General Anesthesia Practice Questions

Q: What is the recommended initial dose of propofol for induction of anesthesia in adults?

2 mg/kg. **Explanation:** Propofol (2,6-diisopropylphenol) is the most commonly used intravenous induction agent due to its rapid onset and smooth recovery profile. **Why Option B is Correct:** The standard recommended induction dose for a healthy adult (ASA I or II) is **1.5 to 2.5 mg/kg** (commonly simplified to **2 mg/kg** in exams). This dose is calculated based on lean body mass. It provides rapid loss of consciousness (within 30–40 seconds) by enhancing GABAergic neurotransmission in the CNS. **Why Other Options are Incorrect:** * **Option A (1 mg/kg):** This dose is generally insufficient for induction in healthy adults but is the preferred range for **elderly patients** (over 65) or those with hemodynamic instability (ASA III/IV), as they have reduced volume of distribution and slower clearance. * **Option C (3 mg/kg):** This is higher than the standard adult dose. However, it is the typical induction dose for **children**, who require higher doses per kg due to a larger volume of distribution and higher metabolic rate. * **Option D (5 mg/kg):** This dose is excessive and would likely lead to profound hypotension and prolonged apnea. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Acts on **GABA-A** receptors (increases chloride conductance). * **Metabolism:** Primarily hepatic; however, **extrahepatic metabolism** (lungs) accounts for its rapid clearance, making it ideal for TIVA (Total Intravenous Anesthesia). * **Side Effects:** Causes significant **hypotension** (decreases SVR) and is the most common induction agent to cause **pain on injection**. * **Unique Properties:** It possesses **anti-emetic** properties (at sub-hypnotic doses of 10–20 mg) and is the drug of choice for day-care surgeries. * **Contraindication:** Known hypersensitivity to egg or soy (though controversial in newer formulations).

Q: All of the following are true about fospropofol EXCEPT:

It causes pain on injection, similar to propofol.. **Explanation:** Fospropofol is a water-soluble **prodrug** of propofol, developed to overcome the limitations of the lipid emulsion formulation of propofol. **1. Why Option D is the Correct Answer (The False Statement):** Unlike propofol, which is highly lipid-soluble and formulated in an emulsion that causes significant **pain on injection**, fospropofol is **water-soluble**. Because it does not require a lipid vehicle and is inactive until metabolized, it **does not cause pain at the injection site**. This is one of its primary clinical advantages. Instead of injection pain, patients often experience transient **paresthesia or pruritus** (commonly in the perineal region). **2. Analysis of Other Options:** * **Option A:** Fospropofol is indeed a water-soluble phosphate ester. It is metabolized by the enzyme **alkaline phosphatase** in the blood and liver into propofol, phosphate, and formaldehyde. * **Option B:** Because it is a prodrug requiring enzymatic conversion, its **onset of action is significantly slower** (approx. 4–8 minutes) compared to propofol (approx. 30–60 seconds). * **Option C:** The conversion process and larger volume of distribution lead to a **slower recovery/offset** compared to the rapid emergence seen with propofol. **Clinical Pearls for NEET-PG:** * **Metabolism:** 1 mg of fospropofol yields 0.54 mg of propofol. * **Indication:** Primarily used for **monitored anesthesia care (MAC)** or sedation during diagnostic procedures (e.g., colonoscopy). * **Side Effects:** Perineal pruritus is a classic "buzzword" side effect associated with fospropofol. * **Advantage:** No risk of lipid-related complications like hypertriglyceridemia or Propofol Infusion Syndrome (PRIS).

Q: Which of the following statements is true about ether as an anesthetic agent?

Slow induction. **Explanation:** The correct answer is **Slow induction**. This is primarily due to the **high blood-gas solubility coefficient** of diethyl ether (approximately 12). In anesthesia, the speed of induction is inversely proportional to an agent's solubility in blood. Because ether is highly soluble, the blood acts as a large reservoir, taking a long time to become saturated before the partial pressure in the brain can rise sufficiently to produce anesthesia. **Analysis of Options:** * **A. Used with a muscle relaxant:** This is incorrect. Ether has significant **curare-like neuromuscular blocking properties**. It provides excellent muscle relaxation on its own, often making the addition of neuromuscular blockers unnecessary for most abdominal surgeries. * **C. High risk of cardiac arrhythmia:** This is incorrect. Unlike halothane, ether does not sensitize the myocardium to catecholamines. It stimulates the sympathetic nervous system, which helps maintain heart rate and blood pressure, making it relatively **cardio-stable**. * **D. Recovery is faster:** This is incorrect. Due to its high blood-gas solubility, ether remains in the body tissues for a prolonged period. This results in a **slow, prolonged recovery** often associated with a high incidence of post-operative nausea and vomiting (PONV). **High-Yield Clinical Pearls for NEET-PG:** * **Safety Margin:** Ether has a wide therapeutic index, making it one of the safest agents in terms of respiratory and cardiovascular collapse. * **Explosive Property:** Its use has been largely abandoned in modern practice because it is **highly inflammable and explosive** when mixed with air or oxygen. * **Irritant:** It is a potent irritant to the respiratory mucosa, leading to increased secretions and laryngospasm if induction is not managed carefully.

