General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 561: Who coined the term "balanced anaesthesia"?

A. Simpson
B. Fischer
C. Morton
D. Lundy (John S. Lundy) (Correct Answer)

Explanation: ***Lundy (John S. Lundy)*** - **John S. Lundy** is credited with coining the term "**balanced anaesthesia**" in the early 20th century. - This concept describes the use of **multiple anesthetic agents** in combination, each contributing to different aspects of anesthesia (e.g., hypnosis, analgesia, muscle relaxation). *Simpson* - **Sir James Young Simpson** was a Scottish physician who pioneered the use of **chloroform** and ether as anesthetics in the mid-19th century. - While he significantly advanced the field of anesthesia, he did not coin the term "balanced anaesthesia." *Fischer* - **Emil Fischer** was a German chemist who won the Nobel Prize in Chemistry for his work on sugar and purine syntheses. - His contributions were primarily in organic chemistry and biochemistry, not directly in the field of clinical anesthesia terminology. *Morton* - **William T.G. Morton** was an American dentist who famously demonstrated the first public use of **ether** for surgical anesthesia in 1846. - He is known for popularizing ether as a surgical anesthetic but did not coin the term "balanced anaesthesia."

Question 562: What is a significant disadvantage of ketamine?

A. Increased heart rate
B. Increased ICT
C. Delirium (Correct Answer)
D. All of the options

Explanation: ***Delirium*** - Ketamine is known to cause **emergence phenomena**, which include **vivid dreams, hallucinations**, and **delirium**, particularly during recovery from anesthesia. - This psychotomimetic effect can be distressing for patients and may necessitate the co-administration of a **benzodiazepine** to mitigate these symptoms. *Increased heart rate* - While ketamine does cause an **increase in heart rate** and **blood pressure** due to sympathetic stimulation, this is often considered a disadvantage but not the *most significant* when compared to the unique cognitive side effects. - This effect can be beneficial in patients with **hemodynamic instability**, but can be problematic in those with **cardiovascular disease**. *Increased ICT* - It is often considered a contraindication in patients with **elevated intracranial pressure (ICP)** as it can potentially increase **cerebral blood flow** and thus ICP. - However, recent studies suggest that in adequately ventilated patients, the effect on ICP may be less pronounced than previously thought, making delirium a more consistent and prominent disadvantage for many patients. *All of the options* - While ketamine can cause an **increased heart rate** and potentially affect **intracranial pressure**, **delirium** and other emergence phenomena are often highlighted as a unique and significant disadvantage because they are highly distressing and difficult to manage. - The psychotomimetic effects are a hallmark side effect that often governs its cautious use without concurrent medication.

Question 563: Which anesthetic agent is known for providing smooth induction?

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

Explanation: ***Isoflurane*** - **Isoflurane** is frequently chosen for its capacity to induce a **smooth and rapid loss of consciousness**, primarily due to its low blood solubility which facilitates quick changes in anesthetic depth. - Its **minimal irritation** to the respiratory tract and **stable cardiovascular profile** during induction contribute to a smoother process for the patient. *Sevoflurane* - While sevoflurane also offers a **smooth and rapid induction** due to its low solubility, it is sometimes associated with a higher incidence of **airway irritation** (e.g., coughing) compared to isoflurane, especially in children. - It is known for its **pleasant odor**, making it a good choice for mask induction in pediatric patients. *Halothane* - **Halothane** provides a relatively smooth induction but has a higher risk of **hepatotoxicity** and cardiac arrhythmias, which have led to its decreased use. - Its higher blood solubility means a **slower onset and offset** compared to modern volatile agents like isoflurane. *Enflurane* - **Enflurane** can cause **CNS excitation** at deeper levels of anesthesia, potentially leading to seizures, making its induction less smooth and predictable. - It also has a greater potential to cause **myocardial depression** and arrhythmias than isoflurane.

Question 564: Which inhalational anesthetic agent is known to be hepatotoxic?

