NEET-PG 2013 - Anesthesiology Practice Questions

Q: Which of the following statements about Nitrous Oxide (N2O) is true?

Least potent inhalational anesthetic. **Least potent inhalational anesthetic** - Nitrous oxide has a **high Minimum Alveolar Concentration (MAC)** of approximately 104%, making it the least potent of the commonly used inhalational anesthetics. - Its high MAC means a very high concentration is required to achieve surgical anesthesia, which is why it is typically used as an adjunct to more potent agents. *Lighter than air* - The molecular weight of nitrous oxide (N2O) is 44, which is **heavier than air** (average molecular weight approximately 29 g/mol). - Its density is greater than air, meaning it would tend to sink rather than rise. *Effective muscle relaxant* - Nitrous oxide provides **minimal to no skeletal muscle relaxation** benefits. - If muscle relaxation is required, a neuromuscular blocking agent must be administered separately. *Does not cause diffusion hypoxia* - Nitrous oxide rapidly diffuses out of the blood into the alveoli during emergence, diluting the oxygen and carbon dioxide there. - This rapid diffusion can lead to **diffusion hypoxia** (also known as the "second gas effect"), necessitating the administration of 100% oxygen during recovery to prevent this complication.

Q: Which anaesthetic is contraindicated in renal failure?

Methoxyflurane. ***Methoxyflurane*** - Methoxyflurane undergoes significant **metabolism** to produce inorganic **fluoride ions**, which are directly **nephrotoxic**. - This nephrotoxicity can cause **high-output renal failure** with reduced concentrating ability, making it contraindicated in patients with pre-existing renal impairment. *Isoflurane* - Isoflurane is minimally metabolized and produces very low levels of **fluoride ions**, making it generally **safe** for use in patients with renal failure. - Its elimination is primarily via the **lungs**, with very little hepatic metabolism or renal excretion of active compounds. *Desflurane* - Desflurane is also minimally metabolized, similar to isoflurane, and therefore produces negligible amounts of **fluoride ions**. - It is considered a **safe option** for patients with renal impairment due to its predominantly pulmonary elimination and lack of nephrotoxic metabolites. *Halothane* - While halothane can cause **hepatotoxicity**, it is generally **not directly nephrotoxic** in the way methoxyflurane is. - Its metabolism, though more extensive than isoflurane or desflurane, does not produce clinically significant levels of nephrotoxic fluoride ions to contraindicate its use in renal failure.

Q: Intraocular pressure is increased by which anaesthetic?

Ketamine. ***Ketamine*** - **Ketamine** is known to increase **intraocular pressure (IOP)**, making it generally avoided in patients with glaucoma or penetrating eye injuries. - This effect is thought to be due to its dissociative properties, causing **nystagmus**, and stimulating extraocular muscles. *Nitrous Oxide* - **Nitrous oxide** by itself has minimal or no direct effect on **intraocular pressure (IOP)**. - However, in cases of an air-filled globe (e.g., after retinal detachment surgery), it can increase IOP by expanding the gas bubble. *Isoflurane* - **Isoflurane**, like most volatile anesthetics, typically **decreases intraocular pressure (IOP)**. - This reduction is generally due to its effects on reducing aqueous humor production and increasing uveoscleral outflow. *Propofol* - **Propofol** is known for its ability to **decrease intraocular pressure (IOP)**. - This effect is mediated by a reduction in aqueous humor production and an increase in uveoscleral outflow, making it a favorable choice in ophthalmic surgery.

Q: Regarding propofol, which one of the following statements is false?

