General Anesthesia Practice Questions

Q: An asthmatic patient is posted for elective hernia repair. Which of the following inhalational anesthetic agents is preferred for induction?

Sevoflurane. **Explanation:** The primary goal in the anesthetic management of an asthmatic patient is to avoid airway irritation and bronchospasm. **Sevoflurane** is the preferred inhalational agent for induction in these patients due to its unique pharmacological profile. **Why Sevoflurane is Correct:** 1. **Bronchodilation:** Sevoflurane is a potent bronchodilator, which helps counteract airway hyper-reactivity. 2. **Non-pungency:** It has a pleasant odor and is non-irritating to the respiratory mucosa. This allows for a smooth "gas induction" without triggering coughing, breath-holding, or laryngospasm, which are common precursors to bronchospasm in asthmatics. **Analysis of Incorrect Options:** * **Desflurane:** It is highly pungent and a known airway irritant. It can trigger coughing and increase airway resistance, making it contraindicated for inhalation induction in patients with reactive airway disease. * **Isoflurane:** While it has bronchodilatory properties, it is moderately pungent. It is generally avoided for induction because it can cause airway irritation, though it is safe for maintenance of anesthesia. * **Enflurane:** It is less commonly used today and is more irritating to the airway compared to Sevoflurane. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for Induction (Asthma):** Sevoflurane (Inhalational) or Propofol (Intravenous). * **Ketamine:** The preferred IV induction agent in hemodynamically unstable asthmatics due to its sympathomimetic, bronchodilatory effects. * **Avoid:** Thiopentone (can cause histamine release) and Desflurane (airway irritant). * **Pre-medication:** Anticholinergics (like Glycopyrrolate) can be used to reduce secretions and provide mild bronchodilation.

Q: What is the recommended dose of thiopentone to prevent arterial spasm following intra-arterial injection?

2.5%. Thiopentone sodium is an ultra-short-acting barbiturate used for the induction of anesthesia. The standard clinical concentration used is **2.5%**. ### **Why 2.5% is the Correct Answer** Accidental intra-arterial injection of thiopentone is a medical emergency. Thiopentone is highly alkaline (pH 10.5). When injected into an artery, it reacts with blood to form **crystals**, which cause intense chemical endarteritis, severe vasospasm, and subsequent thrombosis. * **The 2.5% concentration** is the maximum recommended clinical concentration because it is less likely to cause permanent tissue damage or gangrene compared to higher concentrations. It is isotonic and less irritating to the vessel wall. ### **Analysis of Incorrect Options** * **Option A (5%):** Historically, 5% thiopentone was used, but it was abandoned because it is highly hypertonic and significantly increases the risk of severe arterial spasm, thrombosis, and limb gangrene if accidentally injected intra-arterially. * **Options C & D (2% and 1.5%):** While lower concentrations are safer, they are not the standard clinical preparation for thiopentone induction. 2.5% is the established "gold standard" concentration that balances efficacy with safety. ### **High-Yield Clinical Pearls for NEET-PG** * **Management of Intra-arterial Thiopentone:** 1. **Leave the needle in situ** to administer drugs. 2. Inject **Vasodilators** (e.g., Papaverine, Procaine, or Lidocaine) to relieve spasm. 3. Perform a **Stellate Ganglion Block** or Brachial Plexus block to cause sympathetic washout and vasodilation. 4. **Heparinization** to prevent thrombosis. * **Storage:** Thiopentone is stored under **Nitrogen** to prevent reaction with atmospheric CO₂ (which would lower the pH and cause the drug to precipitate). * **Contraindication:** Absolute contraindication in **Porphyria** (induces ALA synthetase).

Q: Which of the following is NOT a side effect of succinylcholine?

