IV Sed Hyp Non GABA

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Questions and Answers

What is the incidence of emergence reactions in adults when ketamine is a major part of the anesthetic?

20-40%

30-50%

5-10%

10-30% (correct)

What is the proposed neuroprotective effect of ketamine?

NMDA receptor agonism

Stimulation of the EEG

Alpha-2a agonism

NMDA receptor antagonism (correct)

Which personality type is associated with a higher incidence of emergence reactions when ketamine is used as an anesthetic in adults?

Low psychotism score

Extroverted

High psychotism score (correct)

Introverted

What effect does ketamine have on the EEG at high doses?

Burst suppression Signup and view all the answers

What effect does ketamine have on the seizure threshold in epileptic patients?

No change in threshold Signup and view all the answers

What is the duration of increased systemic blood pressure caused by ketamine?

10-20 minutes Signup and view all the answers

What effect does ketamine have on minute ventilation following a bolus dose?

Brief decrease Signup and view all the answers

What is a rare side effect of ketamine related to platelet aggregation?

Inhibition of platelet aggregation Signup and view all the answers

Which receptor does dexmedetomidine act as an agonist on?

Alpha2 receptor Signup and view all the answers

What effect does alpha2 agonism have on the respiratory drive?

Minimal effect on respiratory drive Signup and view all the answers

What is the primary site of action for dexmedetomidine?

Spinal cord Signup and view all the answers

Which organ system is affected by dexmedetomidine, leading to decreased salivation and minimal depression of ventilation?

Respiratory system Signup and view all the answers

What is the clinical use of dexmedetomidine in reducing the minimum alveolar concentration (MAC) of isoflurane?

Adjunct to general anesthesia Signup and view all the answers

Which organ system experiences hypotension and bradycardia due to the central and peripheral mechanisms of dexmedetomidine?

Cardiovascular system Signup and view all the answers

What is the primary clinical use of scopolamine?

Antiemetic Signup and view all the answers

What is the side effect associated with scopolamine that could lead to restlessness, hallucinations, or somnolence?

Central anticholinergic syndrome Signup and view all the answers

What is the primary organ affected by droperidol to achieve the goal of detached, pain-free state of immobilization?

Nervous system Signup and view all the answers

What is the main effect of droperidol on the respiratory system when used alone?

Minimal effect on respiration Signup and view all the answers

What is the primary clinical use of droperidol in combination with an opioid such as fentanyl?

Prophylaxis for postoperative nausea and vomiting (PONV) Signup and view all the answers

Which receptor inhibition by droperidol leads to CNS depression, sedation, and occasional extrapyramidal symptoms?

GABAA receptors and α2 -acetylcholine receptors Signup and view all the answers

What is the main effect of droperidol on myocardial repolarization and the QT interval?

Prolongation of the QT interval Signup and view all the answers

What was the 2007 International Consensus Panel's recommended primary use for droperidol?

Prophylaxis for postoperative nausea and vomiting (PONV) Signup and view all the answers

What is the primary mechanism of action of ketamine?

Inhibits binding of glutamate with NMDA receptors Signup and view all the answers

What is the significant difference between the S(+) isomer and R(-) isomer of ketamine?

The S(+) isomer has a greater affinity for phencyclidine binding site on NMDA receptor than R(-) isomer Signup and view all the answers

What is the major pathway of metabolism for ketamine?

Metabolism by hepatic microsomal enzymes leading to norketamine Signup and view all the answers

What is the effect of ketamine on cerebral blood flow (CBF)?

Increases CBF which speeds delivery of drug to the brain Signup and view all the answers

At what doses does ketamine achieve analgesia without causing anesthesia?

0.2 - 0.5 mg/kg IV Signup and view all the answers

What is a concern associated with increased psychomimetic reactions when using ketamine for postoperative sedation and analgesia?

Increased risk of emergence reactions Signup and view all the answers

What is the onset of action for intravenous (IV) administration of ketamine for induction of anesthesia?

30-60 seconds Signup and view all the answers

What is a potential concern with chronic dosing of ketamine?

Induction of enzymes responsible for its metabolism Signup and view all the answers

What effect does ketamine have on spinal nocioceptive pathways?

Excitation via activation of NMDA receptors Signup and view all the answers

What contributes to the rapid onset of action of ketamine?

High lipid solubility Signup and view all the answers

What effect does the S(+) isomer of ketamine have on muscarinic receptors?

It acts as an antagonist at muscarinic receptors Signup and view all the answers

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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