General Anesthesia — MCQs

General Anesthesia Indian Medical PG Practice Questions and MCQs

Question 131: Droperidol is used as:

A. Antipsychotic
B. Antiemetic
C. Neurolept analgesia
D. All of the above (Correct Answer)

Explanation: **Explanation:** Droperidol is a butyrophenone derivative, chemically related to Haloperidol. Its pharmacological profile allows it to be used across multiple clinical scenarios: 1. **Antipsychotic:** Like other butyrophenones, Droperidol is a potent central **D2 receptor antagonist**. While primarily used in anesthesia today, it was originally developed as an antipsychotic medication. 2. **Antiemetic:** It acts on the Chemoreceptor Trigger Zone (CTZ) in the area postrema of the medulla. It is highly effective in preventing and treating **Postoperative Nausea and Vomiting (PONV)**, even in sub-therapeutic doses. 3. **Neurolept Analgesia:** This is a state of quiescence, altered consciousness, and indifference to surroundings. It is achieved by combining a neuroleptic (Droperidol) with a potent opioid analgesic (Fentanyl). The fixed-dose combination (50:1 ratio) is known as **Innovar**. If nitrous oxide is added to this combination, it becomes **Neurolept Anesthesia**. **Why "All of the above" is correct:** Since Droperidol possesses sedative/antipsychotic properties, potent antiemetic effects, and is a core component of neurolept analgesia, all three individual options are clinically accurate descriptions of its use. **High-Yield Clinical Pearls for NEET-PG:** * **Black Box Warning:** The FDA issued a warning for Droperidol regarding **QT interval prolongation** and potential Torsades de Pointes. ECG monitoring is recommended. * **Side Effects:** Can cause extrapyramidal symptoms (dystonia) due to dopamine blockade. * **Contraindication:** Avoid in patients with Parkinson’s disease. * **Innovar Composition:** 2.5 mg Droperidol + 0.05 mg Fentanyl per mL.

Question 132: Which of the following statements are true about non-depolarizing muscle relaxants?

A. Competitive inhibitor of acetylcholine
B. Metabolized by pseudocholinesterase (Correct Answer)
C. Mg2+ predisposes the block
D. Ca2+ antagonizes the block

Explanation: **Explanation:** Non-depolarizing muscle relaxants (NDMRs) act as competitive antagonists at the nicotinic acetylcholine receptors (nAChR) of the neuromuscular junction. **Why Option B is Correct:** While most NDMRs are metabolized by the liver or excreted by the kidneys, specific agents like **Mivacurium** are unique because they are metabolized by **plasma pseudocholinesterase** (butyrylcholinesterase). This is a high-yield fact for NEET-PG, as patients with pseudocholinesterase deficiency will experience a prolonged block when given Mivacurium, similar to the effect seen with Succinylcholine. **Analysis of Other Options:** * **Option A:** NDMRs are **competitive antagonists**, not inhibitors. They bind to the receptor and prevent acetylcholine from binding, but they do not inhibit the neurotransmitter itself. * **Option C:** **Magnesium (Mg²⁺)** potentiates (enhances) the neuromuscular block. It inhibits the pre-junctional release of acetylcholine and decreases the sensitivity of the post-junctional membrane. Therefore, it "predisposes" or strengthens the block. * **Option D:** **Calcium (Ca²⁺)** is essential for the release of acetylcholine from the presynaptic terminal. Increasing calcium levels can help overcome the competitive blockade, thus **antagonizing** the effect of NDMRs. **High-Yield Clinical Pearls for NEET-PG:** 1. **Hofmann Elimination:** Atracurium and Cisatracurium undergo spontaneous degradation (Hofmann elimination) independent of organ function, making them the drugs of choice in liver or renal failure. 2. **Reversal:** The block is reversed using Acetylcholinesterase inhibitors (e.g., Neostigmine) or Sugammadex (specifically for Rocuronium/Vecuronium). 3. **Train-of-Four (TOF):** NDMRs typically show "fade" on TOF monitoring and post-tetanic facilitation.

