General Anesthesia Practice Questions

Q: Which muscles are the first to recover after administration of muscle relaxants?

Diaphragm. **Explanation:** The sensitivity of muscles to neuromuscular blocking agents (NMBAs) follows a predictable pattern based on muscle fiber type, blood flow, and the density of acetylcholine receptors. **1. Why the Diaphragm is Correct:** The **diaphragm** is the most resistant muscle to NMBAs and is the **first to recover** from a neuromuscular block. This is due to its high density of acetylcholine receptors and its central location, which ensures high regional blood flow, allowing for rapid delivery and subsequent washout of the relaxant. Conversely, because it is resistant, the diaphragm is also the **last to be paralyzed** during induction. **2. Analysis of Incorrect Options:** * **Laryngeal muscles (A):** These recover after the diaphragm but before the peripheral muscles. They are relatively resistant but not as much as the diaphragm. * **Abdominal muscles (B):** These are intermediate in sensitivity. They are paralyzed after the diaphragm but before the small muscles of the hand. * **Thenar muscles (D):** These are peripheral muscles (like the adductor pollicis). Peripheral muscles are the **first to be paralyzed** and the **last to recover**. This is why monitoring the adductor pollicis with a nerve stimulator is a "safe" indicator; if the thumb has recovered, the diaphragm has certainly recovered. **3. High-Yield Clinical Pearls for NEET-PG:** * **Sequence of Paralysis:** Small muscles (eyes/fingers) → Limbs → Trunk (Abdomen) → Intercostals → Diaphragm. * **Sequence of Recovery:** Exactly the reverse (Diaphragm recovers first; Eye muscles recover last). * **Monitoring Tip:** To monitor **onset** (intubation readiness), the orbicularis oculi is preferred (reflects the diaphragm). To monitor **recovery** (extubation readiness), the adductor pollicis is preferred (reflects the return of airway protection).

Q: Which of the following is the muscle relaxant of choice in renal failure?

Atracurium. **Explanation:** The muscle relaxant of choice in renal failure is **Atracurium** (or its isomer, Cisatracurium). **1. Why Atracurium is the Correct Choice:** Most neuromuscular blocking agents (NMBAs) rely on renal or hepatic excretion for clearance. In renal failure, these drugs accumulate, leading to prolonged paralysis. Atracurium is unique because it undergoes **Hofmann Elimination**—a spontaneous, non-enzymatic degradation at physiological pH and temperature—and ester hydrolysis. Since its metabolism is independent of organ function, its duration of action remains unchanged in patients with end-stage renal disease (ESRD). **2. Why the Other Options are Incorrect:** * **Pancuronium:** This is a long-acting NMBA primarily excreted by the kidneys (approx. 80%). It is strictly contraindicated in renal failure due to the high risk of profound, prolonged neuromuscular blockade. * **Rocuronium:** It is primarily eliminated by the liver, but a significant portion (up to 30%) is excreted unchanged in the urine. Its duration of action is unpredictable and often prolonged in renal failure. * **Rapacurium:** This was a rapid-onset agent withdrawn from the market worldwide due to a high incidence of severe bronchospasm. **Clinical Pearls for NEET-PG:** * **Cisatracurium** is more potent than atracurium and is often preferred because it produces less **laudanosine** (a metabolite that can cause seizures) and does not cause histamine release. * **Vecuronium** is mostly biliary-excreted but has an active metabolite (3-desacetyl vecuronium) that accumulates in renal failure. * **Sugammadex** (a reversal agent) is generally avoided in severe renal impairment because the sugammadex-rocuronium complex is cleared renally.

Q: What is the duration of action of flumazenil?

