Respiratory and Airway Management Practice Questions

Q: Who developed the Laryngeal Mask Airway (LMA) ProSeal?

Brain. **Explanation:** The **Laryngeal Mask Airway (LMA)** and its subsequent variations, including the **LMA ProSeal**, were developed by **Dr. Archie Brain**, a British anesthesiologist. He introduced the classic LMA in 1981 (commercially available in 1988), revolutionizing airway management by bridging the gap between a face mask and an endotracheal tube. The **LMA ProSeal**, introduced in 2000, is a second-generation supraglottic airway device (SAD) featuring a gastric drainage tube and a modified cuff to allow for higher seal pressures, making it suitable for controlled ventilation. **Analysis of Incorrect Options:** * **Bailey:** Known for the "Bailey Maneuver," which involves exchanging an endotracheal tube for an LMA at the end of surgery to allow for a "deep" emergence and minimize coughing/bucking. * **Macewan:** William Macewan was a pioneer in anesthesia known for performing the first recorded endotracheal intubation using a flexible metal tube (introducer) in 1878. * **Magill:** Sir Ivan Magill was a legendary anesthesiologist who developed the Magill forceps, the Magill circuit (Mapleson A), and standardized wide-bore endotracheal tubes. **High-Yield Clinical Pearls for NEET-PG:** * **LMA ProSeal vs. Classic:** The ProSeal has a **gastric port** (to vent air/drain gastric contents) and a **posterior cuff** (improving the seal up to 30 cm H₂O). * **LMA Fastrach (ILMA):** Also developed by Dr. Brain; specifically designed to facilitate blind intubation in difficult airway scenarios. * **LMA Supreme:** A single-use version that combines features of the ProSeal and Fastrach. * **Contraindication:** LMAs are generally contraindicated in patients with a "full stomach" (high risk of aspiration), though the ProSeal offers slightly better protection than the Classic.

Q: The clinical use of which of the following drugs has been discontinued due to its association with severe bronchospasm?

Rapacuronium. **Explanation:** **Rapacuronium (Option A)** is the correct answer. It was introduced as a non-depolarizing neuromuscular blocking agent (NMBA) with a rapid onset and short duration, intended to be an alternative to Succinylcholine. However, it was voluntarily withdrawn from the market worldwide in 2001 shortly after its release. The primary reason was its association with an unacceptably high incidence of **severe, life-threatening bronchospasm**, particularly in pediatric patients. The underlying mechanism is attributed to its potent **antimuscarinic effects at M2 receptors** (which normally inhibit acetylcholine release), leading to an unchecked release of acetylcholine and subsequent stimulation of M3 receptors on bronchial smooth muscle. **Why other options are incorrect:** * **Rocuronium (Option B):** Currently the most widely used rapid-onset NMBA. It does not cause significant histamine release or bronchospasm and is considered safe for asthmatic patients. * **Atracurium (Option C):** Known for causing **histamine release**, which can lead to mild bronchoconstriction, flushing, and hypotension, but it is not discontinued and remains in clinical use (metabolized by Hofmann elimination). * **Mivacurium (Option D):** A short-acting benzylisoquinolinium that also triggers histamine release. While it should be used cautiously in patients with reactive airways, it has not been discontinued. **High-Yield Clinical Pearls for NEET-PG:** * **Rapacuronium:** Remember the "Rapid" onset but "Fatal" bronchospasm. * **M2 vs. M3:** Bronchospasm in Rapacuronium is due to **M2 blockade** (presynaptic) leading to increased ACh. * **Drug of Choice for RSI:** Rocuronium is the preferred non-depolarizing agent for Rapid Sequence Induction (RSI) when Succinylcholine is contraindicated. * **Histamine Releasers:** Atracurium, Mivacurium, and Tubocurarine (the "curium/curarine" group) are the classic histamine releasers in anesthesia.

Q: Which of the following is the earliest and shortest-acting skeletal muscle relaxant?