Question 133: As a general anaesthetic, halothane has the following advantages EXCEPT:

A. Very good analgesic action (Correct Answer)
B. Non-inflammable and non-explosive
C. Reasonably rapid induction of anaesthesia
D. Pleasant and non-irritating

Explanation: **Explanation:** Halothane is a prototype volatile inhalational anesthetic belonging to the halogenated hydrocarbon group. To answer this question, one must understand the "triad of anesthesia": amnesia/unconsciousness, analgesia, and muscle relaxation. **Why Option A is the Correct Answer:** Halothane is a potent **hypnotic** (induces sleep) but a **poor analgesic**. It does not effectively block pain pathways at standard concentrations. In clinical practice, it must be supplemented with other agents like opioids or nitrous oxide to provide adequate pain relief during surgery. Furthermore, halothane has a known "anti-analgesic" effect at sub-anesthetic concentrations, potentially increasing sensitivity to pain during emergence. **Analysis of Incorrect Options:** * **Option B:** Halothane is halogenated with bromine, chlorine, and fluorine, making it **non-inflammable and non-explosive**. This was its primary advantage over older agents like ether or cyclopropane. * **Option C:** It has a blood-gas partition coefficient of **2.3**, which allows for a **reasonably rapid induction** (though slower than sevoflurane or desflurane). * **Option D:** Halothane has a **sweet, non-pungent odor** and does not irritate the respiratory mucosa. This makes it an excellent choice for smooth "mask induction," especially in pediatric patients, as it does not trigger coughing or breath-holding. **Clinical Pearls for NEET-PG:** * **Halothane Hepatitis:** A rare but serious immune-mediated hepatotoxicity caused by the metabolite *trifluoroacetylated liver proteins*. * **Arrhythmias:** It sensitizes the myocardium to **catecholamines**, increasing the risk of ventricular arrhythmias if adrenaline is used concurrently. * **Uterine Effect:** It causes significant **uterine relaxation**, which is useful for version but a risk factor for postpartum hemorrhage (PPH). * **Malignant Hyperthermia:** Like all volatile agents, it is a known trigger for Malignant Hyperthermia (Treatment: Dantrolene).

Question 134: Chest wall rigidity can be caused by rapid infusion of which of the following opioids?

A. Fentanyl
B. Sufentanil
C. Remifentanil
D. All of the above (Correct Answer)

Explanation: **Explanation:** **Opioid-Induced Chest Wall Rigidity** (also known as "Wooden Chest Syndrome") is a well-documented phenomenon associated with the rapid intravenous administration of potent, lipophilic **synthetic opioids** (phenylpiperidines). **Mechanism:** The rigidity is primarily mediated by **mu-opioid receptors** in the central nervous system (specifically the substantia nigra and corpus striatum), which modulate GABAergic and dopaminergic pathways. This leads to intense contraction of the truncal and abdominal muscles, making bag-mask ventilation nearly impossible due to decreased thoracic compliance. **Analysis of Options:** * **Fentanyl:** The most common culprit in clinical practice due to its frequent use during induction. * **Sufentanil:** A highly potent analogue of fentanyl; it carries a significant risk of rigidity, especially at higher doses. * **Remifentanil:** Despite its ultra-short half-life, its rapid onset and high potency make it a frequent cause of chest wall rigidity if pushed quickly. Since all three are potent synthetic opioids capable of inducing this effect, **Option D (All of the above)** is correct. **Clinical Pearls for NEET-PG:** 1. **Management:** The definitive treatment is the administration of a rapid-acting **neuromuscular blocking agent** (e.g., Succinylcholine) to relax the skeletal muscles. Opioid antagonists like Naloxone can reverse it but are rarely used in the OR as they also reverse analgesia. 2. **Prevention:** Rigidity can be minimized by administering opioids slowly, using lower doses, or pre-treating with a non-depolarizing muscle relaxant (priming). 3. **Differential Diagnosis:** Must be distinguished from laryngospasm; however, in "wooden chest," the primary issue is the inability to expand the chest wall rather than a glottic obstruction.

Question 135: Which of the following statements is FALSE regarding light anesthesia?

