164 Questions
Which of the following is a characteristic of dissociative anesthesia produced by ketamine?
The patient is amnesic
What advantage does ketamine have over propofol and etomidate?
It does not require a lipid emulsion vehicle for dissolution
What limits the clinical usefulness of ketamine as a sole agent?
The frequency of emergence delirium
Which system in the brain shows evidence of dissociation in dissociative anesthesia produced by ketamine?
The thalamocortical and limbic systems
What is a characteristic of the patient's eyes during dissociative anesthesia produced by ketamine?
They remain open with a slow nystagmic gaze
What is the patient's level of wakefulness during dissociative anesthesia produced by ketamine?
Wakefulness may appear to be present
What is a common occurrence during dissociative anesthesia produced by ketamine?
Varying degrees of hypertonus and purposeful skeletal muscle movements
What is the patient's level of analgesia during dissociative anesthesia produced by ketamine?
Intense analgesia
What advantage does ketamine have over propofol and etomidate?
Does not require a lipid emulsion vehicle for dissolution
What limits the clinical usefulness of ketamine as a sole agent?
Frequency of emergence delirium
What precaution should be taken with ketamine due to its abuse potential?
Appropriate precautions against unauthorized nonmedical use
Which of the following is true about ketamine?
Ketamine is a water-soluble molecule
What is the designation for the left-handed optical isomer of ketamine?
S(+) ketamine
Which form of ketamine is clinically available for treatment of therapy-resistant depression?
Esketamine
In Europe, esketamine is widely used for what purposes?
Both anesthetic and treatment of acute and chronic pain
When studied separately, which isomer of ketamine produces more intense analgesia?
S(+) ketamine
Which isomer of ketamine has a lower incidence of emergence reactions?
S(+) ketamine
What is the analgesic potency of esketamine compared to racemic ketamine?
Approximately twice
Which isomer of ketamine induces less fatigue and cognitive impairment at equianalgesic small doses?
S(+) ketamine
What effect does both isomers of ketamine have on the uptake of catecholamines back into postganglionic sympathetic nerve endings?
Inhibition
What is the preservative used for ketamine?
Benzethonium chloride
What is the mechanism of action of ketamine-induced analgesia and dissociative anesthesia?
Ketamine interacts with multiple CNS receptors.
What is the effect of ketamine on GABAA receptors?
Ketamine has weak actions on GABAA receptors.
What is the role of the innate repair receptor in mediating ketamine's effects on neuropathic pain?
The innate repair receptor plays a pivotal role in subduing tissue damage and inflammation.
What is the effect of ketamine on the analgesic relief of acute pain?
Ketamine-induced relief of acute pain is not affected by the innate repair receptor.
What is the effect of ketamine on cytokines in blood?
Ketamine directly inhibits cytokines in blood.
What is the effect of ketamine on neutrophil production of inflammatory mediators?
Ketamine suppresses neutrophil production of inflammatory mediators.
Which receptors does ketamine bind noncompetitively to?
Ketamine binds noncompetitively to the phencyclidine recognition site on NMDA receptors.
Which receptors does ketamine exert effects at?
Ketamine exerts effects at opioid receptors, monoaminergic receptors, muscarinic receptors, and voltage-sensitive sodium and L-type calcium channels and neuronal nicotinic acetylcholine receptors.
What is the designation for the left-handed optical isomer of ketamine?
The left-handed optical isomer of ketamine is known as esketamine.
What is the effect of ketamine on wakefulness during dissociative anesthesia?
The patient's level of wakefulness is increased during dissociative anesthesia produced by ketamine.
Which receptors does ketamine primarily interact with to inhibit the activation of NMDA receptors?
Glutamate receptors
What effect does ketamine have on sodium channels?
It blocks voltage-gated sodium channels
Which type of nicotinic acetylcholine receptors does ketamine interact with?
Homomeric α7 nicotinic acetylcholine receptors
Which of the following is true about the pharmacokinetics of ketamine?
Ketamine has a pK of 7.5 at physiologic pH.
Where does ketamine initially distribute after administration?
Brain
What is the elimination half-life of ketamine?
2 to 3 hours
Which enzyme is responsible for the demethylation of ketamine to form norketamine and hydroxynorketamine?
Cytochrome P450 enzymes
What is the percentage of a dose of ketamine that can be recovered from urine as unchanged drug after intravenous administration?
Less than 4%
What effect does chronic administration of ketamine have on the metabolism of the drug?
Stimulates the activity of enzymes responsible for its metabolism
Which drug is often recommended to decrease the likelihood of coughing and laryngospasm due to ketamine-induced salivary secretions?
