the anesthesia team wants to use an intravenous anesthetic with antiemetic properties to reduce the risk of postoperative nausea and vomiting. Which agent would be most appropriate?
Which intravenous anesthetic primarily exerts its effects through selective α2-adrenergic receptor agonism?
Which intravenous anesthetic primarily exerts its effects through selective α2-adrenergic receptor agonism?
A patient undergoing anesthesia experiences unexpected muscle rigidity, particularly in the chest wall, making ventilation difficult. Which intravenous anesthetic could be the cause?
A patient undergoing anesthesia experiences unexpected muscle rigidity, particularly in the chest wall, making ventilation difficult. Which intravenous anesthetic could be the cause?
In the context of neuroleptanalgesia, what is the primary purpose of combining fentanyl with droperidol?
In the context of neuroleptanalgesia, what is the primary purpose of combining fentanyl with droperidol?
Which of the following is an advantage of intravenous anesthetics over inhalation anesthetics?
Which of the following is an advantage of intravenous anesthetics over inhalation anesthetics?
How does ketamine's mechanism of action differ from that of propofol regarding receptor targets?
How does ketamine's mechanism of action differ from that of propofol regarding receptor targets?
A patient with a known allergy to ester-type local anesthetics requires a rapidly acting opioid analgesic during a surgical procedure. Which opioid is the MOST suitable choice?
A patient with a known allergy to ester-type local anesthetics requires a rapidly acting opioid analgesic during a surgical procedure. Which opioid is the MOST suitable choice?
Which property of etomidate makes it a desirable choice for inducing anesthesia in hemodynamically unstable patients?
Which property of etomidate makes it a desirable choice for inducing anesthesia in hemodynamically unstable patients?
What is the primary advantage of using dexmedetomidine for sedation in the ICU compared to other sedatives like propofol or benzodiazepines?
What is the primary advantage of using dexmedetomidine for sedation in the ICU compared to other sedatives like propofol or benzodiazepines?
A patient receiving ketamine begins to experience vivid dreams and hallucinations during emergence from anesthesia. Which drug would be most appropriate to manage these symptoms?
A patient receiving ketamine begins to experience vivid dreams and hallucinations during emergence from anesthesia. Which drug would be most appropriate to manage these symptoms?
Why is propofol considered a good choice for outpatient surgery?
Why is propofol considered a good choice for outpatient surgery?
Which statement accurately describes the effect of intravenous anesthetics on cerebral blood flow (CBF)?
Which statement accurately describes the effect of intravenous anesthetics on cerebral blood flow (CBF)?
A patient with severe cardiovascular disease requires anesthesia. Which intravenous anesthetic would be MOST appropriate to minimize cardiovascular depression?
A patient with severe cardiovascular disease requires anesthesia. Which intravenous anesthetic would be MOST appropriate to minimize cardiovascular depression?
What is a key difference between fentanyl and remifentanil concerning their metabolism and duration of action?
What is a key difference between fentanyl and remifentanil concerning their metabolism and duration of action?
What is the primary risk associated with prolonged infusions of propofol, and how is it best managed?
What is the primary risk associated with prolonged infusions of propofol, and how is it best managed?
A patient undergoing general anesthesia experiences significant respiratory depression. Which intravenous agent, when used as part of the anesthetic regimen, would be MOST readily reversible with a specific antagonist?
A patient undergoing general anesthesia experiences significant respiratory depression. Which intravenous agent, when used as part of the anesthetic regimen, would be MOST readily reversible with a specific antagonist?
Which intravenous anesthetic is contraindicated in patients with a history of acute intermittent porphyria due to its potential to exacerbate the condition?
Which intravenous anesthetic is contraindicated in patients with a history of acute intermittent porphyria due to its potential to exacerbate the condition?
In which clinical scenario would ketamine be the MOST appropriate intravenous anesthetic, considering its unique pharmacological profile?
In which clinical scenario would ketamine be the MOST appropriate intravenous anesthetic, considering its unique pharmacological profile?
Dexmedetomidine provides sedation and analgesia without significant respiratory depression. By what mechanism does Dexmedetomidine exert its analgesic effects?
Dexmedetomidine provides sedation and analgesia without significant respiratory depression. By what mechanism does Dexmedetomidine exert its analgesic effects?
A patient with a known allergy to eggs requires anesthesia. Which intravenous anesthetic should be avoided?
