General Anesthesia Practice Questions

Q: What is true about ketamine?

Bronchodilator. **Explanation:** Ketamine is a unique intravenous anesthetic agent known as a **"dissociative anesthetic."** It acts primarily as an NMDA receptor antagonist. **1. Why Option A is Correct:** Ketamine is a potent **bronchodilator**. It achieves this through two mechanisms: directly relaxing bronchial smooth muscle and indirectly by increasing the release of endogenous catecholamines (sympathomimetic effect). This makes it the **induction agent of choice for patients with status asthmaticus** or reactive airway disease. **2. Why the Other Options are Incorrect:** * **Option B:** Unlike most induction agents, ketamine **preserves airway reflexes** (cough and laryngeal reflexes). However, it also increases salivation, which can paradoxically lead to laryngospasm; hence, it is often co-administered with glycopyrrolate. * **Option C:** Ketamine is a **sympathomimetic**. It increases heart rate, cardiac output, and blood pressure. This makes it the **induction agent of choice for patients in hypovolemic or septic shock**. * **Option D:** Ketamine is a cerebral vasodilator that **increases intracranial pressure (ICP)**, cerebral blood flow, and intraocular pressure. It is generally avoided in patients with head injuries or intracranial space-occupying lesions. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** NMDA receptor antagonist. * **Dissociative Anesthesia:** Characterized by a "trance-like" state where the patient's eyes remain open with a slow nystagmic gaze. * **Analgesia:** Provides profound systemic analgesia even at sub-anesthetic doses. * **Side Effects:** Associated with **emergence delirium** and hallucinations (minimized by pre-treatment with benzodiazepines like midazolam). * **Contraindications:** Hypertension, Preeclampsia, Raised ICP, and Open globe injuries.

Q: Thiopentone is contraindicated in which of the following conditions?

All the above. **Explanation:** Thiopentone sodium is an ultra-short-acting barbiturate used for the induction of anesthesia. Its contraindications are high-yield topics for NEET-PG due to its specific physiological effects. 1. **Acute Intermittent Porphyria (AIP):** This is an **absolute contraindication**. Thiopentone induces the enzyme **ALA synthetase**, which increases the production of porphyrins. In patients with AIP, this can precipitate a life-threatening crisis characterized by abdominal pain, neuropsychiatric symptoms, and paralysis. 2. **Bronchial Asthma:** Thiopentone causes **histamine release** and does not sufficiently suppress airway reflexes. This can trigger bronchospasm or laryngospasm in patients with hyperreactive airways. 3. **Shock:** Thiopentone is a potent **venodilator and myocardial depressant**. In hypovolemic or cardiogenic shock, the compensatory sympathetic drive is crucial; thiopentone abolishes this drive, leading to a profound and potentially fatal drop in blood pressure. **Why "All the above" is correct:** Each condition listed represents a scenario where the pharmacological profile of Thiopentone (enzyme induction, histamine release, and cardiovascular depression) poses a significant risk to the patient. **High-Yield Clinical Pearls for NEET-PG:** * **Status Epilepticus:** Thiopentone is a drug of choice for refractory status epilepticus due to its potent anticonvulsant properties and ability to decrease Cerebral Metabolic Rate ($CMRO_2$). * **Extravasation:** If injected intra-arterially, it causes intense vasoconstriction and gangrene. Treatment includes **Phentolamine** or **Papaverine** and sympathetic block (Stellate ganglion block). * **pH:** It is highly alkaline (pH 10.5); therefore, it cannot be mixed with acidic drugs like vecuronium in the same syringe.

Q: Which of the following is a known effect of suxamethonium?