It causes severe vomiting. ***It causes severe vomiting*** - Propofol is actually known for its **antiemetic properties**, meaning it helps *prevent* rather than cause nausea and vomiting. - This makes it a preferred anesthetic for procedures where **postoperative nausea and vomiting (PONV)** are a concern. *It is used as an intravenous induction agent* - **Propofol** is a widely used **intravenous anesthetic** for the **induction and maintenance of general anesthesia**. - It provides a rapid onset of unconsciousness due to its high lipid solubility. *It is painful on injecting intravenously* - Injection of propofol can often cause **pain at the injection site**, particularly when administered into smaller veins. - This pain can be mitigated by co-administering **lidocaine** or using larger veins. *It has no muscle relaxant property* - Propofol does **not possess intrinsic muscle relaxant properties**; patients require additional neuromuscular blocking agents for surgical relaxation. - It facilitates intubation by causing **loss of consciousness** and **reducing airway reflexes**, but does not directly relax skeletal muscles.

Q: Which anaesthetic drug contributes to green house effect?

Desflurane. **Desflurane** - **Desflurane** has the highest **global warming potential (GWP)** among commonly used volatile anesthetics, primarily due to its long atmospheric half-life and potent infrared absorption. - Its environmental impact is also amplified by its high **minimum alveolar concentration (MAC)** and low blood solubility, requiring higher delivered concentrations for anesthesia. *Enflurane* - **Enflurane** has a lower GWP compared to desflurane and is less commonly used in modern practice. - While it contributes to the greenhouse effect, its impact is significantly less than that of desflurane due to differences in chemical structure and atmospheric persistence. *Sevoflurane* - **Sevoflurane** has a relatively low GWP and a short atmospheric half-life compared to desflurane, making it a more environmentally friendly option among volatile anesthetics. - Although it still contributes to atmospheric warming, its overall environmental impact is considerably less than desflurane's. *Halothane* - **Halothane** is a potent greenhouse gas but is no longer used in many parts of the world due to concerns about hepatotoxicity and its significant ozone-depleting potential. - While it contributes to atmospheric warming, its current lack of clinical use limits its ongoing contribution to the greenhouse effect compared to currently utilized agents.

Q: What is the definition of conscious sedation?

Sedation with ability to respond to verbal commands. ***Sedation with ability to respond to verbal commands*** - Conscious sedation involves a drug-induced depression of consciousness during which the patient **retains the ability to respond purposefully to verbal commands**. - This level of sedation ensures that the patient's **airway reflexes** and **ventilatory function** remain intact. *CNS depression with unconsciousness* - This describes **general anesthesia** or **deep sedation**, where the patient is unable to respond purposefully to verbal commands. - In such states, spontaneous ventilation may be **inadequate**, and **airway support** is often required. *Sedation with inability to respond to verbal commands* - This definition aligns with **deep sedation** or **general anesthesia**, where the patient's consciousness is significantly depressed. - At this level, patients may require assistance in maintaining a **patent airway** and adequate ventilation. *None of the options* - This option is incorrect because one of the provided definitions accurately describes conscious sedation. - The definition of conscious sedation is well-established in clinical practice, emphasizing the **preservation of responsiveness**.

Q: Which of the following anesthetic agents is most notable for its analgesic properties?

Ketamine. ***Ketamine*** - **Ketamine** is unique among general anesthetics for its significant **analgesic properties**, which stem from its action as an **NMDA receptor antagonist**. - Its ability to provide pain relief makes it useful in scenarios where both **anesthesia** and **analgesia** are desired, such as for painful procedures or in trauma settings. *Propofol* - While **propofol** is a widely used intravenous anesthetic, it lacks intrinsic **analgesic properties**. Its primary effects are **sedation** and **hypnosis**. - Pain during propofol injection is common, and other analgesics are usually co-administered for painful procedures. *Thiopentone* - **Thiopentone** is an ultrashort-acting barbiturate primarily used for **induction of anesthesia** due to its rapid onset and profound hypnotic effects. - It has **no analgesic properties** and can even lower the pain threshold, requiring concurrent administration of analgesics.

Q: Circuit of choice for controlled ventilation ?