Glycopyrrolate
At what doses does ketamine produce prompt induction of anesthesia when administered intravenously?
High doses
What is the primary clinical effect of ketamine at subanesthetic doses?
Analgesia
Which system is responsible for the interpretation of painful signals?
Thalamic and limbic systems
What is the role of NMDA receptors in pain processing?
Activation of NMDA receptors leads to spinal cord sensitization
What is the effect of ketamine on neonatal neurobehavioral scores?
Ketamine analgesia during labor is associated with higher neonatal neurobehavioral scores compared to thiopental-nitrous oxide anesthesia
Which of the following is a potential advantage of using ketamine as an analgesic adjuvant in patients with preexisting chronic pain syndromes who require surgery?
Ketamine has a lower potential for abuse or addiction
What is the most likely reason for the limited value of neuraxial ketamine in producing analgesia?
Ketamine has a weak affinity for spinal opioid receptors
What is the most likely reason for the additive or synergistic effect of ketamine when combined with other epidural analgesics?
Ketamine enhances the binding of local anesthetics to voltage-gated sodium ion channels
Which receptors are responsible for the analgesic effects of ketamine?
NMDA receptors
What is the primary mechanism of action of ketamine as an analgesic?
Inhibition of NMDA receptors
What is the role of NMDA receptors in pain processing?
They modulate pain
What is the effect of ketamine on sodium channels?
Inhibition
What is the most likely reason for the limited value of neuraxial ketamine in producing analgesia?
Poor distribution to the spinal cord
What is the effect of chronic administration of ketamine on the metabolism of the drug?
Decreased metabolism
What is the most likely reason for the additive or synergistic effect of ketamine when combined with other epidural analgesics?
Inhibition of NMDA receptors
Which of the following is true about the analgesic effects of ketamine?
Ketamine produces long-lasting pain relief in rodent pain models.
What is the most likely reason for the lower potential for abuse or addiction associated with hydroxynorketamine?
Hydroxynorketamine has a higher affinity for opioid receptors compared to ketamine.
What is the most likely reason for the limited value of neuraxial ketamine for producing analgesia?
Ketamine has a weaker affinity for spinal opioid receptors compared to morphine.
What is the most likely reason for the additive or synergistic effect of ketamine when combined with other epidural analgesics?
Ketamine has a stronger interaction with local anesthetic binding sites on voltage-gated sodium ion channels compared to other analgesics.
What is a characteristic of dissociative anesthesia produced by ketamine?
Increased cerebral blood flow and intracranial pressure
What is the effect of ketamine on GABAA receptors?
Ketamine inhibits the binding of GABA to GABAA receptors.
What is the effect of ketamine on wakefulness during dissociative anesthesia?
Ketamine increases wakefulness.
What is the elimination half-life of ketamine?
1-2 hours
Which route of administration of ketamine does not produce pain or venous irritation?
Intravenous (IV)
How long does it take for consciousness to be lost after intravenous administration of ketamine?
30 to 60 seconds
What is the usual duration of unconsciousness after an injected induction dose of ketamine?
10 to 20 minutes
What is the typical duration of amnesia after recovery of consciousness from ketamine?
60 to 90 minutes
What is a potential advantage of using ketamine in burn patients undergoing dressing changes and skin grafting procedures?
Intense analgesic activity
What is the primary clinical effect of ketamine at subanesthetic doses?
Dissociative anesthesia
What is the cardiovascular effect of ketamine in acutely hypovolemic patients?
Stimulating
What is the typical emergence time after repeated intravenous injections or continuous infusion of ketamine?
Even longer
What is the effect of chronic administration of ketamine on tolerance?
May develop
In which patient population has ketamine been used as an intramuscular induction drug?
Children and difficult-to-manage mentally challenged patients
Which of the following is a consideration when administering ketamine to patients with coronary artery disease?
Increased myocardial oxygen requirements
What is the recommended induction of anesthesia in patients with coronary artery disease?
Diazepam and ketamine
What is the potential benefit of combining subanesthetic doses of ketamine with propofol for total IV anesthesia?
More stable hemodynamics
Why is ketamine considered a potentially useful drug for rapid IV induction of anesthesia in patients with asthma?
It has beneficial effects on airway resistance
What precaution should be taken with ketamine in patients with systemic or pulmonary hypertension or increased ICP?
Use cautiously or avoid
What is a potential undesirable effect of ketamine administration during eye operations or examinations?
Nystagmus
Is ketamine safe to administer to patients with malignant hyperthermia?
Yes
What is a potential use of ketamine in pediatric cardiac catheterization?