Suxamethonium. ### Explanation **Correct Answer: D. Suxamethonium (Succinylcholine)** **Mechanism and Rationale:** Suxamethonium is the only **depolarizing neuromuscular blocker** used clinically. It works by mimicking the action of acetylcholine at the nicotinic receptors of the motor endplate, causing persistent depolarization. * **Onset:** It has the fastest onset of action (**30–60 seconds**), making it the gold standard for Rapid Sequence Induction (RSI). * **Duration:** It is the shortest-acting relaxant because it is rapidly hydrolyzed by **pseudocholinesterase (plasma cholinesterase)** in the blood. Its clinical effect lasts only **5–10 minutes**. **Analysis of Incorrect Options:** All other options belong to the **Non-depolarizing** class (competitive antagonists), which generally have a slower onset and longer duration than Suxamethonium: * **A. Rocuronium:** An aminosteroid with the fastest onset among non-depolarizers (60–90 seconds), but its duration is intermediate (30–40 minutes). * **B. Vecuronium:** An intermediate-acting aminosteroid (duration 30–40 minutes) with a slower onset (2–3 minutes) than Rocuronium. * **C. Atracurium:** An intermediate-acting benzylisoquinolinium (duration 30–45 minutes). It is unique for its metabolism via **Hofmann elimination**, making it safe in liver and kidney failure. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** For Rapid Sequence Induction (RSI) and when a "difficult airway" is anticipated (due to short duration). * **Side Effects:** Muscle fasciculations (prevented by a "pre-curarization" dose), hyperkalemia (avoid in burns/trauma), and it is a potent trigger for **Malignant Hyperthermia**. * **Prolonged Apnea:** Occurs in patients with **pseudocholinesterase deficiency** (diagnosed by a low Dibucaine Number). * **Mivacurium:** The shortest-acting *non-depolarizing* muscle relaxant, but it is still slower and longer-acting than Suxamethonium.

Q: Identify the pictured airway device.

Nasopharyngeal airway. ***Nasopharyngeal airway*** - Features a **soft, flexible tube** with a **beveled distal tip** and **proximal flange with safety pin** to prevent migration into the nostril. - Designed for **nasal insertion** to maintain airway patency, particularly useful in patients with **intact gag reflex** or **oral trauma**. *Oropharyngeal airway* - Has a **rigid, curved plastic design** that follows the **natural curve of the tongue** and lacks the flexible tube structure. - Inserted through the **mouth** and requires **absence of gag reflex**, making it unsuitable for conscious patients. *Proseal airway* - A **supraglottic airway device** with an **inflatable cuff** and **gastric drainage tube** for advanced airway management. - Much **larger and more complex** than simple airway adjuncts, designed for **mechanical ventilation** under anesthesia. *Flexometallic LMA* - Features a **wire-reinforced flexible shaft** with an **inflatable laryngeal mask** at the distal end. - Designed for **supraglottic ventilation** during procedures requiring **head and neck positioning** where standard LMAs might kink.

Q: In a young patient with extensive soft tissue and muscle injury, which muscle relaxant used for endotracheal intubation might lead to cardiac arrest?

Suxamethonium. **Explanation:** The correct answer is **Suxamethonium (Succinylcholine)**. **Why Suxamethonium is the correct answer:** Suxamethonium is a depolarizing neuromuscular blocker that acts by mimicking acetylcholine at the nicotinic receptors. In patients with **extensive soft tissue injury, major burns, or denervation injuries**, there is an "upregulation" of extrajunctional acetylcholine receptors. When Suxamethonium is administered, these receptors open, causing a massive efflux of potassium from the muscle cells into the extracellular fluid. This **acute hyperkalemia** can lead to severe cardiac arrhythmias and sudden **cardiac arrest**. This risk typically peaks 24–48 hours after the injury and can persist for months. **Why other options are incorrect:** * **Atracurium:** A non-depolarizing muscle relaxant (NDMR) that does not cause potassium release. It is metabolized by Hofmann elimination and is safe in renal/hepatic failure. * **Vecuronium:** An intermediate-acting NDMR with a stable cardiovascular profile; it does not cause hyperkalemia. * **Pancuronium:** A long-acting NDMR. While it may cause tachycardia (vagolytic effect), it does not trigger hyperkalemia or cardiac arrest in trauma patients. **High-Yield Clinical Pearls for NEET-PG:** * **Normal K+ rise:** In a healthy individual, Suxamethonium raises serum potassium by approximately **0.5 mEq/L**. * **Contraindications:** Avoid Suxamethonium in burns (>24 hours old), crush injuries, spinal cord injuries (paraplegia/quadriplegia), and muscular dystrophies. * **Drug of Choice for RSI:** Despite this risk, Suxamethonium remains the gold standard for Rapid Sequence Induction (RSI) due to its rapid onset and short duration, provided no contraindications exist.

