General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 571: What is the primary clinical use of Sugammadex in anesthesia?

A. Organophosphate poisoning
B. Reversal of NM blockers (Correct Answer)
C. Treatment of local anaesthetic poisoning
D. Treatment of central anticholinergic syndrome

Explanation: ***Reversal of NM blockers*** - **Sugammadex** is a modified gamma-cyclodextrin that specifically encapsulates steroidal **neuromuscular blocking agents (NMBAs)** like **rocuronium** and **vecuronium**. - This encapsulation rapidly inactivates the NMBAs, leading to a dose-dependent and swift **reversal of neuromuscular blockade**. *Organophosphate poisoning* - Organophosphate poisoning is treated with **atropine** to block muscarinic effects and **pralidoxime** to reactivate inhibited acetylcholinesterase. - Sugammadex has no role in antagonizing the effects of **organophosphates** or regenerating acetylcholinesterase. *Treatment of local anaesthetic poisoning* - Local anesthetic systemic toxicity (LAST) is primarily managed with supportive care, including airway management, and the administration of **lipid emulsion therapy**. - Sugammadex does not bind to local anesthetics and therefore has no efficacy in treating local anesthetic poisoning. *Treatment of central anticholinergic syndrome* - Central anticholinergic syndrome is typically treated with **physostigmine**, an acetylcholinesterase inhibitor that can cross the blood-brain barrier. - Sugammadex is not an anticholinergic antagonist and does not affect the central nervous system to reverse anticholinergic effects.

Question 572: Which of the following statements about halothane is false?

A. Volatile liquid with sweet odour
B. Constricts bronchii (Correct Answer)
C. Causes malignant hyperthermia
D. Sensitises heart to adrenaline

Explanation: ***Constricts bronchii*** - Halothane is a **bronchodilator** that relaxes bronchial smooth muscle, making it useful in patients with asthma or COPD. - The statement that it constricts bronchi is **false**. *Volatile liquid with sweet odour* - **Halothane** is a **volatile liquid** and is known for its characteristic **sweet, non-pungent odour**. - This property makes it well-tolerated during induction of anesthesia, particularly in pediatric patients. *Sensitises heart to adrenaline* - Halothane **sensitizes the myocardium** to the effects of **catecholamines**, including adrenaline (epinephrine). - This can lead to the development of **cardiac arrhythmias**, especially ventricular arrhythmias, when adrenaline is administered or endogenous levels are high. *Causes malignant hyperthermia* - Halothane is a potent trigger for **malignant hyperthermia**, a rare but life-threatening pharmacogenetic disorder. - This condition is characterized by a rapid and severe increase in body temperature, muscle rigidity, and metabolic derangements due to uncontrolled release of calcium from the sarcoplasmic reticulum.

Question 573: The "MAC" of desflurane is:

A. 1.15
B. 4
C. 6 (Correct Answer)
D. 2

Explanation: ***6*** - The **Minimum Alveolar Concentration (MAC)** of desflurane is approximately **6%**. It is one of the highest MAC values among commonly used volatile anesthetics. - A higher MAC value indicates **lower potency** of the anesthetic agent. *1.15* - This value is close to the MAC of **isoflurane** (around 1.15%), which is significantly more potent than desflurane. - Using 1.15% desflurane would not provide adequate anesthesia for surgical stimulation. *2* - This MAC value is similar to that of **sevoflurane** (around 2%), another commonly used inhalational anesthetic. - Sevoflurane is less potent than isoflurane but more potent than desflurane. *4* - A MAC of 4% would indicate an anesthetic with potency between sevoflurane and desflurane, but it does not correspond to the MAC of any primary volatile anesthetic agent. - While desflurane's MAC is high, 4% is still too low for its actual value.

Question 574: Who is known for demonstrating the levels of ether anesthesia?