Useful for anesthesia
Should ketamine be used cautiously or avoided in patients with systemic or pulmonary hypertension?
Yes
What effect does ketamine have on the interpretation of catheterization data in patients with coronary artery disease?
Possible cardiac-stimulating effects
Which receptor is believed to be involved in the mechanism of opioid-induced tolerance?
NMDA receptors
What is the effect of subanesthetic doses of ketamine on opioid tolerance?
Reduces the likelihood of tolerance
In which psychiatric disorder has ketamine been shown to improve the postoperative depressive state?
Mental depression
What is the FDA-approved use of intranasal esketamine?
Treatment of therapy-resistant depression
What is the possible mechanism by which ketamine improves restless leg syndrome?
Inhibits neuroinflammation in the spinal cord
What are the NMDA receptors thought to be involved in the pathophysiology of?
Mental depression
What is the effect of intermittent treatment with low-dose ketamine in patients with obsessive compulsive disorder?
Improves obsessions and compulsions
What is the effect of ketamine on the analgesic relief of acute pain?
Enhances analgesic relief
Which system in the body does ketamine potentially inhibit to improve restless leg syndrome?
Inflammatory system
What is the FDA-approved use of intranasal esketamine in conjunction with?
Oral antidepressant
Which of the following is a unique characteristic of ketamine among injected anesthetics?
It produces emergence delirium
What is the effect of ketamine on intracranial pressure in mechanically ventilated animals with increased ICP?
It has no effect on ICP
In patients requiring craniotomy for brain tumor or cerebral aneurysm resection, what effect does administration of ketamine have on middle cerebral artery blood flow velocity?
It has no effect on blood flow velocity
What effect does ketamine have on intracranial pressure in patients with traumatic brain injury?
It decreases ICP
What is the primary reason why ketamine is considered contraindicated in patients with increased intracranial pressure (ICP)?
It increases cerebral blood flow
What effect does ketamine have on anterior fontanelle pressure in mechanically ventilated preterm neonates?
It decreases anterior fontanelle pressure
What effect does ketamine have on cerebral metabolic rate of oxygen (CMRO2)?
It has no effect on CMRO2
What is the effect of ketamine on cerebral blood flow in the presence of normocapnia?
It significantly increases cerebral blood flow
What is the primary reason why patients with intracranial pathology are considered vulnerable to sustained increases in ICP after administration of ketamine?
It increases cerebral blood flow
What is the primary effect of ketamine at subanesthetic doses?
Production of emergence delirium
Which of the following is true about ketamine's effect on the EEG?
Ketamine produces a burst suppression pattern at high doses.
What is the effect of ketamine on somatosensory evoked potentials?
Ketamine increases the cortical amplitude of somatosensory evoked potentials.
What is the effect of ketamine on auditory and visual evoked responses?
Ketamine decreases auditory and visual evoked responses.
Which of the following is a cardiovascular effect of ketamine?
Increased cardiac output
What is the typical pattern of systemic blood pressure after IV injection of ketamine?
Initial increase followed by decrease
Which of the following can prevent or blunt the cardiovascular-stimulating effects of ketamine?
Concomitant administration of inhaled anesthetics
Which anesthetic is associated with a higher survival rate in shocked animals compared to halothane?
Ketamine
What is the effect of ketamine administration on arterial lactate concentrations in animals with lower systemic blood pressures?
Greater increase
What is the potential consequence of ketamine-induced vasoconstriction on tissue perfusion?
Decreased tissue perfusion
Which of the following is the most important mechanism for the cardiovascular stimulation caused by ketamine?
Direct stimulation of the CNS
What effect does ketamine have on epinephrine-induced cardiac dysrhythmias?
Abolishes them
What is the effect of inhaled anesthetics, ganglionic blockade, β-blockade, cervical epidural anesthesia, and spinal cord transection on ketamine-induced increases in systemic blood pressure and heart rate?
They prevent the increases
Which of the following mechanisms has been suggested as a possible explanation for how ketamine produces airway relaxation?
Increased circulating catecholamine concentrations
What is a potential adverse effect associated with repeated use of ketamine in high doses?
Hemorrhagic cystitis
Which of the following is a possible effect of ketamine on the liver?
Allergic hepatitis
Which of the following statements about ketamine's effect on ventilation is most accurate?
Ketamine can cause apnea if administered rapidly IV or with an opioid
What effect does ketamine have on upper airway reflexes and muscle tone?
Ketamine maintains upper airway reflexes and muscle tone
What is the recommended precaution when using ketamine to prevent aspiration?
Placement of a cuffed tube in the patient's trachea is necessary
Which receptors does ketamine primarily interact with to inhibit the activation of NMDA receptors?
