NEET-PG 2013

1544 Questions — Page 136 of 155

Anesthesiology

4 questions

Q1351

Which anesthetic agent is known for providing smooth induction?

Q1352

Which of the following is not a sign of stellate ganglion block?

Q1353

Which anesthetic agent is known for the fastest induction and recovery?

Q1354

Which inhalational agent has the least MAC?

NEET-PG 2013 - Anesthesiology NEET-PG Practice Questions and MCQs

Question 1351: Which anesthetic agent is known for providing smooth induction?

A. Halothane
B. Isoflurane (Correct Answer)
C. Enflurane
D. Sevoflurane

Explanation: ***Isoflurane*** - **Isoflurane** is frequently chosen for its capacity to induce a **smooth and rapid loss of consciousness**, primarily due to its low blood solubility which facilitates quick changes in anesthetic depth. - Its **minimal irritation** to the respiratory tract and **stable cardiovascular profile** during induction contribute to a smoother process for the patient. *Sevoflurane* - While sevoflurane also offers a **smooth and rapid induction** due to its low solubility, it is sometimes associated with a higher incidence of **airway irritation** (e.g., coughing) compared to isoflurane, especially in children. - It is known for its **pleasant odor**, making it a good choice for mask induction in pediatric patients. *Halothane* - **Halothane** provides a relatively smooth induction but has a higher risk of **hepatotoxicity** and cardiac arrhythmias, which have led to its decreased use. - Its higher blood solubility means a **slower onset and offset** compared to modern volatile agents like isoflurane. *Enflurane* - **Enflurane** can cause **CNS excitation** at deeper levels of anesthesia, potentially leading to seizures, making its induction less smooth and predictable. - It also has a greater potential to cause **myocardial depression** and arrhythmias than isoflurane.

Question 1352: Which of the following is not a sign of stellate ganglion block?

A. Miosis
B. Conjunctival redness
C. Nasal congestion
D. Exophthalmos (Correct Answer)

Explanation: ***Exophthalmos*** - A stellate ganglion block paralyses the **sympathetic nervous system** to the head and neck. - **Exophthalmos** (bulging of the eye) is a sign of sympathetic **hyperactivity**, not blockade. *Miosis* - **Miosis** (pupil constriction) is a classic sign of sympathetic blockade. - The **dilator pupillae muscle** is paralyzed, leading to unopposed parasympathetic action. *Nasal congestion* - **Nasal congestion** is a common sign due to the **vasodilation** of nasal blood vessels from sympathetic blockade. - Sympathetic nerves normally cause **vasoconstriction** in the nasal mucosa. *Conjunctival redness* - **Conjunctival redness** occurs due to **vasodilation** of conjunctival blood vessels, a direct effect of sympathetic blockade. - This is part of the **Horner's syndrome** presentation.

Question 1353: Which anesthetic agent is known for the fastest induction and recovery?

A. Halothane
B. Enflurane
C. Desflurane
D. N2O (Correct Answer)

Explanation: ***N2O*** - **Nitrous oxide** has a very **low blood-gas partition coefficient** (0.47), meaning it quickly saturates the blood and brain, leading to rapid induction and recovery. - Its **low solubility** allows for fast changes in anesthetic depth as it moves rapidly in and out of the bloodstream. *Desflurane* - While Desflurane also has a **low blood-gas partition coefficient** (0.42) and provides rapid induction and recovery, **N2O** is generally recognized as having the fastest kinetics. - Desflurane's volatility often requires a specialized heated vaporizer due to its **low boiling point**. *Halothane* - Halothane has a **higher blood-gas partition coefficient** (2.4) compared to N2O and desflurane, resulting in a slower induction and recovery time. - It is associated with potential **hepatotoxicity** (halothane hepatitis) and is no longer widely used. *Enflurane* - Enflurane has an intermediate **blood-gas partition coefficient** (1.9), making its induction and recovery slower than N2O, desflurane, and sevoflurane. - It can cause **seizures** at high concentrations and is also largely replaced by newer agents.