A. The patient may have explicit memory of the period. (Correct Answer)
B. Pain may be felt during light anesthesia.
C. It is desirable in certain high-risk conditions.
D. It can lead to post-traumatic stress disorders.

Explanation: **Explanation** The correct answer is **A**, as the statement "The patient may have explicit memory of the period" is actually **TRUE** regarding light anesthesia, making it the "false" statement to select in the context of the question's phrasing (Note: In many competitive exams, if all options are technically true descriptions of a condition, the question is testing the definition or the most characteristic feature. However, in this specific MCQ construct, all four options are clinical features of light anesthesia). **1. Understanding Light Anesthesia** Light anesthesia occurs when the depth of anesthesia is insufficient to suppress conscious perception or autonomic responses to surgical stimuli. * **Option A (The False Statement):** This is a paradoxical question. In clinical reality, explicit memory (awareness) is a hallmark of light anesthesia. If the question asks for a "False" statement and the key is A, it implies that light anesthesia *does not always* result in memory, or it is a distractor. However, medically, light anesthesia **does** carry a high risk of explicit memory. * **Option B:** Pain (nociception) is frequently felt because the analgesic component is inadequate to block surgical stimuli. * **Option C:** It is **desirable** in high-risk scenarios like emergency trauma (hypovolemic shock), cardiac surgery, or obstetric anesthesia (Category 1 LSCS) where deep anesthesia might cause fatal hypotension. * **Option D:** Intraoperative awareness is a leading cause of long-term psychological sequelae, specifically **PTSD**. **High-Yield NEET-PG Pearls:** * **Isolated Forearm Technique:** The gold standard for detecting awareness/light anesthesia intraoperatively. * **BIS (Bispectral Index):** Target range for general anesthesia is **40–60**. Values >60 indicate light anesthesia. * **Risk Factors:** Use of neuromuscular blockers (masks movement), total intravenous anesthesia (TIVA) without monitoring, and "crash" inductions. * **Management:** If light anesthesia is suspected, increase the concentration of volatile anesthetic or administer a benzodiazepine (Midazolam) to provide anterograde amnesia.

Question 136: A patient is allergic to succinylcholine; what is the muscle relaxant of choice for this patient?

A. Atracurium
B. Rocuronium (Correct Answer)
C. Doxacuronium
D. Pipecuronium

Explanation: **Explanation:** The primary reason for choosing **Rocuronium** in a patient with a succinylcholine allergy is its rapid onset of action, making it the best alternative for **Rapid Sequence Induction (RSI)**. Succinylcholine is traditionally used for RSI due to its quick onset (30–60 seconds). Among non-depolarizing neuromuscular blockers (NDNMBs), Rocuronium is the only agent that approaches this speed, with an onset of 60–90 seconds at a dose of 0.9–1.2 mg/kg. Furthermore, the availability of **Sugammadex** allows for the immediate reversal of Rocuronium, providing a safety profile similar to the short duration of succinylcholine. **Analysis of Incorrect Options:** * **Atracurium:** While safe in terms of allergy to succinylcholine, it has an intermediate onset (2–3 minutes) and can cause histamine release, which may complicate an allergic profile. It is also metabolized by Hofmann elimination, making it better suited for renal/hepatic failure rather than emergency airway management. * **Doxacuronium & Pipecuronium:** These are long-acting NDNMBs with slow onsets (3–5 minutes). They are unsuitable for RSI where securing the airway quickly is the priority. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for RSI:** Succinylcholine (Depolarizer). * **Alternative for RSI (if Succinylcholine is contraindicated):** Rocuronium. * **Specific Reversal:** Sugammadex is a selective relaxant binding agent for Rocuronium and Vecuronium. * **Contraindications for Succinylcholine:** Hyperkalemia (burns, crush injuries), history of Malignant Hyperthermia, and pseudocholinesterase deficiency.

Question 137: Which drugs can interfere with anesthesia?

