General Anesthesia Practice Questions

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

Xenon anesthesia allows for rapid induction and recovery.. ***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.

Q: What is the primary reason ether is not commonly used in modern surgical practice?

Highly explosive. ***Highly explosive*** - Ether is highly **flammable and explosive**, posing a significant risk in operating theaters where electrical equipment and potential ignition sources are present. - This risk of combustion and explosion made its use dangerous, leading to its replacement by safer alternatives. *Poor anaesthetic* - While modern anesthetics offer better control and fewer side effects, ether was historically an **effective general anesthetic** for many procedures. - Its efficacy as an anesthetic is not the primary reason for its discontinuation, but rather its safety profile. *Less favored due to side effects* - Ether does have side effects such as **postoperative nausea and vomiting**, and respiratory irritation, which contributed to its decline. - However, the **explosive nature** was a more critical safety concern than its typical side effects compared to contemporary alternatives. *Requires specific delivery systems* - All volatile anesthetics require specific delivery systems (vaporizers) for accurate dosing, and this is **not unique to ether**. - The need for a delivery system was not a primary reason for its disuse, as such systems were developed for its administration.

Q: Neuromuscular blocker of choice in renal failure is:

Atracurium. ***Atracurium*** - **Atracurium** is metabolized by **Hofmann elimination** and ester hydrolysis, which are non-organ dependent metabolic pathways [2]. - This makes it a suitable choice in patients with **renal or hepatic impairment** as its clearance is not significantly affected by organ dysfunction. *Pancuronium* - **Pancuronium** is primarily eliminated via **renal excretion**, with approximately 80% of the unchanged drug excreted by the kidneys. - In patients with renal failure, its **duration of action is significantly prolonged**, increasing the risk of prolonged paralysis. *Rocuronium* - **Rocuronium** is predominantly eliminated by the **liver**, but a significant portion (10-20%) is also excreted unchanged by the kidneys [1]. - While generally considered safer than pancuronium in renal failure, its **duration of action can still be moderately prolonged** in severe renal impairment [1]. *Tubocurare* - **Tubocurare** is primarily eliminated via **renal excretion**, with a small amount also metabolized by the liver. - Its use has largely been superseded by newer neuromuscular blockers due to its **tendency to cause histamine release** and significant prolongation of action in renal failure [3].

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

Ketamine. ***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.

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

Ketamine. ***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.

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

Succinylcholine. ***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.

Q: Which anaesthetic agent is contraindicated in patients with emphysema?

Nitrous oxide (N2O). ***Nitrous oxide (N2O)*** - **Nitrous oxide** diffuses rapidly into air-filled cavities, such as **bullae** in emphysema, causing them to expand. - This expansion can lead to **pneumothorax** or worsen existing respiratory compromise by increasing the size of trapped gas. *Halothane* - While it can cause **bronchodilation**, its use in emphysema is limited due to its potential for **cardiac depression** and **hepatotoxicity**. - It is not specifically contraindicated due to its effect on bullae or air trapping. *Diethyl ether* - This agent is largely obsolete due to its **flammability** and high incidence of **postoperative nausea and vomiting**. - Its effects on emphysematous lungs are less of a concern than its general anesthetic properties and side effects. *Isoflurane* - **Isoflurane** is often preferred in patients with respiratory disease due to its potent **bronchodilating properties** and minimal cardiac depression. - It does not expand air-filled spaces and is considered relatively safe for patients with emphysema.

Q: Which of the following inhalational anesthetic agents is known to cross the blood-brain barrier most effectively?

Desflurane. ***Desflurane*** - **Desflurane** has a **low blood-gas partition coefficient (0.42)**, meaning it is poorly soluble in blood. - This low solubility facilitates its rapid uptake into the brain and quick elimination, making it cross the **blood-brain barrier** very effectively and leading to a rapid onset and offset of anesthesia. *Methoxyflurane* - **Methoxyflurane** has a **high blood-gas partition coefficient (12.0)**, leading to slow induction and emergence from anesthesia. - Its high solubility in blood means it poorly crosses the **blood-brain barrier** compared to less soluble agents. *Sevoflurane* - **Sevoflurane** has a **moderate blood-gas partition coefficient (0.69)**, allowing for relatively rapid induction and emergence, but not as rapid as desflurane. - While it effectively crosses the **blood-brain barrier**, its solubility is higher than desflurane, making it slightly less effective in this regard. *Nitrous oxide* - **Nitrous oxide** has a very low blood-gas partition coefficient (0.46), leading to an extremely rapid onset and offset. - However, its **low potency (high MAC)** means it cannot achieve deep anesthetic states on its own, and its primary mechanism involves displacement of nitrogen from air-filled cavities, which differs from direct BBB crossing for maintenance of anesthesia.

