General Anesthesia Practice Questions

Q: Which inhalational anesthetic agent has the lowest blood-gas coefficient?

Xenon. **Explanation:** The **Blood-Gas Partition Coefficient** is the primary determinant of the speed of induction and recovery of an inhalational anesthetic. A lower coefficient indicates low solubility in the blood, meaning the partial pressure in the alveoli rises rapidly, leading to faster equilibration with the brain and quicker induction/emergence. **Why Xenon is Correct:** Xenon is an inert gas that possesses the **lowest blood-gas partition coefficient (0.115–0.14)** among all known anesthetic agents. This makes it the fastest-acting anesthetic in terms of induction and recovery. It is also considered an "ideal" anesthetic because it is non-explosive, provides NMDA antagonism, and has minimal hemodynamic side effects. **Why Other Options are Incorrect:** * **Nitrous Oxide (B):** While very insoluble, its coefficient is **0.47**, which is significantly higher than Xenon. * **Isoflurane (A):** A commonly used volatile liquid with a coefficient of **1.4**, making it much more soluble and slower to act than Xenon. * **Enflurane (D):** Has a high coefficient of **1.8**, leading to slower induction and recovery compared to modern agents. **High-Yield NEET-PG Pearls:** 1. **Order of Solubility (Lowest to Highest):** Xenon (0.14) < Desflurane (0.42) < Nitrous Oxide (0.47) < Sevoflurane (0.65) < Isoflurane (1.4) < Halothane (2.4). 2. **Desflurane** has the lowest coefficient among *volatile liquids* (0.42), but **Xenon** is the lowest among all *gaseous* agents. 3. **MAC Value:** Xenon has a high MAC (approx. 63–71%), meaning it is less potent than volatile liquids like Halothane (MAC 0.75%). 4. **Second Gas Effect:** Nitrous oxide is typically used to speed up the induction of a second volatile agent.

Q: Arrhythmias are most common when adrenaline is used with which of the following inhaled anesthetics?

Halothane. **Explanation:** The correct answer is **Halothane**. **1. Why Halothane is correct:** Halothane is notorious for **sensitizing the myocardium to the arrhythmogenic effects of catecholamines** (like adrenaline). It inhibits the reuptake of norepinephrine and interferes with the conduction system, significantly lowering the threshold for ventricular arrhythmias. When exogenous adrenaline is administered (e.g., for local hemostasis) during halothane anesthesia, it can trigger premature ventricular contractions (PVCs), ventricular tachycardia, or even fibrillation. Clinical guidelines suggest limiting adrenaline to no more than **1 µg/kg** when using halothane. **2. Why other options are incorrect:** * **Isoflurane, Enflurane, and Sevoflurane:** These are modern halogenated ethers. While all volatile anesthetics sensitize the heart to catecholamines to some degree, they do so significantly less than halothane (an alkane). * **Sevoflurane and Isoflurane** are considered much safer; the dose of adrenaline required to produce arrhythmias is several times higher (approx. 3–5 times) than that required with halothane. **3. High-Yield Clinical Pearls for NEET-PG:** * **Arrhythmogenic Potency:** Halothane > Enflurane > Isoflurane > Sevoflurane/Desflurane. * **Halothane Hepatitis:** A rare but serious immune-mediated hepatotoxicity associated with repeat exposure. * **Catecholamine Limit:** In the presence of halothane, the maximum dose of adrenaline is **1 µg/kg**; with isoflurane, it is approximately **3 µg/kg**. * **Drug of Choice:** For induction in pediatric cases (due to sweet smell and non-irritancy), **Sevoflurane** has largely replaced halothane.

Q: Which of the following statements regarding Non-Depolarizing Muscle Relaxants is FALSE?

