General Anesthesia Practice Questions

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 - Its use has largely been superseded by newer neuromuscular blockers due to its **tendency to cause histamine release** and significant prolongation of action in renal failure [3].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 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 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 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: 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: 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.

Q: Which of the following agents is most commonly used to induce anesthesia?

Propofol. ***Propofol*** - **Propofol** is one of the most commonly used intravenous anesthetics for both induction and maintenance due to its rapid onset, short duration of action, and favorable recovery profile with less postoperative nausea and vomiting. - Its mechanism involves potentiation of **GABA-A receptors**, leading to CNS depression and anesthesia. *Thiopentone sodium* - **Thiopentone** is an ultrashort-acting barbiturate that was historically very popular for induction but has largely been replaced by propofol due to a slower recovery profile and higher incidence of cardiovascular depression. - It also acts on **GABA-A receptors**, enhancing chloride influx and hyperpolarizing neurons. *Methohexitone sodium* - **Methohexitone** is another ultrashort-acting barbiturate, similar to thiopentone, used for induction, particularly in electroconvulsive therapy (ECT) due to its lower incidence of post-ictal confusion. - However, it is associated with a higher risk of **muscle twitching** and **hiccups** compared to propofol. *Etomidate* - **Etomidate** is a short-acting intravenous anesthetic known for its excellent **cardiovascular stability**, making it a preferred choice in patients with compromised cardiac function or hemodynamic instability. - A significant drawback is its association with **adrenocortical suppression**, even after a single dose, which limits its widespread use for maintenance.

Q: What effect does Propofol have on the EEG?

Induces EEG depression. ***Induces EEG depression*** - Propofol, an intravenous anesthetic, primarily acts as a **GABA-A receptor agonist**, enhancing inhibitory neurotransmission in the brain. - This leads to a dose-dependent reduction in brain electrical activity, characterized by a decrease in the **amplitude and frequency of EEG waves**, effectively causing EEG depression. *Causes no significant change in EEG* - This statement is incorrect because propofol has profound effects on brain electrical activity, as measured by the EEG. - Its anesthetic properties are directly linked to its ability to alter neuronal excitability significantly. *Causes EEG activation* - EEG activation typically involves an increase in fast-frequency, low-amplitude waves, often associated with states of arousal or epileptic activity. - Propofol's primary effect is to depress brain activity, which is the opposite of activation. *None of the options* - This option is incorrect because propofol has a well-documented and significant effect on the EEG, which is precisely EEG depression.

Question 1

Neuromuscular blocker of choice in renal failure is:

Accepted Answer

Atracurium

Answer

Pancuronium

Answer

Rocuronium

Answer

Tubocurare

Question 2

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

Accepted Answer

Ketamine

Answer

Propofol

Answer

Halothane

Answer

Thiopentone

Question 3

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 4

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 5

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 6

Which anaesthetic agent is contraindicated in patients with emphysema?

Accepted Answer

Nitrous oxide (N2O)

Answer

Halothane

Answer

Diethyl ether

Answer

Isoflurane

Question 7

Ether was first used as an anesthetic by?

Accepted Answer

Morton

Answer

Wells

Answer

Simpson

Answer

Priestly

Question 8

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

Accepted Answer

Cisatracurium

Answer

Atracurium

Answer

Vecuronium

Answer

Rocuronium

Question 9

Which of the following agents is most commonly used to induce anesthesia?

Accepted Answer

Propofol

Answer

Etomidate

Answer

Methohexitone sodium

Answer

Thiopentone sodium

Question 10

What effect does Propofol have on the EEG?

Accepted Answer

Induces EEG depression

Answer

Causes no significant change in EEG

Answer

Causes EEG activation

Answer

None of the options

General Anesthesia — MCQs

General Anesthesia — MCQs

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