Tachycardia. **Explanation:** Succinylcholine is a depolarizing neuromuscular blocker that acts as an agonist at the nicotinic acetylcholine receptors (nAChR) at the motor endplate. **Why Tachycardia is the correct answer:** Succinylcholine typically causes **bradycardia**, not tachycardia. This occurs because succinylcholine is structurally two molecules of acetylcholine joined together; it stimulates muscarinic receptors in the sinus node of the heart. This effect is particularly pronounced in children and after a second dose in adults. **Analysis of Incorrect Options:** * **Hyperkalemia:** During prolonged depolarization, potassium ions leak out of the muscle cells into the extracellular fluid. A typical dose increases serum potassium by 0.5 mEq/L, which can be life-threatening in patients with burns, crush injuries, or denervation. * **Increased Intracranial Pressure (ICP):** Succinylcholine causes a transient rise in ICP, likely due to increased muscle afferent activity and cerebral blood flow. This requires caution in patients with head injuries. * **Increased Intragastric Pressure:** Fasciculations of the abdominal wall muscles lead to an increase in intragastric pressure. However, it also increases lower esophageal sphincter tone, usually preventing aspiration. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Still preferred for **Rapid Sequence Induction (RSI)** due to its rapid onset (30–60s) and short duration (5–10 mins). * **Metabolism:** Metabolized by **Pseudocholinesterase** (Plasma cholinesterase). * **Malignant Hyperthermia:** Succinylcholine is a known triggering agent. * **Masseter Spasm:** An early warning sign of Malignant Hyperthermia. * **Dual Block (Phase II Block):** Occurs with high doses or continuous infusion, where the block takes on characteristics of a non-depolarizing block.

Q: Which of the following volatile anesthetic agents are pungent?

Sevoflurane. ### Explanation The pungency of a volatile anesthetic agent refers to its tendency to irritate the airway, which can trigger coughing, breath-holding, or laryngospasm during induction. **Why Sevoflurane is the Correct Answer (in the context of non-pungency):** *Note: There appears to be a discrepancy in the provided key. In clinical practice and standard textbooks (Miller, Morgan & Mikhail), **Sevoflurane is non-pungent** and sweet-smelling. This makes it the gold standard for **inhalational induction**, especially in pediatric patients.* **Analysis of Options:** * **Desflurane & Isoflurane:** These are highly **pungent** agents. They cause significant airway irritation and are generally avoided for mask induction as they can trigger coughing and laryngospasm. Desflurane is the most pungent of all. * **Halothane:** This is a **non-pungent**, sweet-smelling agent. Historically, it was the preferred agent for smooth inhalational induction before Sevoflurane became widely available. * **Sevoflurane:** This is **non-pungent**. It is the agent of choice for smooth induction due to its pleasant odor and lack of airway irritation. **NEET-PG High-Yield Pearls:** 1. **Agent of Choice for Induction:** Sevoflurane (due to non-pungency and rapid onset). 2. **Most Pungent Agent:** Desflurane (causes most airway irritation). 3. **Blood-Gas Partition Coefficient:** Desflurane (0.42) < Sevoflurane (0.65) < Isoflurane (1.4) < Halothane (2.4). Lower coefficient means faster induction/recovery. 4. **Soda Lime Reaction:** Sevoflurane can react with dry soda lime to produce **Compound A** (nephrotoxic in rats), while Desflurane/Isoflurane can produce **Carbon Monoxide**.

Q: Lactated Ringer's solution (Hartmann's solution) contains all of the following electrolytes in approximately the same proportion as human extracellular fluid EXCEPT?

Bicarbonate. **Explanation:** Lactated Ringer’s (LR) is a balanced salt solution designed to mimic the electrolyte composition of human extracellular fluid (ECF). However, it differs significantly in its buffer system. **Why Bicarbonate is the correct answer:** LR does **not** contain bicarbonate. Instead, it contains **Sodium Lactate** (28 mEq/L). Bicarbonate is unstable in plastic bags and can cause calcium precipitation. Once infused, the liver metabolizes lactate into bicarbonate, providing a buffering effect. Therefore, while LR is "physiologically balanced," it does not contain bicarbonate in its pre-infused state. **Analysis of Incorrect Options:** * **Sodium (130 mEq/L):** This is close to the ECF concentration (135–145 mEq/L). While slightly hyponatremic, it is the primary cation in both. * **Potassium (4 mEq/L):** This is nearly identical to the normal ECF range (3.5–5.0 mEq/L), making LR safer than Normal Saline for maintaining potassium balance. * **Chloride (109 mEq/L):** This is very close to the ECF range (98–107 mEq/L). In contrast, 0.9% Normal Saline has 154 mEq/L of Chloride, which can lead to hyperchloremic metabolic acidosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Composition of LR:** Na⁺ (130), Cl⁻ (109), K⁺ (4), Ca²⁺ (3), and Lactate (28). 2. **Osmolarity:** LR is slightly hypotonic (273 mOsm/L) compared to plasma (285–295 mOsm/L). 3. **Contraindication:** LR should not be used as a diluent for **blood transfusions** because the Calcium in LR can bind to the Citrate anticoagulant in blood bags, leading to clot formation. 4. **Metabolic Effect:** Large volumes of LR can lead to **iatrogenic metabolic alkalosis** due to the conversion of lactate to bicarbonate.