Q: Generally accepted indications for mechanical ventilatory support include which of the following?

Respiratory rate greater than 35 breaths/min. ### Explanation Mechanical ventilation is indicated when a patient’s spontaneous respiratory effort is insufficient to maintain adequate oxygenation, ventilation, or airway protection. The decision is based on clinical assessment and specific physiological thresholds. **1. Why Option D is Correct:** A **respiratory rate (RR) > 35 breaths/min** is a classic indication for mechanical ventilation. Such high rates significantly increase the work of breathing, leading to respiratory muscle fatigue, increased dead space ventilation, and eventual CO2 retention. It signifies impending respiratory failure. **2. Why the Other Options are Incorrect:** * **Option A:** The units and values are incorrect. A PaO2 of 50 **mmHg** (with pH 350–450 mmHg** while breathing 100% O2. A difference of 150 kPa (approx. 1125 mmHg) is physiologically impossible as it exceeds the pressure of 100% oxygen at sea level. * **Option C:** A **Vital Capacity (VC) 0.6**. * **PaO2/FiO2 Ratio:** A ratio **< 200** (suggestive of ARDS) often necessitates ventilatory support. * **Clinical Priority:** Always treat the patient, not the monitor. Tachypnea and the use of accessory muscles often precede blood gas abnormalities.

Question 1

Who developed the Laryngeal Mask Airway (LMA) ProSeal?

Accepted Answer

Brain

Answer

Bailey

Answer

Macewan

Answer

Magill

Question 2

Which of the following is NOT a step in rapid sequence intubation?

Accepted Answer

Bag and mask ventilation is used for positive pressure ventilation.

Answer

Intravenous thiopental and intravenous succinylcholine are used for induction and paralysis.

Answer

Sellick’s maneuver is used to prevent aspiration.

Answer

Pre-oxygenation is mandatory.

Question 3

The clinical use of which of the following drugs has been discontinued due to its association with severe bronchospasm?

Accepted Answer

Rapacuronium

Answer

Rocuronium

Answer

Atracurium

Answer

Mivacurium

Question 4

Which of the following is the earliest and shortest-acting skeletal muscle relaxant?

Accepted Answer

Suxamethonium

Answer

Rocuronium

Answer

Vecuronium

Answer

Atracurium

Question 5

Identify the pictured airway device.

Accepted Answer

Nasopharyngeal airway

Answer

Oropharyngeal airway

Answer

Proseal airway

Answer

Flexometallic LMA

Question 6

In a young patient with extensive soft tissue and muscle injury, which muscle relaxant used for endotracheal intubation might lead to cardiac arrest?

Accepted Answer

Suxamethonium

Answer

Atracurium

Answer

Vecuronium

Answer

Pancuronium

Question 7

What is true about laryngoscopy and intubation?

Accepted Answer

Hypertension

Answer

Tachycardia

Answer

Increased intracranial pressure

Answer

Increased intraocular pressure

Question 8

Tracheostomy reduces dead space by:

Accepted Answer

By-passing the upper airway

Answer

Increasing V/Q ratio

Answer

Raising airflow resistance

Answer

By all of the above mechanisms

Question 9

Generally accepted indications for mechanical ventilatory support include which of the following?

Accepted Answer

Respiratory rate greater than 35 breaths/min

Answer

PaO2 of less than 70 kPa and PaCO2 of greater than 50 kPa while breathing room air

Answer

Alveolar-arterial oxygen tension difference of 150 kPa while breathing 100% O2

Answer

Vital capacity of 40-60 mL/kg

Question 10

What are the pulmonary changes in the lateral position in an anesthetized patient?

Accepted Answer

Dependent lung is relatively under-ventilated and over-perfused.

Answer

Dependent lung is relatively over-ventilated and over-perfused.

Answer

Dependent lung is relatively over-ventilated and under-perfused.

Answer

Dependent lung is relatively under-ventilated and under-perfused.

Respiratory and Airway Management — MCQs

Respiratory and Airway Management — MCQs

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