INI-CET 2025 — Anesthesiology

Q: A 65-year-old patient is on mechanical ventilation for acute respiratory distress syndrome (ARDS). Suddenly, the patient becomes hypotensive, tachycardic, and shows absent breath sounds on the left side with tracheal deviation to the right. What is the most common cause of this in patients receiving mechanical ventilation?

Barotrauma due to high airway pressure. ***Barotrauma due to high airway pressure*** - The clinical triad (hypotension, tachycardia, absent breath sounds, and tracheal deviation) is highly suggestive of a **Tension Pneumothorax**. - In mechanically ventilated patients, high inspiratory pressures (**Barotrauma**) are the most common cause of alveolar rupture leading to air leakage and subsequent tension pneumothorax. *High tidal volume* - While high tidal volume can cause barotrauma, it is a **setting** (cause), not the most descriptive immediate mechanism of the complication (pneumothorax) itself. - The primary harm from high tidal volume is often considered **Volutrauma**, leading to ventilator-induced lung injury (VILI) over a longer duration. *Endotracheal tube malposition* - Tube malposition (e.g., slipped into the right bronchus) causes absent breath sounds, usually on the **left side**, but does not typically cause rapid onset **tension physiology** (hypotension and tracheal shift). - It is a relative common complication, but does not usually lead directly to clinical deterioration as severe as tension pneumothorax. *Oxygen toxicity* - This complication occurs due to prolonged exposure to high fractions of inspired oxygen (**FiO2**) and primarily causes diffuse alveolar damage, thickening of the alveolar-capillary membrane, and impairment of gas exchange. - It is a **chronic injury** and does not cause acute, life-threatening mechanical collapse like tension pneumothorax. [Practice more Anesthesiology PYQs on OnCourse]

Q: A 50-year-old male patient underwent lower abdominal surgery under general anaesthesia. Vecuronium was administered as a muscle relaxant during the procedure. At the end of the surgery, which of the following is the most appropriate agent to reverse the effects of vecuronium?

Neostigmine. ***Neostigmine*** - Neostigmine is an **acetylcholinesterase inhibitor** that increases the amount of acetylcholine at the neuromuscular junction, effectively reversing the competitive block caused by **non-depolarizing muscle relaxants** like vecuronium. - It is the standard pharmacological agent used for reversal of intermediate-acting neuromuscular blockades at the end of general anesthesia. *Baclofen* - Baclofen is a **centrally acting skeletal muscle relaxant** that works as a GABAB receptor agonist, typically used for managing **spasticity**. - It has no meaningful effect on the **nicotinic acetylcholine receptors** at the neuromuscular junction and cannot reverse the paralytic effects of vecuronium. *Atropine* - Atropine is an **anticholinergic agent** used to block the muscarinic side effects (e.g., bradycardia, hypersalivation) that occur when **neostigmine** is administered. - While often given concurrently with neostigmine, atropine itself **does not reverse** the skeletal muscle paralysis induced by vecuronium. *Drotaverine* - Drotaverine is a **smooth muscle antispasmodic** (PDE IV inhibitor) primarily used for conditions such as biliary or renal colic. - It targets smooth muscle and is entirely ineffective in reversing the **neuromuscular blockade** affecting skeletal muscles caused by vecuronium. [Practice more Anesthesiology PYQs on OnCourse]

Q: According to the Muir-Barclay formula, which of the following is considered the best colloid for volume replacement?

Albumin. ***Albumin*** - The **Muir-Barclay formula** relates to the effectiveness of colloids by considering various factors like viscosity, molecular weight, and oncotic pressure. - **Albumin** is considered the ideal colloid because it closely mimics the physiological properties of plasma and has the highest plasma volume expansion efficiency per unit of volume administered, according to the principles evaluated by this formula. ***Packed Red Blood Cells (PRBC)*** - PRBCs are used for improving oxygen-carrying capacity (treating anemia) and are **not classified as routine volume expanders (colloids)**. - PRBCs are indicated for significant **blood loss** or symptomatic anemia, not primarily for colloid-based volume resuscitation per the Muir-Barclay criteria. ***Fresh Frozen Plasma (FFP)*** - FFP is primarily used to replace **clotting factors** in patients with consumptive coagulopathy or massive transfusion, not typically as the best pure colloid for volume replacement. - While FFP contains albumin, its use for simple volume resuscitation is usually reserved for situations where **coagulation defects** are present. ***Dextran 40*** - Dextrans are synthetic colloids that can cause significant side effects, including **anaphylaxis** and potential **coagulopathy** (by coating platelets). - Its molecular weight profile and stability make it less favorable than albumin, and it is largely associated with a risk of **acute kidney injury** (osmotic nephrosis). [Practice more Anesthesiology PYQs on OnCourse]

3 Previous Year Questions with Answers & Explanations

Questions

A 65-year-old patient is on mechanical ventilation for acute respiratory distress syndrome (ARDS). Suddenly, the patient becomes hypotensive, tachycardic, and shows absent breath sounds on the left side with tracheal deviation to the right. What is the most common cause of this in patients receiving mechanical ventilation?

A 50-year-old male patient underwent lower abdominal surgery under general anaesthesia. Vecuronium was administered as a muscle relaxant during the procedure. At the end of the surgery, which of the following is the most appropriate agent to reverse the effects of vecuronium?

