NEET-PG 2012 - Anesthesiology Practice Questions

Q: Which anaesthetic agent is neither metabolised by liver nor by kidney?

Atracurium. ***Atracurium*** - **Atracurium** undergoes **Hofmann elimination**, a non-enzymatic chemical degradation in plasma, and also **ester hydrolysis** by non-specific plasma esterases [2]. - This unique metabolism makes its elimination largely independent of **liver** and **kidney function**, making it a good choice for patients with organ dysfunction [2]. *Vecuronium* - Primarily metabolized by the **liver** into active and inactive metabolites [1]. - Its elimination can be prolonged in patients with **hepatic impairment** [1]. *Pancuronium* - Undergoes significant **hepatic metabolism** and subsequent **renal excretion** of both parent drug and metabolites [1]. - Its duration of action is significantly affected by both **liver** and **kidney dysfunction** [1]. *Rocuronium* - Primarily eliminated unchanged via **biliary excretion** (liver) [1]. - Its duration of action is prolonged in patients with **hepatic impairment** [1].

Q: What is the critical temperature of Nitrous Oxide (N2O)?

-36.5°C. **-36.5°C** - The **critical temperature** of **nitrous oxide (N2O)** is **36.5°C**, which is the temperature above which it cannot be liquefied by pressure alone. - This value is important for understanding the **physical state** and safe handling of N2O, as deviations can lead to phase changes or storage issues. *-118°C* - This temperature is significantly lower than the actual critical temperature of N2O and is incorrect. - This value might be related to the **boiling point of other gases** but not the critical temperature of N2O. *-36°C* - While close, **-36°C** is not the precise critical temperature for nitrous oxide. - This small difference can be significant in contexts requiring **exact physical properties** of gases. *-30°C* - This temperature is incorrect and is higher than the actual critical temperature of N2O. - At this temperature, N2O would still behave as a **liquefiable gas** under sufficient pressure, indicating it is below its critical point.

Q: Fast induction and recovery is seen in?

N2O. ***N2O*** - **Nitrous oxide (N2O)** has a very **low blood-gas partition coefficient**, meaning it rapidly equilibrates between the alveolar gas and blood. - This rapid equilibration leads to a **fast onset of anesthetic action** (induction) and quick elimination from the body (recovery). *methoxyflurane* - **Methoxyflurane** has a **high blood-gas partition coefficient**, which means it has high solubility in blood. - This high solubility leads to **slow induction and prolonged recovery** as more anesthetic needs to be dissolved and then eliminated from the blood. *ether* - **Diethyl ether** also has a relatively **high blood-gas partition coefficient**, resulting in slow induction and recovery. - Its high solubility in blood and tissues means it takes longer to achieve and then dissipate its anesthetic effect. *halothane* - **Halothane** has a **moderate blood-gas partition coefficient**, leading to a slower induction and recovery compared to N2O. - While faster than methoxyflurane or ether, its solubility is still significant enough to delay its onset and offset.

Q: Cocaine was first used as a local anesthetic by?

Carl Koller. ***Carl Koller*** - **Carl Koller** (1857-1944), an Austrian ophthalmologist, is credited with the first clinical use of cocaine as a local anesthetic in 1884. - He demonstrated its efficacy for topical anesthesia in eye surgery, revolutionizing surgical practices. *Holmer Wells* - **Horace Wells** (not Holmer) was an American dentist who pioneered the use of **nitrous oxide** as an anesthetic in dentistry in the 1840s, preceding Koller's work with cocaine. - His contributions were focused on general anesthesia for pain relief during tooth extractions. *Morton* - **William T.G. Morton** was another American dentist who famously demonstrated the use of **ether** as a surgical anesthetic in 1846. - His work popularized surgical anesthesia, but it was not related to cocaine as a local anesthetic. *None of the options* - This option is incorrect because Carl Koller is historically recognized as the pioneer for the clinical use of **cocaine as a local anesthetic**.

Q: Which of the following is NOT a contraindication for spinal anaesthesia?

Hypertension. ***Hypertension*** - While **severe uncontrolled hypertension** may necessitate blood pressure stabilization before surgery, **mild to moderate hypertension** is not an absolute contraindication for spinal anesthesia. - In fact, spinal anesthesia can sometimes be beneficial in hypertensive patients due to its **vasodilatory effects**, which may help lower blood pressure. *Bleeding disorder* - A **bleeding disorder** (e.g., thrombocytopenia, coagulopathy) is a **major contraindication** due to the high risk of **epidural or spinal hematoma** formation. - A hematoma can lead to **spinal cord compression** and irreversible neurological damage. *Raised intracranial tension* - **Raised intracranial tension (ICT)** is a **strict contraindication** because the drop in cerebrospinal fluid (CSF) pressure during spinal anesthesia can worsen the pressure gradient across the foramen magnum. - This can precipitate **herniation of the brainstem** and lead to catastrophic neurological injury or death. *Infection at injection site* - The presence of an **infection at the injection site** is an absolute contraindication as it poses a significant risk of introducing bacteria into the **subarachnoid space**. - This can lead to serious complications such as **meningitis** or a **spinal abscess**.

