General Anesthesia Practice Questions

Q: Which of the following is NOT true about thiopental sodium?

It is an intermediate-acting barbiturate.. **Explanation:** **1. Why Option A is the correct answer:** Thiopental sodium is an **ultra-short-acting barbiturate**, not an intermediate-acting one. Its rapid onset of action (within 30–45 seconds) and short duration of effect (5–10 minutes) are due to its high lipid solubility, which allows it to cross the blood-brain barrier quickly. The termination of its clinical effect is primarily due to **redistribution** from the brain to less vascular tissues like muscle and fat, rather than metabolism. **2. Analysis of incorrect options:** * **Option B (Cerebroprotective):** This is a true statement. Thiopental reduces the Cerebral Metabolic Rate of Oxygen consumption ($CMRO_2$) and causes cerebral vasoconstriction, which lowers Intracranial Pressure (ICP). This makes it beneficial for patients with head injuries. * **Option C (Narcoanalysis):** This is a true statement. Known as "truth serum," thiopental is used in sub-anesthetic doses to induce a state of relaxation and disinhibition, making it a classic agent for narcoanalysis. * **Option D (Porphyria):** This is a true statement. Barbiturates induce the enzyme ALA synthetase, which can precipitate a life-threatening crisis in patients with **Acute Intermittent Porphyria**. **High-Yield Clinical Pearls for NEET-PG:** * **pH:** Thiopental is highly alkaline (pH 10.5). Accidental **intra-arterial injection** causes severe vasospasm and gangrene. Treatment includes Heparin, Papaverine, and Lidocaine (to vasodilate). * **Garlic Taste:** Patients often report a metallic or garlic-like taste immediately after injection. * **Context-Sensitive Half-life:** It has a long elimination half-life; prolonged infusions lead to "saturation" of fat stores, causing delayed recovery.

Q: Which of the following statements regarding ether as an anesthetic agent is false?

It allows for rapid recovery.. **Explanation:** Diethyl ether is a historical anesthetic agent, and understanding its pharmacological profile is high-yield for NEET-PG. **Why Option D is the Correct (False) Statement:** Ether has a **high Blood-Gas Partition Coefficient (approx. 12.1)**. In anesthesia, the solubility of a gas in blood determines its speed of onset and recovery. Because ether is highly soluble in blood, it acts as a large reservoir, taking a long time to saturate the blood (slow induction) and an equally long time to be eliminated (prolonged/slow recovery). Modern agents like Sevoflurane have low solubility, allowing for the "rapid recovery" that ether lacks. **Analysis of Other Options:** * **Option A (Inflammable):** Ether is highly flammable and explosive, especially when mixed with oxygen or nitrous oxide. This is the primary reason it is no longer used in modern operating theaters where cautery is common. * **Option B (Hyperglycemia):** Ether stimulates the sympathetic nervous system, leading to catecholamine release. This triggers glycogenolysis in the liver, resulting in an increase in blood glucose levels. * **Option C (Muscle Relaxation):** Ether has a direct curare-like effect on the neuromuscular junction, providing excellent skeletal muscle relaxation, which historically made it favorable for abdominal surgeries. **High-Yield Clinical Pearls for NEET-PG:** * **Vomiting:** Ether is highly emetogenic; postoperative nausea and vomiting (PONV) are very common. * **Respiration:** It is a potent bronchodilator and irritates the airways, leading to increased secretions (often requiring atropine premedication). * **Safety:** It is considered 100% safe for the heart as it does not sensitize the myocardium to catecholamines (unlike halothane). * **Induction:** It is the classic agent used in the **Guedel’s stages of anesthesia**.

Q: Which induction agent possesses anti-emetic properties?

