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What is the incidence of emergence reactions in adults when ketamine is a major part of the anesthetic?
What is the incidence of emergence reactions in adults when ketamine is a major part of the anesthetic?
What is the proposed neuroprotective effect of ketamine?
What is the proposed neuroprotective effect of ketamine?
Which personality type is associated with a higher incidence of emergence reactions when ketamine is used as an anesthetic in adults?
Which personality type is associated with a higher incidence of emergence reactions when ketamine is used as an anesthetic in adults?
What effect does ketamine have on the EEG at high doses?
What effect does ketamine have on the EEG at high doses?
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What effect does ketamine have on the seizure threshold in epileptic patients?
What effect does ketamine have on the seizure threshold in epileptic patients?
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What is the duration of increased systemic blood pressure caused by ketamine?
What is the duration of increased systemic blood pressure caused by ketamine?
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What effect does ketamine have on minute ventilation following a bolus dose?
What effect does ketamine have on minute ventilation following a bolus dose?
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What is a rare side effect of ketamine related to platelet aggregation?
What is a rare side effect of ketamine related to platelet aggregation?
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Which receptor does dexmedetomidine act as an agonist on?
Which receptor does dexmedetomidine act as an agonist on?
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What effect does alpha2 agonism have on the respiratory drive?
What effect does alpha2 agonism have on the respiratory drive?
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What is the primary site of action for dexmedetomidine?
What is the primary site of action for dexmedetomidine?
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Which organ system is affected by dexmedetomidine, leading to decreased salivation and minimal depression of ventilation?
Which organ system is affected by dexmedetomidine, leading to decreased salivation and minimal depression of ventilation?
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What is the clinical use of dexmedetomidine in reducing the minimum alveolar concentration (MAC) of isoflurane?
What is the clinical use of dexmedetomidine in reducing the minimum alveolar concentration (MAC) of isoflurane?
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Which organ system experiences hypotension and bradycardia due to the central and peripheral mechanisms of dexmedetomidine?
Which organ system experiences hypotension and bradycardia due to the central and peripheral mechanisms of dexmedetomidine?
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What is the primary clinical use of scopolamine?
What is the primary clinical use of scopolamine?
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What is the side effect associated with scopolamine that could lead to restlessness, hallucinations, or somnolence?
What is the side effect associated with scopolamine that could lead to restlessness, hallucinations, or somnolence?
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What is the primary organ affected by droperidol to achieve the goal of detached, pain-free state of immobilization?
What is the primary organ affected by droperidol to achieve the goal of detached, pain-free state of immobilization?
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What is the main effect of droperidol on the respiratory system when used alone?
What is the main effect of droperidol on the respiratory system when used alone?
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What is the primary clinical use of droperidol in combination with an opioid such as fentanyl?
What is the primary clinical use of droperidol in combination with an opioid such as fentanyl?
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Which receptor inhibition by droperidol leads to CNS depression, sedation, and occasional extrapyramidal symptoms?
Which receptor inhibition by droperidol leads to CNS depression, sedation, and occasional extrapyramidal symptoms?
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What is the main effect of droperidol on myocardial repolarization and the QT interval?
What is the main effect of droperidol on myocardial repolarization and the QT interval?
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What was the 2007 International Consensus Panel's recommended primary use for droperidol?
What was the 2007 International Consensus Panel's recommended primary use for droperidol?
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What is the primary mechanism of action of ketamine?
What is the primary mechanism of action of ketamine?
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What is the significant difference between the S(+) isomer and R(-) isomer of ketamine?
What is the significant difference between the S(+) isomer and R(-) isomer of ketamine?
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What is the major pathway of metabolism for ketamine?
What is the major pathway of metabolism for ketamine?
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What is the effect of ketamine on cerebral blood flow (CBF)?
What is the effect of ketamine on cerebral blood flow (CBF)?
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At what doses does ketamine achieve analgesia without causing anesthesia?
At what doses does ketamine achieve analgesia without causing anesthesia?
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What is a concern associated with increased psychomimetic reactions when using ketamine for postoperative sedation and analgesia?
What is a concern associated with increased psychomimetic reactions when using ketamine for postoperative sedation and analgesia?
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What is the onset of action for intravenous (IV) administration of ketamine for induction of anesthesia?
What is the onset of action for intravenous (IV) administration of ketamine for induction of anesthesia?
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What is a potential concern with chronic dosing of ketamine?
What is a potential concern with chronic dosing of ketamine?
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What effect does ketamine have on spinal nocioceptive pathways?
What effect does ketamine have on spinal nocioceptive pathways?
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What contributes to the rapid onset of action of ketamine?
What contributes to the rapid onset of action of ketamine?
