NEET-PG 2013 — Anesthesiology
33 Previous Year Questions with Answers & Explanations
Ether was first used as an anesthetic by?
Which anaesthetic agent has maximum MAC ?
Phase II block is seen with:
What is the drug of choice for reversing muscle relaxants after anesthesia?
What is the primary clinical use of Sugammadex in anesthesia?
In which vein is Central Venous Pressure (CVP) most accurately monitored?
Central venous monitoring is typically used for all of the following except:
What is the PRIMARY application of capnography during patient monitoring?
Which of the following is a characteristic of the Supreme Laryngeal Mask Airway (LMA)?
Critical temperature of oxygen is?
NEET-PG 2013 - Anesthesiology NEET-PG Practice Questions and MCQs
Question 1: Ether was first used as an anesthetic by?
- A. Morton (Correct Answer)
- B. Wells
- C. Simpson
- D. Priestly
Explanation: ***Morton*** - **William T.G. Morton**, a dentist, publicly demonstrated the use of **ether as a surgical anesthetic** in 1846 during a tooth extraction at Massachusetts General Hospital. - This event marked a pivotal moment in medicine, revolutionizing surgical practices by providing effective pain relief. *Priestly* - **Joseph Priestley** was an 18th-century chemist who discovered several gases, including **oxygen**, but was not involved in the anesthetic use of ether. - His work was foundational to understanding the composition of air but did not extend to surgical applications of inhaled substances. *Wells* - **Horace Wells**, an American dentist, was an early pioneer in anesthesia who experimented with **nitrous oxide** as an anesthetic for tooth extractions. - While significant, his work predated and differed from Morton's successful public demonstration and widespread adoption of ether. *Simpson* - **James Young Simpson**, a Scottish obstetrician, is credited with pioneering the use of **chloroform** as an anesthetic, particularly in childbirth. - His contributions were later than Morton's use of ether and involved a different anesthetic agent.
Question 2: Which anaesthetic agent has maximum MAC ?
- A. Ether
- B. Methoxyfluorane
- C. Halothane
- D. Nitrous Oxide (N2O) (Correct Answer)
Explanation: ***Nitrous Oxide (N2O)*** - **Nitrous Oxide** has the highest **minimum alveolar concentration (MAC)** of all commonly used inhalational anesthetics, approximately 104%. - A high MAC indicates **low potency**, meaning that a large concentration is required to achieve anesthetic effects. *Ether* - **Ether** has a MAC of about 1.92%, which is significantly lower than that of Nitrous Oxide. - Its use has largely been replaced due to its flammability, slow induction, and recovery times. *Methoxyfluorane* - **Methoxyfluorane** is known for having a very low MAC, around 0.16%, making it the most potent inhalational anesthetic. - Due to its high potency and significant nephrotoxicity, its use is now very limited. *Halothane* - **Halothane** has a MAC of approximately 0.75%. - While it was a widely used inhalational anesthetic, it has largely been replaced due to concerns about **halothane hepatitis** and arrhythmogenicity.
Question 3: Phase II block is seen with:
- A. SCh infusion (Correct Answer)
- B. Single dose SCh
- C. Mivacurium
- D. None of the options
Explanation: ***SCh infusion*** - A **prolonged infusion or high dose** of succinylcholine (SCh) can lead to a **Phase II block**, a desensitizing block resembling that of a non-depolarizing neuromuscular blocker. - This occurs due to the **persistent presence of SCh** at the neuromuscular junction, which initially depolarizes the endplate (Phase I) but eventually leads to **receptor desensitization** and repolarization, preventing further muscle contraction. *Single dose SCh* - A **single bolus dose of succinylcholine** typically produces a **Phase I block**, characterized by initial muscle fasciculations followed by flaccid paralysis due to persistent depolarization of the motor endplate. - It resolves relatively quickly as **succinylcholine is rapidly hydrolyzed** by pseudocholinesterase, usually not leading to a prolonged desensitization characteristic of Phase II. *Mivacurium* - **Mivacurium** is an intermediate-acting, **non-depolarizing neuromuscular blocker**. - Its mechanism of action involves **competitively binding to nicotinic acetylcholine receptors** at the neuromuscular junction, thereby preventing acetylcholine from binding and initiating muscle contraction, which is fundamentally different from a Phase II block caused by prolonged depolarization. *None of the options* - This option is incorrect because **SCh infusion** is a recognized cause of Phase II block. - The phenomenon of Phase II block is a well-established pharmacological response to **excessive and prolonged exposure** to depolarizing neuromuscular blockers like succinylcholine.
Question 4: What is the drug of choice for reversing muscle relaxants after anesthesia?