40 minutes. **Explanation:** **Flumazenil** is a specific competitive antagonist at the benzodiazepine receptor. It is used to reverse the sedative and respiratory-depressant effects of benzodiazepines (like Midazolam or Diazepam). **Why Option D is Correct:** The duration of action of flumazenil is approximately **30 to 60 minutes** (with a mean clinical effect of roughly **40 minutes**). This is significantly shorter than the half-life of most benzodiazepines it is intended to reverse. Because it is rapidly cleared by the liver, its antagonistic effect wears off quickly. **Why Other Options are Incorrect:** * **Options A & B (10-20 mins):** While the onset of action is rapid (1–2 minutes), the clinical duration is longer than 20 minutes. * **Option C (30 mins):** While 30 minutes is the lower end of the range, 40 minutes is the standard textbook value cited in major anesthesia references (like Miller’s) and frequently tested in NEET-PG as the definitive duration. **Clinical Pearls & High-Yield Facts:** 1. **Resedation (Recurarization):** Because flumazenil’s duration (40 mins) is shorter than that of benzodiazepines (e.g., Diazepam lasts hours), patients may experience "resedation" once the flumazenil wears off. Monitoring for at least 2 hours is essential. 2. **Seizure Risk:** Flumazenil can precipitate acute withdrawal or seizures in patients on long-term benzodiazepine therapy or in cases of mixed tricyclic antidepressant overdose. 3. **Metabolism:** It is metabolized exclusively by the liver (high hepatic extraction ratio). 4. **Dose:** Typically administered in increments of 0.2 mg IV, up to a total of 1 mg.

Q: Which of the following agents can be used for anaesthesia in dogs?

All of the above. **Explanation:** In veterinary anesthesia, particularly for dogs, a multimodal approach is used to ensure sedation, analgesia, and muscle relaxation. All three agents listed are standard components of canine anesthetic protocols. 1. **Ketamine (Option A):** A dissociative anesthetic and NMDA receptor antagonist. It provides excellent somatic analgesia and is frequently used in dogs for induction or as part of a "triple drip" (Ketamine-Guaifenesin-Xylazine) to maintain anesthesia. 2. **Medetomidine hydrochloride (Option B):** A potent alpha-2 adrenergic agonist. It is widely used in veterinary medicine for sedation, premedication, and analgesia. It provides reliable chemical restraint in dogs and is often preferred over xylazine due to higher specificity. 3. **Midazolam (Option C):** A short-acting benzodiazepine used for its anxiolytic, anticonvulsant, and muscle-relaxant properties. In dogs, it is commonly used as a pre-anesthetic medication to facilitate smooth induction and reduce the dose of induction agents like Propofol. **Why "All of the above" is correct:** These drugs are often used in combination (e.g., the "Ket-Mid" protocol) to achieve balanced anesthesia, minimizing the side effects of any single agent while ensuring the animal remains unconscious and pain-free. **High-Yield Clinical Pearls for NEET-PG:** * **Ketamine** is unique because it stimulates the sympathetic nervous system (increasing HR and BP), making it useful in hemodynamically unstable patients, though it increases intracranial pressure. * **Atipamezole** is the specific reversal agent for Medetomidine. * **Flumazenil** is the reversal agent for Midazolam. * In veterinary anesthesia, **Xylazine** is another common alpha-2 agonist, but it is highly emetic in cats.

Q: Which of the following anesthetic agents are known to cause pain on injection?

Etomidate, Methohexitone, and Propofol. **Explanation:** The sensation of pain during the intravenous injection of anesthetic agents is a common clinical challenge, primarily caused by the **osmolality** of the formulation or the presence of **propylene glycol** as a solvent, which irritates the venous intima. **1. Why Option C is Correct:** * **Propofol:** The most notorious for causing pain (reported in up to 70% of patients). The pain is attributed to the activation of the **kallikrein-kinin system** and the release of bradykinin. * **Etomidate:** Formulated in 35% propylene glycol, which is highly hyperosmolar and irritating to the veins. * **Methohexitone:** An oxybarbiturate that frequently causes pain on injection and is also associated with excitatory phenomena like myoclonus. **2. Why Other Options are Incorrect:** * **Thiopentone (Options B & D):** While highly alkaline (pH ~10.5) and capable of causing tissue necrosis if injected intra-arterially, it typically does **not** cause significant pain when injected into a large, patent vein. * **Ketamine (Option B):** Generally considered painless upon intravenous injection. **Clinical Pearls for NEET-PG:** * **Prevention:** Pain from Propofol can be reduced by using larger veins (antecubital fossa), prior administration of **IV Lidocaine**, or mixing lidocaine with the drug. * **Excitatory Phenomena:** Both Etomidate and Methohexitone are associated with high incidences of **myoclonus** and hiccups. * **Drug of Choice:** Despite the pain, Etomidate remains the drug of choice for induction in **hemodynamically unstable** patients due to its minimal cardiovascular effects. * **Contraindication:** Avoid Methohexitone and Etomidate in patients with a history of **seizures** (though Methohexitone is used to prolong seizures in ECT).