Muscle fasciculation. **Explanation:** **Suxamethonium (Succinylcholine)** is the only depolarizing neuromuscular blocking agent used clinically. It acts as an agonist at the nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction. **Why Option D is Correct:** Unlike non-depolarizing agents, suxamethonium causes prolonged depolarization of the post-synaptic membrane. This initial stimulation leads to disorganized contractions of muscle units known as **muscle fasciculations** before the onset of flaccid paralysis. These fasciculations are often associated with postoperative myalgia. **Why Other Options are Incorrect:** * **A & B (Jaundice & Splenomegaly):** Suxamethonium has no known hepatotoxic effects or impact on splenic volume. Jaundice is more classically associated with repeated exposure to Halothane (Halothane hepatitis). * **C (Atrial Fibrillation):** While suxamethonium can cause arrhythmias, its most characteristic cardiac effect is **bradycardia** (especially in children or upon a second dose) due to its action on muscarinic receptors in the sinus node. It may also cause ventricular arrhythmias secondary to hyperkalemia, but not typically atrial fibrillation. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism:** Hydrolyzed by **pseudocholinesterase** (butyrylcholinesterase). Deficiency leads to prolonged apnea (Suxamethonium apnea). * **Electrolyte Shift:** Causes a transient **increase in serum potassium** (approx. 0.5 mEq/L); contraindicated in burns, crush injuries, and upper motor neuron lesions due to risk of fatal hyperkalemia. * **Pressure Changes:** Increases intraocular, intragastric, and intracranial pressure. * **Malignant Hyperthermia:** It is a potent trigger for Malignant Hyperthermia (Treatment: Dantrolene).

Q: A 21-year-old woman with a history of hypersensitivity to neostigmine is scheduled for an elective cesarean section under general anesthesia. Which muscle relaxant is the best choice for this patient?

Atracurium. **Explanation:** The core clinical challenge in this scenario is the patient’s **hypersensitivity to neostigmine**. Neostigmine is the standard pharmacological reversal agent for non-depolarizing neuromuscular blocking agents (NDMRs). If a patient cannot receive neostigmine, the anesthesiologist must select a muscle relaxant that does not strictly depend on pharmacological reversal for the termination of its effects. **Why Atracurium is the Correct Choice:** Atracurium (and its isomer Cisatracurium) undergoes **Hofmann elimination**—a spontaneous, non-enzymatic degradation at physiological pH and temperature. Because it is self-terminating and does not rely on hepatic metabolism or renal excretion, the block wears off predictably on its own. In a patient where neostigmine is contraindicated, choosing a drug with a reliable "spontaneous recovery" profile is the safest strategy. **Analysis of Incorrect Options:** * **Pancuronium (A):** A long-acting NDMR primarily excreted by the kidneys. It requires mandatory reversal to avoid residual paralysis, making it unsuitable here. * **Rocuronium (C) & Vecuronium (D):** These are intermediate-acting aminosteroid compounds. While Rocuronium can be reversed with Sugammadex (a non-anticholinesterase agent), in the context of standard NEET-PG questions, Atracurium remains the classic answer for "avoiding neostigmine" due to its unique organ-independent elimination. **High-Yield Clinical Pearls for NEET-PG:** * **Hofmann Elimination:** Dependent on **pH and Temperature**. Rate increases with alkalosis/hyperthermia and decreases with acidosis/hypothermia. * **Laudanosine:** A metabolite of atracurium that can cross the blood-brain barrier and potentially cause seizures (though rare in clinical doses). * **Drug of Choice:** Atracurium/Cisatracurium are the drugs of choice in **Renal and Hepatic failure**.

Q: Which volatile anesthetic agent causes the most renal toxicity?

Methoxyflurane. **Explanation:** The correct answer is **Methoxyflurane**. The primary mechanism behind its renal toxicity is the extensive hepatic metabolism of the drug, which releases **inorganic fluoride ions ($F^-$)**. 1. **Why Methoxyflurane is correct:** Methoxyflurane undergoes the highest degree of metabolism (approx. 50–75%) among all volatile agents. This results in high serum fluoride levels (often exceeding 50 µmol/L). These fluoride ions cause **vasopressin-resistant high-output renal failure** (polyuric renal failure) by damaging the distal convoluted tubules and collecting ducts, making them unresponsive to ADH. Due to this severe nephrotoxicity, it is no longer used for general anesthesia. 2. **Why other options are incorrect:** * **Ether:** Primarily known for its irritant effect on airways and flammability; it does not produce toxic fluoride metabolites. * **Isoflurane:** It is very stable and undergoes minimal metabolism (0.2%), making it exceptionally safe for the kidneys. * **Sevoflurane:** While it does release fluoride ions and can produce **Compound A** (a nephrotoxin in rats) when reacting with soda lime, clinical studies have shown no significant evidence of renal toxicity in humans when used at recommended flow rates. **High-Yield Clinical Pearls for NEET-PG:** * **Fluoride-induced nephrotoxicity:** Characterized by polyuria, hypernatremia, and increased serum creatinine. * **Metabolism Ranking (Highest to Lowest):** Methoxyflurane (50-75%) > Halothane (20%) > Sevoflurane (2-5%) > Enflurane (2%) > Isoflurane (0.2%) > Desflurane (0.02%). * **Compound A:** Associated with **Sevoflurane**; formed by degradation in carbon dioxide absorbers (especially with low-flow anesthesia). * **Agent of choice in Renal Failure:** Isoflurane or Desflurane.

