General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 541: During the induction of general anesthesia, if a patient exhibits signs of aspiration, what should be the immediate management to minimize complications?

A. Suction the oropharynx and apply cricoid pressure (Correct Answer)
B. Administer prophylactic antibiotics
C. Perform rapid sequence intubation
D. Place the patient in a supine position

Explanation: **Suction the oropharynx and apply cricoid pressure** * **Aspiration** of gastric contents during induction can lead to severe **pneumonitis** and **ARDS**. Prompt **suctioning of the oropharynx** and applying **cricoid pressure** helps prevent the aspiration of already regurgitated material and occludes the esophagus to prevent further reflux, buying time for intubation. * **Cricoid pressure (Sellick maneuver)** effectively compresses the esophagus against the vertebral column, preventing gastric contents from reaching the pharynx and subsequently the trachea, until a definitive airway is secured. *Perform rapid sequence intubation* * While rapid sequence intubation (RSI) is the definitive step to secure the airway in patients at risk of aspiration, it should only be performed *after* immediate measures like **suctioning** and **cricoid pressure** have been implemented to protect the airway and clear obvious material. * Attempting intubation without first clearing the airway can push gastric contents deeper into the trachea, worsening the aspiration event. *Administer prophylactic antibiotics* * **Prophylactic antibiotics** are generally not indicated for aspiration events; **aspiration pneumonitis** is a chemical burn, not a bacterial infection, in its initial stages. * Antibiotics would only be considered if there is evidence of a secondary bacterial infection or **aspiration pneumonia**, which develops hours to days later, not as an immediate management strategy. *Place the patient in a supine position* * Placing an aspirating patient in a **supine position** is contraindicated as it can facilitate the flow of gastric contents into the trachea and lungs due to gravity. * Instead, positioning the patient in a **head-down (Trendelenburg)** or **lateral (recovery)** position might be considered to help drain gastric contents from the pharynx, although immediate suction and cricoid pressure are paramount.

Question 542: Which agent is commonly used for the induction of anesthesia in rapid sequence intubation?

A. Propofol
B. Ketamine
C. Etomidate (Correct Answer)
D. Thiopental

Explanation: ***Etomidate*** - **Etomidate** is frequently chosen for rapid sequence intubation (RSI) due to its **hemodynamic stability**, making it safe for critically ill patients. - It has a **rapid onset** and short duration of action, facilitating quick intubation. *Propofol* - While propofol is a common induction agent, it can cause **significant hypotension** due to its vasodilatory effects, which may be detrimental in critically ill patients undergoing RSI. - Its longer duration of action compared to etomidate might not be ideal for situations requiring rapid recovery or reassessment. *Ketamine* - **Ketamine** provides both sedation and analgesia but can cause **hypertension** and **tachycardia**, which may be undesirable in certain patient populations. - It can also increase intracranial pressure, making it less favorable in patients with head injuries unless hypotension is a major concern. *Thiopental* - **Thiopental** is a potent barbiturate with a rapid onset, but it can cause **pronounced cardiovascular depression** (hypotension and decreased myocardial contractility). - Its use has largely been replaced by newer agents like etomidate and propofol due to its less favorable hemodynamic profile and narrow therapeutic window.

Question 543: A patient under general anesthesia develops tachycardia and hypertension following the administration of an inhalational anesthetic. Which agent is most likely responsible?

A. Halothane
B. Sevoflurane
C. Desflurane (Correct Answer)
D. Isoflurane

Explanation: ***Desflurane*** - **Desflurane** is well-known for causing a **sympathetic nervous system stimulation** at higher concentrations or with rapid increases in concentration, leading to **tachycardia** and **hypertension**. - This effect is often due to its **pungent odor** and rapid onset, which can irritate airways and trigger reflex responses. *Halothane* - **Halothane** is more associated with **myocardial depression** and can cause **bradycardia** rather than tachycardia. - It also has a higher propensity for causing **arrhythmias**, particularly in the presence of exogenous catecholamines. *Sevoflurane* - **Sevoflurane** is known for its **smooth induction** and **minimal cardiovascular depression**, making it suitable for pediatric patients. - While it can cause some vasodilation, it typically does not lead to significant tachycardia or hypertension unless in very high concentrations or in specific patient populations. *Isoflurane* - **Isoflurane** can cause **dose-dependent peripheral vasodilation**, which can lead to a compensatory increase in heart rate. - However, the hypertension and marked tachycardia described are less characteristic of isoflurane than of desflurane's sympathetic stimulation.

Question 544: What is the purpose of administering preoxygenation before the induction of general anesthesia?