A patient with a known allergy to eggs requires anesthesia. Which intravenous anesthetic should be avoided?
What is the primary mechanism by which etomidate causes adrenal suppression?
What is the primary mechanism by which etomidate causes adrenal suppression?
A patient receiving dexmedetomidine for sedation begins to exhibit a significantly decreased heart rate. What is the most likely mechanism contributing to this bradycardia?
A patient receiving dexmedetomidine for sedation begins to exhibit a significantly decreased heart rate. What is the most likely mechanism contributing to this bradycardia?
What is the primary reason for using flumazenil in the context of intravenous anesthesia?
What is the primary reason for using flumazenil in the context of intravenous anesthesia?
A patient premedicated with diazepam prior to receiving ketamine is less likely to experience which of the following side effects?
A patient premedicated with diazepam prior to receiving ketamine is less likely to experience which of the following side effects?
A patient with limited cardiovascular reserve is scheduled for a minor surgical procedure. Which intravenous anesthetic would be the MOST appropriate for induction, considering its minimal impact on cardiovascular function?
A patient with limited cardiovascular reserve is scheduled for a minor surgical procedure. Which intravenous anesthetic would be the MOST appropriate for induction, considering its minimal impact on cardiovascular function?
What is a significant advantage of Remifentanil compared to other opioids used in anesthesia?
What is a significant advantage of Remifentanil compared to other opioids used in anesthesia?
A patient undergoing anesthesia with propofol experiences a significant drop in blood pressure. What is the primary mechanism contributing to this hypotension?
A patient undergoing anesthesia with propofol experiences a significant drop in blood pressure. What is the primary mechanism contributing to this hypotension?
When is dexmedetomidine most appropriate for use?
When is dexmedetomidine most appropriate for use?
What is a common adverse effect associated with etomidate administration, which may require pretreatment with another medication?
What is a common adverse effect associated with etomidate administration, which may require pretreatment with another medication?
Which of the following intravenous anesthetics is known to cause cardiovascular stimulation?
Which of the following intravenous anesthetics is known to cause cardiovascular stimulation?
Flashcards
Intravenous Anesthetics
Intravenous Anesthetics
Rapid onset; quick induction of stage III surgical anesthesia.
Thiopental's Effects
Thiopental's Effects
Enhances GABA effects, opens GABA channels at higher doses, depresses function, and doesn't increase cerebral blood flow.
IV Benzodiazepines Action
IV Benzodiazepines Action
It enhances GABA effects leading to CNS depression, but does not open channels in absence of GABA.
Ketamine Characteristics
Ketamine Characteristics
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Ketamine
Ketamine
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Propofol
Propofol
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Etomidate Characteristics
Etomidate Characteristics
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Dexmedetomidine (Precedex)
Dexmedetomidine (Precedex)
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Opioid Analgesics
Opioid Analgesics
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Neuroleptanesthesia
Neuroleptanesthesia
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Short-Acting Barbiturates recovery
Short-Acting Barbiturates recovery
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Ketamine
Ketamine
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Etomidate
Etomidate
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Study Notes
- General anesthetics are administered intravenously via anesthetics
- James Porter, Ph. D.