Propofol. **Explanation:** **Propofol** is the induction agent of choice for patients at high risk of Postoperative Nausea and Vomiting (PONV). Its **anti-emetic properties** are attributed to its ability to decrease dopamine levels in the area postrema and its antagonistic effect on 5-HT3 receptors. Even at sub-hypnotic doses (10–20 mg), it effectively suppresses nausea, making it a cornerstone of Total Intravenous Anesthesia (TIVA). **Analysis of Incorrect Options:** * **Thiopentone (A):** A barbiturate that is considered "emetic-neutral." It neither significantly causes nor prevents nausea and vomiting. * **Methohexitone (B):** Another barbiturate, often used in Electroconvulsive Therapy (ECT). Like thiopentone, it lacks specific anti-emetic properties and can occasionally trigger excitatory phenomena. * **Propanidid (C):** An older eugenol derivative (now largely obsolete). It was notorious for a high incidence of excitatory movements and did not possess anti-emetic activity. **High-Yield Clinical Pearls for NEET-PG:** * **Propofol** is also the drug of choice for **day-care surgery** due to its rapid recovery profile ("clear-headed" recovery). * **Pain on injection** is a common side effect of Propofol; this is minimized by using larger veins or pre-treatment with Lidocaine. * **Etomidate** is the induction agent of choice for patients with **cardiovascular instability**, but it is associated with a *high* incidence of PONV and adrenocortical suppression. * **Ketamine** is known to *increase* the risk of PONV and causes emergence delirium.

Q: Which of the following anesthetic agents possesses anti-pruritic properties?

Propofol. **Explanation:** **Propofol (Option B)** is the correct answer because it possesses unique **anti-pruritic** properties. While the exact mechanism is not fully elucidated, it is believed that sub-hypnotic doses of propofol (approx. 10 mg) can effectively relieve itching, particularly **opioid-induced pruritus** and pruritus associated with cholestatic liver disease. This effect is likely mediated through the suppression of the spinal cord's dorsal horn activity and interaction with the GABA-A receptors. **Analysis of Incorrect Options:** * **Thiopentone (Option A):** A barbiturate primarily known for its rapid onset and potent anticonvulsant properties. It does not possess anti-pruritic effects; in fact, like other barbiturates, it can occasionally trigger histamine release, which might worsen itching. * **Etomidate (Option C):** An imidazole derivative used for induction in hemodynamically unstable patients. Its side effect profile is dominated by myoclonus and adrenocortical suppression, with no known effect on pruritus. * **Ketamine (Option D):** A dissociative anesthetic that acts as an NMDA receptor antagonist. While it provides excellent analgesia and bronchodilation, it is not used for treating pruritus. **High-Yield Clinical Pearls for NEET-PG:** * **Propofol** is also a potent **anti-emetic** (due to its action on the chemoreceptor trigger zone and vagal nuclei). * **Drug of Choice:** Propofol is the agent of choice for Day Care Surgery due to its rapid recovery ("clear-headed" emergence). * **Contraindication:** Avoid propofol in patients with egg or soy allergies (due to the lipid emulsion vehicle). * **Ketamine** is the only induction agent that is a potent bronchodilator and increases sympathetic outflow (BP and HR).

Q: What is the final common metabolism of atracurium, mivacurium, and succinylcholine?

Hydrolysis. **Explanation:** The correct answer is **Hydrolysis**. This is because all three drugs—atracurium, mivacurium, and succinylcholine—contain **ester bonds** in their chemical structure, which are cleaved by various esterases through the addition of water (hydrolysis). * **Succinylcholine:** A depolarizing muscle relaxant rapidly hydrolyzed by **pseudocholinesterase** (butyrylcholinesterase) in the plasma. * **Mivacurium:** A short-acting non-depolarizing relaxant also primarily metabolized by **pseudocholinesterase** via hydrolysis. * **Atracurium:** Undergoes two methods of elimination: **Hofmann elimination** (spontaneous non-enzymatic degradation) and **ester hydrolysis** (catalyzed by non-specific plasma esterases). **Why other options are incorrect:** * **Conjugation & Acetylation:** These are Phase II metabolic reactions (e.g., glucuronidation or N-acetyltransferase) typically occurring in the liver for drugs like morphine or isoniazid. They do not play a primary role in the breakdown of these neuromuscular blockers. * **Reduction:** This is a Phase I reaction involving the gain of electrons, which is not the mechanism for ester-linked anesthetic agents. **High-Yield Clinical Pearls for NEET-PG:** 1. **Pseudocholinesterase Deficiency:** Patients with atypical pseudocholinesterase (prolonged dibucaine number) will experience prolonged paralysis after receiving succinylcholine or mivacurium. 2. **Organ Independent Elimination:** Atracurium and Cisatracurium are the drugs of choice in **liver or renal failure** because their metabolism (Hofmann elimination/ester hydrolysis) does not depend on these organs. 3. **Laudanosine:** A metabolite of atracurium hydrolysis which, in high concentrations, can cross the blood-brain barrier and potentially cause seizures.

