NEET-PG 2015 Practice Questions

Q: Which anesthetic agent is safe to use in patients with elevated intracranial pressure (ICP)?

Thiopentone. ***Thiopentone*** - **Thiopentone** is a barbiturate that **decreases cerebral blood flow** and **metabolic rate**, leading to a reduction in intracranial pressure (ICP). - Its rapid onset and short duration of action make it suitable for inducing anesthesia in patients with elevated ICP. *Halothane* - **Halothane** is a potent **vasodilator** that can increase cerebral blood flow and consequently **elevate intracranial pressure**, making it unsuitable. - It also has a **slow onset and offset**, which can be problematic in emergent situations involving ICP. *Ketamine* - **Ketamine** is known to significantly **increase cerebral blood flow** and **intracranial pressure**, making it generally contraindicated in patients with elevated ICP. - It can also cause **dissociative states** and **emergence delirium**, which can further complicate neurological assessment. *Ether* - **Ether** is an older anesthetic agent known to cause **significant cerebral vasodilation** and an **increase in intracranial pressure**. - It is **highly flammable** and rarely used in modern clinical practice due to its side effects and safety profile.

Q: At the end of anaesthesia after discontinuation of nitrous oxide and removal of endotracheal tube, 100% oxygen is administered to the patient to prevent:

Diffusion Hypoxia. ***Diffusion Hypoxia*** - Post-anaesthesia administration of 100% oxygen prevents **diffusion hypoxia**, a phenomenon where **nitrous oxide** rapidly diffuses out of the blood into the alveoli, diluting alveolar oxygen and carbon dioxide. - This rapid outflow of nitrous oxide can lead to a significant drop in **partial pressure of oxygen** in the alveoli, causing hypoxemia if not counteracted with high inspired oxygen. *Second gas effect* - The **second gas effect** refers to the phenomenon where the rapid uptake of a highly soluble anesthetic (like nitrous oxide) accelerates the uptake of a co-administered less soluble anesthetic. - This is an effect related to the **induction phase** of anesthesia, not emergence, and is distinct from the issues arising from nitrous oxide washout. *Bronchospasm* - **Bronchospasm** is an acute constriction of the bronchioles, often triggered by irritants, allergens, or certain medications. - While it can occur during emergence from anesthesia, it is not directly prevented by administering 100% oxygen and is typically managed with bronchodilators. *Hyperoxia* - **Hyperoxia** is a condition of excess oxygen in the body, which can be detrimental, but it is not the primary concern immediately following the discontinuation of nitrous oxide. - Administering 100% oxygen in this context is a **controlled, short-term measure** to prevent a more immediate and severe issue (hypoxia) rather than causing chronic hyperoxia.

Q: Post dural puncture headache usually presents within ?

12-72 Hrs. ***12-72 Hrs*** - The onset of a **post-dural puncture headache (PDPH)** typically occurs within **12 to 72 hours** after the dural puncture. - This delay is thought to be related to the time it takes for significant **cerebrospinal fluid (CSF) leakage** and corresponding intracranial hypotension to develop. *0-6 Hrs* - Headaches presenting within this timeframe are less likely to be true **PDPH** as the typical latency period for significant CSF leakage and its symptomatic effects hasn't usually manifested. - Such early headaches might be due to other causes like **anxiety**, **dehydration**, or mild irritation from the procedure. *6-12 Hrs* - While possible, onset within this timeframe is less common than the 12-72 hour window for **classic PDPH**. - Moderate **CSF leakage** might lead to symptoms in some individuals, but the vast majority present later. *72-96 Hrs* - Although PDPH can persist for days or even weeks, its **onset** is significantly less common in this range. - A headache beginning this late may prompt consideration of other differential diagnoses, though late-onset PDPH is not unheard of.

Q: What is the composition of soda lime?

4% NaOH, 80% Ca(OH)2, trace elements, 15% H2O. ***4% NaOH, 80% Ca(OH)2, trace elements, 15% H2O*** - **Soda lime** is primarily composed of **calcium hydroxide (Ca(OH)2)**, typically around 80%, which acts as the main absorbent. - It also contains **sodium hydroxide (NaOH)**, around 4%, which serves as an activator, along with approximately 15% **water (H2O)** to facilitate the reaction, and **trace elements** like potassium hydroxide. *4% NaOH, 90% Ca(OH)2, 1% KOH, 5% H2O* - This option shows a higher percentage of **calcium hydroxide (90%)** and a lower percentage of **water (5%)** than the standard composition. - The reduced water content might impair the efficiency of **carbon dioxide absorption**. *4% NaOH, 80% Ca(OH)2, 1% KOH, 15% H2O* - While the percentages of NaOH, Ca(OH)2, and H2O are closer to correct, this option specifically mentions **potassium hydroxide (KOH)** as a distinct component at 1%, rather than general trace elements. - The standard composition usually encompasses trace elements more broadly, and specific percentages for KOH are not always highlighted as a primary component. *15% NaOH, 80% Ca(OH)2, trace elements, 4% H2O* - This composition incorrectly suggests a significantly higher percentage of **sodium hydroxide (15%)** and a critically low percentage of **water (4%)**. - A higher NaOH concentration can increase the risk of **carbon monoxide formation** from halogenated anesthetics, and inadequate water reduces absorptive capacity.