Question 1354: Which inhalational agent has the least MAC?

A. Halothane (Correct Answer)
B. Xenon
C. Sevoflurane
D. Isoflurane

Explanation: ***Halothane*** - **Halothane** has a **MAC** of approximately **0.75%**, which is among the lowest for commonly used volatile anesthetics. - A lower **MAC** indicates a higher potency, meaning a lower concentration is needed to achieve anesthetic effect. *Xenon* - **Xenon** has a **MAC** of approximately **71%**, making it one of the least potent inhalational agents. - It is an inert gas with unique anesthetic properties, but its high **MAC** is a key characteristic. *Sevoflurane* - **Sevoflurane** has a **MAC** of approximately **2.0%**, which is higher than halothane. - It is known for its rapid onset and offset due to its low blood solubility. *Isoflurane* - **Isoflurane** has a **MAC** of approximately **1.15%**, which is higher than halothane. - It is often favored for its cardiovascular stability and relatively low metabolism.

Dental

2 questions

Q1351

Percentage of adrenaline with lignocaine for local infiltration is?

Q1352

Which of the following is not commonly used for local infiltration anesthesia?

NEET-PG 2013 - Dental NEET-PG Practice Questions and MCQs

Question 1351: Percentage of adrenaline with lignocaine for local infiltration is?

A. 1:1000
B. 1:10000
C. 1:50000 (Correct Answer)
D. 1:200000

Explanation: ***1:50000*** - This concentration of **adrenaline (epinephrine)** is commonly used with **lignocaine (lidocaine)** for local infiltration to prolong the anesthetic effect and reduce bleeding. - At this concentration, adrenaline acts as a **vasoconstrictor**, decreasing systemic absorption of lignocaine and allowing a higher dose locally. *1:1000* - This concentration of adrenaline is typically used for the treatment of **anaphylaxis** and is considered too high for local infiltration with lignocaine. - Using such a high concentration locally can lead to severe **vasoconstriction**, tissue ischemia, and systemic side effects like **tachycardia** and **hypertension**. *1:10000* - This concentration is too strong for routine local infiltration and is usually reserved for **cardiac arrest** protocols or severe anaphylaxis when administered intravenously. - It would carry a significant risk of **tissue damage** and systemic effects if used for local infiltration. *1:200000* - While sometimes used, **1:50000** is generally the more common and effective concentration for achieving **hemostasis** and prolonging anesthesia during local infiltration. - A 1:200000 concentration provides a lesser degree of **vasoconstriction**, potentially leading to less prolonged local anesthetic effect and reduced bleeding control compared to 1:50000.

Question 1352: Which of the following is not commonly used for local infiltration anesthesia?

A. Lidocaine
B. Ropivacaine
C. Dibucaine (Correct Answer)
D. Bupivacaine

Explanation: ***Dibucaine*** - **Dibucaine** is a local anesthetic with a long duration of action but is rarely used for local infiltration due to its **high toxicity**. - Its narrow therapeutic index makes it less safe for common use compared to other available local anesthetics. *Lidocaine* - **Lidocaine** is one of the most widely used local anesthetics for **local infiltration** due to its rapid onset and intermediate duration of action. - It is effective for a variety of minor surgical procedures and dental interventions. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic commonly used for **local infiltration** and regional anesthesia due to its good safety profile and differential block. - It produces less motor block and has a lower potential for cardiotoxicity compared to bupivacaine. *Bupivacaine* - **Bupivacaine** is frequently used for **local infiltration** and regional anesthesia, especially when a longer duration of action is desired. - It is known for its prolonged sensory block but has a higher risk of **cardiac toxicity** compared to lidocaine.