Non-depolarizing agents trigger malignant hyperthermia.. ### Explanation **1. Why Option D is the Correct (False) Statement:** Malignant Hyperthermia (MH) is a pharmacogenetic hypermetabolic state triggered exclusively by **volatile inhalational anesthetics** (e.g., Halothane, Isoflurane) and the **depolarizing** muscle relaxant **Succinylcholine**. Non-depolarizing muscle relaxants (NDMRs) like Vecuronium, Atracurium, and Pancuronium do **not** trigger MH. In fact, NDMRs are considered safe alternatives for patients susceptible to MH. **2. Analysis of Other Options:** * **Option A (True):** Vecuronium is primarily metabolized by the liver and excreted via bile (40-70%). While a small portion is excreted renally, it is considered relatively safe in renal failure compared to long-acting agents like Pancuronium. (Note: Cisatracurium is the gold standard for renal failure due to Hofmann elimination). * **Option B (True):** Aminoglycosides (e.g., Gentamicin, Neomycin) inhibit the pre-junctional release of Acetylcholine and decrease post-junctional sensitivity. This synergistically **potentiates** the blockade of NDMRs, especially in renal failure where drug clearance is reduced. * **Option C (True):** Pancuronium is a long-acting NDMR that possesses **vagolytic** properties (blocks muscarinic receptors in the SA node), leading to tachycardia and hypertension. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hofmann Elimination:** A non-enzymatic, pH and temperature-dependent degradation unique to **Atracurium** and **Cisatracurium**, making them the drugs of choice in liver and kidney failure. * **Mivacurium:** The only NDMR metabolized by **pseudocholinesterase**. * **Rocunorium:** Has the fastest onset among NDMRs, making it suitable for Rapid Sequence Induction (RSI) when Succinylcholine is contraindicated. * **Reversal:** Sugammadex specifically reverses aminosteroid NDMRs (Rocunorium > Vecuronium).

Q: Polygelin content is found in which of the following fluids?

Haemaccel. **Explanation:** **Haemaccel** is a synthetic colloid used for volume replacement. It is specifically composed of **Polygeline**, which is a polymer of degraded gelatin cross-linked with urea. It has a molecular weight of approximately 30,000 Daltons and is unique because it contains significant concentrations of electrolytes, specifically **Calcium (6.25 mmol/L)** and Potassium. **Analysis of Options:** * **Gelofuscine (Option A):** This is also a gelatin-based colloid, but it consists of **succinylated gelatin** in isotonic saline. Unlike Haemaccel, it does not contain calcium and is not cross-linked with urea. * **Hartmann's Solution (Option B):** This is a crystalloid, also known as **Ringer's Lactate**. It contains sodium chloride, sodium lactate, potassium chloride, and calcium chloride, but no gelatin or polygeline. * **Hetastarch (Option D):** This is a **Hydroxyethyl Starch (HES)**, a synthetic colloid derived from amylopectin. It is a glucose polymer, not a protein/gelatin derivative. **High-Yield Clinical Pearls for NEET-PG:** 1. **Calcium Content:** Because Haemaccel contains calcium, it should **not** be infused through the same line as citrated blood, as it may cause clotting (recalcification of blood). 2. **Anaphylaxis:** Gelatins (Haemaccel and Gelofuscine) have a higher incidence of anaphylactoid reactions compared to starches or crystalloids due to histamine release. 3. **Renal Safety:** Unlike older Hydroxyethyl starches, polygelins have a minimal effect on renal function and coagulation profiles. 4. **Metabolism:** Polygelin is primarily excreted unchanged by the kidneys.

Q: Which of the following is the fastest acting anesthetic agent?

Sevoflurane. **Explanation:** The speed of induction and recovery of an inhalational anesthetic agent is primarily determined by its **Blood-Gas Partition Coefficient (λ)**. A lower coefficient indicates lower solubility in blood, allowing the partial pressure of the gas in the alveoli to rise rapidly, leading to faster equilibration with the brain. **Why Sevoflurane is the Correct Answer:** While **Desflurane** actually has a lower blood-gas partition coefficient (0.42) than **Sevoflurane** (0.65), Sevoflurane is clinically considered the fastest agent for **inhalation induction**. This is because Desflurane is highly pungent and irritates the airway, causing coughing, breath-holding, and laryngospasm, making it unsuitable for rapid mask induction. Sevoflurane is non-pungent, pleasant-smelling, and a potent bronchodilator, allowing for a smooth and rapid "single-breath" induction, especially in pediatric practice. **Analysis of Incorrect Options:** * **B. Desflurane:** Although it has the fastest *emergence* (recovery) due to its lowest solubility, its pungency prevents it from being the fastest agent for *induction*. * **C. Isoflurane:** It has a higher blood-gas partition coefficient (1.4), making it significantly slower in both induction and recovery compared to Sevoflurane and Desflurane. **High-Yield Clinical Pearls for NEET-PG:** * **Lowest Blood-Gas Coefficient:** Desflurane (0.42) > Sevoflurane (0.65) > Nitrous Oxide (0.47) > Isoflurane (1.4) > Halothane (2.4). * **Agent of Choice for Induction:** Sevoflurane (due to non-pungency). * **Agent of Choice for Maintenance in Day-care Surgery:** Desflurane (due to fastest recovery). * **Compound A:** A nephrotoxic byproduct formed when Sevoflurane reacts with dry soda lime. * **Carbon Monoxide:** Highest production is seen with Desflurane when used with dry CO2 absorbers.