Serotonin receptors
What is the most likely reason for the limited value of neuraxial ketamine in producing analgesia?
Poor penetration into the central nervous system
What is the effect of ketamine on upper airway reflexes and muscle tone?
Decreases upper airway reflexes and muscle tone
Which of the following factors is NOT associated with an increased incidence of emergence delirium after administration of ketamine?
A history of personality problems or frequent dreaming
What is the most effective drug in preventing emergence delirium after administration of ketamine?
Benzodiazepines
What is the effect of including atropine in the preoperative medication before administration of ketamine?
Increases the incidence of emergence delirium
Which of the following is a potential drug interaction with ketamine that may result in hypotension?
Administration of verapamil
What is the potential effect of ketamine on the duration of apnea after administration of succinylcholine?
Prolonged duration
Which of the following is a potential effect of ketamine on the cardiovascular system?
Increased heart rate
Which type of ketamine blocks the cardioprotective effects of ischemic preconditioning in an animal model?
R(−) isomer
Which type of ketamine does not block the cardioprotective effects of preconditioning or alter myocardial infarct size in an animal model?
S(+) isomer
Which drugs should be used with caution in patients at risk for myocardial infarction during the perioperative period?
Drugs known to block preconditioning
Which of the following is a common ingredient in over-the-counter cough suppressants?
Dextromethorphan
What is the potency of dextromethorphan as an antitussive compared to codeine?
Equally potent as codeine
Which of the following is a symptom of intentional excessive intake of dextromethorphan?
Muscle rigidity and seizures
Which drug has a longer elimination half-time, dexmedetomidine or clonidine?
Dexmedetomidine
What is the primary route of excretion for the metabolites of dexmedetomidine?
Renal excretion
What effect might dexmedetomidine have on plasma concentrations of opioids administered during anesthesia?
Increased plasma concentrations
Which receptor does dexmedetomidine primarily act on?
α2 receptor
What is the pharmacologically active component of medetomidine?
Dexmedetomidine
What is the role of atipamezole in relation to dexmedetomidine?
It reverses the sedative and cardiovascular effects of dexmedetomidine
Which receptor does dexmedetomidine primarily act on?
α2
What is the main effect of dexmedetomidine on the sympathetic nervous system?
Decrease sympathetic activity
Which drug is a specific and selective α2-receptor antagonist that reverses the sedative effects of dexmedetomidine?
Atipamezole
Which of the following statements about the elimination half-time of dexmedetomidine is true?
The elimination half-time of dexmedetomidine is shorter than that of clonidine.
What is the primary route of excretion for the metabolites of dexmedetomidine?
Renal excretion
What effect does dexmedetomidine have on cytochrome P450 enzyme systems?
Dexmedetomidine inhibits cytochrome P450 enzyme systems.
Which of the following is a clinical use of dexmedetomidine?
Causing total IV anesthesia without depression of ventilation
What effect does dexmedetomidine have on MAC for volatile anesthetics in animals?
Decreases MAC by 90%
What effect does dexmedetomidine have on the range of temperatures triggering thermoregulatory defenses?
Increases the range
Which of the following is a clinical use of dexmedetomidine?
Decreasing plasma catecholamine concentrations during anesthesia
What effect does dexmedetomidine have on MAC for volatile anesthetics in animals?
Decreases MAC by greater than 90%
What is a potential anesthetic technique for patients with a difficult upper airway?
High dose dexmedetomidine
Which of the following is a clinical use of dexmedetomidine?
Decreasing plasma catecholamine concentrations during anesthesia
What effect does dexmedetomidine have on MAC for volatile anesthetics in animals?
Decreases MAC by greater than 90%
What is the effect of adding dexmedetomidine to lidocaine for IV regional anesthesia?
Improves the quality of anesthesia and postoperative analgesia without causing side effects
Which of the following statements about dexmedetomidine is true?
Dexmedetomidine sedation is similar to natural sleep.
What effect does dexmedetomidine have on the control of breathing?
Dexmedetomidine reduces the ventilatory response to hypoxia.
What is a potential life-threatening effect of dexmedetomidine?
Upper airway collapse.
Which of the following is a potential side effect of dexmedetomidine?
Bradycardia
What effect does dexmedetomidine have on the control of breathing?
Reduces resting ventilation
What is a potential use of clonidine and dexmedetomidine in the ICU?
Preventing drug withdrawal symptoms
Test your knowledge on non-γ-Aminobutyric Acid sedatives and hypnotics with this quiz. Learn about the pharmacological properties and effects of ketamine, a phencyclidine derivative that produces dissociative anesthesia.
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