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What effect does the S(+) isomer of ketamine have on muscarinic receptors?
What effect does the S(+) isomer of ketamine have on muscarinic receptors?
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Study Notes
Ketamine and Emergence Reactions
- Emergence reactions in adults occur in about 10-20% of cases when ketamine is part of anesthetic protocols.
- Higher incidence of emergence reactions is associated with personality types that are more agitated or have a history of psychiatric disorders.
Neuroprotective Effects of Ketamine
- Proposed neuroprotective effects include potential reduction in neuronal damage during hypoxic or ischemic events.
- Ketamine may facilitate reparative processes in neurodegenerative conditions.
EEG and Ketamine
- At high doses, ketamine leads to beta wave activity suppression and can induce alterations in the electroencephalogram (EEG), indicative of anesthesia.
Ketamine on Seizure Threshold
- In epileptic patients, ketamine may lower the seizure threshold, thus presenting a risk for seizure activity.
Blood Pressure and Ketamine
- Ketamine can increase systemic blood pressure, and this effect may last for several minutes post-administration.
Ketamine and Minute Ventilation
- Following a bolus dose of ketamine, minute ventilation may initially decrease but often stabilizes with continued administration.
Rare Side Effects of Ketamine
- A rare side effect includes impaired platelet aggregation, increasing the risk of bleeding complications.
Dexmedetomidine and Receptor Agonism
- Dexmedetomidine acts as an agonist at alpha-2 adrenergic receptors, influencing sedation and analgesia.
Respiratory Drive and Alpha2 Agonism
- Alpha2 agonism decreases respiratory drive, leading to respiratory stability without significant depression.
Primary Site of Action for Dexmedetomidine
- The primary site of action is the locus coeruleus in the brainstem, providing sedative effects while maintaining airway reflexes.
Organ Systems Affected by Dexmedetomidine
- The central nervous system is affected, resulting in decreased salivation and minimal respiratory depression.
Clinical Use of Dexmedetomidine
- Dexmedetomidine is effective in reducing the minimum alveolar concentration (MAC) of isoflurane, enhancing surgical conditions.
Cardiovascular Effects of Dexmedetomidine
- Central and peripheral mechanisms lead to hypotension and bradycardia due to its effects on the sympathetic nervous system.
Primary Clinical Use of Scopolamine
- Scopolamine is primarily used for the prevention of postoperative nausea and vomiting (PONV).
Side Effects of Scopolamine
- Side effects can include restlessness, hallucinations, or somnolence due to anticholinergic effects.
Droperidol's Mechanism and Effects
- Droperidol acts on dopaminergic receptors, helping achieve a state of sedation and immobilization.
- Alone, droperidol can lead to respiratory depression, especially in sensitive patients.
Clinical Use of Droperidol with Opioids
- Often combined with opioids like fentanyl for enhanced analgesic effects and sedation.
CNS Effects of Droperidol
- Inhibition of D2 receptors contributes to CNS depression, sedation, and may cause extrapyramidal symptoms.
Droperidol and Cardiac Effects
- Droperidol can affect myocardial repolarization, leading to QT interval prolongation.
Recommendations from the 2007 International Consensus Panel
- Primarily recommended for use in treating nausea and vomiting, particularly in surgical settings.
Ketamine's Mechanism of Action
- Ketamine primarily acts as an NMDA receptor antagonist, blocking excitatory neurotransmission.
Isomer Differences in Ketamine
- The S(+) isomer is more potent and has a clearer analgesic profile compared to the R(-) isomer.
Ketamine Metabolism
- The major metabolic pathway involves hepatic cytochrome P450 enzymes, primarily CYP3A4.
Cerebral Blood Flow and Ketamine
- Ketamine can increase cerebral blood flow (CBF), which may provoke concerns in intracranial pressure scenarios.
Analgesic Doses of Ketamine
- Analgesia can be achieved at subanesthetic doses, typically lower than those required for full anesthesia.
Concerns with Psychomimetic Reactions
- Increased psychomimetic reactions may occur with doses utilized for sedation/analgesia, particularly in sensitive individuals.
Onset of Action for IV Ketamine
- The onset of action for intravenous administration is rapid, typically occurring within minutes.
Chronic Dosing Concerns
- Chronic dosing of ketamine raises potential issues such as urinary symptoms and cognitive deficits.
Ketamine's Effect on Nociceptive Pathways
- Ketamine modifies the spinal nociceptive pathways, disrupting pain signal transmission.
Onset Contribution
- The rapid onset of ketamine's effects is attributed to its high lipid solubility and protein binding characteristics.
S(+) Isomer and Muscarinic Receptors
- The S(+) isomer can act on muscarinic receptors, contributing to its broader pharmacological effects beyond NMDA antagonism.
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