- A. Pralidoxine
- B. Neostigmine (Correct Answer)
- C. Atropine
- D. None of the options
Explanation: ***Neostigmine*** - **Neostigmine** is an **acetylcholinesterase inhibitor** that increases the amount of acetylcholine at the neuromuscular junction, thereby reversing the effects of non-depolarizing muscle relaxants. - It is often co-administered with an **anticholinergic agent** like atropine or glycopyrrolate to counteract its muscarinic side effects (e.g., bradycardia, increased secretions). *Pralidoxine* - **Pralidoxine (2-PAM)** is an **oxime cholinesterase reactivator** used primarily to treat organophosphate poisoning. - It works by regenerating acetylcholinesterase that has been inhibited by organophosphates, which is not the mechanism of action required for reversing typical muscle relaxants. *Atropine* - **Atropine** is an **anticholinergic drug** that blocks muscarinic acetylcholine receptors. - While it is often given with neostigmine to counteract muscarinic side effects like bradycardia, it does not directly reverse the neuromuscular blockade caused by muscle relaxants. *None of the options* - This option is incorrect because **neostigmine** is a well-established and commonly used drug for reversing non-depolarizing muscle relaxants.
Question 5: What is the primary clinical use of Sugammadex in anesthesia?
- A. Organophosphate poisoning
- B. Reversal of NM blockers (Correct Answer)
- C. Treatment of local anaesthetic poisoning
- D. Treatment of central anticholinergic syndrome
Explanation: ***Reversal of NM blockers*** - **Sugammadex** is a modified gamma-cyclodextrin that specifically encapsulates steroidal **neuromuscular blocking agents (NMBAs)** like **rocuronium** and **vecuronium**. - This encapsulation rapidly inactivates the NMBAs, leading to a dose-dependent and swift **reversal of neuromuscular blockade**. *Organophosphate poisoning* - Organophosphate poisoning is treated with **atropine** to block muscarinic effects and **pralidoxime** to reactivate inhibited acetylcholinesterase. - Sugammadex has no role in antagonizing the effects of **organophosphates** or regenerating acetylcholinesterase. *Treatment of local anaesthetic poisoning* - Local anesthetic systemic toxicity (LAST) is primarily managed with supportive care, including airway management, and the administration of **lipid emulsion therapy**. - Sugammadex does not bind to local anesthetics and therefore has no efficacy in treating local anesthetic poisoning. *Treatment of central anticholinergic syndrome* - Central anticholinergic syndrome is typically treated with **physostigmine**, an acetylcholinesterase inhibitor that can cross the blood-brain barrier. - Sugammadex is not an anticholinergic antagonist and does not affect the central nervous system to reverse anticholinergic effects.
Question 6: In which vein is Central Venous Pressure (CVP) most accurately monitored?
- A. Anterior jugular vein
- B. External jugular vein
- C. Inferior vena cava
- D. Internal jugular vein (Correct Answer)
Explanation: ***Internal jugular vein*** - The **internal jugular vein** provides the **most direct and consistent access** to the superior vena cava and right atrium, where CVP is accurately measured. - Its straight course and reliable anatomical landmarks make it a preferred site for CVP catheter insertion. *Anterior jugular vein* - The **anterior jugular vein** is smaller and often has a more tortuous course, making consistent and reliable CVP monitoring difficult. - It is not typically chosen for central venous access due to its anatomical variability and smaller caliber. *External jugular vein* - The **external jugular vein** is superficially located and easier to access but often has valves and a more oblique angle to the subclavian vein, making catheter advancement to the central circulation challenging. - Catheter tip placement is less consistent for accurate CVP measurements compared to the internal jugular vein. *Inferior vena cava* - While the **inferior vena cava** eventually drains into the right atrium, access is typically via the femoral vein, which is associated with a higher risk of infection and deep vein thrombosis for long-term CVP monitoring. - Measurements from the inferior vena cava or femoral vein can be affected by **intra-abdominal pressure** and are not as accurately reflective of right atrial pressure as those from the superior vena cava.