Q: Which of the following cannot be given by epidural anaesthesia?

Remifentanil. ***Remifentanil*** - **Remifentanil** is specifically designed for **intravenous administration** and is rapidly metabolized by plasma esterases, making it unsuitable for epidural use. - Due to its short half-life and rapid metabolism, epidural administration would provide inconsistent and fleeting analgesia, and its breakdown products are not inert in the epidural space, potentially causing **neurotoxicity**. *Morphine* - **Morphine** is a commonly used opioid for **epidural analgesia** due to its hydrophilicity, allowing for prolonged action in the cerebrospinal fluid. - It provides effective **postoperative pain relief** and has a relatively slow onset but long duration of action when administered epidurally. *Alfentanil* - **Alfentanil** is a synthetic opioid that has been used for **epidural analgesia**, though less commonly than fentanyl or sufentanil, sometimes in conjunction with local anesthetics. - It has a faster onset and shorter duration of action compared to morphine, but still provides effective **analgesia** when administered epidurally. *Fentanyl* - **Fentanyl** is a widely used lipophilic opioid for **epidural analgesia**, often combined with local anesthetics, for both surgical and obstetric pain. - Its lipophilicity allows for rapid absorption and a relatively quick onset of action, providing effective **segmental analgesia**.

Q: What does the Dibucaine number indicate in clinical practice?

Atypical acetylcholinesterase activity. ***Atypical acetylcholinesterase activity*** - The **Dibucaine number** quantifies the inhibition of **pseudocholinesterase (butyrylcholinesterase)** by the local anesthetic dibucaine. - A low Dibucaine number (e.g., < 20-30) indicates a genetically determined **atypical variant** of pseudocholinesterase, leading to prolonged duration of action of drugs like succinylcholine. *Potency of muscle relaxants* - The potency of muscle relaxants is typically assessed by the **ED95**, which is the dose required to produce 95% suppression of twitch response. - While Dibucaine is a local anesthetic that can cause muscle relaxation, the **Dibucaine number** specifically evaluates an enzyme's activity, not the strength of the relaxant itself. *Potency of general anesthetics* - The potency of general anesthetics is primarily measured by the **Minimum Alveolar Concentration (MAC)** required to prevent movement in 50% of patients in response to a noxious stimulus. - The Dibucaine number is unrelated to the mechanism or potency of general anesthetic agents. *None of the options* - This option is incorrect because **Atypical acetylcholinesterase activity** accurately describes what the Dibucaine number indicates. - The Dibucaine number is a specific laboratory test used to identify genetic variations in butyrylcholinesterase, which has significant clinical implications for drug metabolism.

Q: Calcium homeostasis disturbance is the predominant pathophysiological mechanism in

Malignant hyperthermia. ***Malignant hyperthermia*** - Malignant hyperthermia is caused by a genetic defect in the **ryanodine receptor (RYR1)** in skeletal muscle, leading to an uncontrolled release of **intracellular calcium** from the sarcoplasmic reticulum. - This excessive calcium release results in sustained muscle contraction, increased metabolism, and a rapid rise in body temperature. *Duchenne Muscular Dystrophy (DMD)* - DMD is primarily caused by a mutation in the **dystrophin gene**, which leads to the absence or severe deficiency of the **dystrophin protein**. - This deficiency results in muscle fiber fragility, cycles of degeneration and regeneration, and eventual replacement of muscle with fibrous and fatty tissue, rather than a primary calcium homeostasis disturbance. *Limb Girdle Muscular Dystrophy* - This group of disorders is characterized by progressive weakness and wasting of muscles, primarily affecting the **shoulders and hips**. - The pathophysiology involves genetic defects in various proteins that are crucial for muscle function and integrity, such as **sarcoglycans** or **calpain-3**, not primarily calcium dysregulation. *Tibial Muscular Dystrophy* - Tibial muscular dystrophy is a rare, late-onset disorder characterized by progressive weakness of the **anterior tibial muscles**. - It is typically caused by mutations in the **TTN gene**, encoding for the protein **titin**, which plays a vital role in muscle elasticity and structural integrity, rather than a primary calcium imbalance.

Q: What is a significant disadvantage of ketamine?