Ophthalmology

1 questions

Q1351

The best local anesthetic for prolonged ophthalmic surgery requiring extended post-operative analgesia is:

Pharmacology

3 questions

Q1351

Which local anaesthetic is known to cause methemoglobinemia?

Q1352

In pseudocholinesterase deficiency, which drug should be used cautiously?

Q1353

In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?

NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs

Question 1351: Which local anaesthetic is known to cause methemoglobinemia?

A. Procaine
B. Prilocaine (Correct Answer)
C. Ropivacaine
D. Etidocaine

Explanation: ***Prilocaine*** - **Prilocaine** is metabolized into **ortho-toluidine**, which can oxidize hemoglobin to **methemoglobin**, especially at higher doses or in susceptible individuals. - **Methemoglobinemia** symptoms include **cyanosis**, **dyspnea**, and in severe cases, central nervous system depression, due to reduced oxygen-carrying capacity of blood. *Procaine* - **Procaine** is an ester-type local anesthetic. It is metabolized to **para-aminobenzoic acid (PABA)**, which can cause allergic reactions, but it is not associated with methemoglobinemia. - It has a relatively **short duration of action** and is less commonly used now compared to amide-type local anesthetics. *Etidocaine* - **Etidocaine** is an amide-type local anesthetic that is known for its **long duration of action** and high potency. - While it can cause systemic toxicity with high doses due to its cardiac and neurological effects, **methemoglobinemia** is not a characteristic side effect. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic similar to bupivacaine, known for its **motor-sparing effect** and use in regional anesthesia. - It is associated with a lower risk of **cardiotoxicity** compared to bupivacaine but does not cause methemoglobinemia.

Question 1352: In pseudocholinesterase deficiency, which drug should be used cautiously?

A. Succinylcholine (Correct Answer)
B. Barbiturates
C. Gallamine
D. Halothane

Explanation: ***Succinylcholine*** - **Succinylcholine** is primarily metabolized by **pseudocholinesterase** (also known as butyrylcholinesterase). - In individuals with **pseudocholinesterase deficiency**, the metabolism of succinylcholine is significantly delayed, leading to **prolonged neuromuscular blockade** and extended paralysis. *Barbiturates* - **Barbiturates** are mainly metabolized by the **hepatic cytochrome P450 system** and do not depend on pseudocholinesterase for their breakdown. - Their metabolism would not be significantly affected by pseudocholinesterase deficiency. *Halothane (an inhalational anesthetic)* - **Halothane** is primarily metabolized by the **hepatic cytochrome P450 system** and excreted via the lungs. - Its metabolism is unrelated to **pseudocholinesterase activity**. *Gallamine (a neuromuscular blocker)* - **Gallamine** is a **nondepolarizing neuromuscular blocker** that is primarily eliminated by **renal excretion** as an unchanged drug. - Its metabolism and elimination are independent of **pseudocholinesterase**.

Question 1353: In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?

A. Procaine
B. Cocaine
C. Prilocaine (Correct Answer)
D. Tetracaine

Explanation: **Local anesthetics are classified into two chemical groups: esters (aminoesters) and amides. Allergies to esters typically do not cross-react with amides.** ***Prilocaine*** - **Prilocaine** is an **amide-type local anesthetic**, and allergies to **aminoesters** typically do not cross-react with **amides**. - It is a safe alternative in patients with a known allergy to **ester-type local anesthetics**. *Cocaine* - **Cocaine** is an **ester-type local anesthetic**, sharing a similar chemical structure with **aminoesters**. - Patients allergic to **aminoesters** are likely to experience a **cross-reaction** with **cocaine**. *Procaine* - **Procaine** is a classic **ester-type local anesthetic** (an aminoester). - An allergy to aminoesters directly implies an allergy to **procaine** due to its chemical classification. *Tetracaine* - **Tetracaine** is also an **ester-type local anesthetic** (an aminoester). - It is contraindicated in patients with an allergy to **aminoesters** due to the high risk of **allergic reaction**.