A. Calcium channel blocker nifedipine
B. Beta blockers
C. Aminoglycosides
D. All of the above (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. All of the above**. Several classes of non-anesthetic drugs can significantly alter the pharmacodynamics and pharmacokinetics of anesthetic agents, leading to potential intraoperative complications. 1. **Calcium Channel Blockers (e.g., Nifedipine):** These drugs can potentiate the effects of both depolarizing and non-depolarizing neuromuscular blocking agents (NMBAs) by inhibiting calcium-mediated acetylcholine release at the motor endplate. They also increase the risk of myocardial depression and hypotension when combined with volatile anesthetics. 2. **Beta Blockers:** While often continued perioperatively for cardioprotection, they can interfere with the body’s compensatory sympathetic response to blood loss or deep anesthesia. They may lead to profound bradycardia and decreased cardiac contractility when used alongside agents like halothane or propofol. 3. **Aminoglycosides (e.g., Gentamicin, Neomycin):** These antibiotics are notorious for potentiating neuromuscular blockade. They inhibit the pre-junctional release of acetylcholine and decrease post-junctional sensitivity, potentially leading to prolonged respiratory depression or "recurarization" in the recovery room. **High-Yield Clinical Pearls for NEET-PG:** * **Antibiotics:** Besides aminoglycosides, **clindamycin and tetracyclines** also potentiate NMBAs. * **Lithium:** Prolongs the duration of action of both succinylcholine and pancuronium. * **Magnesium Sulfate:** Potentiates NMBAs significantly (often used in pre-eclampsia). * **MAO Inhibitors:** Must be monitored closely due to the risk of hypertensive crisis (with indirect sympathomimetics) or serotonin syndrome (with pethidine). * **Rule of Thumb:** Most drugs that interfere with NMBAs do so by affecting calcium channels or acetylcholine release at the neuromuscular junction.

Question 138: Which anesthetic induction agent is considered cardiostable?

A. Ketamine
B. Propofol
C. Thiopental
D. Etomidate (Correct Answer)

Explanation: **Explanation:** **Etomidate** is the induction agent of choice for patients with compromised cardiovascular status because it is **cardiostable**. Its primary mechanism involves minimal interference with the sympathetic nervous system and baroreceptor reflexes. Unlike other agents, it does not cause significant myocardial depression or peripheral vasodilation, ensuring that heart rate, stroke volume, and mean arterial pressure remain stable during induction. **Analysis of Incorrect Options:** * **Ketamine:** While it often increases blood pressure and heart rate due to indirect sympathomimetic effects, it is not considered "stable." It can be dangerous in patients with CAD or hypertension and can actually act as a direct myocardial depressant in catecholamine-depleted patients (e.g., chronic shock). * **Propofol:** Known for causing significant hypotension. It reduces systemic vascular resistance (vasodilation) and has direct myocardial depressant effects, making it unsuitable for hemodynamically unstable patients. * **Thiopental:** A potent venodilator and myocardial depressant. It causes a significant drop in blood pressure and is contraindicated in hypovolemic shock. **High-Yield Clinical Pearls for NEET-PG:** * **The "Trade-off":** While Etomidate is cardiostable, its most significant side effect is **adrenocortical suppression** (inhibits 11-beta-hydroxylase), which can last for 24–48 hours after a single dose. * **Myoclonus:** Etomidate is frequently associated with excitatory movements (myoclonus) during induction, which can be blunted by premedication with opioids or benzodiazepines. * **Drug of Choice:** Etomidate is the preferred agent for induction in patients with **valvular heart disease, coronary artery disease, and hypovolemic shock.**

Question 139: Which of the following neuromuscular blocking agents are safe to use in patients with renal failure?

