What is a significant disadvantage of ketamine?
Which of the following statements about Nitrous Oxide (N2O) is true?
Which of the following statements is NOT true regarding rapid induction of anesthesia?
Which drug is commonly used for emergency intubation?
Which of the following is not a sign of stellate ganglion block?
Which anesthetic agent is known for providing smooth induction?
Drug of choice for Bier's block ?
What is the definition of conscious sedation?
Which anaesthetic is contraindicated in renal failure?
Inhalational agent of choice for neurosurgery?
NEET-PG 2013 - Anesthesiology NEET-PG Practice Questions and MCQs
Question 21: What is a significant disadvantage of ketamine?
- A. Increased heart rate
- B. Increased ICT
- C. Delirium (Correct Answer)
- D. All of the options
Explanation: ***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.
Question 22: Which of the following statements about Nitrous Oxide (N2O) is true?
- A. Least potent inhalational anesthetic (Correct Answer)
- B. Lighter than air
- C. Effective muscle relaxant
- D. Does not cause diffusion hypoxia
Explanation: **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.
Question 23: Which of the following statements is NOT true regarding rapid induction of anesthesia?
- A. Suxamethonium is often used.
- B. Mechanical ventilation is typically avoided before intubation.
- C. Pre-oxygenation is mandatory
- D. Sellick's maneuver is always required. (Correct Answer)
Explanation: ***Sellick's maneuver is always required.*** - **Sellick's maneuver**, or cricoid pressure, is applied to compress the esophagus against the vertebrae, aiming to prevent **gastric regurgitation** and aspiration during rapid sequence intubation (RSI). - While historically considered a standard component of RSI, its routine use has been increasingly questioned due to a lack of strong evidence supporting its efficacy and potential to impede glottic visualization and intubation. It is not "always" required; its application is often at the discretion of the anesthetist based on patient factors and risk assessment. *Pre-oxygenation is mandatory* - **Pre-oxygenation** is a critical step in rapid sequence induction, involving administering 100% oxygen for several minutes prior to induction. - This denitrogenates the functional residual capacity (FRC), creating an oxygen reservoir that extends the safe apnea time, thus preventing **hypoxemia** during the intubation attempt. *Suxamethonium is often used.* - **Suxamethonium** (succinylcholine) is a depolarizing neuromuscular blocker primarily used in rapid sequence intubation due to its **ultra-rapid onset** (30-60 seconds) and short duration of action (5-10 minutes). - Its rapid action facilitates quick muscle relaxation for tracheal intubation, which is crucial for minimizing the risk of aspiration in patients with a full stomach or other risk factors. *Mechanical ventilation is typically avoided before intubation.* - During rapid sequence induction, **positive pressure ventilation** with a bag-valve mask is typically avoided before intubation to prevent gastric insufflation. - Gastric insufflation can increase the risk of **regurgitation** and pulmonary aspiration of gastric contents, which is a major concern in patients undergoing RSI.
Question 24: Which drug is commonly used for emergency intubation?
- A. None of the options
- B. Etomidate (Correct Answer)
- C. Propofol
- D. Ketamine
Explanation: ***Etomidate*** - Etomidate is a **short-acting nonbenzodiazepine hypnotic** often preferred for rapid sequence intubation (RSI) due to its minimal impact on **hemodynamic stability**. - It induces **rapid unconsciousness** with a quick onset and offset, making it suitable for emergency airway management in patients who are hemodynamically compromised. *Propofol* - Propofol is a **potent intravenous anesthetic** that can cause significant **hypotension** due to vasodilation and myocardial depression. - While it provides rapid onset of sedation and amnesia, its cardiovascular side effects make it less ideal for patients with **unstable hemodynamics** during emergency intubation. *Ketamine* - Ketamine is a **dissociative anesthetic** that causes a cataleptic state, amnesia, and analgesia, often leading to **bronchodilation** and cardiovascular stimulation. - While useful in patients with **reactive airway disease** or hypotension, it can increase intracranial pressure and may induce sympathetic stimulation, which might not be ideal for all emergency intubation scenarios. *None of the options* - This option is incorrect because **Etomidate is a commonly used drug** for emergency intubation, particularly where hemodynamic stability is a concern. - Other agents are also used but Etomidate is a clear clinical choice in many situations.
Question 25: 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 26: 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 27: Drug of choice for Bier's block ?
- A. Bupivacaine
- B. Etidocaine
- C. Ropivacaine
- D. Lidocaine (Correct Answer)
Explanation: ***Lidocaine*** - **Lidocaine** is the preferred local anesthetic for **Bier's block** (intravenous regional anesthesia) due to its rapid onset and good safety profile. - Its relatively short duration of action and **minimal cardiotoxicity** upon systemic release are favorable for this technique. *Bupivacaine* - **Bupivacaine** has a **longer duration of action** and is associated with a higher risk of **cardiotoxicity** when inadvertently delivered systemically, making it less suitable for Bier's block. - Its use in Bier's block is generally avoided due to the potential for significant adverse events if the tourniquet malfunctions or is released prematurely. *Etidocaine* - **Etidocaine** is a potent, **long-acting local anesthetic** with a similar toxicity profile to bupivacaine, making it less ideal for Bier's block. - Its prolonged action and higher potential for systemic toxicity make it less favorable for a procedure where rapid washout and lower systemic risk are desired. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic with a similar efficacy to bupivacaine but with a **lower potential for cardiotoxicity**. - While safer than bupivacaine, **lidocaine** is still generally preferred for Bier's block due to its established safety record, faster onset, and lower cost.
Question 28: What is the definition of conscious sedation?
- A. CNS depression with unconsciousness
- B. Sedation with inability to respond to verbal commands
- C. Sedation with ability to respond to verbal commands (Correct Answer)
- D. None of the options
Explanation: ***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**.
Question 29: Which anaesthetic is contraindicated in renal failure?
- A. Isoflurane
- B. Desflurane
- C. Halothane
- D. Methoxyflurane (Correct Answer)
Explanation: ***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.
Question 30: Inhalational agent of choice for neurosurgery?
- A. Halothane
- B. Enflurane
- C. Isoflurane (Correct Answer)
- D. N2O
Explanation: ***Isoflurane*** - **Isoflurane** is preferred in neurosurgery due to its minimal impact on **cerebral blood flow** and **intracranial pressure (ICP)**, allowing cerebral autoregulation to be largely preserved. - It maintains **cerebral perfusion pressure** well and has a relatively fast onset and offset, facilitating neurological assessment post-operatively. *Halothane* - **Halothane** significantly increases **cerebral blood flow** and **intracranial pressure (ICP)**, which is undesirable in neurosurgical patients. - Its slow elimination can prolong recovery and neurological assessment, making it unsuitable for neurosurgery. *Enflurane* - **Enflurane** can cause central nervous system excitation and has been associated with **seizure activity** at higher concentrations, making it contraindicated in neurosurgical procedures. - Like halothane, it can also increase **cerebral blood flow** and **intracranial pressure**. *N2O* - **Nitrous oxide (N2O)** should be avoided in neurosurgery, especially if there's a risk of **intracranial air** or **pneumocephalus**, as it can expand air-filled spaces and increase ICP. - It also has a weak anesthetic effect and is often combined with other agents, but its cerebral vasodilatory properties can still be problematic.