General Anesthesia Practice Questions

Q: If ketamine is the only agent used in reducing a dislocated shoulder, what are its actions?

Analgesia. **Explanation:** Ketamine is a unique anesthetic agent that produces **dissociative anesthesia**, characterized by a functional dissociation between the thalamocortical and limbic systems. **1. Why Analgesia is Correct:** Ketamine is a potent **NMDA receptor antagonist**. Even at sub-anesthetic doses, it provides profound **analgesia** (pain relief), making it an ideal choice for painful short procedures like reducing a dislocated shoulder. Unlike most other induction agents, it maintains protective airway reflexes and spontaneous respiration while eliminating pain. **2. Why Other Options are Incorrect:** * **Hypotension & Bradycardia (A & D):** Ketamine is a **sympathomimetic** agent. It inhibits the reuptake of catecholamines (norepinephrine), leading to an **increase** in heart rate (tachycardia) and blood pressure (hypertension). It is the induction agent of choice for patients in hemorrhagic or septic shock. * **Respiratory Depression (B):** One of ketamine’s primary advantages is that it causes **minimal respiratory depression**. It acts as a potent bronchodilator (useful in asthmatics) and generally preserves the patient's drive to breathe. **High-Yield Clinical Pearls for NEET-PG:** * **Emergence Delirium:** A common side effect characterized by hallucinations and vivid dreams; it can be prevented by co-administering **Benzodiazepines** (e.g., Midazolam). * **Secretions:** Ketamine increases salivation (sialagogue effect); **Atropine or Glycopyrrolate** is often given to counteract this. * **Contraindications:** Avoid in patients with raised Intracranial Pressure (ICP), Intraocular Pressure (IOP), or severe Ischemic Heart Disease. * **Status Asthmaticus:** Ketamine is the induction agent of choice due to its bronchodilatory properties.

Q: Which of the following is a feature of depolarizing blockade?

Progression to dual blockade. **Explanation:** Neuromuscular blockers are classified into **Depolarizing (Phase I)** and **Non-depolarizing (Phase II)** agents. Succinylcholine is the only clinically used depolarizing agent. **Why Option C is Correct:** A **Phase I (Depolarizing) block** occurs when succinylcholine mimics acetylcholine, causing persistent depolarization of the motor endplate. However, with prolonged exposure or high doses (typically >2-4 mg/kg), the block transitions into a **Phase II block (Dual Blockade)**. In this state, the membrane repolarizes but becomes desensitized to acetylcholine, clinically resembling a non-depolarizing block. **Why the other options are incorrect:** * **A & B (Tetanic fade and Post-tetanic potentiation):** These are classic features of **Non-depolarizing** blocks. In a pure Phase I depolarizing block, there is no fade; the muscle response is diminished but remains sustained (constant) during tetanic stimulation. * **D (Antagonism by anticholinesterases):** Anticholinesterases (like Neostigmine) increase acetylcholine levels. In a Phase I block, this actually **potentiates (worsens)** the blockade because it provides more substrate for depolarization. Neostigmine only antagonizes non-depolarizing blocks or a well-established Phase II block. **High-Yield NEET-PG Pearls:** * **Succinylcholine** is the drug of choice for Rapid Sequence Induction (RSI) due to its rapid onset and short duration. * **Fasciculations:** A hallmark of Phase I block, caused by the initial disorganized contraction of muscle units. * **Pseudocholinesterase:** The enzyme responsible for succinylcholine metabolism. Deficiency leads to prolonged apnea. * **Train-of-Four (TOF) Ratio:** In Phase I, the ratio is >0.7 (no fade); in Phase II/Non-depolarizing, the ratio is <0.7 (fade present).

Q: Which of the following is NOT an action of depolarizing agents?

Hypokalemia. **Explanation:** The correct answer is **B. Hypokalemia**. Depolarizing neuromuscular blocking agents, specifically **Succinylcholine (Suxamethonium)**, are known to cause **Hyperkalemia**, not hypokalemia. **1. Why Hypokalemia is the correct answer (The Mechanism):** Succinylcholine acts by mimicking acetylcholine at the nicotinic receptors of the neuromuscular junction. It causes prolonged depolarization of the muscle membrane. During this process, sodium channels open to allow sodium influx, while **potassium ions leak out** of the muscle cells into the extracellular fluid. In a healthy individual, this typically raises serum potassium by **0.5 mEq/L**. However, in patients with burns, massive trauma, or denervation injuries, this rise can be life-threatening. **2. Analysis of Incorrect Options:** * **A. Bradycardia:** Succinylcholine can stimulate muscarinic receptors in the sinus node, leading to bradycardia. This is especially common in children or after a second dose in adults. * **C. Increased Intracranial Tension (ICT):** Depolarization and associated muscle fasciculations can lead to a transient increase in cerebral blood flow and ICT. * **D. Increased Intraocular Pressure (IOP):** Succinylcholine causes a transient rise in IOP (approx. 5-10 mmHg) due to the contraction of extraocular muscles and choroidal vascular dilation. It should be used with caution in penetrating eye injuries. **NEET-PG High-Yield Pearls:** * **Drug of Choice:** Succinylcholine remains the drug of choice for **Rapid Sequence Induction (RSI)** due to its rapid onset (30-60s) and short duration (5-10 mins). * **Metabolism:** It is metabolized by **Pseudocholinesterase** (Plasma cholinesterase). * **Malignant Hyperthermia:** Succinylcholine is a potent trigger for Malignant Hyperthermia. * **Fasciculations:** These are visible muscle twitches caused by initial depolarization, which can lead to postoperative myalgia.