Q: Which of the following increases intraocular pressure?

Ketamine. **Explanation:** **Ketamine** is the correct answer because it is one of the few anesthetic agents that **increases intraocular pressure (IOP)**. The mechanism is attributed to an increase in extraocular muscle tone and a rise in choroidal blood flow due to sympathetic stimulation. Consequently, Ketamine is generally avoided in patients with penetrating eye injuries or glaucoma where a rise in IOP could lead to the expulsion of intraocular contents or optic nerve damage. **Analysis of Incorrect Options:** * **Thiopentone & Barbiturates (Options A & D):** Most intravenous induction agents, particularly barbiturates, significantly **decrease IOP**. They achieve this by depressing the central nervous system, reducing aqueous humor production, and improving its outflow. * **Althesin (Option B):** This is a steroid-based anesthetic (now largely obsolete due to anaphylaxis) that also causes a **decrease in IOP**, similar to the profile of most non-ketamine induction agents. **High-Yield Clinical Pearls for NEET-PG:** * **IOP & Intubation:** While most induction agents (Propofol, Etomidate, Thiopentone) decrease IOP, the act of **Laryngoscopy and Intubation** causes a sharp rise in IOP. * **Muscle Relaxants:** **Succinylcholine** (Suxamethonium) is notorious for increasing IOP (by ~5-10 mmHg) due to prolonged contraction of extraocular muscles. It is contraindicated in open globe injuries. * **Inhalational Agents:** Most volatile anesthetics (e.g., Sevoflurane, Isoflurane) decrease IOP. * **Exceptions:** Only **Ketamine** and **Succinylcholine** are classic "red flags" for increasing intraocular pressure in anesthesia.

Q: Which of the following drugs can cause bradycardia during anaesthesia?

Propofol. **Explanation:** **Propofol (Correct Answer):** Propofol is a potent intravenous anesthetic agent that frequently causes **bradycardia** and hypotension. The underlying mechanism involves a significant reduction in sympathetic tone and an inhibition of the baroreceptor reflex. Unlike other induction agents, propofol resets the baroreflex, meaning the heart rate does not increase reflexively in response to the drop in blood pressure. In some cases, it can lead to profound vagotonic effects, occasionally resulting in asystole. **Analysis of Incorrect Options:** * **Pancuronium:** This is a long-acting non-depolarizing neuromuscular blocker (NMBA) known for causing **tachycardia**. It has vagolytic properties and stimulates the release of norepinephrine from cardiac sympathetic nerve endings. * **Vecuronium:** This is considered a **cardiovascularly stable** NMBA. It lacks significant vagolytic or histamine-releasing effects, typically resulting in no change in heart rate. * **Atracurium:** While it can cause hypotension due to **histamine release**, the physiological response to this hypotension is usually a compensatory **reflex tachycardia**, not bradycardia. **High-Yield Clinical Pearls for NEET-PG:** * **Propofol Infusion Syndrome (PRIS):** A rare but fatal complication of long-term high-dose infusion characterized by metabolic acidosis, rhabdomyolysis, hyperkalemia, and cardiac failure. * **Drug of Choice:** Propofol is the drug of choice for Day Care Surgery due to its rapid recovery and anti-emetic properties. * **Ketamine vs. Propofol:** While Propofol causes bradycardia and hypotension, Ketamine is the "opposite," causing tachycardia and hypertension (sympathomimetic).