Q: Which muscle relaxant is excreted exclusively by the kidney?

Gallamine. **Explanation:** The correct answer is **Gallamine**. This is a classic high-yield fact in anesthesiology regarding the elimination kinetics of neuromuscular blocking agents (NMBAs). **1. Why Gallamine is Correct:** Gallamine is a long-acting, non-depolarizing muscle relaxant that is unique because it is **excreted 100% unchanged by the kidneys**. Because it lacks any hepatic metabolism or biliary excretion, it is strictly contraindicated in patients with renal failure, as it would lead to profound, prolonged paralysis (recurarization). **2. Why the Other Options are Incorrect:** * **Atracurium:** It undergoes **Hofmann elimination** (spontaneous non-enzymatic degradation at physiological pH and temperature) and ester hydrolysis. It is the drug of choice in renal or hepatic failure. * **Cisatracurium:** An isomer of atracurium, it also undergoes **Hofmann elimination**. It is more potent and produces less histamine than atracurium. * **Succinylcholine:** A depolarizing muscle relaxant that is rapidly hydrolyzed by **pseudocholinesterase** (plasma cholinesterase) in the blood, not the kidneys. **3. Clinical Pearls for NEET-PG:** * **Pancuronium:** Primarily renal (80%), but has some biliary excretion. * **Vecuronium/Rocuronium:** Primarily eliminated via **biliary/hepatic** routes. * **Mnemonic for Renal Failure:** Avoid "Gallamine and Pancuronium" (Long-acting/Renal dependent). Use "Atracurium or Cisatracurium." * **Side Effect Note:** Gallamine is also known for causing significant **tachycardia** due to its strong vagolytic effect on the M2 receptors of the heart.

Q: Which of the following statements regarding halothane is true except?

It is contraindicated in patients with bronchial asthma.. **Explanation:** The correct answer is **D**, as Halothane is actually **indicated** (not contraindicated) in patients with bronchial asthma. **1. Why Option D is the Correct Answer (The Exception):** Halothane is a potent **bronchodilator**. It reduces airway resistance by relaxing bronchial smooth muscle and inhibiting airway reflexes. Historically, it was the agent of choice for inducing anesthesia in patients with reactive airway diseases like asthma. Therefore, stating it is contraindicated in asthma is medically incorrect. **2. Analysis of Other Options:** * **Option A (True):** Halothane is a potent cerebral vasodilator. This increases cerebral blood flow (CBF) and, consequently, **intracranial pressure (ICP)**. Therefore, it is generally avoided or used with extreme caution in patients with space-occupying intracranial lesions. * **Option B (True):** Halothane causes dose-dependent **hypotension**. This occurs primarily through direct myocardial depression (decreased cardiac output) rather than peripheral vasodilation. * **Option C (True):** Halothane has a pleasant, non-pungent odor and does not irritate the airways. This allows for a **smooth and rapid inhalation induction**, making it a classic choice for pediatric anesthesia (though largely replaced by Sevoflurane in modern practice). **NEET-PG High-Yield Pearls:** * **Halothane Hepatitis:** A rare but serious immune-mediated hepatotoxicity (more common in obese females after multiple exposures). * **Catecholamine Sensitivity:** Halothane sensitizes the myocardium to endogenous and exogenous catecholamines, increasing the risk of **ventricular arrhythmias** (especially if adrenaline is used). * **Malignant Hyperthermia:** Like all volatile anesthetics, Halothane is a known trigger. * **Blood-Gas Partition Coefficient:** 2.3 (higher than Sevoflurane/Desflurane, leading to slower recovery).

Q: All of the following factors decrease the Minimum Alveolar Concentration (MAC) of an inhalation anesthetic agent except?