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

Explanation: ***Halothane*** - Halothane is historically known for causing **halothane hepatitis**, a severe and sometimes fatal liver injury. - This toxicity is thought to be due to its metabolism to **trifluoroacetyl (TFA) halides**, which can bind to hepatocyte proteins, leading to an immune reaction. *Enflurane* - Enflurane can cause a small amount of **nephrotoxicity** due to fluoride ion production, but it is not typically associated with significant hepatotoxicity. - Its metabolism is limited, resulting in lower fluoride levels compared to older agents but still can be a concern in patients with renal impairment. *Desflurane* - Desflurane is minimally metabolized and is considered one of the safest inhalational agents in terms of organ toxicity. - Due to its low solubility and rapid elimination, it has a very low risk of causing **organ damage**, including the liver. *Sevoflurane* - Sevoflurane is generally considered safe for the liver and is widely used, particularly in pediatric anesthesia. - While it undergoes some metabolism to fluoride ions, it is not associated with significant **hepatotoxicity** in clinical practice, though it can interact with desiccated CO2 absorbents to produce Compound A.

Question 565: Which of the following statements is NOT true regarding rapid induction of anesthesia?

A. Suxamethonium is often used.
B. Mechanical ventilation is typically avoided before intubation.
C. Pre-oxygenation is mandatory
D. Sellick's maneuver is always required. (Correct Answer)

Explanation: ***Sellick's maneuver is always required.*** - **Sellick's maneuver**, or cricoid pressure, is applied to compress the esophagus against the vertebrae, aiming to prevent **gastric regurgitation** and aspiration during rapid sequence intubation (RSI). - While historically considered a standard component of RSI, its routine use has been increasingly questioned due to a lack of strong evidence supporting its efficacy and potential to impede glottic visualization and intubation. It is not "always" required; its application is often at the discretion of the anesthetist based on patient factors and risk assessment. *Pre-oxygenation is mandatory* - **Pre-oxygenation** is a critical step in rapid sequence induction, involving administering 100% oxygen for several minutes prior to induction. - This denitrogenates the functional residual capacity (FRC), creating an oxygen reservoir that extends the safe apnea time, thus preventing **hypoxemia** during the intubation attempt. *Suxamethonium is often used.* - **Suxamethonium** (succinylcholine) is a depolarizing neuromuscular blocker primarily used in rapid sequence intubation due to its **ultra-rapid onset** (30-60 seconds) and short duration of action (5-10 minutes). - Its rapid action facilitates quick muscle relaxation for tracheal intubation, which is crucial for minimizing the risk of aspiration in patients with a full stomach or other risk factors. *Mechanical ventilation is typically avoided before intubation.* - During rapid sequence induction, **positive pressure ventilation** with a bag-valve mask is typically avoided before intubation to prevent gastric insufflation. - Gastric insufflation can increase the risk of **regurgitation** and pulmonary aspiration of gastric contents, which is a major concern in patients undergoing RSI.

Question 566: Regarding propofol, which one of the following statements is false?

A. It is painful on injecting intravenously
B. It has no muscle relaxant property
C. It is used as an intravenous induction agent
D. It causes severe vomiting (Correct Answer)

Explanation: ***It causes severe vomiting*** - Propofol is actually known for its **antiemetic properties**, meaning it helps *prevent* rather than cause nausea and vomiting. - This makes it a preferred anesthetic for procedures where **postoperative nausea and vomiting (PONV)** are a concern. *It is used as an intravenous induction agent* - **Propofol** is a widely used **intravenous anesthetic** for the **induction and maintenance of general anesthesia**. - It provides a rapid onset of unconsciousness due to its high lipid solubility. *It is painful on injecting intravenously* - Injection of propofol can often cause **pain at the injection site**, particularly when administered into smaller veins. - This pain can be mitigated by co-administering **lidocaine** or using larger veins. *It has no muscle relaxant property* - Propofol does **not possess intrinsic muscle relaxant properties**; patients require additional neuromuscular blocking agents for surgical relaxation. - It facilitates intubation by causing **loss of consciousness** and **reducing airway reflexes**, but does not directly relax skeletal muscles.

Question 567: Which anaesthetic is contraindicated in renal failure?