Q: What is the ideal inhalational inducing agent of choice?

Sevoflurane. **Explanation:** The ideal inhalational inducing agent must be non-irritating to the airways and have a rapid onset of action. **Sevoflurane** is the agent of choice for inhalational induction because it possesses a **low blood-gas partition coefficient (0.65)**, ensuring rapid induction and recovery, and is **non-pungent**. Unlike other agents, it does not cause coughing, breath-holding, or laryngospasm, making it particularly ideal for pediatric anesthesia where intravenous access may be difficult to establish initially. **Analysis of Incorrect Options:** * **Halothane (A):** Historically used for induction due to its pleasant odor, it is no longer the "ideal" choice because of its slow onset (higher blood-gas solubility), potential for "Halothane Hepatitis," and its tendency to sensitize the myocardium to catecholamines, leading to arrhythmias. * **Desflurane (B):** Although it has the fastest onset/offset (lowest blood-gas solubility of 0.42), it is **highly pungent** and an airway irritant. It causes coughing and tachycardia, making it unsuitable for induction. * **Isoflurane (D):** Like Desflurane, Isoflurane is pungent and can trigger airway reflexes. It is primarily used for maintenance rather than induction. **High-Yield Clinical Pearls for NEET-PG:** * **Agent of choice for Day Care Surgery:** Sevoflurane or Desflurane (due to rapid recovery). * **Soda Lime Reaction:** Sevoflurane reacts with soda lime to produce **Compound A** (nephrotoxic in rats, though clinical significance in humans is debated). * **Induction Speed:** Inversely proportional to the Blood-Gas Partition Coefficient. * **Potency:** Directly proportional to Lipid Solubility (Meyer-Overton Hypothesis) and inversely proportional to MAC (Minimum Alveolar Concentration).

Q: Which of the following is a contraindication for halothane use?

Recent halothane use. **Explanation:** The correct answer is **Recent halothane use**. Halothane is a potent volatile anesthetic agent that is metabolized in the liver (up to 20%) by the cytochrome P450 system. This metabolism can lead to the formation of trifluoroacetylated liver proteins, which may trigger an immune-mediated response known as **Halothane Hepatitis**. 1. **Why "Recent halothane use" is correct:** Repeated exposure to halothane within a short period (typically less than 3–6 months) significantly increases the risk of halothane-induced liver injury. The sensitization of the immune system during the first exposure leads to a more severe, potentially fatal hepatic necrosis upon re-exposure. Therefore, a history of halothane use in the preceding months is a major contraindication. 2. **Why other options are incorrect:** * **Male sex:** Halothane hepatitis actually shows a higher predilection for **females** (2:1 ratio). Being male is not a contraindication. * **Middle age:** While halothane hepatitis is more common in adults (especially obese middle-aged women), halothane is historically the agent of choice for pediatric induction due to its non-pungent odor. Age itself is not a contraindication, though risk profiles vary. **NEET-PG High-Yield Pearls:** * **Metabolism:** Halothane is the most metabolized volatile anesthetic (20%), whereas Desflurane is the least (0.02%). * **Halothane Shiver:** Occurs during recovery due to its effect on the hypothalamus. * **Catecholamine Sensitization:** Halothane sensitizes the myocardium to epinephrine, increasing the risk of ventricular arrhythmias. * **Malignant Hyperthermia:** Like all volatile anesthetics, halothane is a known trigger.

Q: Which of the following inhalational agents potentiates neuromuscular blockers the most?

Desflurane. ### Explanation **Concept:** All volatile inhalational anesthetics potentiate the action of non-depolarizing neuromuscular blocking agents (NDMRs) by decreasing the sensitivity of the post-junctional membrane to acetylcholine and increasing skeletal muscle blood flow. The degree of potentiation is directly proportional to the **lipid solubility** and the **MAC (Minimum Alveolar Concentration) hours** of the agent used. **Why Desflurane is Correct:** The order of potentiation of neuromuscular blockade by inhalational agents is: **Desflurane > Sevoflurane > Isoflurane > Halothane > Nitrous Oxide.** Desflurane provides the greatest enhancement of NDMRs, allowing for a significant reduction (up to 30-50%) in the required dose of the muscle relaxant to achieve the same level of surgical blockade. **Analysis of Incorrect Options:** * **A. Halothane:** It has the least potentiating effect among the volatile liquids. It is a potent bronchodilator but has minimal effect on the neuromuscular junction compared to ethers. * **B. Isoflurane:** While it potentiates NDMRs significantly more than halothane, it is less potent in this regard than the newer fluorinated ethers like Sevoflurane and Desflurane. * **C. Sevoflurane:** It significantly potentiates NDMRs (more than Isoflurane), but clinical studies consistently rank Desflurane as the most potent enhancer of the bunch. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Potentiation occurs via central effect on alpha-motor neurons and peripheral effect at the nicotinic ACh receptors. * **Dose Reduction:** When using Desflurane, the dose of vecuronium or rocuronium should be reduced to prevent prolonged recovery. * **Exception:** Nitrous Oxide (N₂O) does **not** significantly potentiate neuromuscular blockers. * **Mnemonic:** Remember **"D-S-I-H"** (Des > Sevo > Iso > Halo) for the decreasing order of muscle relaxant potentiation.