A. Morton
B. Guedel (Correct Answer)
C. Thompson
D. None of the options

Explanation: ***Guedel*** - Arthur Guedel developed and refined the **stages and planes of ether anesthesia** based on clinical observations of respiratory patterns, eye signs, and muscle tone. - His classification system, known as the **Guedel stages**, provided a systematic approach to monitoring anesthetic depth, especially useful before the advent of modern anesthetic agents and monitoring equipment. *Morton* - **William T.G. Morton** is credited with the first successful public demonstration of sulfuric ether as a surgical anesthetic in 1846 during a tooth extraction. - While he pioneered the use of ether for anesthesia, he did not develop the classic stages of anesthetic depth. *Thompson* - There is no widely recognized historical figure named Thompson who is primarily known for defining the **levels or stages of ether anesthesia**. - This name is not associated with the primary discovery or classification of anesthetic depth. *None of the options* - This option is incorrect because **Guedel** is specifically known for his work in defining the stages of ether anesthesia. - Guedel's contributions were significant in standardizing anesthetic practice for many years.

Question 575: Stages of anesthesia were established by

A. Diethyl ether (Correct Answer)
B. Nitrous oxide
C. Halothane
D. Chloroform

Explanation: ***Diethyl ether** - The classic stages of anesthesia (analgesia, excitement, surgical anesthesia, medullary depression) were originally described in relation to the administration of **diethyl ether**. - Its slow onset and prolonged half-life allowed for the clear observation and definition of these distinct stages. *Nitrous oxide* - This gaseous anesthetic has a rapid onset and offset, making it difficult to clearly delineate all four classical stages with its use. - It is often used as an adjunct to other anesthetics rather than as a sole agent for prolonged surgical anesthesia. *Halothane* - Halothane is a potent volatile anesthetic that became popular after ether, but its use also does not typically involve the clear, step-wise progression through all four anesthetic stages as seen with ether. - It was one of the first widely used inhaled anesthetics that largely replaced ether due to better patient control and fewer side effects. *Chloroform* - Chloroform was another early anesthetic but was associated with significant cardiac and hepatic toxicity, leading to its limited use and eventual discontinuation. - While it induced anesthesia, the clear staging of anesthetic depth was primarily established and standardized using diethyl ether.

Question 576: Which of the following statements about xenon anesthesia is true?

A. Xenon anesthesia allows for rapid induction and recovery. (Correct Answer)
B. Xenon anesthesia is of low potency.
C. Xenon anesthesia has high blood solubility.
D. All of the above are true

Explanation: ***Xenon anesthesia allows for rapid induction and recovery.*** - Xenon has a **low blood-gas partition coefficient**, meaning it is poorly soluble in blood and tissues. - This **low solubility** facilitates rapid uptake and elimination, leading to quick onset and offset of anesthetic effects. *Xenon anesthesia is of low potency.* - Xenon is actually a **potent anesthetic**, with a minimum alveolar concentration (MAC) of approximately 71%. - It provides **effective anesthesia** at concentrations lower than some other inhaled agents. *Xenon anesthesia has high blood solubility.* - This statement is incorrect; xenon has **very low blood solubility**. - Its **low solubility** is precisely what contributes to its rapid pharmacokinetics (quick induction and recovery). *All of the above are true* - As stated, two of the options are incorrect, making this option false. - Only the statement regarding **rapid induction and recovery** is correct.

Question 577: Which of the following anesthetic agents does not cause hypotension on injection?

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

Explanation: ***Ketamine*** - Ketamine often causes a **transient increase in blood pressure and heart rate**, due to sympathomimetic effects, rather than hypotension. - It is preferred in patients with **hypovolemia** or compromised cardiovascular function where maintaining blood pressure is crucial. *Propofol* - Propofol is a potent **vasodilator** and myocardial depressant, commonly causing a dose-dependent decrease in blood pressure upon injection. - Its hypotensive effect is a major concern, particularly in patients who are **hemodynamically unstable** or elderly. *Halothane* - Halothane is a volatile anesthetic that frequently causes **myocardial depression** and peripheral vasodilation, leading to hypotension. - While its use has declined, it is known for causing a **dose-dependent decrease in blood pressure**. *Thiopentone* - Thiopentone (sodium thiopental) is a barbiturate that typically causes **peripheral vasodilation** and myocardial depression, leading to a reduction in blood pressure. - This hypotensive effect can be significant, especially with **rapid administration** or in hypovolemic patients.