Hypocalcemia. **Explanation:** Minimum Alveolar Concentration (MAC) is the concentration of an inhalation anesthetic at 1 atmosphere that prevents skeletal muscle movement in response to a noxious stimulus in 50% of patients. It is an index of anesthetic potency: the lower the MAC, the more potent the agent. **Why Hypocalcemia is the Correct Answer:** Serum electrolyte levels generally have a predictable effect on MAC, but **Hypocalcemia** (and Hypercalcemia) has **no significant effect** on MAC. While calcium is vital for neurotransmitter release, clinical variations in calcium levels do not alter the requirement for volatile anesthetics. **Analysis of Incorrect Options (Factors that DO decrease MAC):** * **Hypothermia:** MAC decreases by approximately 2–5% for every 1°C drop in body temperature. Lower temperatures reduce cerebral metabolic rate and increase the solubility of the gas in the blood. * **Hyponatremia:** Low sodium levels in the extracellular fluid lead to decreased neuronal excitability and increased sedation, thereby reducing the anesthetic requirement. (Conversely, Hypernatremia increases MAC). * **Anemia:** Severe anemia (Hemoglobin < 5 g/dL) decreases MAC because it reduces the oxygen-carrying capacity, leading to a degree of cerebral hypoxia which potentiates anesthesia. **High-Yield Clinical Pearls for NEET-PG:** * **Factors Increasing MAC:** Hyperthermia, Hypernatremia, Chronic alcoholism, and drugs that increase central neurotransmitters (MAO inhibitors, Cocaine, Ephedrine, Levodopa). * **Factors Decreasing MAC:** Pregnancy (due to progesterone), Acute alcohol intoxication, Old age, Hypoxia ($PaO_2 < 38$ mmHg), and Hypotension (MAP $< 40$ mmHg). * **Factors with NO effect on MAC:** Gender, Duration of anesthesia, Thyroid status (unless severe/myxedema), and Hyper/Hypokalemia.

Question 1

Which of the following is NOT true about thiopental sodium?

Accepted Answer

It is an intermediate-acting barbiturate.

Answer

It is cerebroprotective.

Answer

It is an agent of choice for narcoanalysis.

Answer

It is contraindicated in acute intermittent porphyria.

Question 2

Thiopentone is contraindicated in all except?

Accepted Answer

Porphyria cutanea tarda

Answer

Status asthmaticus

Answer

Shock

Answer

Acute intermittent porphyria

Question 3

Which of the following statements regarding ether as an anesthetic agent is false?

Accepted Answer

It allows for rapid recovery.

Answer

It is highly inflammable.

Answer

It can cause hyperglycemia.

Answer

It provides good muscle relaxation.

Question 4

Which induction agent possesses anti-emetic properties?

Accepted Answer

Propofol

Answer

Thiopentone

Answer

Methohexitone

Answer

Propanidid

Question 5

Which of the following anesthetic agents possesses anti-pruritic properties?

Accepted Answer

Propofol

Answer

Thiopentone

Answer

Etomidate

Answer

Ketamine

Question 6

What is the final common metabolism of atracurium, mivacurium, and succinylcholine?

Accepted Answer

Hydrolysis

Answer

Conjugation

Answer

Reduction

Answer

Acetylation

Question 7

Ketamine should be avoided in which of the following conditions?

Accepted Answer

The presence of increased intracranial pressure

Answer

Pregnancy

Answer

Hypovolemic shock

Answer

Asthma

Question 8

Which muscle relaxant is excreted exclusively by the kidney?

Accepted Answer

Gallamine

Answer

Atracurium

Answer

Cisatracurium

Answer

Succinylcholine

Question 9

Which of the following statements regarding halothane is true except?

Accepted Answer

It is contraindicated in patients with bronchial asthma.

Answer

It is contraindicated in patients with intracranial lesions.

Answer

It can cause hypotension.

Answer

It allows smooth and rapid loss of unconsciousness.

Question 10

All of the following factors decrease the Minimum Alveolar Concentration (MAC) of an inhalation anesthetic agent except?

Accepted Answer

Hypocalcemia

Answer

Hypothermia

Answer

Hyponatremia

Answer

Anemia

General Anesthesia — MCQs

General Anesthesia — MCQs

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