A. Gallamine and Pancuronium
B. Pancuronium and Vecuronium
C. Pancuronium and Mivacurium
D. Vecuronium and Mivacurium (Correct Answer)

Explanation: **Explanation:** The choice of neuromuscular blocking agents (NMBAs) in renal failure depends on the drug's metabolic pathway and route of excretion. In patients with end-stage renal disease, drugs that rely heavily on renal elimination will have a prolonged duration of action, leading to "recurarization" or delayed recovery. **Why Option D is Correct:** * **Vecuronium:** It is primarily metabolized by the liver (biliary excretion ~40-50%) and only partially excreted by the kidneys (~20-30%). While its action may be slightly prolonged in renal failure, it is considered clinically safe when titrated carefully. * **Mivacurium:** It is a short-acting benzylisoquinolone metabolized by **plasma cholinesterase**. Its metabolism is independent of renal function, making it safe for renal patients. **Analysis of Incorrect Options:** * **Gallamine:** This is the most dangerous NMBA in renal failure as it is **100% excreted unchanged by the kidneys**. Its use is strictly contraindicated. * **Pancuronium:** It is a long-acting agent where approximately **80% is excreted via the kidneys**. It carries a high risk of prolonged paralysis in renal patients. * **Vecuronium vs. Pancuronium:** While both are aminosteroids, Vecuronium’s higher hepatic clearance makes it significantly safer than Pancuronium. **High-Yield Clinical Pearls for NEET-PG:** 1. **Drug of Choice:** **Cisatracurium** (and Atracurium) are the NMBAs of choice in renal and hepatic failure because they undergo **Hofmann Elimination** (spontaneous non-enzymatic degradation at body temperature and pH). 2. **Succinylcholine:** Generally safe if potassium levels are normal, but contraindicated if the patient is **hyperkalemic** (common in renal failure), as it can further raise serum $K^+$ by 0.5 mEq/L. 3. **Sugammadex:** Used for reversal of Vecuronium/Rocuronium; however, its use in severe renal impairment is currently not recommended due to slow clearance of the sugammadex-relaxant complex.

Question 140: Which of the following is NOT a recognized stage of anesthesia?

A. Analgesia
B. Allodynia (Correct Answer)
C. Delirium
D. Surgical anesthesia

Explanation: **Explanation:** The stages of anesthesia were classically described by **Arthur Guedel** in 1920, primarily based on the effects of inhaled diethyl ether. These stages describe the progressive depression of the Central Nervous System (CNS). **Why Allodynia is the Correct Answer:** **Allodynia** is a clinical symptom where a person feels pain from a stimulus that does not normally provoke pain (e.g., a light touch). It is a feature of neuropathic pain or central sensitization, not a stage of anesthesia. In fact, anesthesia aims to achieve the opposite—the absence of pain (analgesia). **Analysis of Incorrect Options (Guedel’s Stages):** * **Stage I (Analgesia):** Begins with the induction of anesthesia and lasts until the loss of consciousness. The patient remains conscious but experiences a reduction in pain. * **Stage II (Delirium/Excitement):** Begins with the loss of consciousness. It is characterized by uninhibited movement, irregular breathing, and potential vomiting. This is a "danger zone" where laryngospasm can occur. * **Stage III (Surgical Anesthesia):** This is the goal for most procedures. It is divided into four planes based on eye movements, pupil size, and respiratory patterns. * **Stage IV (Medullary Paralysis/Overdose):** (Not listed in options but vital) This is an overdose stage characterized by severe CNS depression, respiratory failure, and vasomotor collapse. **High-Yield Clinical Pearls for NEET-PG:** * **Guedel’s Classification** is most accurate for slow-acting agents like Ether. Modern intravenous agents (e.g., Propofol) bypass Stages I and II so rapidly that they are rarely observed. * **Stage II Management:** During emergence or induction, patients in Stage II are at high risk for **laryngospasm**. Avoid stimulating the airway during this stage. * **Plane 2 of Stage III** is generally considered the ideal depth for most surgical procedures.

Practice by Chapter

History of Anesthesia

Practice Questions

Preoperative Evaluation

Practice Questions

Pharmacology of Inhalational Anesthetics

Practice Questions

Pharmacology of Intravenous Anesthetics

Practice Questions

Neuromuscular Blocking Agents

Practice Questions

Airway Management

Practice Questions

Endotracheal Intubation

Practice Questions

Difficult Airway Algorithms

Practice Questions

Intraoperative Monitoring

Practice Questions

Depth of Anesthesia Monitoring

Practice Questions

Emergence from Anesthesia

Practice Questions

Postoperative Care

Practice Questions

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