General Anesthesia Practice Questions

Q: Which of the following is NOT an aminosteroid non-depolarizing neuromuscular blocker?

Gantacurium. **Explanation:** Neuromuscular blocking agents (NMBAs) are broadly classified into two chemical classes: **Aminosteroids** and **Benzylisoquinolines**. **Why Gantacurium is the correct answer:** Gantacurium belongs to the **Benzylisoquinoline** class (specifically a chlorofumarate derivative). It is a newer, ultra-short-acting non-depolarizing agent designed to be degraded by non-enzymatic cysteine adduction and ester hydrolysis. Unlike aminosteroids, benzylisoquinolines are generally associated with histamine release but do not have the steroid nucleus. **Analysis of incorrect options:** * **Pancuronium:** A long-acting **aminosteroid**. It is known for its vagolytic effect, which can cause tachycardia. * **Pipecuronium:** A long-acting **aminosteroid** similar to pancuronium but without the significant cardiovascular side effects (vagolytic activity). * **Vecuronium:** An intermediate-acting **aminosteroid**. It is the mono-quaternary analog of pancuronium, lacks vagolytic effects, and is primarily excreted via bile. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Aminosteroids:** Remember the suffix **"-curonium"** (Pancuronium, Vecuronium, Rocuronium, Pipecuronium). * **Mnemonic for Benzylisoquinolines:** Remember the suffix **"-curium"** (Atracurium, Cisatracurium, Mivacurium, Gantacurium). * **Rocuronium** is the aminosteroid with the fastest onset, making it an alternative for Rapid Sequence Induction (RSI) when Succinylcholine is contraindicated. * **Sugammadex** is a specific reversal agent that works only for aminosteroids (Rocuronium > Vecuronium > Pancuronium) by encapsulation; it has no effect on Gantacurium or other benzylisoquinolines.

Q: Etomidate causes all of the following except:

Coronary insufficiency. **Explanation:** **Etomidate** is a carboxylated imidazole derivative used for the induction of general anesthesia. It is famously known for its **hemodynamic stability**, making it the induction agent of choice for patients with cardiovascular disease or shock. **Why Option A is the Correct Answer:** Etomidate **does not cause coronary insufficiency**. In fact, it maintains stable systemic blood pressure, heart rate, and myocardial oxygen delivery. It has minimal effect on sympathetic tone and does not cause histamine release, ensuring that coronary perfusion pressure is well-maintained. **Analysis of Incorrect Options:** * **B. Decreased steroidogenesis:** This is the most characteristic side effect of Etomidate. It causes dose-dependent inhibition of the enzyme **11-beta-hydroxylase**, which is essential for cortisol and aldosterone synthesis. This can lead to adrenocortical suppression even after a single dose. * **C. Decreased intracranial tension (ICT):** Etomidate is a potent cerebral vasoconstrictor. It reduces cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO2), which subsequently leads to a decrease in ICT. * **D. Nausea and vomiting:** Postoperative nausea and vomiting (PONV) is significantly more common with Etomidate compared to other induction agents like propofol. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** For induction in patients with **valvular heart disease, coronary artery disease, or hypovolemia**. * **Myoclonus:** Etomidate frequently causes involuntary muscle movements (myoclonus) during induction, which can be attenuated by pre-medication with opioids or benzodiazepines. * **Solvent:** It is traditionally formulated in **propylene glycol**, which can cause pain on injection. * **Contraindication:** Relative contraindication in patients with **sepsis** due to its effect on the adrenal axis.

Q: Which of the following drugs produces a subjective feeling of well-being on emergence, thus conferring a potential for substance abuse?

Propofol. **Explanation:** The correct answer is **Propofol (Option B)**. Propofol is a short-acting intravenous anesthetic agent that acts primarily via the GABA-A receptor. It is unique among induction agents for producing a **subjective feeling of well-being, euphoria, and clear-headedness** during the emergence phase. This "pleasant" recovery is attributed to the release of dopamine in the nucleus accumbens (the brain's reward center). Consequently, Propofol has a documented potential for **substance abuse**, particularly among healthcare professionals with easy access to the drug. **Analysis of Incorrect Options:** * **A. Thiopentone:** A barbiturate that often causes a "hangover" effect or grogginess upon emergence. It does not typically produce euphoria. * **C. Etomidate:** Known for its cardiovascular stability, but it is associated with a high incidence of postoperative nausea and vomiting (PONV) and myoclonus, making the recovery period less pleasant. * **D. Ketamine:** Produces "dissociative anesthesia." While it can cause hallucinations, the emergence period is often characterized by **emergence delirium**, agitation, and vivid unpleasant dreams rather than a simple feeling of well-being. **High-Yield NEET-PG Pearls:** * **Propofol** is the drug of choice for Day Care (Ambulatory) Surgery due to its rapid metabolism and anti-emetic properties. * **Propofol Infusion Syndrome (PRIS):** A rare but fatal complication characterized by metabolic acidosis, rhabdomyolysis, and cardiac failure (seen with high doses/long duration). * **Pain on injection** is a common side effect of Propofol (minimized by using larger veins or pre-treatment with Lidocaine). * **Egg/Soy Allergy:** Use caution, as Propofol is formulated in a lipid emulsion containing soybean oil and egg lecithin.