Q: Which of the following conditions is most commonly associated with cauda equina syndrome?

Herniated disc. ***Herniated disc*** - A **large central disc herniation**, especially at the L4-L5 or L5-S1 level, often compresses multiple nerve roots of the **cauda equina** [1]. - This compression leads to the characteristic symptoms of **saddle anesthesia**, **bowel/bladder dysfunction**, and **bilateral leg weakness**. *Trauma* - While **severe trauma** to the lumbar spine (e.g., fractures, dislocations) can cause cauda equina syndrome, it is a less common cause than disc herniation [1]. - Trauma typically involves an acute, high-energy injury, distinct from the more gradual onset seen with disc pathology. *Tumor* - **Spinal tumors**, both primary and metastatic, can compress the cauda equina, but they are relatively rare compared to disc herniations [1]. - Tumor-related cauda equina syndrome often presents with more insidious symptom progression and may include systemic symptoms or a history of malignancy. *Spinal stenosis* - **Spinal stenosis** can cause compression of nerve roots, typically leading to neurogenic claudication. - While severe stenosis can contribute to cauda equina symptoms, it generally involves diffuse narrowing over multiple levels and is less likely to cause acute, severe cauda equina syndrome than a single, large disc herniation.

Q: Which of the following is a long-acting local anesthetic?

Dibucaine. ***Dibucaine*** - **Dibucaine** is a **long-acting amide local anesthetic** with a duration of action up to 10 hours. - Its high **lipid solubility** contributes to its prolonged effect and greater potency compared to other local anesthetics. *Prilocaine* - **Prilocaine** is considered an **intermediate-duration amide local anesthetic**, with a duration of action typically 1-2 hours. - It carries a risk of **methemoglobinemia** at higher doses, which differentiates it from longer-acting agents. *Procaine* - **Procaine** is a **short-acting ester local anesthetic**, with a duration of action usually less than 1 hour. - It is known for its relatively **high allergenicity** due to its metabolism to para-aminobenzoic acid (PABA). *Lignocaine* - **Lignocaine (Lidocaine)** is an **intermediate-acting amide local anesthetic**, with a duration of action around 1-3 hours. - It is one of the most commonly used local anesthetics, but its duration is not as long as that of dibucaine.

Q: Suxamethonium primarily acts on which type of receptors?

Nicotinic acetylcholine receptors. ***Nicotinic acetylcholine receptors*** - **Suxamethonium** is a depolarizing muscle relaxant that acts as an **agonist at nicotinic acetylcholine receptors** at the neuromuscular junction. - This initial activation leads to muscle fasciculations followed by prolonged depolarization, causing **flaccid paralysis**. *Potassium channels* - While some drugs may affect potassium channels to alter neuronal excitability, suxamethonium's primary mechanism of action is not on these channels. - Blocking potassium channels is characteristic of drugs like **certain antiarrhythmics** or **sulfonylureas**. *Calcium channels* - **Calcium channels** play a role in muscle contraction, but they are not the primary target of suxamethonium. - Drugs like **dihydropyridines** (e.g., nifedipine) target calcium channels for their antihypertensive effects. *Chloride channels* - Chloride channels are involved in maintaining resting membrane potential and inhibitory neurotransmission. - Drugs such as **benzodiazepines** indirectly enhance GABA-mediated chloride influx, which is distinct from suxamethonium's action.

Q: Which of the following is not considered a contraindication for undergoing an MRI?

Ryle's tube. ***Ryle's tube*** - A **Ryle's tube** is a form of nasogastric tube made of radiopaque plastic, which is entirely **MRI-safe** and does not interact with magnetic fields. - It is made from inert materials that are **non-ferromagnetic**, posing no risk during an MRI scan. *Cardiac pacemaker* - **Cardiac pacemakers** contain metallic components that can malfunction, demagnetize, or migrate due to the strong magnetic fields and radiofrequency pulses of an MRI. - This can lead to **arrhythmias**, **pacemaker failure**, or **heating of leads**, posing a significant risk to the patient. *Cochlear implant* - **Cochlear implants** contain strong magnets and electronic components that can be damaged or displaced by the MRI's magnetic field. - This can cause **pain**, **implant damage**, or **hearing loss** for the patient. *Metallic splinter in eye* - A **metallic splinter in the eye** is a severe contraindication because the strong magnetic field can cause the metal fragment to move. - This movement can lead to **tissue damage**, **hemorrhage**, or **blindness** if it dislodges in the delicate structures of the eye.

