Respiratory and Airway Management Practice Questions

Q: A 65-year-old patient with severe COPD (FEV1 40% predicted) requires colonoscopy. During propofol sedation, SpO2 drops to 85% despite supplemental oxygen. What is the most appropriate immediate management?

Stop propofol, provide jaw thrust and assist ventilation. ***Stop propofol, provide jaw thrust and assist ventilation*** - In the setting of **procedural sedation-induced hypoxemia**, the first priority is to **discontinue the offending sedative** and restore the airway and ventilation. - **Airway maneuvers** such as **jaw thrust** relieve upper airway obstruction, while assisted ventilation (e.g., **Bag-Valve-Mask**) addresses hypoxemia in a patient with **COPD** who has limited respiratory reserve. *Start non-invasive positive pressure ventilation* - While **NIV** is used for chronic management of **COPD exacerbations**, it is not the primary immediate response for **acute respiratory depression** during sedation where physical airway maneuvers are required. - Securing the airway manually and ensuring the patient is breathing is more critical than setting up a **BiPAP/CPAP** machine during an acute desaturation event. *Administer flumazenil* - **Flumazenil** is a specific reversal agent for **benzodiazepines** and has no effect on the respiratory depression caused by **propofol**. - There is no **antagonist** available for propofol; therefore, management is strictly supportive via **airway control** and ventilation. *Increase propofol depth and intubate* - Increasing the dose of **propofol** would worsen the **respiratory depression** and potentially cause cardiovascular collapse in a compromised COPD patient. - **Endotracheal intubation** is a secondary measure; basic life support maneuvers like **bag-mask ventilation** should always be attempted first to reverse transient hypoxemia.

Q: Which of the following indicates anticipated difficult bag-mask ventilation?

Beard. **Explanation:** The correct answer is **Beard**. Bag-mask ventilation (BMV) requires an airtight seal between the patient’s face and the mask to generate positive pressure. A **beard** acts as a physical barrier, preventing an adequate seal and allowing gas to leak, which directly leads to difficult BMV. **Analysis of Options:** * **Age > 30 years (Incorrect):** While age is a predictor, the threshold for difficult BMV is typically **age > 55 years**. This is due to loss of tissue elasticity and potential edentulousness (lack of teeth), which causes facial collapse. * **BMI > 20 kg/m² (Incorrect):** A BMI of 20 is within the normal range. The risk factor for difficult BMV is **Obesity**, specifically a **BMI > 26–30 kg/m²**. Excess soft tissue in the upper airway increases resistance and reduces compliance. * **Beard (Correct):** As discussed, facial hair interferes with the mask-to-skin interface. **High-Yield Clinical Pearl: The MOANS Mnemonic** For NEET-PG, remember the **MOANS** mnemonic to predict difficult bag-mask ventilation: 1. **M – Mask Seal:** Beard, facial trauma, or drainage. 2. **O – Obesity/Obstruction:** BMI > 26 kg/m², pregnancy, or upper airway masses (e.g., epiglottitis). 3. **A – Age:** > 55 years. 4. **N – No teeth (Edentulous):** Causes the cheeks to cave in (Note: Leaving dentures in during BMV can actually improve the seal). 5. **S – Stiff lungs/Snoring:** Increased airway resistance or decreased compliance (e.g., COPD, ARDS, or OSA). **Key Fact:** The most common cause of airway obstruction during BMV in an unconscious patient is the **tongue** falling back against the posterior pharynx. This is managed by the "Head tilt-Chin lift" or "Jaw thrust" maneuver.

Q: What is true about volume control ventilation?

