General Anesthesia Practice Questions

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

All of the above. **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.

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

Rocuronium. **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.

Q: Which anesthetic induction agent is considered cardiostable?

Etomidate. **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.**

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

Allodynia. **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.

Q: All of the following are intravenous anesthetic induction agents except?

Bupivacaine. **Explanation:** The correct answer is **D. Bupivacaine**. The fundamental distinction here lies between **General Anesthetics** and **Local Anesthetics**. * **Why Bupivacaine is the correct answer:** Bupivacaine is a potent, long-acting **Local Anesthetic (LA)** of the amide group. It works by blocking voltage-gated sodium channels in peripheral nerves or the spinal cord to prevent signal conduction. It is used for regional anesthesia (spinal, epidural) and nerve blocks, but it is **never** used as an intravenous induction agent for general anesthesia. In fact, accidental intravenous injection of Bupivacaine is highly toxic, leading to severe cardiotoxicity. **Analysis of Incorrect Options (Intravenous Induction Agents):** * **A. Thiopentone Sodium:** An ultra-short-acting barbiturate. It was the gold standard for induction for decades. It acts via GABA-A receptors. * **B. Ketamine:** A dissociative anesthetic that acts as an NMDA receptor antagonist. It is unique because it provides significant analgesia and maintains sympathetic tone. * **C. Etomidate:** An imidazole derivative used for induction, favored in hemodynamically unstable patients (e.g., trauma or heart failure) due to its minimal effect on blood pressure and heart rate. **High-Yield Clinical Pearls for NEET-PG:** * **Propofol:** Currently the most common induction agent; known for its anti-emetic properties and "milk of amnesia" appearance. * **Etomidate Side Effect:** Can cause transient **adrenocortical suppression** by inhibiting the enzyme 11-beta-hydroxylase. * **Ketamine:** The drug of choice for induction in **bronchial asthma** (bronchodilator) and **hypovolemic shock**. * **Bupivacaine Toxicity:** If systemic toxicity (LAST) occurs, the specific antidote is **Intralipid (20% Lipid Emulsion)**.

Q: Which of the following is contraindicated in chronic renal failure (CRF)?

Enflurane. **Explanation:** The primary concern when using volatile anesthetics in patients with Chronic Renal Failure (CRF) is the production of **inorganic fluoride ions** during hepatic metabolism. High levels of fluoride are nephrotoxic, causing a vasopressin-resistant polyuric state (nephrogenic diabetes insipidus). **Why Enflurane is the Correct Answer:** Enflurane undergoes significant metabolism (approx. 2.4%), releasing high concentrations of inorganic fluoride. In patients with pre-existing renal impairment, the kidney's inability to excrete these ions increases the risk of further parenchymal damage. Therefore, it is traditionally contraindicated in CRF. **Analysis of Other Options:** * **Halothane:** It is primarily associated with hepatotoxicity ("Halothane Hepatitis") rather than nephrotoxicity. It undergoes minimal metabolism to fluoride. * **Isoflurane:** It is highly stable with very low metabolism (0.2%). It produces negligible fluoride levels, making it one of the safest choices for patients with renal failure. * **Desflurane:** It has the lowest metabolism rate (0.02%) among all potent volatile agents. It is considered safe in CRF due to minimal fluoride production. **High-Yield Clinical Pearls for NEET-PG:** 1. **Sevoflurane & Compound A:** While Sevoflurane produces fluoride, the main concern in renal patients is **Compound A**, a nephrotoxic byproduct formed when Sevoflurane reacts with dry soda lime. 2. **Drug of Choice:** **Isoflurane** is often considered the volatile agent of choice in renal failure due to its cardiovascular stability and minimal metabolism. 3. **Muscle Relaxant of Choice:** **Atracurium or Cisatracurium** are preferred in CRF because they undergo **Hofmann elimination**, which is independent of renal function.

Q: What is the approximate incidence of hepatitis following halothane use?

1 in 30,000. **Explanation:** Halothane-induced hepatotoxicity is a classic pharmacological concept categorized into two types. Type I (minor) is common, characterized by a transient rise in transaminases. Type II (major) is **Halothane Hepatitis**, a rare but severe immune-mediated fulminant hepatic failure. **1. Why Option C is Correct:** Large-scale epidemiological studies (such as the National Halothane Study) established that the incidence of severe halothane hepatitis is approximately **1 in 30,000** exposures. The mechanism involves the metabolism of halothane by Cytochrome P450 to **trifluoroacetyl chloride**, which binds to hepatic proteins. In susceptible individuals, these "neo-antigens" trigger an IgG-mediated immune response, leading to massive hepatic necrosis. **2. Why Other Options are Incorrect:** * **Options A (20%) and B (40%):** These percentages are far too high for a rare idiosyncratic drug reaction. However, roughly 20% of patients may show a subclinical, transient rise in liver enzymes (Type I), which should not be confused with true hepatitis. * **Option D (1 in 3,000):** While some older studies suggested higher rates in specific high-risk populations (e.g., obese females undergoing multiple exposures), the globally accepted standard for the general population remains 1 in 30,000. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** "Middle-aged, obese females" is the classic demographic. Multiple exposures within a short period (less than 28 days) significantly increase risk. * **Metabolism:** Halothane undergoes significant hepatic metabolism (~20%), much higher than Isoflurane (0.2%) or Desflurane (0.02%), explaining its higher hepatotoxic potential. * **Clinical Presentation:** Fever, jaundice, and eosinophilia typically appear 3–14 days post-exposure. * **Pediatrics:** Children are remarkably resistant to halothane hepatitis, making it historically popular in pediatric anesthesia.

Question 1

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

Accepted Answer

All of the above

Answer

Fentanyl

Answer

Sufentanil

Answer

Remifentanil

Question 2

Which of the following statements is FALSE regarding light anesthesia?

Accepted Answer

The patient may have explicit memory of the period.

Answer

Pain may be felt during light anesthesia.

Answer

It is desirable in certain high-risk conditions.

Answer

It can lead to post-traumatic stress disorders.

Question 3

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

Accepted Answer

Rocuronium

Answer

Atracurium

Answer

Doxacuronium

Answer

Pipecuronium

Question 4

Which anesthetic induction agent is considered cardiostable?

Accepted Answer

Etomidate

Answer

Ketamine

Answer

Propofol

Answer

Thiopental

Question 5

Which of the following is NOT a recognized stage of anesthesia?

Accepted Answer

Allodynia

Answer

Analgesia

Answer

Delirium

Answer

Surgical anesthesia

Question 6

All of the following are intravenous anesthetic induction agents except?

Accepted Answer

Bupivacaine

Answer

Thiopentone sodium

Answer

Ketamine

Answer

Etomidate

Question 7

All of the following are considered stages of anesthesia except:

Accepted Answer

Allodynia

Answer

Analgesia

Answer

Delirium

Answer

Surgical anesthesia

Question 8

Which of the following is contraindicated in chronic renal failure (CRF)?

Accepted Answer

Enflurane

Answer

Halothane

Answer

Desflurane

Answer

Isoflurane

Question 9

Which of the following statements about cisatracurium, the pure cis isomer of atracurium, is FALSE?

Accepted Answer

It produces more laudanosine than an equipotent dose of atracurium.

Answer

It is metabolized primarily by Hoffman degradation.

Answer

It is cardiovascularly stable.

Answer

It has an onset and duration similar to atracurium.

Question 10

What is the approximate incidence of hepatitis following halothane use?

Accepted Answer

1 in 30,000

Answer

20%

Answer

40%

Answer

1 in 3,000

General Anesthesia — MCQs

General Anesthesia — MCQs

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