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

Explanation: ***Methoxyflurane*** - Methoxyflurane undergoes significant **metabolism** to produce inorganic **fluoride ions**, which are directly **nephrotoxic**. - This nephrotoxicity can cause **high-output renal failure** with reduced concentrating ability, making it contraindicated in patients with pre-existing renal impairment. *Isoflurane* - Isoflurane is minimally metabolized and produces very low levels of **fluoride ions**, making it generally **safe** for use in patients with renal failure. - Its elimination is primarily via the **lungs**, with very little hepatic metabolism or renal excretion of active compounds. *Desflurane* - Desflurane is also minimally metabolized, similar to isoflurane, and therefore produces negligible amounts of **fluoride ions**. - It is considered a **safe option** for patients with renal impairment due to its predominantly pulmonary elimination and lack of nephrotoxic metabolites. *Halothane* - While halothane can cause **hepatotoxicity**, it is generally **not directly nephrotoxic** in the way methoxyflurane is. - Its metabolism, though more extensive than isoflurane or desflurane, does not produce clinically significant levels of nephrotoxic fluoride ions to contraindicate its use in renal failure.

Question 568: Intraocular pressure is increased by which anaesthetic?

A. Ketamine (Correct Answer)
B. Nitrous Oxide
C. Isoflurane
D. Propofol

Explanation: ***Ketamine*** - **Ketamine** is known to increase **intraocular pressure (IOP)**, making it generally avoided in patients with glaucoma or penetrating eye injuries. - This effect is thought to be due to its dissociative properties, causing **nystagmus**, and stimulating extraocular muscles. *Nitrous Oxide* - **Nitrous oxide** by itself has minimal or no direct effect on **intraocular pressure (IOP)**. - However, in cases of an air-filled globe (e.g., after retinal detachment surgery), it can increase IOP by expanding the gas bubble. *Isoflurane* - **Isoflurane**, like most volatile anesthetics, typically **decreases intraocular pressure (IOP)**. - This reduction is generally due to its effects on reducing aqueous humor production and increasing uveoscleral outflow. *Propofol* - **Propofol** is known for its ability to **decrease intraocular pressure (IOP)**. - This effect is mediated by a reduction in aqueous humor production and an increase in uveoscleral outflow, making it a favorable choice in ophthalmic surgery.

Question 569: Which of the following statements about Nitrous Oxide (N2O) is true?

A. Least potent inhalational anesthetic (Correct Answer)
B. Lighter than air
C. Effective muscle relaxant
D. Does not cause diffusion hypoxia

Explanation: **Least potent inhalational anesthetic** - Nitrous oxide has a **high Minimum Alveolar Concentration (MAC)** of approximately 104%, making it the least potent of the commonly used inhalational anesthetics. - Its high MAC means a very high concentration is required to achieve surgical anesthesia, which is why it is typically used as an adjunct to more potent agents. *Lighter than air* - The molecular weight of nitrous oxide (N2O) is 44, which is **heavier than air** (average molecular weight approximately 29 g/mol). - Its density is greater than air, meaning it would tend to sink rather than rise. *Effective muscle relaxant* - Nitrous oxide provides **minimal to no skeletal muscle relaxation** benefits. - If muscle relaxation is required, a neuromuscular blocking agent must be administered separately. *Does not cause diffusion hypoxia* - Nitrous oxide rapidly diffuses out of the blood into the alveoli during emergence, diluting the oxygen and carbon dioxide there. - This rapid diffusion can lead to **diffusion hypoxia** (also known as the "second gas effect"), necessitating the administration of 100% oxygen during recovery to prevent this complication.

Question 570: Which anaesthetic agent has maximum MAC ?

A. Ether
B. Methoxyfluorane
C. Halothane
D. Nitrous Oxide (N2O) (Correct Answer)

Explanation: ***Nitrous Oxide (N2O)*** - **Nitrous Oxide** has the highest **minimum alveolar concentration (MAC)** of all commonly used inhalational anesthetics, approximately 104%. - A high MAC indicates **low potency**, meaning that a large concentration is required to achieve anesthetic effects. *Ether* - **Ether** has a MAC of about 1.92%, which is significantly lower than that of Nitrous Oxide. - Its use has largely been replaced due to its flammability, slow induction, and recovery times. *Methoxyfluorane* - **Methoxyfluorane** is known for having a very low MAC, around 0.16%, making it the most potent inhalational anesthetic. - Due to its high potency and significant nephrotoxicity, its use is now very limited. *Halothane* - **Halothane** has a MAC of approximately 0.75%. - While it was a widely used inhalational anesthetic, it has largely been replaced due to concerns about **halothane hepatitis** and arrhythmogenicity.

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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