Q: Which of the following solutions is a colloid?

Albumin. **Explanation:** Intravenous fluids are broadly classified into two categories: **Crystalloids** and **Colloids**, based on their molecular weight and ability to cross the semi-permeable capillary membrane. **Why Albumin is the Correct Answer:** **Albumin** is a natural **colloid**. Colloids contain large, high-molecular-weight molecules (usually >30,000 Daltons) that do not easily cross the healthy capillary endothelium. Because they remain within the intravascular compartment, they exert **oncotic pressure**, effectively drawing fluid into or maintaining fluid within the blood vessels. This makes them highly effective for rapid volume expansion. **Analysis of Incorrect Options:** * **Normal Saline (0.9% NaCl):** An isotonic **crystalloid**. It contains small electrolytes that freely pass through capillary pores into the interstitial space. * **Ringer’s Lactate (RL):** A balanced salt **crystalloid**. Like saline, it distributes throughout the entire extracellular fluid (ECF) compartment. * **Dextrose 5% (D5W):** A hypotonic **crystalloid**. Once the glucose is metabolized, it leaves behind free water which distributes across all body compartments (Intracellular + Extracellular). **High-Yield Clinical Pearls for NEET-PG:** * **Volume Expansion Ratio:** For every 100 mL of blood lost, you need ~300 mL of crystalloid (3:1 ratio) but only ~100 mL of colloid (1:1 ratio) to maintain hemodynamics. * **Synthetic Colloids:** Include Hydroxyethyl Starches (HES), Gelatins, and Dextrans. Note that HES is now restricted due to risks of acute kidney injury (AKI). * **Albumin Concentrations:** Available as 5% (iso-oncotic) and 25% (hyper-oncotic). * **Key Concept:** Crystalloids are the first-line choice for fluid resuscitation; colloids are reserved for specific indications like severe hypoalbuminemia or when crystalloids fail to achieve volume targets.

Q: Which intravenous anesthetic agent produces a cocaine-like effect on the cardiovascular system?

Ketamine. ### Explanation **Correct Answer: C. Ketamine** Ketamine is a unique intravenous anesthetic that acts as a **sympathomimetic** agent. Its "cocaine-like" effect on the cardiovascular system is due to two primary mechanisms: 1. **Direct Stimulation:** It stimulates the central sympathetic nervous system. 2. **Inhibition of Reuptake:** Like cocaine, it inhibits the neuronal reuptake of catecholamines (norepinephrine) into postganglionic sympathetic nerve endings. This results in an **increase in heart rate, arterial blood pressure, and cardiac output**, making it the induction agent of choice for patients in hypovolemic shock. --- ### Why the other options are incorrect: * **A. Thiopentone:** A barbiturate that causes dose-dependent myocardial depression and peripheral vasodilation (venodilation), leading to a **decrease in blood pressure**. * **B. Propofol:** Known for causing the most significant **hypotension** among induction agents due to profound vasodilation and decreased myocardial contractility. It also blunts the baroreceptor reflex. * **D. Etomidate:** Renowned for its **cardiovascular stability**. It causes minimal changes in heart rate and blood pressure, making it ideal for patients with cardiac disease, but it does not produce a sympathomimetic "cocaine-like" surge. --- ### High-Yield Clinical Pearls for NEET-PG: * **Dissociative Anesthesia:** Ketamine produces a state where the patient appears awake (eyes open) but is unconscious and feels no pain. * **Bronchodilation:** Ketamine is the induction agent of choice for **Asthmatic patients**. * **Contraindications:** Avoid Ketamine in patients with **Ischemic Heart Disease (IHD)** or Hypertension (due to increased myocardial oxygen demand) and in cases of **increased Intracranial Pressure (ICP)**. * **Emergence Delirium:** A common side effect of Ketamine, which can be pre-treated with Benzodiazepines (e.g., Midazolam).