Q: What is the dose of thiopentone used for induction?

5 mg/kg. **Explanation:** Thiopentone sodium is an ultra-short-acting barbiturate that has long been the "gold standard" induction agent in anesthesia. The standard intravenous induction dose for a healthy adult is **3–5 mg/kg** (commonly cited as **5 mg/kg** in exams). **Why Option C is correct:** At a dose of 5 mg/kg, thiopentone rapidly crosses the blood-brain barrier due to its high lipid solubility, causing loss of consciousness within one arm-brain circulation time (approx. 30 seconds). Its action is terminated by **redistribution** from the brain to lean tissues (muscle and fat), rather than metabolism. **Why other options are incorrect:** * **A (1 mg/kg):** This is a sub-therapeutic dose for induction. However, small doses (0.5–1 mg/kg) may be used to treat intractable seizures or to relieve pruritus associated with spinal opioids. * **B (2 mg/kg):** This is the standard induction dose for **Propofol** (1.5–2.5 mg/kg) or **Etomidate** (0.3 mg/kg), but insufficient for reliable induction with Thiopentone. * **D (10 mg/kg):** This dose is excessive and can lead to severe cardiovascular depression, profound hypotension, and prolonged respiratory apnea. **High-Yield Clinical Pearls for NEET-PG:** * **Preparation:** It is stored as a yellow powder (mixed with 6% anhydrous sodium carbonate to prevent precipitation) and reconstituted as a **2.5% solution**. * **Contraindication:** It is strictly contraindicated in **Porphyria** (induces ALA synthetase). * **Complication:** Intra-arterial injection causes severe vasospasm and gangrene. Treatment includes injecting **Papaverine**, Lidocaine, or performing a Stellate ganglion block. * **Context:** It provides excellent **cerebral protection** by decreasing the cerebral metabolic rate of oxygen (CMRO2) and intracranial pressure (ICP).

Q: What is the maintenance fluid requirement per hour for a 60 kg adult?

100 ml/hour. The maintenance fluid requirement in adults is traditionally calculated using the **Holliday-Segar Rule (4-2-1 Rule)**. This is a high-yield concept for NEET-PG as it forms the basis of perioperative fluid management. ### **Explanation of the Correct Answer** According to the **4-2-1 Rule**, the hourly fluid requirement is calculated as follows: * **First 10 kg:** 4 ml/kg/hr (10 × 4 = 40 ml) * **Next 10 kg (11–20 kg):** 2 ml/kg/hr (10 × 2 = 20 ml) * **Each kg thereafter (>20 kg):** 1 ml/kg/hr **For a 60 kg adult:** * First 20 kg = 60 ml (40 + 20) * Remaining 40 kg (60 - 20) = 40 kg × 1 ml/kg/hr = 40 ml * **Total = 60 + 40 = 100 ml/hour.** Alternatively, for any adult weighing over 20 kg, a quick shortcut is: **Weight in kg + 40**. (60 + 40 = 100 ml/hr). ### **Analysis of Incorrect Options** * **B (80 ml/hour):** This would be the requirement for a 40 kg patient (40 + 40). * **C (120 ml/hour):** This would be the requirement for an 80 kg patient (80 + 40). * **D (60 ml/hour):** This only accounts for the first 20 kg of body weight and ignores the remaining 40 kg. ### **High-Yield Clinical Pearls for NEET-PG** 1. **Isotonic Crystalloids:** Balanced salt solutions (like Ringer’s Lactate or Plasmalyte) are now preferred over Normal Saline to avoid hyperchloremic metabolic acidosis. 2. **The "4-2-1 Rule" vs. "2-1-0.5 Rule":** While 4-2-1 is the standard for maintenance, some modern guidelines suggest more restrictive strategies (2-1-0.5) to prevent fluid overload in specific surgical cohorts. 3. **NPO Deficit:** To calculate the total fluid deficit, multiply the hourly maintenance rate by the number of hours the patient was NPO. This is typically replaced as 50% in the 1st hour, 25% in the 2nd, and 25% in the 3rd hour of surgery.

