NEET-PG 2015 Practice Questions

Q: Laryngeal mask airway [LMA] is contraindicated in?

Pregnant female. ***Pregnant female*** - **Pregnant patients** are at an increased risk of **gastric reflux and aspiration pneumonitis** due to decreased lower esophageal sphincter tone and increased intra-abdominal pressure. - The LMA does not provide a secure airway seal against aspiration, making it contraindicated in cases where **aspiration risk is high**, such as pregnancy or full stomach. *Difficult airways* - The LMA is often considered a **rescue device** in difficult airway algorithms when tracheal intubation fails. - It can be used as a conduit for **fiberoptic intubation** or as a temporary airway while preparing for a definitive airway. *Ocular surgeries* - LMAs are generally suitable for ocular surgeries as they provide a stable airway without the use of a mask, which can obstruct the surgical field. - They tend to cause **less coughing and straining** upon insertion and maintenance compared to endotracheal tubes, which is beneficial in preventing increases in intraocular pressure. *In CPR* - The LMA can be an effective airway device during **cardiopulmonary resuscitation (CPR)** when endotracheal intubation is not immediately feasible. - It provides a relatively quick and easy way to establish an airway, facilitate ventilation, and reduce the risk of gastric insufflation during chest compressions.

Q: Which one of the following agents sensitizes the myocardium to catecholamines?

Halothane. ***Halothane*** - **Halothane** sensitizes the myocardium to the arrhythmogenic effects of **catecholamines**, leading to an increased risk of ventricular arrhythmias, especially in the presence of exogenous adrenaline. - This sensitization occurs due to its effect on myocardial **calcium ion** regulation and increased automaticity in cardiac pacemaker cells. *Isoflurane* - **Isoflurane** causes minimal sensitization of the myocardium to catecholamines compared to halothane. - It maintains **cardiac output** with a dose-dependent decrease in systemic vascular resistance. *Ether* - **Diethylether** historically caused sympathetic stimulation, which could mask some depressant effects but did not primarily sensitize the myocardium to arrhythmias from exogenous catecholamines. - Its use has largely been replaced due to its flammability and slower induction/recovery. *Propofol* - **Propofol** generally causes myocardial depression and vasodilation, but it does **not sensitize** the myocardium to catecholamines in a clinically significant way that increases arrhythmogenic risk. - It often leads to a decrease in **blood pressure** and heart rate.

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: What type of respiratory failure is most commonly observed in post-operative patients?

Hypoxemic respiratory failure. ***Hypoxemic respiratory failure*** - **Hypoxemic respiratory failure** (Type I) is characterized by a **PaO2 less than 60 mmHg** with a normal or low PaCO2, often due to **V/Q mismatch** and **shunt**. - Post-operative patients frequently develop **atelectasis**, **pneumonia**, or **pulmonary edema**, leading to impaired gas exchange and reduced oxygenation. - This is the **most commonly observed type** in the immediate post-operative period. *Hypercapnic respiratory failure* - **Hypercapnic respiratory failure** (Type II) is primarily due to **alveolar hypoventilation**, resulting in a **PaCO2 greater than 50 mmHg**. - While it can occur post-operatively, it is less common than hypoxemic failure and is typically seen with significant **sedation**, **neuromuscular blockade**, or severe **obstructive lung disease**. *Mixed respiratory failure* - **Mixed respiratory failure** involves both **hypoxemia** and **hypercapnia**, indicating severe impairment in both oxygenation and ventilation. - Although it can occur in severe post-operative complications, it is not the *most commonly observed initial presentation* compared to isolated hypoxemia. *Perioperative respiratory failure* - **Perioperative respiratory failure** (Type III) occurs specifically in the surgical setting and involves atelectasis from changes in chest wall mechanics. - While this occurs in the post-operative context, the term is less commonly used, and the **underlying mechanism is primarily hypoxemic** in nature.

Question 1

Laryngeal mask airway [LMA] is contraindicated in?

Accepted Answer

Pregnant female

Answer

Ocular surgeries

Answer

Difficult airways

Answer

In CPR

Question 2

Which one of the following agents sensitizes the myocardium to catecholamines?

Accepted Answer

Halothane

Answer

Isoflurane

Answer

Ether

Answer

Propofol

Question 3

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

Accepted Answer

Thiopentone

Answer

Halothane

Answer

Ketamine

Answer

Ether

Question 4

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 5

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 6

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 7

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 8

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

Accepted Answer

Dibucaine

Answer

Prilocaine

Answer

Procaine

Answer

Lignocaine

Question 9

Suxamethonium primarily acts on which type of receptors?

Accepted Answer

Nicotinic acetylcholine receptors

Answer

Potassium channels

Answer

Calcium channels

Answer

Chloride channels

Question 10

What type of respiratory failure is most commonly observed in post-operative patients?

Accepted Answer

Hypoxemic respiratory failure

Answer

Hypercapnic respiratory failure

Answer

Mixed respiratory failure

Answer

Perioperative respiratory failure

NEET-PG 2015

Anesthesiology

Orthopaedics

Pharmacology

Surgery