Intravenous Anesthetics
- Intravenous anesthetics have a rapid onset, which allows for a quick induction of stage III surgical anesthesia
- They are easy to administer
- Intravenous anesthetics cannot be reversed by ventilation
- There is a need to be more cautious to avoid severe medullary depression
Short-Acting Barbiturates
- Sodium thiopental, also known as Pentothal, and methohexital, also known as Brevital sodium, are examples of short-acting barbiturates
- They enhance the effects of GABA on GABAA channels, and at higher doses, they open GABAA channels in the absence of GABA
- Short-acting barbiturates depress respiratory and cardiac function by decreasing MAP and CO
- They do not increase cerebral blood flow, which is advantageous for head trauma and brain tumors
- Short-acting barbiturates are metabolized by the liver
- They induce hepatic ALA synthase, which is the rate-limiting step in heme synthesis, potentially precipitating acute intermittent porphyria
- Short-acting barbiturates are highly lipid-soluble, allowing for rapid induction
- Rapid redistribution from the CNS allows for rapid recovery
IV Benzodiazepines
- Diazepam, also known as Valium, and midazolam, known as Versed are IV Benzodiazepines; Midazolam is water-soluble
- IV Benzodiazepines enhance the effects of GABA on GABAA channels
- Unlike barbiturates, inhalation anesthetics, and ethanol, benzodiazepines do not open channels in the absence of GABA
- IV Benzodiazepines depress the CNS to a level below a true anesthetic state
- IV Benzodiazepines can be used for preoperative sedation and amnesia
- These drugs can depress respiratory function
Benzodiazepines
- Flumazenil serves as a benzodiazepine receptor antagonist
- It is used to accelerate recovery from benzo sedation
- Respiratory depression is less reversible with Flumazenil
Ketamine (Ketalar)
- Ketamine, also known as Ketalar, induces dissociative anesthesia, causing amnesia, catatonia, and analgesia
- Patients may not lose consciousness, and their eyes may remain open
- It has a rapid, short duration
- Ketamine is chemically related to PCP
- Blocks NMDA receptors, which are excitatory receptors activated by glutamate
- Ketamine is the only IV anesthetic that produces cardiovascular stimulation via central stimulation of the sympathetic system
- It increases heart rate, blood pressure, and cardiac output
- Ketamine is useful for poor-risk geriatric patients and those with cardiogenic or septic shock
- Ketamine increases cerebral blood flow and intracranial pressure
- Emergence reactions, such as vivid dreams and hallucinations, can occur
- Diazepam or midazolam given prior to ketamine reduces the incidence of these reactions
Propofol (Diprivan)
- Propofol, also known as Diprivan, is an extremely important IV anesthetic that enhances GABAA-mediated inhibition
- It has a very rapid onset and recovery, especially for outpatient surgery, because it is rapidly metabolized by the liver
- Propofol also serves as an antiemetic, reducing postoperative nausea and vomiting
- This drug is used for induction and maintenance
- It depresses respiratory function
- Propofol causes marked hypotension due to vasodilation
- It is a negative inotrope
- Prolonged infusion of propofol does not increase its half-life
Etomidate (Amidate)
- Etomidate, also known as Amidate, causes minimal cardiovascular and respiratory depression
- It is used in patients with limited cardiovascular reserve
- Etomidate enhances GABA-mediated inhibition
- It has no analgesic effects and may require coadministered opioids
- This drug has a rapid onset and recovery due to redistribution and is extensively metabolized by the liver
- Adverse effects include pain on injection, involuntary muscle movements in 50% of patients, postoperative nausea and vomiting, and adrenal suppression via inhibition of steroidogenesis, which blocks 11-β-hydroxylation and decreases cortisol after a single dose
Dexmedetomidine (Precedex)
- Dexmedetomidine, known as Precedex, is a highly selective α2-adrenergic agonist
- It induces hypnosis, presumably from the stimulation of α2 receptors in the locus coeruleus, which resembles a physiologic sleep state by activating endogenous sleep pathways
- It also has an analgesic effect in the spinal cord
- Dexmedetomidine decreases heart rate and systemic vascular resistance, which can lead to decreased blood pressure
- It has mild respiratory effects
- This is a water-soluble parenteral formulation
- It provides sedative and analgesic effects without respiratory depression
- Dexmedetomidine is used for short-term sedation of intubated and ventilated patients in an ICU setting
- It can be an adjunct to general anesthesia or provide sedation during awake fiberoptic tracheal intubation or regional anesthesia
- Dexmedetomidine decreases the dose requirements for inhaled and injected anesthetics
Opioid Analgesics
- Fentanyl, available as Sublimaze, is a potent analgesic
- It acts as a Mu opioid receptor agonist
- Fentanyl has a shorter duration of action than other opioids
- High IV doses can cause chest wall rigidity and prolonged postoperative respiratory depression
- Remifentanil, available as Ultiva, is an extremely short-acting opioid that is rapidly metabolized by esterases in blood and muscle
- Opioid analgesics have minimal cardiovascular effects; thus, they may be used in patients with minimal circulatory reserve
- Opioid effects can be reversed by the antagonist naloxone
Neuroleptanesthesia
- Neuroleptanesthesia is a combination of Fentanyl, droperidol (a neuroleptic related to haloperidol, which is a dopamine receptor blocker), and nitrous oxide
- If droperidol is given to control nausea and vomiting, note that it has no analgesic effect
- Nâ‚‚O often causes nausea and vomiting
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