A. To increase oxygen reserve during the apnea period (Correct Answer)
B. To sedate the patient
C. To reduce the anesthetic requirement
D. To prevent postoperative nausea and vomiting

Explanation: ***To increase oxygen reserve during the apnea period*** - Preoxygenation flushes out **nitrogen** from the functional residual capacity (FRC) in the lungs, replacing it with **100% oxygen**. - This creates an **oxygen reservoir** that extends the time a patient can tolerate apnea after induction without desaturating, allowing for safe intubation. *To sedate the patient* - **Preoxygenation** itself does not have sedative properties; its primary effect is physiological rather than neurological. - **Sedation** is typically achieved through other premedication agents or the induction drugs themselves. *To reduce the anesthetic requirement* - While proper oxygenation is critical for patient safety, **preoxygenation** does not directly reduce the amount of anesthetic required for induction or maintenance. - Anesthetic requirements are influenced by factors like patient age, comorbidities, and the specific agents used. *To prevent postoperative nausea and vomiting* - **Postoperative nausea and vomiting (PONV)** prevention involves a multi-modal approach with specific antiemetic medications or techniques, not preoxygenation. - The goal of preoxygenation is to optimize respiratory physiology before induction, not to manage post-operative complications.

Question 545: A patient undergoing craniotomy for tumor resection under general anesthesia develops hyperkalemia. Which muscle relaxant is most likely responsible for this condition?

A. Atracurium
B. Succinylcholine (Correct Answer)
C. Rocuronium
D. Cisatracurium

Explanation: **Succinylcholine** * **Succinylcholine** is a depolarizing muscle relaxant that can cause **hyperkalemia** by transiently binding to nicotinic acetylcholine receptors, leading to widespread depolarization and potassium efflux from muscle cells. * This effect is particularly pronounced in patients with conditions like burns, crush injuries, stroke, or severe muscle trauma due to an **upregulation of acetylcholine receptors**, increasing potassium release. * *Atracurium* * **Atracurium** is a non-depolarizing neuromuscular blocker that typically does not cause significant **hyperkalemia** because it acts as an antagonist at the acetylcholine receptor without causing depolarization. * It undergoes **Hofmann elimination** and ester hydrolysis, making its elimination independent of renal or hepatic function, which is useful in certain patient populations. * *Rocuronium* * **Rocuronium** is a non-depolarizing neuromuscular blocker that competitively blocks acetylcholine receptors, preventing muscle contraction without causing **depolarization or potassium release**. * It has a **rapid onset of action** and is primarily eliminated by the liver, making it a common choice for rapid sequence intubation when succinylcholine is contraindicated. * *Cisatracurium* * **Cisatracurium** is an isomer of atracurium and is also a non-depolarizing neuromuscular blocker that does not cause **hyperkalemia**. * It is primarily metabolized by **Hofmann elimination**, making it a good choice for patients with renal or hepatic dysfunction, similar to atracurium but with fewer histamine release properties.

Question 546: A patient with myasthenia gravis requires surgery. Which muscle relaxant requires the most caution and dose adjustment?

A. Atracurium (Correct Answer)
B. Rocuronium
C. Vecuronium
D. Succinylcholine (a depolarizing muscle relaxant)

Explanation: ***Atracurium*** - While **atracurium** can be used in patients with myasthenia gravis, its prolonged duration of action and **non-depolarizing** mechanism necessitate careful **dose reduction** and close monitoring. - Patients with myasthenia gravis have fewer **acetylcholine receptors** at the neuromuscular junction, making them highly sensitive to non-depolarizing muscle relaxants. *Rocuronium* - **Rocuronium** is a **non-depolarizing** muscle relaxant with a relatively short onset but a longer duration of action, typically requiring significant dose reduction in myasthenia gravis patients. - Its use necessitates careful titration due to increased sensitivity and potential for **prolonged paralysis**. *Vecuronium* - **Vecuronium** is an intermediate-acting **non-depolarizing** muscle relaxant that requires substantial dose reduction in patients with myasthenia gravis. - Its effects can be prolonged, leading to an increased risk of **residual neuromuscular blockade**. *Succinylcholine (a depolarizing muscle relaxant)* - Patients with myasthenia gravis are often **resistant** to succinylcholine due to the reduced number of **acetylcholine receptors** at the neuromuscular junction. - While a higher dose might be needed, it still carries risks due to unpredictable responses and potential for **prolonged phase II block** in susceptible individuals.

Question 547: Which anesthetic agent is known to lead to bradycardia?

A. Desflurane
B. Sevoflurane
C. Propofol (Correct Answer)
D. Isoflurane

Explanation: ***Propofol*** - Propofol can cause **bradycardia** and **hypotension** due to its effects on the autonomic nervous system, leading to a decrease in sympathetic tone and an increase in vagal activity. - This effect is often more pronounced with **rapid bolus administration** or in patients with preexisting cardiovascular conditions. *Sevoflurane* - Sevoflurane is an inhaled anesthetic that typically causes **little change in heart rate** or can lead to a slight increase, rather than bradycardia. - It is known for its **hemodynamic stability** and is often preferred for induction, especially in pediatric patients. *Isoflurane* - Isoflurane, another inhaled anesthetic, tends to cause **tachycardia** due to its ability to increase heart rate, especially at higher concentrations. - This effect is mediated by sympathetic activation and a decrease in systemic vascular resistance. *Desflurane* - Desflurane is an inhaled anesthetic that can cause significant and rapid increases in **heart rate** and blood pressure, particularly with rapid increases in concentration. - This **sympathetic stimulation** often necessitates careful titration to avoid adverse cardiovascular effects.