Q: What percentage of Halothane is metabolized?

25%. **Explanation:** The metabolism of volatile anesthetic agents occurs primarily in the liver via the **Cytochrome P450 (CYP2E1)** enzyme system. Among the potent inhalational agents, **Halothane** undergoes the most extensive hepatic metabolism. **1. Why 25% is Correct:** Approximately **20% to 25%** of Halothane is metabolized in the liver. This high rate of metabolism is clinically significant because it leads to the production of reactive intermediates (like trifluoroacetylated proteins). These metabolites can trigger an immune-mediated response, leading to **Halothane Hepatitis**, a rare but severe form of liver injury. **2. Analysis of Incorrect Options:** * **A (50%):** No commonly used volatile anesthetic reaches this level of metabolism. * **B (5%):** This is the approximate metabolism rate for **Sevoflurane** (2%–5%). * **C (2.50%):** This does not correspond to a specific major agent; however, **Enflurane** is metabolized at a rate of about 2%. * **D (25%):** This is the established high-yield value for Halothane. **3. High-Yield NEET-PG Clinical Pearls:** * **Metabolism Ranking (Highest to Lowest):** Halothane (25%) > Sevoflurane (2-5%) > Enflurane (2%) > Isoflurane (0.2%) > Desflurane (0.02%). * **Halothane Hepatitis:** More common in adults, females, and obese patients upon repeat exposure. * **Metabolite:** The oxidative metabolism of Halothane produces **trifluoroacetic acid**. * **Rule of Thumb:** Desflurane is the least metabolized (most stable), while Halothane is the most metabolized (least stable).

Q: A 40-year-old dental assistant presents with increased weakness and fatigue. Lab tests reveal megaloblastic anemia. Which of the following is most likely responsible for the presence of this anemia?

Nitrous oxide. **Explanation:** The correct answer is **Nitrous oxide (N₂O)**. The clinical presentation of megaloblastic anemia in a dental assistant—who has chronic occupational exposure to anesthetic gases—is a classic scenario for Nitrous oxide toxicity. **Mechanism of Action:** Nitrous oxide irreversibly oxidizes the cobalt atom of **Vitamin B12 (cobalamin)** from the monovalent (Co+) to the bivalent (Co++) state. This inactivation inhibits the enzyme **Methionine Synthase**, which is essential for converting homocysteine to methionine. This process is critical for DNA synthesis; its inhibition leads to impaired erythropoiesis, resulting in **megaloblastic anemia** and, in severe cases, subacute combined degeneration of the spinal cord. **Why other options are incorrect:** * **Propofol:** An intravenous sedative-hypnotic that acts via GABA-A receptors. It is associated with "Propofol Infusion Syndrome" (acidosis, rhabdomyolysis) but does not affect Vitamin B12 or DNA synthesis. * **Lignocaine:** An amide-type local anesthetic that blocks sodium channels. Toxicity typically involves CNS (seizures) and CVS (arrhythmias) effects, not hematological changes. * **Halothane:** An inhaled volatile anesthetic primarily associated with hepatotoxicity ("Halothane Hepatitis") due to the formation of trifluoroacetylated liver proteins. **High-Yield Clinical Pearls for NEET-PG:** * **Enzyme Inhibited:** Methionine Synthase. * **Occupational Hazard:** Most common in dental surgeons and operating room personnel without adequate scavenging systems. * **Bone Marrow Changes:** Acute exposure (e.g., prolonged sedation in ICU) can cause megaloblastic changes within 12–24 hours. * **Contraindication:** Avoid N₂O in patients with pre-existing Vitamin B12 deficiency or pernicious anemia.