Q: Ether was first used as an anesthetic by?

Morton. ***Morton*** - **William T.G. Morton**, a dentist, publicly demonstrated the use of **ether as a surgical anesthetic** in 1846 during a tooth extraction at Massachusetts General Hospital. - This event marked a pivotal moment in medicine, revolutionizing surgical practices by providing effective pain relief. *Priestly* - **Joseph Priestley** was an 18th-century chemist who discovered several gases, including **oxygen**, but was not involved in the anesthetic use of ether. - His work was foundational to understanding the composition of air but did not extend to surgical applications of inhaled substances. *Wells* - **Horace Wells**, an American dentist, was an early pioneer in anesthesia who experimented with **nitrous oxide** as an anesthetic for tooth extractions. - While significant, his work predated and differed from Morton's successful public demonstration and widespread adoption of ether. *Simpson* - **James Young Simpson**, a Scottish obstetrician, is credited with pioneering the use of **chloroform** as an anesthetic, particularly in childbirth. - His contributions were later than Morton's use of ether and involved a different anesthetic agent.

Q: The anaesthesia of choice in renal disease is which one of the following:

Cisatracurium. ***Cisatracurium*** - **Cisatracurium** is preferred in renal disease because it undergoes **Hofmann elimination**, a chemical breakdown independent of renal or hepatic function. - Its metabolism generates **laudanosine**, a metabolite that can accumulate in renal failure but has minimal clinical significance at typical doses. *Atracurium* - **Atracurium** also undergoes **Hofmann elimination** and ester hydrolysis, making it suitable for renal patients, but it produces more **laudanosine** than cisatracurium. - Higher levels of **laudanosine** can potentially cause central nervous system excitation (seizures) with prolonged use or in very high doses, although this is rare in clinical practice. *Vecuronium* - **Vecuronium** is primarily eliminated by the **liver** and, to a lesser extent, by the kidneys, so its duration of action can be prolonged in renal failure. - Its active metabolites, particularly **3-desacetylvecuronium**, accumulate significantly in renal insufficiency, leading to prolonged neuromuscular blockade. *Rocuronium* - **Rocuronium** is mainly eliminated by the **liver** (approximately 70-80%), with a smaller portion excreted renally. - In patients with renal failure, its duration of action can be significantly prolonged due to reduced renal clearance and potential alterations in hepatic elimination.

Question 1

Which of the following statements about xenon anesthesia is true?

Accepted Answer

Xenon anesthesia allows for rapid induction and recovery.

Answer

Xenon anesthesia is of low potency.

Answer

Xenon anesthesia has high blood solubility.

Answer

All of the above are true

Question 2

What is the primary reason ether is not commonly used in modern surgical practice?

Accepted Answer

Highly explosive

Answer

Less favored due to side effects

Answer

Poor anaesthetic

Answer

Requires specific delivery systems

Question 3

Neuromuscular blocker of choice in renal failure is:

Accepted Answer

Atracurium

Answer

Pancuronium

Answer

Rocuronium

Answer

Tubocurare

Question 4

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

Accepted Answer

Ketamine

Answer

Propofol

Answer

Halothane

Answer

Thiopentone

Question 5

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

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Etomidate

Answer

Propofol with lidocaine

Question 6

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

Accepted Answer

Succinylcholine

Answer

Vecuronium

Answer

Rocuronium

Answer

Mivacurium

Question 7

Which anaesthetic agent is contraindicated in patients with emphysema?

Accepted Answer

Nitrous oxide (N2O)

Answer

Halothane

Answer

Diethyl ether

Answer

Isoflurane

Question 8

Which of the following inhalational anesthetic agents is known to cross the blood-brain barrier most effectively?

Accepted Answer

Desflurane

Answer

Methoxyflurane

Answer

Sevoflurane

Answer

Nitrous oxide

Question 9

Ether was first used as an anesthetic by?

Accepted Answer

Morton

Answer

Wells

Answer

Simpson

Answer

Priestly

Question 10

The anaesthesia of choice in renal disease is which one of the following:

Accepted Answer

Cisatracurium

Answer

Atracurium

Answer

Vecuronium

Answer

Rocuronium

General Anesthesia — MCQs

General Anesthesia — MCQs

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