According to the Muir-Barclay formula, which of the following is considered the best colloid for volume replacement?

INI-CET 2025 - Anesthesiology INI-CET Practice Questions and MCQs

Question 1: A 65-year-old patient is on mechanical ventilation for acute respiratory distress syndrome (ARDS). Suddenly, the patient becomes hypotensive, tachycardic, and shows absent breath sounds on the left side with tracheal deviation to the right. What is the most common cause of this in patients receiving mechanical ventilation?

A. Barotrauma due to high airway pressure (Correct Answer)
B. Endotracheal tube malposition
C. Oxygen toxicity
D. High tidal volume

Explanation: ***Barotrauma due to high airway pressure*** - The clinical triad (hypotension, tachycardia, absent breath sounds, and tracheal deviation) is highly suggestive of a **Tension Pneumothorax**. - In mechanically ventilated patients, high inspiratory pressures (**Barotrauma**) are the most common cause of alveolar rupture leading to air leakage and subsequent tension pneumothorax. *High tidal volume* - While high tidal volume can cause barotrauma, it is a **setting** (cause), not the most descriptive immediate mechanism of the complication (pneumothorax) itself. - The primary harm from high tidal volume is often considered **Volutrauma**, leading to ventilator-induced lung injury (VILI) over a longer duration. *Endotracheal tube malposition* - Tube malposition (e.g., slipped into the right bronchus) causes absent breath sounds, usually on the **left side**, but does not typically cause rapid onset **tension physiology** (hypotension and tracheal shift). - It is a relative common complication, but does not usually lead directly to clinical deterioration as severe as tension pneumothorax. *Oxygen toxicity* - This complication occurs due to prolonged exposure to high fractions of inspired oxygen (**FiO2**) and primarily causes diffuse alveolar damage, thickening of the alveolar-capillary membrane, and impairment of gas exchange. - It is a **chronic injury** and does not cause acute, life-threatening mechanical collapse like tension pneumothorax.

Question 2: A 50-year-old male patient underwent lower abdominal surgery under general anaesthesia. Vecuronium was administered as a muscle relaxant during the procedure. At the end of the surgery, which of the following is the most appropriate agent to reverse the effects of vecuronium?

A. Baclofen
B. Neostigmine (Correct Answer)
C. Atropine
D. Drotaverine

Explanation: ***Neostigmine*** - Neostigmine is an **acetylcholinesterase inhibitor** that increases the amount of acetylcholine at the neuromuscular junction, effectively reversing the competitive block caused by **non-depolarizing muscle relaxants** like vecuronium. - It is the standard pharmacological agent used for reversal of intermediate-acting neuromuscular blockades at the end of general anesthesia. *Baclofen* - Baclofen is a **centrally acting skeletal muscle relaxant** that works as a GABAB receptor agonist, typically used for managing **spasticity**. - It has no meaningful effect on the **nicotinic acetylcholine receptors** at the neuromuscular junction and cannot reverse the paralytic effects of vecuronium. *Atropine* - Atropine is an **anticholinergic agent** used to block the muscarinic side effects (e.g., bradycardia, hypersalivation) that occur when **neostigmine** is administered. - While often given concurrently with neostigmine, atropine itself **does not reverse** the skeletal muscle paralysis induced by vecuronium. *Drotaverine* - Drotaverine is a **smooth muscle antispasmodic** (PDE IV inhibitor) primarily used for conditions such as biliary or renal colic. - It targets smooth muscle and is entirely ineffective in reversing the **neuromuscular blockade** affecting skeletal muscles caused by vecuronium.

Question 3: According to the Muir-Barclay formula, which of the following is considered the best colloid for volume replacement?

A. Fresh Frozen Plasma (FFP)
B. Packed Red Blood Cells (PRBC)
C. Dextran 40
D. Albumin (Correct Answer)

Explanation: ***Albumin*** - The **Muir-Barclay formula** relates to the effectiveness of colloids by considering various factors like viscosity, molecular weight, and oncotic pressure. - **Albumin** is considered the ideal colloid because it closely mimics the physiological properties of plasma and has the highest plasma volume expansion efficiency per unit of volume administered, according to the principles evaluated by this formula. ***Packed Red Blood Cells (PRBC)*** - PRBCs are used for improving oxygen-carrying capacity (treating anemia) and are **not classified as routine volume expanders (colloids)**. - PRBCs are indicated for significant **blood loss** or symptomatic anemia, not primarily for colloid-based volume resuscitation per the Muir-Barclay criteria. ***Fresh Frozen Plasma (FFP)*** - FFP is primarily used to replace **clotting factors** in patients with consumptive coagulopathy or massive transfusion, not typically as the best pure colloid for volume replacement. - While FFP contains albumin, its use for simple volume resuscitation is usually reserved for situations where **coagulation defects** are present. ***Dextran 40*** - Dextrans are synthetic colloids that can cause significant side effects, including **anaphylaxis** and potential **coagulopathy** (by coating platelets). - Its molecular weight profile and stability make it less favorable than albumin, and it is largely associated with a risk of **acute kidney injury** (osmotic nephrosis).