Q: All are done to minimize radiation exposure to the patient under fluoroscopy, except which of the following?

Increasing fluoroscopic time. ***Increasing fluoroscopic time*** - **Increasing fluoroscopic time** directly leads to a greater cumulative dose of radiation received by the patient. - This action goes against the principle of **ALARA (As Low As Reasonably Achievable)** for radiation safety. *Decreasing fluoroscopic time* - **Decreasing fluoroscopic time** reduces the total duration of X-ray exposure, thereby minimizing the radiation dose to the patient. - This is a fundamental practice in radiation protection. *Using low dose of radiation* - Employing **low-dose radiation protocols** means using the minimum amount of radiation necessary to obtain diagnostic images. - This directly reduces the patient's exposure while maintaining image quality for diagnosis. *Decrease in field of view* - A **decrease in the field of view** (collimation) restricts the X-ray beam to only the area of interest, limiting irradiation of surrounding healthy tissues. - This targeted approach significantly reduces the overall radiation dose to the patient.

Q: Substance used for PET scan is

18F-FDG. ***18F-FDG*** - **18F-FDG (Fluorodeoxyglucose)** is a glucose analog labeled with a **positron-emitting radioisotope**, fluorine-18 (18F). - It is the most commonly used radiotracer in PET scans, as it accumulates in cells with high metabolic activity, particularly **cancer cells** and activated brain cells. *Gadolinium* - **Gadolinium** is a paramagnetic contrast agent primarily used in **MRI scans** to enhance the visualization of blood vessels and abnormal tissues. - It does not emit positrons and is therefore not suitable for PET imaging. *Gastrografin* - **Gastrografin** is an oral, water-soluble contrast agent containing **iodine**, typically used in **X-rays** and **CT scans** of the gastrointestinal tract. - It is not a radioactive tracer and has no application in PET imaging. *Iodine* - **Iodine** in various forms can be used as a contrast agent in **X-rays** and **CT scans**, or as a radioactive isotope (e.g., **I-131**) for **thyroid imaging** and treatment. - While some isotopes of iodine are radioactive, they are not typically used for PET imaging, which relies on positron emission.

Question 1

Which anesthetic agent is safe to use in patients with elevated intracranial pressure (ICP)?

Accepted Answer

Thiopentone

Answer

Halothane

Answer

Ketamine

Answer

Ether

Question 2

At the end of anaesthesia after discontinuation of nitrous oxide and removal of endotracheal tube, 100% oxygen is administered to the patient to prevent:

Accepted Answer

Diffusion Hypoxia

Answer

Second gas effect

Answer

Bronchospasm

Answer

Hyperoxia

Question 3

Post dural puncture headache usually presents within ?

Accepted Answer

12-72 Hrs

Answer

0-6 Hrs

Answer

6-12 Hrs

Answer

72-96 Hrs

Question 4

What is the composition of soda lime?

Accepted Answer

4% NaOH, 80% Ca(OH)2, trace elements, 15% H2O

Answer

4% NaOH, 90% Ca(OH)2, 1% KOH, 5% H2O

Answer

15% NaOH, 80% Ca(OH)2, trace elements, 4% H2O

Answer

4% NaOH, 80% Ca(OH)2, 1% KOH, 15% H2O

Question 5

Which of the following conditions is most commonly associated with cauda equina syndrome?

Accepted Answer

Herniated disc

Answer

Trauma

Answer

Tumor

Answer

Spinal stenosis

Question 6

Which of the following is a long-acting local anesthetic?

Accepted Answer

Dibucaine

Answer

Prilocaine

Answer

Procaine

Answer

Lignocaine

Question 7

Suxamethonium primarily acts on which type of receptors?

Accepted Answer

Nicotinic acetylcholine receptors

Answer

Potassium channels

Answer

Calcium channels

Answer

Chloride channels

Question 8

Which of the following is not considered a contraindication for undergoing an MRI?

Accepted Answer

Ryle's tube

Answer

Cardiac pacemaker

Answer

Cochlear implant

Answer

Metallic splinter in eye

Question 9

All are done to minimize radiation exposure to the patient under fluoroscopy, except which of the following?

Accepted Answer

Increasing fluoroscopic time

Answer

Decreasing fluoroscopic time

Answer

Using low dose of radiation

Answer

Decrease in field of view

Question 10

Substance used for PET scan is

Accepted Answer

18F-FDG

Answer

Gadolinium

Answer

Gastrografin

Answer

Iodine

NEET-PG 2015

Anesthesiology

Internal Medicine

Pharmacology

Radiology