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

Ischemic heart disease. **Explanation:** **Ketamine** is a unique intravenous anesthetic agent that acts as a **direct myocardial depressant** but an **indirect sympathomimetic**. It inhibits the reuptake of catecholamines, leading to increased heart rate, cardiac output, and arterial blood pressure. 1. **Why Ischemic Heart Disease (IHD) is the correct answer:** The sympathomimetic effects of Ketamine significantly increase **myocardial oxygen demand**. In patients with IHD, the coronary arteries cannot meet this increased demand, potentially precipitating myocardial ischemia, infarction, or heart failure. Therefore, it is strictly contraindicated in IHD and severe hypertension. 2. **Why the other options are incorrect:** * **Bronchial Asthma:** Ketamine is the **induction agent of choice** for asthmatics because it causes bronchodilation (via catecholamine release) and preserves airway reflexes. * **Shock:** Ketamine is the **induction agent of choice in hypovolemic/hemorrhagic shock** because its pressor effects help maintain blood pressure (provided catecholamine stores are not exhausted). * **Tetralogy of Fallot (TOF):** Ketamine is preferred in cyanotic heart diseases like TOF because it increases Systemic Vascular Resistance (SVR), which reduces the right-to-left shunt and improves oxygenation. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** NMDA receptor antagonist. * **Dissociative Anesthesia:** Characterized by a "trance-like" state, eyes remaining open with a slow nystagmic gaze. * **Hallucinations:** "Emergence delirium" is a common side effect, which can be minimized by co-administering Benzodiazepines (e.g., Midazolam). * **Intracranial Pressure (ICP):** Traditionally contraindicated in head injuries as it increases ICP and Intraocular pressure (IOP). * **Secretions:** It causes significant salivation (Sialagogue effect); premedication with Glycopyrrolate is often required.

Q: Which anesthetic agent is known for providing a smooth induction?

Halothane. **Explanation:** The "smoothness" of an inhalational induction is primarily determined by the **non-irritant nature** of the gas on the airway and its **pleasant odor**. **Why Halothane is Correct:** Halothane is the classic agent of choice for smooth inhalational induction, particularly in pediatric anesthesia. It is **non-pungent**, sweet-smelling, and does not irritate the respiratory mucosa. This prevents complications like coughing, breath-holding, or laryngospasm during the induction phase. While Sevoflurane has largely replaced it in modern practice due to a faster onset (lower blood-gas solubility), Halothane remains the historically correct answer for its lack of pungency. **Analysis of Incorrect Options:** * **Diethyl ether:** Highly pungent and irritating to the airways. It causes significant secretions and a prolonged, stormy induction (Stage II of anesthesia). * **Isoflurane:** Known for its **pungency**. It is a potent airway irritant that can trigger coughing and laryngospasm, making it unsuitable for mask induction. * **Nitrous oxide:** While non-irritating, it is an incomplete anesthetic (MAC > 100%). It is used as an adjuvant to speed up induction (Second Gas Effect) but cannot provide smooth induction as a standalone agent. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for Induction:** In modern practice, **Sevoflurane** is the preferred agent for smooth induction due to low pungency and rapid onset. * **Halothane Hepatitis:** A rare but serious post-operative complication caused by the metabolite trifluoroacetylated liver proteins. * **Arrhythmogenic Potential:** Halothane sensitizes the myocardium to catecholamines, increasing the risk of arrhythmias. * **Pungent Agents (Avoid for induction):** Desflurane and Isoflurane.

Q: Which of the following inhalational agents is the most soluble in blood?

Halothane. The speed of induction and recovery from inhalational anesthesia is primarily determined by the **Blood-Gas Partition Coefficient**. This value represents the solubility of the anesthetic agent in the blood relative to the alveolar gas. ### 1. Why Halothane is Correct **Halothane** has a Blood-Gas Partition Coefficient of approximately **2.3 to 2.54**. Among the options provided, this is the highest value. High blood solubility means the agent dissolves extensively in the blood, acting as a large reservoir. This results in a slower rise in the partial pressure of the anesthetic in the alveoli and brain, leading to a **slower induction and recovery** compared to less soluble agents. ### 2. Analysis of Incorrect Options * **Enflurane (BGP ~1.8-1.9):** It is less soluble than Halothane but more soluble than Isoflurane. * **Isoflurane (BGP ~1.4):** It has intermediate solubility. While it is a commonly used maintenance agent, it is significantly less soluble than Halothane. * **Desflurane (BGP ~0.42):** This is the **least soluble** agent among the options. Low solubility allows for the fastest induction and the most rapid emergence from anesthesia. ### 3. NEET-PG High-Yield Pearls * **Solubility vs. Speed:** Solubility is **inversely proportional** to the speed of induction. (High Solubility = Slow Induction; Low Solubility = Fast Induction). * **Potency:** Potency is determined by the **MAC (Minimum Alveolar Concentration)**. Halothane has the lowest MAC (~0.75%), making it the most potent agent listed. * **Order of Solubility (Highest to Lowest):** Ether (12) > Halothane (2.4) > Enflurane (1.9) > Isoflurane (1.4) > Sevoflurane (0.65) > Nitrous Oxide (0.47) > Desflurane (0.42). * **Clinical Note:** Halothane is rarely used in modern practice due to the risk of "Halothane Hepatitis" and its tendency to sensitize the myocardium to catecholamines (arrhythmogenic).

