Questions and Answers
What is a primary advantage of using benzodiazepines in anesthesia?
Which of the following is NOT a commonly reported side effect of ketamine?
How do opioid analgesics like morphine and fentanyl affect myocardial activity?
What is the main purpose of epidural anesthesia?
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What is a primary difference between epidural anesthesia and spinal anesthesia?
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Which condition contraindicates the use of ketamine?
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Which statement is true regarding the use of ketamine as an anesthetic?
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What is one of the disadvantages of using benzodiazepines during anesthesia?
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What is the primary mechanism by which local anesthetics block nerve impulses?
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Which local anesthetic classification is metabolized by pseudocholinesterase?
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What desirable property of local anesthetics ensures minimal irritation to tissues?
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What characteristic of the amine end of local anesthetic molecules contributes to their delivery in solution?
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Which local anesthetic has a longer duration of action due to its metabolism in the liver?
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Which of the following factors is NOT a desirable property of local anesthetics?
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What route is primarily used for administering spinal anesthesia?
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Which local anesthetic structure features both a hydrophilic amine group and a lipophilic aromatic group?
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Which of the following are adverse effects associated with status epilepticus treatment?
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What advantage does Etomidate have over other anesthetic agents?
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What is a notable disadvantage of Propofol that medical professionals should consider?
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In which of the following considerations is Etomidate specifically contraindicated?
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Which characteristic does not apply to Propofol?
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Which of the following statements about Etomidate's effects during induction is true?
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Study Notes
Ketamine
- Induces dissociative anesthesia, providing amnesia and analgesia while preserving consciousness.
- Administered via IV, IM, oral, or rectal routes.
- Mechanism: NMDA receptor antagonist.
- Notable pharmacokinetics: large volume of distribution and rapid clearance.
- Metabolized in the liver; renal excretion.
Advantages
- No associated vomiting or hypotension.
- Acts as a bronchodilator; beneficial for asthmatics.
- Effective in children through IM or rectal administration.
- Useful for changing burn dressings.
- Minimal impairment of pharyngeal and laryngeal reflexes.
Disadvantages
- No muscle relaxation; may elevate blood pressure.
- Increased cerebral blood flow and oxygen consumption.
- Potential for hallucinations and disorientation.
- Possible involuntary movements.
Contraindications
- Contraindicated during pregnancy due to oxytocic effects.
- Avoid in patients with a history of mental illness, hypertension, glaucoma, or head injury.
Benzodiazepines (Diazepam, Lorazepam, Midazolam)
- Used for induction, maintenance, and supplementation of anesthesia.
- Induce sedation and amnesia within 5 minutes.
- Do not cause respiratory or cardiovascular depression.
- Preferred for endoscopic procedures and cardiac catheterization.
Opioid Analgesics (Morphine & Fentanyl)
- Administered at the beginning of painful procedures.
- Frequently used in cardiac surgeries due to minimal effects on myocardial activity.
- Fentanyl combined with benzodiazepines for diagnostic and minor procedures.
Local Anesthesia
- Provides localized pain relief without loss of consciousness.
- Epidural anesthesia: Medication injected into epidural space; effects occur in 10-15 minutes.
- Spinal anesthesia: Medication injected into CSF; effects last 1-2 hours.
Classifications
- Local anesthetics (LAs) are weak bases, characterized by an amine group and an aromatic ring.
- Esters (e.g., cocaine, procaine): metabolized by pseudocholinesterase; short duration.
- Amides (e.g., lidocaine, bupivacaine): metabolized by liver enzymes; longer duration.
Mechanism of Action
- LAs block sodium channels, preventing Na+ influx essential for nerve impulse transmission.
Desirable Properties
- Non-irritating to tissues.
- Should not permanently alter nerve structure.
- Low systemic toxicity.
- Quick onset and sufficient potency.
- Long enough duration for procedure completion.
- Free from allergic reactions.
Adverse Effects
- Potential for apnea, hypotension, respiratory depression, necrosis, and gangrene if injected into arteries.
- Risk of porphyria, shivering, and delirium during recovery.
Contraindications
- Avoid in patients with porphyria, shock, or asthma.
Non-barbiturate Anesthetics
Etomidate
- Wide safety margin; suitable for patients with poor cardiac function (e.g., coronary artery disease).
- Onset: 30-60 seconds; duration: 5-10 minutes.
- Possible injection site pain; may require lidocaine.
- Potential for myoclonic movements; often used with diazepam.
Advantages
- Rapid induction and recovery.
- Does not sensitize myocardium to adrenaline.
- Minimal nausea and vomiting.
Disadvantages
- Involuntary movements may occur during induction.
- Prolonged use may suppress adrenal function and cause electrolyte imbalances.
- Not indicated for status epilepticus.
Propofol
- Similar mechanism of action to thiopental; widely used.
- Onset: 30-40 seconds; duration: 5-10 minutes.
- Extensively metabolized; antiemetic properties.
- Must be discarded 8 hours after opening due to bacterial growth.
Advantages
- Effective for induction and maintenance of anesthesia.
- Safe during pregnancy; crosses the placenta.
- Ideal for outpatient procedures.
Disadvantages
- Can cause hypotension and bradycardia.
- Dose-dependent respiratory depression may occur.
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Description
This quiz covers the pharmacological aspects of ketamine, including its mechanism of action, advantages, and uses in dissociative anesthesia. Explore its applications in various settings, such as IV, IM, and oral administration, while understanding how it affects patients without causing nausea or hypotension.