Question 578: Which of the following anesthetic agents is known to cause the least discomfort during injection?

A. Thiopentone
B. Etomidate
C. Ketamine (Correct Answer)
D. Propofol with lidocaine

Explanation: ***Ketamine*** - While Ketamine can cause burning on injection, particularly in smaller veins or when administered rapidly, it is often considered to cause **less severe pain** compared to drugs like etomidate or propofol without lidocaine. - Its **dissociative properties** might also attenuate the perception of pain during injection. *Thiopentone* - Thiopentone is known to cause **venous irritation** and pain on injection due to its **alkaline pH** and tendency to precipitate in veins. - Extravasation can lead to significant **tissue necrosis**. *Etomidate* - Etomidate is highly associated with **pain on injection**, often described as severe. - This is partly due to its **propylene glycol vehicle**, which causes venous irritation. *Propofol with lidocaine* - **Propofol** itself is notorious for causing **significant pain on injection**, which is a major drawback. - Adding **lidocaine** (1 mL of 1% lidocaine per 20 mL propofol) is a common practice to **reduce or eliminate this pain**, making the injection much more comfortable.

Question 579: Which muscle relaxant is contraindicated for tracheal intubation in a 30-year-old man with paraplegia?

A. Succinylcholine (Correct Answer)
B. Vecuronium
C. Rocuronium
D. Mivacurium

Explanation: ***Succinylcholine*** - **Succinylcholine** is contraindicated in patients with paraplegia due to the risk of life-threatening **hyperkalemia** from massive acetylcholine receptor upregulation and excessive potassium efflux. - This response is particularly concerning in conditions involving denervation or muscle injury, such as paraplegia. *Vecuronium* - **Vecuronium** is a non-depolarizing neuromuscular blocker that does not cause potassium release and is safe for use in patients with paraplegia. - It is commonly used for tracheal intubation and maintenance of muscle relaxation without the risk of hyperkalemia. *Rocuronium* - **Rocuronium** is another non-depolarizing neuromuscular blocker that is a safe alternative for intubation in patients with paraplegia. - It provides rapid onset muscle relaxation and does not cause significant potassium release. *Mivacurium* - **Mivacurium** is a short-acting non-depolarizing neuromuscular blocker that is metabolized by plasma cholinesterase. - Like other non-depolarizing agents, it does not induce the same hyperkalemic response as succinylcholine in patients with paraplegia.

Question 580: Which of the following can be used as a pre-anesthetic medication to decrease secretions and reflux bronchospasm during general anesthesia?

A. Ipratropium.
B. Tiotropium.
C. Glycopyrrolate. (Correct Answer)
D. Atropine.

Explanation: ***Glycopyrrolate*** - It is a **quaternary ammonium anticholinergic** that reduces salivary, tracheobronchial, and pharyngeal secretions effectively. - Due to its **limited ability to cross the blood-brain barrier**, it has fewer central nervous system side effects compared to atropine. *Ipratropium* - This medication is a **short-acting muscarinic antagonist** primarily used as a bronchodilator for conditions like asthma and COPD. - While it can reduce secretions, it's typically administered via inhalation for its local bronchodilatory effects and is not a common systemic pre-anesthetic antisialagogue. *Tiotropium* - **Tiotropium** is a **long-acting muscarinic antagonist** used for maintenance treatment of COPD, administered via inhalation. - Its primary role is sustained bronchodilation, and it is not employed as a systemic pre-anesthetic antisialagogue. *Atropine* - While atropine is an antipsychotic that can reduce secretions and counteract **bradycardia**, it readily **crosses the blood-brain barrier**, leading to more central nervous system side effects such as confusion and delirium. - Its use has decreased in favor of agents like glycopyrrolate that have a better side effect profile for reducing secretions in the perioperative setting.

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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