Delirium. ***Delirium*** - Ketamine is known to cause **emergence phenomena**, which include **vivid dreams, hallucinations**, and **delirium**, particularly during recovery from anesthesia. - This psychotomimetic effect can be distressing for patients and may necessitate the co-administration of a **benzodiazepine** to mitigate these symptoms. *Increased heart rate* - While ketamine does cause an **increase in heart rate** and **blood pressure** due to sympathetic stimulation, this is often considered a disadvantage but not the *most significant* when compared to the unique cognitive side effects. - This effect can be beneficial in patients with **hemodynamic instability**, but can be problematic in those with **cardiovascular disease**. *Increased ICT* - It is often considered a contraindication in patients with **elevated intracranial pressure (ICP)** as it can potentially increase **cerebral blood flow** and thus ICP. - However, recent studies suggest that in adequately ventilated patients, the effect on ICP may be less pronounced than previously thought, making delirium a more consistent and prominent disadvantage for many patients. *All of the options* - While ketamine can cause an **increased heart rate** and potentially affect **intracranial pressure**, **delirium** and other emergence phenomena are often highlighted as a unique and significant disadvantage because they are highly distressing and difficult to manage. - The psychotomimetic effects are a hallmark side effect that often governs its cautious use without concurrent medication.

Q: Which of the following local anesthetics has the highest maximum concentration allowed for epidural block?

Chlorprocaine. ***Chlorprocaine*** - **Chlorprocaine** is an ester-type local anesthetic that can be safely used in higher concentrations for epidural blocks up to **3%**, due to its rapid hydrolysis by plasma pseudocholinesterase, leading to a very short half-life and reduced systemic toxicity. - Its rapid metabolism minimizes the risk of accumulation and systemic toxicity, making it a suitable choice when a dense block is needed and a short duration of action is acceptable. *Lidocaine* - **Lidocaine** is an amide-type local anesthetic commonly used in epidural blocks, but its maximum concentration for this application is typically limited to **2%** to avoid systemic toxicity. - Higher concentrations of lidocaine are associated with an increased risk of neurological and cardiovascular adverse effects. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic that is less cardiotoxic than bupivacaine, with common concentrations for epidural use ranging from **0.2% to 1%**. - Its maximum concentration is significantly lower than chlorprocaine due to its longer duration of action and potential for systemic toxicity at higher doses. *Bupivacaine* - **Bupivacaine** is a potent amide-type local anesthetic with a high risk of cardiotoxicity, and its maximum concentration for epidural use is generally restricted to **0.5%** or even less for continuous infusions. - Using concentrations above this limit significantly increases the risk of severe cardiovascular complications, including arrhythmias and cardiac arrest.

Question 1

Which anaesthetic agent is neither metabolised by liver nor by kidney?

Accepted Answer

Atracurium

Answer

Vecuronium

Answer

Pancuronium

Answer

Rocuronium

Question 2

What is the critical temperature of Nitrous Oxide (N2O)?

Accepted Answer

-36.5°C

Answer

-118°C

Answer

-36°C

Answer

-30°C

Question 3

Fast induction and recovery is seen in?

Accepted Answer

N2O

Answer

Methoxyflurane

Answer

Ether

Answer

Halothane

Question 4

Cocaine was first used as a local anesthetic by?

Accepted Answer

Carl Koller

Answer

Holmer Wells

Answer

Morton

Answer

None of the options

Question 5

Which of the following is NOT a contraindication for spinal anaesthesia?

Accepted Answer

Hypertension

Answer

Raised intracranial tension

Answer

Bleeding disorder

Answer

Infection at injection site

Question 6

Which of the following cannot be given by epidural anaesthesia?

Accepted Answer

Remifentanil

Answer

Morphine

Answer

Alfentanil

Answer

Fentanyl

Question 7

What does the Dibucaine number indicate in clinical practice?

Accepted Answer

Atypical acetylcholinesterase activity

Answer

Potency of muscle relaxants

Answer

Potency of general anesthetics

Answer

None of the options

Question 8

Calcium homeostasis disturbance is the predominant pathophysiological mechanism in

Accepted Answer

Malignant hyperthermia

Answer

Duchenne Muscular Dystrophy (DMD)

Answer

Limb Girdle Muscular Dystrophy

Answer

Tibial Muscular Dystrophy

Question 9

What is a significant disadvantage of ketamine?

Accepted Answer

Delirium

Answer

Increased heart rate

Answer

Increased ICT

Answer

All of the options

Question 10

Which of the following local anesthetics has the highest maximum concentration allowed for epidural block?

Accepted Answer

Chlorprocaine

Answer

Lidocaine

Answer

Ropivacaine

Answer

Bupivacaine

NEET-PG 2012 — Anesthesiology