Type D. **Type D** - The **Type D circuit** (also known as the **Bain circuit** or a modified Mapleson D circuit) is highly efficient for **controlled ventilation** due to its fresh gas flow entering near the patient, effectively sweeping away exhaled gases. - Its design maintains a relatively constant **expiratory resistance**, making it suitable for precise control of ventilation parameters. *Magill circuit* - The **Magill circuit** (Mapleson A) is efficient for **spontaneous ventilation** but requires a high fresh gas flow to prevent rebreathing during controlled ventilation. - During controlled ventilation, a high minute volume is required to flush out expired gases efficiently, which can be wasteful of anesthetic agents. *Type C* - The **Type C circuit** (Mapleson C circuit) is a simple system useful for **resuscitation** and short procedures but is inefficient for prolonged controlled ventilation. - It has a high resistance to gas flow and a tendency for significant rebreathing during both spontaneous and controlled breathing, leading to high CO2 levels. *Type E* - The **Type E circuit** (Mapleson E circuit) is a basic T-piece system, primarily used for **spontaneous breathing in infants and children**. - It lacks a reservoir bag and adjustable pressure limiting valve, making it unsuitable for controlling ventilation effectively in adults.

Q: Critical temperature for liquid nitrogen is ?

-147°C. ***-147°C*** - The **critical temperature** is the temperature above which a gas cannot be liquefied, no matter how much pressure is applied. For **liquid nitrogen**, this value is approximately **-147°C**. - At temperatures above **-147°C**, nitrogen exists only in its gaseous phase. *36.5°C* - This temperature is close to **human body temperature** and is not relevant to the critical temperature of nitrogen. - Nitrogen would be in a gaseous state at this temperature and below its critical pressure. *-20°C* - While a low temperature, **-20°C** is still well above nitrogen's **critical temperature**. - At **-20°C**, nitrogen would be a gas unless subjected to very high pressures. *-242°C* - This temperature is below the **critical temperature** of nitrogen, but it is also below its **boiling point** of **-196°C**. - At **-242°C**, nitrogen would be a liquid, but this value is not its critical temperature.

Q: What is the PRIMARY application of capnography during patient monitoring?

Correct intubation. ***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 1

Which of the following statements about Nitrous Oxide (N2O) is true?

Accepted Answer

Least potent inhalational anesthetic

Answer

Lighter than air

Answer

Effective muscle relaxant

Answer

Does not cause diffusion hypoxia

Question 2

Which anaesthetic is contraindicated in renal failure?

Accepted Answer

Methoxyflurane

Answer

Isoflurane

Answer

Desflurane

Answer

Halothane

Question 3

Intraocular pressure is increased by which anaesthetic?

Accepted Answer

Ketamine

Answer

Nitrous Oxide

Answer

Isoflurane

Answer

Propofol

Question 4

Regarding propofol, which one of the following statements is false?

Accepted Answer

It causes severe vomiting

Answer

It is painful on injecting intravenously

Answer

It has no muscle relaxant property

Answer

It is used as an intravenous induction agent

Question 5

Which anaesthetic drug contributes to green house effect?

Accepted Answer

Desflurane

Answer

Enflurane

Answer

Sevoflurane

Answer

Halothane

Question 6

What is the definition of conscious sedation?

Accepted Answer

Sedation with ability to respond to verbal commands

Answer

CNS depression with unconsciousness

Answer

Sedation with inability to respond to verbal commands

Answer

None of the options

Question 7

Which of the following anesthetic agents is most notable for its analgesic properties?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Propofol

Answer

None of the options

Question 8

Circuit of choice for controlled ventilation ?

Accepted Answer

Type D

Answer

Magill circuit

Answer

Type C

Answer

Type E

Question 9

Critical temperature for liquid nitrogen is ?

Accepted Answer

-147°C

Answer

36.5°C

Answer

-20°C

Answer

-242°C

Question 10

What is the PRIMARY application of capnography during patient monitoring?

Accepted Answer

Correct intubation

Answer

Pulmonary embolism

Answer

Adequate ventilation

Answer

Significant metabolic change

NEET-PG 2013 — Anesthesiology