Question 548: What is the anesthetic agent of choice for patients with asthma?

A. Thiopentone
B. Methexitone
C. Ketamine (Correct Answer)
D. Propofol

Explanation: ***Ketamine*** - **Ketamine** is preferred due to its **bronchodilatory** properties, making it beneficial for patients with reactive airway disease like asthma. - It also maintains **cardiovascular stability** and preserves respiratory drive, reducing the risk of bronchospasm. *Thiopentone* - **Thiopentone** can cause **histamine release**, which may lead to **bronchoconstriction** and exacerbate asthma. - It is known for its **cardiovascular depressant** effects, which can be detrimental in patients with compromised respiratory function. *Methexitone* - **Methohexital**, a barbiturate similar to thiopentone, can also induce **histamine release** and carries a risk of **bronchospasm**. - Its use is generally avoided in asthmatic patients due to potential airway reactivity. *Propofol* - While generally safe and has some **bronchodilatory** effects, **Propofol** can cause significant **respiratory depression** and **hypotension**, which might not be ideal for all asthmatic patients, especially during induction. - However, in specific situations, it can be used cautiously, but **ketamine** remains the agent of choice for its more pronounced bronchodilatory effects without significant cardiorespiratory depression.

Question 549: Which of the following anesthetic agents is the most lipid soluble?

A. Nitrous oxide
B. Methoxyflurane (Correct Answer)
C. Isoflurane
D. Halothane

Explanation: **Methoxyflurane** - Methoxyflurane has a very **high lipid solubility**, reflected in its **blood:gas partition coefficient of 12.1**, which is the highest among common inhaled anesthetics. - This high lipid solubility means it readily dissolves in lipids, allowing for an increased amount of the drug to be taken up by tissues, leading to **slow induction and emergence**. *Nitrous oxide* - Nitrous oxide has very **low lipid solubility**, with a **blood:gas partition coefficient of 0.47**. - This makes it a **fast-acting** agent with rapid induction and emergence due to its minimal dissolution in blood and tissues. *Isoflurane* - Isoflurane has an intermediate lipid solubility among volatile anesthetics, with a **blood:gas partition coefficient of 1.4**. - It is commonly used due to its good balance between **potency** and a reasonably **fast onset/offset**. *Halothane* - Halothane has a relatively high lipid solubility with a **blood:gas partition coefficient of 2.3**. - While higher than isoflurane and nitrous oxide, it is still significantly lower than that of **methoxyflurane**, indicating faster kinetics.

Question 550: Etomidate is not used for long term infusion because?

A. Results in adrenal suppression (Correct Answer)
B. May cause vasospasm
C. Results in cardiac arrhythmias
D. May cause increase in ICP

Explanation: ***Results in adrenal suppression*** - **Etomidate inhibits 11-beta-hydroxylase**, a key enzyme in the adrenal gland responsible for cortisol and aldosterone synthesis. - Prolonged infusion can lead to significant and sustained **adrenal insufficiency**, which can be detrimental, especially in critically ill patients. *May cause vasospasm* - **Vasospasm** is not a known or primary side effect of etomidate, which is generally considered hemodynamically stable. - Other agents, such as some vasopressors or illicit drugs, are more commonly associated with vasospasm. *Results in cardiac arrhythmias* - Etomidate is noted for its **cardiovascular stability** and is often preferred in patients with compromised cardiac function. - It does not typically cause cardiac arrhythmias; rather, it often maintains stable heart rate and blood pressure. *May cause increase in ICP* - On the contrary, etomidate is known to **decrease cerebral blood flow (CBF)** and **intracranial pressure (ICP)** by causing cerebral vasoconstriction. - This property makes it a favorable choice for induction in patients with neurological concerns and elevated ICP.

Practice by Chapter

History of Anesthesia

Practice Questions

Preoperative Evaluation

Practice Questions

Pharmacology of Inhalational Anesthetics

Practice Questions

Pharmacology of Intravenous Anesthetics

Practice Questions

Neuromuscular Blocking Agents

Practice Questions

Airway Management

Practice Questions

Endotracheal Intubation

Practice Questions

Difficult Airway Algorithms

Practice Questions

Intraoperative Monitoring

Practice Questions

Depth of Anesthesia Monitoring

Practice Questions

Emergence from Anesthesia

Practice Questions

Postoperative Care

Practice Questions

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