Q: Which muscle relaxant can be safely administered in patients with renal disease?

Vecuronium. **Explanation:** The choice of muscle relaxant in renal disease depends on the drug's route of elimination. In patients with renal failure, drugs primarily excreted by the kidneys will have a prolonged duration of action and increased risk of toxicity. **Why Vecuronium is the correct answer:** Vecuronium is an intermediate-acting aminosteroid neuromuscular blocker. It is primarily metabolized by the **liver** and excreted via **bile** (approx. 40-50%), with only about 20-30% excreted unchanged in the urine. While its duration may be slightly prolonged in severe renal failure due to its active metabolite (3-desacetyl vecuronium), it is considered significantly safer than long-acting agents. *Note: While Atracurium and Cisatracurium (via Hoffman elimination) are the "gold standard" for renal failure, among the given options, Vecuronium is the safest choice.* **Analysis of Incorrect Options:** * **A. Doxacurium:** A long-acting benzylisoquinolinium that is primarily eliminated by the kidneys. It is contraindicated or used with extreme caution in renal failure. * **B. Pancuronium:** A long-acting agent where approximately 80% is excreted unchanged in the urine. It causes significant "recurarization" in renal patients. * **D. Gallamine:** This drug is **100% excreted by the kidneys**. It is absolutely contraindicated in renal failure as it will not be cleared from the body. **NEET-PG High-Yield Pearls:** * **Drug of Choice for Renal/Hepatic Failure:** **Cisatracurium** (preferred over Atracurium as it does not cause histamine release). * **Hoffman Elimination:** A non-enzymatic, pH and temperature-dependent degradation (used by Atracurium/Cisatracurium). * **Mivacurium:** Metabolized by plasma cholinesterase (like Succinylcholine). * **Rocunorium:** Primarily eliminated by the liver; useful for rapid sequence induction when Succinylcholine is contraindicated.

Question 1

If ketamine is the only agent used in reducing a dislocated shoulder, what are its actions?

Accepted Answer

Analgesia

Answer

Hypotension

Answer

Respiratory depression

Answer

Bradycardia

Question 2

Which of the following is a feature of depolarizing blockade?

Accepted Answer

Progression to dual blockade

Answer

Tetanic fade

Answer

Post-tetanic potentiation

Answer

Antagonism by anticholinesterases

Question 3

The incidence of unpleasant dreams associated with emergence from ketamine anaesthesia can be reduced by the administration of what?

Accepted Answer

Diazepam

Answer

Atropine

Answer

Scopolamine

Answer

Physostigmine

Question 4

Which of the following is NOT an action of depolarizing agents?

Accepted Answer

Hypokalemia

Answer

Bradycardia

Answer

Increased intracranial tension

Answer

Increased intraocular pressure

Question 5

What is the dose of thiopentone used for induction?

Accepted Answer

5 mg/kg

Answer

1 mg/kg

Answer

2 mg/kg

Answer

10 mg/kg

Question 6

What is the maintenance fluid requirement per hour for a 60 kg adult?

Accepted Answer

100 ml/hour

Answer

80 ml/hour

Answer

120 ml/hour

Answer

60 ml/hr

Question 7

Ketamine is contraindicated in which of the following conditions?

Accepted Answer

Ischemic heart disease

Answer

Bronchial asthma

Answer

Shock

Answer

Tetralogy of Fallot

Question 8

Which anesthetic agent is known for providing a smooth induction?

Accepted Answer

Halothane

Answer

Diethyl ether

Answer

Isoflurane

Answer

Nitrous oxide

Question 9

Which of the following inhalational agents is the most soluble in blood?

Accepted Answer

Halothane

Answer

Isoflurane

Answer

Enflurane

Answer

Desflurane

Question 10

Which muscle relaxant can be safely administered in patients with renal disease?

Accepted Answer

Vecuronium

Answer

Doxacurium

Answer

Pancuronium

Answer

Gallamine

General Anesthesia — MCQs

General Anesthesia — MCQs

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