The lung is inflated at a constant flow rate.. In **Volume Control Ventilation (VCV)**, the ventilator is programmed to deliver a preset tidal volume ($V_T$) over a set inspiratory time. To achieve this, the machine delivers gas at a **constant (square-wave) flow rate**. ### Why Option A is Correct: In VCV, the flow rate remains uniform throughout the inspiratory phase. Because the flow is constant, the airway pressure rises linearly as the lungs fill. This is the hallmark of volume-targeted modes, distinguishing them from pressure-targeted modes. ### Why Other Options are Incorrect: * **Option B:** Peak Inspiratory Pressure (PIP) is the pressure required to overcome both airway resistance and lung compliance. **Plateau Pressure ($P_{plat}$)** is measured during an inspiratory pause (zero flow) and reflects only alveolar compliance. Therefore, PIP is always higher than $P_{plat}$ in a dynamic system. * **Option C:** A **decelerating flow rate** is characteristic of **Pressure Control Ventilation (PCV)**. In PCV, flow is highest at the start to reach the target pressure quickly and then tapers off. * **Option D:** Plateau pressure is **not fixed** in VCV. It depends on the patient’s lung compliance and the delivered tidal volume. If compliance decreases (e.g., ARDS or pneumothorax), the plateau pressure will rise. ### High-Yield Clinical Pearls for NEET-PG: * **VCV vs. PCV:** VCV guarantees minute ventilation but risks high peak pressures (barotrauma). PCV limits peak pressure but tidal volume may vary with changes in compliance. * **The "Gap":** A large difference between PIP and $P_{plat}$ (PIP - $P_{plat} > 5\text{ cmH}_2\text{O}$) indicates **increased airway resistance** (e.g., bronchospasm, secretions, or a kinked ETT). * **Monitoring:** In VCV, the most important parameter to monitor to prevent lung injury is the **Plateau Pressure** (should ideally be $< 30\text{ cmH}_2\text{O}$).

Q: Identify the type of endotracheal tube shown.

Laser tube. The correct answer is **Laser tube**. ### **Explanation** Laser-resistant endotracheal tubes are specialized tubes designed for airway surgeries involving CO2, KTP, or Nd:YAG lasers (e.g., laryngeal papilloma excision). Standard PVC tubes are highly flammable and can lead to a catastrophic "airway fire" if struck by a laser beam. The tube in the image is identified by its unique construction: * **Material:** Usually made of stainless steel or wrapped in laser-resistant foil/metal. * **Dual Cuffs:** A hallmark feature. If the outer cuff is accidentally punctured by the laser, the inner cuff remains intact to maintain the seal and prevent oxygen enrichment of the surgical field, which would further fuel a fire. The cuffs are typically inflated with saline (often dyed with methylene blue) to act as a heat sink and provide a visual warning if ruptured. ### **Why other options are incorrect:** * **Flexometallic (Armored) tube:** Contains a wire coil embedded in the wall to prevent kinking. It is used for head and neck surgeries but is **not** laser-resistant; the PVC/silicone coating can still ignite. * **RAE (Ring-Adair-Elwyn) tube:** Pre-formed with a "J" bend to direct the circuit away from the surgical field (Oral or Nasal). It lacks the metallic protection and dual-cuff system. * **Double Lumen Tube (DLT):** Used for one-lung ventilation. It is significantly larger, features two separate lumens, and two distinct cuffs (tracheal and bronchial). ### **NEET-PG High-Yield Pearls:** * **Airway Fire Triad:** Fuel (ET tube), Oxidizer (O2/N2O), and Ignition source (Laser/Cautery). * **Management of Airway Fire:** Immediately stop ventilation, disconnect the circuit, remove the ET tube, and pour saline into the airway. * **Ventilation Tip:** During laser surgery, keep the FiO2 as low as possible (usually <30%) and avoid Nitrous Oxide (N2O), as it supports combustion.

Question 1

A 65-year-old patient with severe COPD (FEV1 40% predicted) requires colonoscopy. During propofol sedation, SpO2 drops to 85% despite supplemental oxygen. What is the most appropriate immediate management?

Accepted Answer

Stop propofol, provide jaw thrust and assist ventilation

Answer

Start non-invasive positive pressure ventilation

Answer

Administer flumazenil

Answer

Increase propofol depth and intubate

Question 2

What is the primary reason for maintaining spontaneous ventilation during anesthesia for bronchoscopic procedures?

Accepted Answer

To maintain negative intrapleural pressure and prevent airway collapse

Answer

To prevent barotrauma in diseased lungs

Answer

To facilitate better visualization of airways

Answer

To reduce anesthetic requirements

Question 3

Which of the following indicates anticipated difficult bag-mask ventilation?

Accepted Answer

Beard

Answer

Age > 30 years

Answer

BMI > 20 kg/m²

Answer

None of the above

Question 4

What is true about volume control ventilation?

Accepted Answer

The lung is inflated at a constant flow rate.

Answer

Peak alveolar pressure is equal to plateau pressure.

Answer

There is a decelerating flow rate.

Answer

Plateau pressure is fixed.

Question 5

Identify the type of endotracheal tube shown.

Accepted Answer

Laser tube

Answer

Flexometallic tube

Answer

RAE tube

Answer

Double lumen tube

Respiratory and Airway Management — MCQs

Respiratory and Airway Management — MCQs

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