Q: What is true about midazolam as an inducing agent?

Does not produce pain on intravenous injection.. **Explanation:** Midazolam is a water-soluble benzodiazepine frequently used for preoperative sedation and induction of anesthesia. **Why Option B is Correct:** Unlike its predecessor Diazepam, which is insoluble in water and requires a propylene glycol solvent (causing significant venous irritation and thrombophlebitis), **Midazolam contains an imidazole ring**. At a pH of less than 4.0, this ring remains open, making the drug **water-soluble**. This eliminates the need for irritating solvents, ensuring that it **does not produce pain on intravenous injection**. Once injected, the physiological pH of the blood (7.4) causes the ring to close, making the drug lipid-soluble so it can cross the blood-brain barrier. **Analysis of Incorrect Options:** * **Option A & D:** Midazolam typically causes a **decrease in systemic vascular resistance (SVR)** and a modest **decrease in blood pressure**. It does not increase peripheral vascular resistance; rather, it has a mild vasodilatory effect. * **Option C:** Benzodiazepines, including midazolam, **decrease cerebral metabolic rate of oxygen consumption (CMRO2)** and cerebral blood flow (CBF) while maintaining the CO2 reactivity of the cerebral vasculature. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Potentiates GABA-A receptors by increasing the **frequency** of chloride channel opening. * **Metabolism:** Metabolized by hepatic CYP3A4 enzymes; its active metabolite is 1-hydroxymidazolam. * **Specific Antagonist:** **Flumazenil** (competitive antagonist) is used to reverse its effects. * **Anterograde Amnesia:** Midazolam is highly effective at producing anterograde amnesia, making it ideal for premedication.

Question 1

Which muscles are the first to recover after administration of muscle relaxants?

Accepted Answer

Diaphragm

Answer

Laryngeal muscles

Answer

Abdominal muscles

Answer

Thenar muscles

Question 2

Which of the following is the muscle relaxant of choice in renal failure?

Accepted Answer

Atracurium

Answer

Rapacurium

Answer

Pancuronium

Answer

Rocuronium

Question 3

Which of the following statements regarding halothane is incorrect?

Accepted Answer

It is generally considered unsuitable for the pediatric population.

Answer

It potentiates the effects of competitive neuromuscular blockers.

Answer

Hepatitis is a known potential adverse effect.

Answer

It is contraindicated in patients with certain cardiac arrhythmias.

Question 4

What is the duration of action of flumazenil?

Accepted Answer

40 minutes

Answer

10 minutes

Answer

20 minutes

Answer

30 minutes

Question 5

Which of the following agents can be used for anaesthesia in dogs?

Accepted Answer

All of the above

Answer

Ketamine

Answer

Medetomidine hydrochloride

Answer

Midazolam

Question 6

Which of the following anesthetic agents are known to cause pain on injection?

Accepted Answer

Etomidate, Methohexitone, and Propofol

Answer

Etomidate and Propofol

Answer

Etomidate, Ketamine, and Thiopentone

Answer

Etomidate, Methohexitone, Propofol, and Thiopentone

Question 7

Which of the following increases intraocular pressure?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Althesin

Answer

Barbiturate

Question 8

Which of the following drugs can cause bradycardia during anaesthesia?

Accepted Answer

Propofol

Answer

Pancuronium

Answer

Vecuronium

Answer

Atracurium

Question 9

What is true about midazolam as an inducing agent?

Accepted Answer

Does not produce pain on intravenous injection.

Answer

Causes an increase in blood pressure.

Answer

Increases cerebral oxygen consumption.

Answer

Increases peripheral vascular resistance.

Question 10

All are false about propofol except?

Accepted Answer

Propofol infusion at a rate >4 mg/hr can cause propofol infusion syndrome.

Answer

Propofol is the best bronchodilator.

Answer

Propofol is a cardiovascular stable drug.

Answer

Propofol causes malignant hyperthermia.

General Anesthesia — MCQs

General Anesthesia — MCQs

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