Q: Which of the following drugs has caused hyperkalemia leading to cardiac arrest in patients with neurological disorders?

Succinylcholine. **Explanation:** **Succinylcholine (Suxamethonium)** is a depolarizing neuromuscular blocker that acts as an agonist at the nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction. **Why Succinylcholine is the correct answer:** In normal individuals, succinylcholine causes a transient rise in serum potassium (~0.5 mEq/L). However, in patients with **neurological disorders** (e.g., stroke, spinal cord injury, burns, or muscular dystrophy), there is an **upregulation of extrajunctional acetylcholine receptors**. When succinylcholine binds to these widespread receptors, it causes massive, prolonged depolarization, leading to an efflux of potassium from the cells into the extracellular fluid. This **exaggerated hyperkalemia** can lead to fatal cardiac arrhythmias and cardiac arrest. **Why the other options are incorrect:** * **Baclofen:** A GABA-B receptor agonist used as a muscle relaxant for spasticity; it does not act on nAChR and does not cause hyperkalemia. * **Dantrolene:** Acts intracellularly by inhibiting the ryanodine receptor (RyR1) to prevent calcium release from the sarcoplasmic reticulum. It is the treatment of choice for Malignant Hyperthermia and does not cause hyperkalemia. * **Tubocurarine:** A non-depolarizing neuromuscular blocker. These drugs are competitive antagonists and do not cause depolarization; therefore, they do not trigger potassium release and are generally safe in patients at risk for hyperkalemia. **NEET-PG High-Yield Pearls:** * **Avoid Succinylcholine in:** Burns (>24 hours), massive trauma, prolonged immobilization, and upper/lower motor neuron lesions. * **Drug of choice for RSI:** Succinylcholine (due to rapid onset and short duration), but **Rocuronium** is the preferred alternative if hyperkalemia is a concern. * **Malignant Hyperthermia:** Succinylcholine is a known trigger.

Question 1

Which inhalational anesthetic agent has the lowest blood-gas coefficient?

Accepted Answer

Xenon

Answer

Isoflurane

Answer

Nitrous oxide

Answer

Enflurane

Question 2

Arrhythmias are most common when adrenaline is used with which of the following inhaled anesthetics?

Accepted Answer

Halothane

Answer

Isoflurane

Answer

Enflurane

Answer

Sevoflurane

Question 3

Which of the following statements regarding Non-Depolarizing Muscle Relaxants is FALSE?

Accepted Answer

Non-depolarizing agents trigger malignant hyperthermia.

Answer

Vecuronium can be used safely in patients with renal failure.

Answer

Aminoglycosides can worsen neuromuscular blockade in patients with renal failure.

Answer

Pancuronium possesses vagolytic effects.

Question 4

Which of the following statements regarding neuromuscular blockers are true?

Accepted Answer

Statements 1, 2, 3, 4, and 5 are true.

Answer

Statements 1, 2, and 3 are true, and statements 4 and 5 are false.

Answer

Statements 1, 2, 3, and 5 are true, and statement 4 is false.

Answer

Statements 1 and 2 are true, and statements 3, 4, and 5 are false.

Question 5

The rate at which the alveolar concentration of an anesthetic approaches inspired concentration is a function of all except?

Accepted Answer

Saturated vapor pressure

Answer

Alveolar ventilation

Answer

Water solubility of agent

Answer

Cardiac output

Question 6

Polygelin content is found in which of the following fluids?

Accepted Answer

Haemaccel

Answer

Gelofuscine

Answer

Hartmann's solution

Answer

Hetastarch

Question 7

Which of the following is the fastest acting anesthetic agent?

Accepted Answer

Sevoflurane

Answer

Desflurane

Answer

Isoflurane

Answer

None of the above

Question 8

Which of the following solutions is a colloid?

Accepted Answer

Albumin

Answer

Normal saline

Answer

Ringer lactate

Answer

Dextrose 5%

Question 9

Which intravenous anesthetic agent produces a cocaine-like effect on the cardiovascular system?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Propofol

Answer

Etomidate

Question 10

Which of the following drugs has caused hyperkalemia leading to cardiac arrest in patients with neurological disorders?

Accepted Answer

Succinylcholine

Answer

Baclofen

Answer

Dantrolene

Answer

Tubocurarine

General Anesthesia — MCQs

General Anesthesia — MCQs

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