Question 7: Central venous monitoring is typically used for all of the following except:
- A. Administering thrombolytics (Correct Answer)
- B. Deciding the need for plasma infusion
- C. Deciding the requirement for blood transfusion
- D. Regulating the speed and amount of fluid infusion
Explanation: ***Administering thrombolytics*** - Central venous monitoring is a technique used to measure central venous pressure (CVP), which reflects right atrial pressure and indirectly **right ventricular preload**. It does not directly relate to the administration of **thrombolytics**. - Thrombolytics are typically administered intravenously through a peripheral or central line to dissolve clots, but CVP monitoring is not a prerequisite or a direct function of this administration. *Regulating the speed and amount of fluid infusion* - **Central venous pressure (CVP)** monitoring is crucial for assessing a patient's **fluid status** and guiding fluid resuscitation. - By continuously monitoring CVP, clinicians can determine whether to increase, decrease, or maintain the rate of **fluid infusion** to optimize cardiac preload without causing fluid overload. *Deciding the need for plasma infusion* - CVP values help assess **circulatory volume** and guide decisions on fluid replacement, including the need for **plasma infusion** in conditions like severe hypovolemia or coagulopathy. - A low CVP in a patient with bleeding or coagulation issues might indicate the need for volume expansion with **plasma**. *Deciding the requirement for blood transfusion* - **Low CVP** can indicate **hypovolemia**, which might be due to blood loss, thereby suggesting the need for a **blood transfusion**. - While not the sole determinant, CVP is one of several physiological parameters used to assess the urgency and amount of **blood products** required to restore circulating volume and oxygen-carrying capacity.
Question 8: What is the PRIMARY application of capnography during patient monitoring?
- A. Correct intubation (Correct Answer)
- B. Pulmonary embolism
- C. Adequate ventilation
- D. Significant metabolic change
Explanation: ***Correct intubation*** - Capnography is the **gold standard** for confirming **endotracheal tube (ETT) placement** by detecting carbon dioxide in exhaled breath. - A persistent waveform indicates the ETT is in the **trachea**, while absence suggests esophageal intubation. *Pulmonary embolism* - While capnography can show a **decrease in end-tidal CO2 (ETCO2)** due to increased dead space in pulmonary embolism, it is not its primary or most definitive diagnostic application. - Other diagnostic methods like CT pulmonary angiogram are preferred for confirming pulmonary embolism. *Adequate ventilation* - Capnography provides information about **ETCO2 levels**, which can indirectly reflect adequate ventilation by showing CO2 elimination. - However, it's more direct application is intubation confirmation, and other measures like **tidal volume** and **respiratory rate** are also crucial for assessing overall ventilation. *Significant metabolic change* - Capnography can show changes in CO2 production reflecting metabolic rate, such as in **hypermetabolic states** (e.g., fever, sepsis) or hypometabolic states. - While useful for monitoring trends, its primary role is not for diagnosing such changes but rather intubation confirmation.
Question 9: Which of the following is a characteristic of the Supreme Laryngeal Mask Airway (LMA)?
- A. Designed specifically for infants
- B. Utilizes high pressure, low volume cuff design
- C. Includes a built-in drain tube (Correct Answer)
- D. Does not have a bite block
Explanation: ***Includes a built-in drain tube*** - The **Supreme Laryngeal Mask Airway (LMA)** features an integrated **drain tube** to facilitate gastric decompression and reduce the risk of aspiration. - This design allows for the passage of a gastric tube, which can be useful during longer procedures or in patients with a higher risk of gastric content regurgitation. *Designed specifically for infants* - While LMAs are available in various sizes for all age groups, the **Supreme LMA** is not designed *specifically* for infants; it is a general-purpose LMA available in multiple sizes for different patient populations. - Other LMA types, such as the LMA Unique, are more commonly associated with a broader pediatric application. *Utilizes high pressure, low volume cuff design* - The **Supreme LMA** actually utilizes a **low pressure, high volume cuff** design, which helps contour to the perilaryngeal anatomy and minimizes pressure on mucosal tissues. - A high pressure, low volume cuff is associated with traditional endotracheal tubes and could lead to increased tissue ischemia if used with an LMA. *Does not have a bite block* - The **Supreme LMA** incorporates an **integrated bite block** within its design to prevent occlusion of the airway tube from patient biting. - This feature helps maintain airway patency and protects the LMA from damage, making it a key characteristic.
Question 10: Critical temperature of oxygen is?
- A. -118°C (Correct Answer)
- B. 400°C
- C. 20°C
- D. 36.5°C
Explanation: ***-118°C*** - The **critical temperature** is the temperature above which a gas cannot be liquefied, no matter how much pressure is applied. - For oxygen, its critical temperature is approximately **-118°C**, meaning it can only exist as a gas above this temperature, regardless of pressure. *400°C* - This temperature is significantly **above** the critical temperature of oxygen, so oxygen would always be a gas at this temperature. - It does not represent any specific physical property of oxygen in relation to its phase changes. *20°C* - This temperature is also well **above** oxygen's critical temperature, so oxygen would remain in its gaseous state. - This is approximately room temperature, where oxygen is commonly found as a gas. *36.5°C* - This is close to typical human body temperature and is far **above** the critical temperature of oxygen. - At this temperature, oxygen exists only as a gas.