Q: Which of the following is true regarding Remifentanil?

All of these. **Explanation:** Remifentanil is a unique, ultra-short-acting synthetic $\mu$-opioid receptor agonist. Its pharmacological profile makes it a high-yield topic for NEET-PG. * **Metabolism (Option B):** Unlike other opioids metabolized by the liver, Remifentanil contains an **ester linkage**. This allows it to be rapidly broken down by **non-specific plasma and tissue esterases**. This metabolism is independent of renal or hepatic function, leading to a predictable, ultra-short duration of action. * **Clinical Use (Option A):** Because of its rapid onset and offset (context-sensitive half-life of ~3–4 minutes), it is ideal for **short, painful procedures** (e.g., retrobulbar blocks, brief endoscopies) and for providing intense intraoperative analgesia via continuous infusion without the risk of drug accumulation. * **Potency (Option C):** Remifentanil is roughly **equipotent to Fentanyl** (both are approximately 100 times more potent than morphine). **Why "All of these" is correct:** Remifentanil satisfies all three criteria: it is highly potent (equipotent to fentanyl), uniquely metabolized by esterases, and specifically indicated for short procedures where rapid recovery is desired. **High-Yield Clinical Pearls for NEET-PG:** 1. **Context-Sensitive Half-life:** It is the only opioid whose context-sensitive half-life remains constant (approx. 3-4 mins) regardless of the duration of infusion. 2. **Opioid-Induced Hyperalgesia:** Rapid offset can lead to "acute opioid tolerance" or hyperalgesia; therefore, longer-acting analgesics must be administered before stopping the infusion. 3. **Side Effects:** Can cause significant bradycardia and chest wall rigidity if administered too rapidly.

Q: What is the clinically relevant dose of neuromuscular blocker required for clinically useful relaxation?

ED95. **Explanation:** In clinical anesthesiology, the potency of a neuromuscular blocking agent (NMBA) is defined by its **ED95**. This represents the dose required to produce a **95% suppression of the twitch height** (usually measured at the adductor pollicis muscle via ulnar nerve stimulation). **Why ED95 is the Correct Answer:** For effective surgical relaxation and to facilitate endotracheal intubation, a near-complete blockade of the neuromuscular junction is required. A 95% reduction in twitch height correlates with clinically useful muscle relaxation. In practice, the "intubating dose" is typically calculated as **2 × ED95**, which ensures rapid onset and excellent intubating conditions for nearly all patients. **Analysis of Incorrect Options:** * **ED50:** This is the dose that produces 50% twitch suppression. While it is a standard pharmacological measure of median potency, it provides insufficient relaxation for surgery or intubation. * **ED75 & ED25:** These doses represent 75% and 25% suppression, respectively. They are occasionally used in dose-response studies but have no practical utility for achieving the profound relaxation required in the operating theater. **High-Yield Clinical Pearls for NEET-PG:** * **Potency vs. Onset:** There is an inverse relationship between potency and onset time. Low-potency drugs (like Succinylcholine or Rocuronium) have a faster onset because more molecules are available to saturate the receptors quickly. * **Monitoring:** Clinical recovery is defined as a **Train-of-Four (TOF) ratio > 0.9**. * **Diaphragm vs. Adductor Pollicis:** The diaphragm is more resistant to NMBAs than peripheral muscles; therefore, an ED95 at the thumb does not guarantee complete diaphragmatic paralysis.

Q: Which of the following anesthetic agents is known to cause dissociative anesthesia?

Ketamine. **Explanation:** **Ketamine** is the correct answer because it is the classic agent used to induce **dissociative anesthesia**. This unique state is characterized by profound analgesia, amnesia, and a "trance-like" state where the patient appears awake (eyes may remain open with a slow nystagmic gaze) but is disconnected from the environment and sensory input. * **Mechanism:** Ketamine acts primarily as a non-competitive antagonist at the **NMDA (N-methyl-D-aspartate) receptors**. It causes functional dissociation between the thalamocortical and limbic systems. **Why other options are incorrect:** * **Thiopentone:** An ultra-short-acting barbiturate used for induction. It causes generalized CNS depression (GABA-A agonist) rather than dissociation. * **Suxamethonium (Succinylcholine):** A depolarizing neuromuscular blocker used for muscle relaxation/intubation. It has no anesthetic or analgesic properties. * **Diazepam:** A benzodiazepine used for sedation and anxiolysis. While it causes amnesia, it does not produce the specific state of dissociative anesthesia. **High-Yield Clinical Pearls for NEET-PG:** * **Hemodynamics:** Unlike most induction agents, Ketamine is **sympathomimetic** (increases HR, BP, and CO), making it the drug of choice for **hypovolemic shock**. * **Airway:** It preserves laryngeal reflexes and causes bronchodilation (drug of choice for **status asthmaticus**). * **Side Effects:** Known for causing **emergence delirium** (hallucinations), which can be pre-treated with benzodiazepines (e.g., Midazolam). * **Contraindications:** Avoid in patients with increased intracranial pressure (ICP) or intraocular pressure (IOP).