Q: Which of the following is NOT a direct effect of a neuromuscular blocker?

Muscle relaxation. **Explanation:** The core principle of balanced anesthesia involves three distinct components: **Amnesia** (loss of memory), **Analgesia** (loss of pain), and **Muscle Relaxation**. **Why "Muscle Relaxation" is the correct answer:** The question asks for the **direct** effect of a neuromuscular blocker (NMB). NMBs (like Succinylcholine or Vecuronium) act specifically at the nicotinic acetylcholine receptors at the neuromuscular junction to inhibit skeletal muscle contraction. Therefore, muscle relaxation is the primary, direct intended effect of these drugs. **Analysis of Incorrect Options:** * **Amnesia & D. Narcosis:** NMBs are quaternary ammonium compounds; they are highly ionized and lipid-insoluble. Consequently, they **do not cross the blood-brain barrier**. They have no effect on the Central Nervous System (CNS) and provide zero sedation, hypnosis, or forgetfulness. A patient given only an NMB would be paralyzed but fully awake and aware. * **Analgesia:** NMBs do not possess any pain-relieving properties. They do not act on opioid receptors or nociceptive pathways. **NEET-PG High-Yield Pearls:** * **The "Awareness" Danger:** Administering an NMB without adequate induction agents (like Propofol) or inhalational anesthetics leads to "accidental awareness under general anesthesia," a traumatic clinical scenario. * **Monitoring:** The effect of NMBs is monitored clinically using a **Train-of-Four (TOF)** stimulator. * **Reversal:** Non-depolarizing NMBs are reversed using Acetylcholinesterase inhibitors (Neostigmine) or selective relaxant binding agents (Sugammadex). * **Order of Blockade:** Small, rapidly moving muscles (eyes, fingers) are paralyzed first, followed by limbs, and finally the **diaphragm** (which is also the first to recover).

Question 1

What is the recommended initial dose of propofol for induction of anesthesia in adults?

Accepted Answer

2 mg/kg

Answer

1 mg/kg

Answer

3 mg/kg

Answer

5 mg/kg

Question 2

Which inhaled anesthetic has the least diffusion coefficient?

Accepted Answer

Nitrous Oxide (N2O)

Answer

Isoflurane

Answer

Enflurane

Answer

Halothane

Question 3

All of the following are true about fospropofol EXCEPT:

Accepted Answer

It causes pain on injection, similar to propofol.

Answer

It is a water-soluble product that is metabolized in vivo to propofol.

Answer

It has a slower onset than propofol.

Answer

It has slower recovery than propofol.

Question 4

Which of the following statements is true about ether as an anesthetic agent?

Accepted Answer

Slow induction

Answer

Used with a muscle relaxant

Answer

High risk of cardiac arrhythmia

Answer

Recovery is faster

Question 5

What is the ideal inhalational inducing agent of choice?

Accepted Answer

Sevoflurane

Answer

Halothane

Answer

Desflurane

Answer

Isoflurane

Question 6

Which of the following is a contraindication for halothane use?

Accepted Answer

Recent halothane use

Answer

Male sex

Answer

Middle age

Answer

All of the above

Question 7

Regarding isoflurane, all of the following are true except?

Accepted Answer

It is implicated in causing seizures.

Answer

It is a respiratory depressant.

Answer

It causes tachycardia.

Answer

It is metabolized to inorganic fluoride ions.

Question 8

Minimum alveolar concentration of an inhaled anesthetic is a marker of:

Accepted Answer

Potency

Answer

Efficacy

Answer

Elimination

Answer

Distribution

Question 9

Which of the following inhalational agents potentiates neuromuscular blockers the most?

Accepted Answer

Desflurane

Answer

Halothane

Answer

Isoflurane

Answer

Sevoflurane

Question 10

Which of the following is NOT a direct effect of a neuromuscular blocker?

Accepted Answer

Muscle relaxation

Answer

Amnesia

Answer

Analgesia

Answer

Narcosis

General Anesthesia — MCQs

General Anesthesia — MCQs

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