Q: A 60-year-old man undergoing an inguinal hernia repair is induced with propofol. Which of the following is most likely to be observed?

Apnea. **Explanation:** Propofol (2,6-diisopropylphenol) is the most commonly used intravenous induction agent. Its primary mechanism of action involves the enhancement of GABA-A receptors in the central nervous system. **Why Apnea is the Correct Answer:** Propofol is a potent respiratory depressant. Following an induction dose (1.5–2.5 mg/kg), it frequently causes **transient apnea** (lasting >30 seconds) by decreasing the sensitivity of the medullary respiratory center to carbon dioxide and reducing the tidal volume and respiratory rate. This effect is more pronounced than with other induction agents like thiopentone. **Analysis of Incorrect Options:** * **A. Hypertension:** Propofol typically causes **hypotension**, not hypertension. It reduces systemic vascular resistance (vasodilation) and myocardial contractility, making it the most hemodynamically unstable induction agent among common choices. * **C. Hyperthermia:** Propofol does not cause hyperthermia. In fact, it is the drug of choice for patients susceptible to **Malignant Hyperthermia**, as it is a non-triggering agent. * **D. Prolonged sedation:** Propofol is characterized by a **rapid recovery** profile. Due to its high lipid solubility and rapid redistribution from the brain to peripheral tissues, patients wake up quickly (usually within 5–10 minutes) with minimal "hangover" effect. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** For day-care (ambulatory) surgeries due to rapid recovery and anti-emetic properties. * **Pain on Injection:** A common side effect; minimized by using larger veins or pre-treatment with lidocaine. * **PRIS (Propofol Infusion Syndrome):** A rare, fatal complication of long-term high-dose infusion characterized by metabolic acidosis, rhabdomyolysis, and cardiac failure. * **Egg/Soy Allergy:** Use with caution as the emulsion contains egg lecithin and soybean oil.

Q: An anesthetic tension in the arterial blood is shown on the graph as a function of time after inhalation. A similar curve for nitrous oxide is also shown. Which of the following best describes the properties of the new anesthetic compared to nitrous oxide?

High blood:gas partition coefficient. ***High blood:gas partition coefficient*** - The slower rise in **FA/FI ratio** (alveolar to inspired concentration) indicates the anesthetic has **high blood solubility**, meaning more drug dissolves in blood before reaching equilibrium. - A **high blood:gas partition coefficient** means the anesthetic is readily taken up by blood, delaying the rise in alveolar concentration compared to nitrous oxide. *Low solubility in the blood* - This would result in a **rapid rise** in FA/FI ratio, similar to or faster than nitrous oxide, which is not shown in the graph. - **Low blood solubility** means less drug dissolves in blood, allowing faster equilibration between alveolar and inspired concentrations. *Rapid onset of action* - The graph shows a **slower equilibration** compared to nitrous oxide, indicating **delayed onset** rather than rapid onset. - **Rapid onset** would be associated with a steep, quick rise in FA/FI ratio, which contradicts the shown curve. *Low potency* - **Potency** is determined by **MAC (Minimum Alveolar Concentration)**, not by the equilibration curve shown in the graph. - The blood:gas partition coefficient and equilibration speed are **independent of potency**, which relates to receptor binding affinity.

Q: Which of the following muscle relaxants is free of cardiovascular effects over the entire clinical dose range?