Q: Hallucination is a major side effect of which of the following agents?

Ketamine. **Explanation:** The correct answer is **Ketamine**. **Why Ketamine is correct:** Ketamine is a phencyclidine derivative that acts primarily as an **NMDA receptor antagonist**. It produces a state known as **"Dissociative Anesthesia,"** where the patient appears awake but is detached from their environment. The most characteristic side effect of Ketamine is **Emergence Delirium**, which includes vivid dreams, illusions, and **hallucinations** during recovery. These psychotomimetic effects occur because Ketamine depresses the thalamocortical system while stimulating the limbic system. These effects can be mitigated by pre-medicating the patient with benzodiazepines (e.g., Midazolam). **Why other options are incorrect:** * **Nitrous Oxide:** Known as "laughing gas," it primarily causes euphoria and mild analgesia. While it can cause diffusion hypoxia, it is not typically associated with clinical hallucinations. * **Fentanyl:** An opioid analgesic. Its major side effects include respiratory depression, miosis, and chest wall rigidity ("wooden chest syndrome"), but not hallucinations. * **Chloroform:** An obsolete anesthetic agent primarily known for its hepatotoxicity and arrhythmogenic potential (sensitizing the myocardium to catecholamines). **High-Yield Clinical Pearls for NEET-PG:** * **Ketamine** is the only intravenous anesthetic that is a **potent analgesic** and a **potent bronchodilator** (drug of choice for asthma). * It is the induction agent of choice in **hypovolemic shock** because it stimulates the sympathetic nervous system (increases HR and BP). * **Contraindications:** It increases Intraocular Pressure (IOP) and Intracranial Pressure (ICP); therefore, it is avoided in head injuries and glaucoma.

Question 1

An asthmatic patient is posted for elective hernia repair. Which of the following inhalational anesthetic agents is preferred for induction?

Accepted Answer

Sevoflurane

Answer

Isoflurane

Answer

Desflurane

Answer

Enflurane

Question 2

What is the recommended dose of thiopentone to prevent arterial spasm following intra-arterial injection?

Accepted Answer

2.5%

Answer

5%

Answer

2%

Answer

1.5%

Question 3

Which of the following is NOT a side effect of succinylcholine?

Accepted Answer

Tachycardia

Answer

Hyperkalemia

Answer

Increased intracranial pressure

Answer

Increased intragastric pressure

Question 4

Which of the following volatile anesthetic agents are pungent?

Accepted Answer

Sevoflurane

Answer

Halothane

Answer

Isoflurane

Answer

Desflurane

Question 5

Lactated Ringer's solution (Hartmann's solution) contains all of the following electrolytes in approximately the same proportion as human extracellular fluid EXCEPT?

Accepted Answer

Bicarbonate

Answer

Chloride

Answer

Potassium

Answer

Sodium

Question 6

Which of the following is true regarding Remifentanil?

Accepted Answer

All of these

Answer

Useful for short painful procedures

Answer

Metabolized by plasma esterases

Answer

Equipotent as fentanyl

Question 7

What is the clinically relevant dose of neuromuscular blocker required for clinically useful relaxation?

Accepted Answer

ED95

Answer

ED50

Answer

ED75

Answer

ED25

Question 8

Which of the following anesthetic agents is known to cause dissociative anesthesia?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Suxamethonium

Answer

Diazepam

Question 9

Hallucination is a major side effect of which of the following agents?

Accepted Answer

Ketamine

Answer

Nitrous oxide

Answer

Fentanyl

Answer

Chloroform

Question 10

Administration of scoline (Sch) produces dangerous hyperkalemia in which of the following conditions?

Accepted Answer

Paraplegia

Answer

Acute renal failure (ARF)

Answer

Raised intracranial tension (ICT)

Answer

Fracture of femur

General Anesthesia — MCQs

General Anesthesia — MCQs

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