Q: All of the following are pharmacological effects of ketamine, EXCEPT?

Severe fall in blood pressure. **Explanation:** Ketamine is a unique intravenous anesthetic agent that acts primarily as an **NMDA receptor antagonist**. It produces a state known as **"Dissociative Anesthesia,"** characterized by a functional dissociation between the thalamocortical and limbic systems. **Why Option B is the Correct Answer:** Unlike most induction agents (like propofol or thiopentone) which cause myocardial depression and vasodilation, Ketamine is a **sympathomimetic**. It inhibits the reuptake of catecholamines (norepinephrine), leading to an **increase in blood pressure (hypertension)**, heart rate, and cardiac output. Therefore, a "severe fall in blood pressure" is pharmacologically incorrect. **Analysis of Other Options:** * **A. Profound Analgesia:** Ketamine provides excellent somatic analgesia even at sub-anesthetic doses, making it ideal for short painful procedures and burn dressings. * **C. Amnesia:** While patients may appear awake (eyes open, slow nystagmic gaze), they experience significant anterograde amnesia and lack of awareness of the procedure. * **D. Increased Cerebral Blood Flow (CBF):** Ketamine is a potent cerebral vasodilator. It increases CBF, cerebral metabolic rate ($CMRO_2$), and consequently, **Intracranial Pressure (ICP)**. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** For induction in patients with **hypovolemic shock** or **bronchial asthma** (due to its bronchodilatory effects). * **Contraindications:** Head injuries (due to $\uparrow$ ICP), Hypertensive emergencies, and Ischemic heart disease. * **Side Effects:** **Emergence delirium** and hallucinations (minimized by co-administering benzodiazepines like Midazolam). * **Reflexes:** Pharyngeal and laryngeal reflexes are usually **preserved**, though the airway is not always fully protected.

Question 1

A 32-year-old female presents with pain in the right lower iliac fossa and positive rebound tenderness. She underwent appendectomy under general anesthesia. Postoperative laboratory findings showed increased levels of transaminases with the absence of increased bilirubin. Which of the following anesthetic agents is most likely responsible for the elevation of the enzymes?

Accepted Answer

Halothane

Answer

Nitrous oxide

Answer

Methoxyflurane

Answer

Enflurane

Question 2

Which of the following statements regarding pancuronium is INCORRECT?

Accepted Answer

It is a vagal stimulant.

Answer

It is an aminosteroid skeletal muscle relaxant.

Answer

Cardiovascular side effects are common.

Answer

It is the second-longest acting neuromuscular blocker after doxacurium.

Question 3

Which of the following statements about sevoflurane is true?

Accepted Answer

It is nephrotoxic at high doses.

Answer

It has the maximum risk of causing convulsions.

Answer

It is cardiostable.

Answer

It can cause fulminant hepatitis.

Question 4

Which of the following is NOT an aminosteroid non-depolarizing neuromuscular blocker?

Accepted Answer

Gantacurium

Answer

Pancuronium

Answer

Pipecuronium

Answer

Vacuronium

Question 5

Etomidate causes all of the following except:

Accepted Answer

Coronary insufficiency

Answer

Decreased steroidogenesis

Answer

Decreased intracranial tension

Answer

Nausea and vomiting

Question 6

Which of the following drugs produces a subjective feeling of well-being on emergence, thus conferring a potential for substance abuse?

Accepted Answer

Propofol

Answer

Thiopentone

Answer

Etomidate

Answer

Ketamine

Question 7

What percentage of Halothane is metabolized?

Accepted Answer

25%

Answer

50%

Answer

5%

Answer

2.50%

Question 8

Depth of anesthesia by inhalation anesthetics depends upon which of the following factors?

Accepted Answer

All of the above

Answer

Respiratory minute volume

Answer

Solubility of the anesthetic agent in blood

Answer

Blood concentration of the anesthetic agent

Question 9

A 40-year-old dental assistant presents with increased weakness and fatigue. Lab tests reveal megaloblastic anemia. Which of the following is most likely responsible for the presence of this anemia?

Accepted Answer

Nitrous oxide

Answer

Propofol

Answer

Lignocaine

Answer

Halothane

Question 10

All of the following are pharmacological effects of ketamine, EXCEPT?

Accepted Answer

Severe fall in blood pressure

Answer

Profound analgesia

Answer

Amnesia

Answer

Increased cerebral blood flow

General Anesthesia — MCQs

General Anesthesia — MCQs

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