Vecuronium. **Explanation:** The cardiovascular stability of neuromuscular blocking agents (NMBAs) depends on their ability to trigger histamine release or interact with autonomic receptors (muscarinic or nicotinic). **Why Vecuronium is Correct:** Vecuronium is a monoquaternary aminosteroid NMBA known for its **cardiovascular stability**. It does not cause histamine release and has negligible effects on autonomic ganglia or muscarinic receptors. Consequently, it does not cause changes in heart rate or blood pressure, even at doses several times the $ED_{95}$, making it the drug of choice for patients where hemodynamic stability is critical. **Analysis of Incorrect Options:** * **Pancuronium:** This is a long-acting aminosteroid that causes **tachycardia** and hypertension. This is due to its vagolytic effect (blocking $M_2$ receptors in the heart) and its ability to stimulate norepinephrine release from sympathetic nerve endings. * **Atracurium:** This benzylisoquinolone is associated with **histamine release**, especially when administered rapidly or at high doses. This can lead to systemic vasodilation (hypotension) and reflex tachycardia. * **Pipecuronium:** While it is more stable than pancuronium, it can still exhibit mild cardiovascular effects at very high doses, though it is much closer to vecuronium in stability. However, vecuronium remains the classic textbook answer for "free of effects over the entire clinical range." **High-Yield NEET-PG Pearls:** * **Rocuronium:** Also cardiovascularly stable but may cause a slight increase in heart rate. * **Cisatracurium:** The most stable benzylisoquinolone (no histamine release), often used in renal/hepatic failure (Hofmann elimination). * **Mivacurium:** Shortest acting non-depolarizer; significant histamine release. * **Succinylcholine:** Can cause **bradycardia** (especially in children or on second dose) due to muscarinic stimulation.

Question 1

What is true about ketamine?

Accepted Answer

Bronchodilator

Answer

Depressed airway reflexes

Answer

Causes hypotension

Answer

Decreases intracranial pressure

Question 2

Thiopentone is contraindicated in which of the following conditions?

Accepted Answer

All the above

Answer

Acute intermittent porphyria

Answer

Bronchial asthma

Answer

Shock

Question 3

Which of the following is a known effect of suxamethonium?

Accepted Answer

Muscle fasciculation

Answer

Jaundice

Answer

Splenomegaly

Answer

Atrial fibrillation

Question 4

A 21-year-old woman with a history of hypersensitivity to neostigmine is scheduled for an elective cesarean section under general anesthesia. Which muscle relaxant is the best choice for this patient?

Accepted Answer

Atracurium

Answer

Pancuronium

Answer

Rocuronium

Answer

Vecuronium

Question 5

Nitrous oxide is contraindicated in which of the following conditions?

Accepted Answer

Mastectomy

Answer

Vitreo-retinal surgeries

Answer

Pneumothorax

Answer

Laser surgery

Question 6

Pain during injection occurs with all anesthetic agents listed below except?

Accepted Answer

Ketamine

Answer

Propofol

Answer

Thiopentone

Answer

Etomidate

Question 7

Which volatile anesthetic agent causes the most renal toxicity?

Accepted Answer

Methoxyflurane

Answer

Ether

Answer

Isoflurane

Answer

Sevoflurane

Question 8

A 60-year-old man undergoing an inguinal hernia repair is induced with propofol. Which of the following is most likely to be observed?

Accepted Answer

Apnea

Answer

Hypertension

Answer

Hyperthermia

Answer

Prolonged sedation

Question 9

An anesthetic tension in the arterial blood is shown on the graph as a function of time after inhalation. A similar curve for nitrous oxide is also shown. Which of the following best describes the properties of the new anesthetic compared to nitrous oxide?

Accepted Answer

High blood:gas partition coefficient

Answer

Low solubility in the blood

Answer

Rapid onset of action

Answer

Low potency

Question 10

Which of the following muscle relaxants is free of cardiovascular effects over the entire clinical dose range?

Accepted Answer

Vecuronium

Answer

Pancuronium

Answer

Atracurium

Answer

Pipecuronium

General Anesthesia — MCQs

General Anesthesia — MCQs

On this page

Practice by Chapter

Want unlimited practice?