Respiratory and Airway Management Practice Questions

Q: An infant with respiratory distress was intubated. What is the fastest and most accurate method to confirm endotracheal tube placement?

Capnography. **Explanation:** **1. Why Capnography is Correct:** Capnography (End-tidal CO2 monitoring) is the **Gold Standard** for confirming endotracheal tube (ETT) placement. It provides a real-time, objective measurement of exhaled carbon dioxide. The presence of a persistent CO2 waveform (at least 5-6 breaths) confirms that the tube is in the trachea and not the esophagus, as the stomach does not produce CO2. It is the fastest method because it provides immediate visual feedback upon the first few breaths. **2. Why Other Options are Incorrect:** * **Clinical Assessment (Auscultation):** While essential, it is subjective and can be misleading. Breath sounds can be transmitted from the stomach or the contralateral lung, and in infants, the chest wall is thin, making localization difficult. * **Chest Radiography:** While it is the best method to determine the **depth** of the tube (position relative to the carina), it is too slow for initial confirmation and cannot be used in emergency settings to rule out esophageal intubation immediately. * **Airway Pressure Measurement:** This monitors lung compliance and resistance but does not differentiate between tracheal and esophageal placement. **3. NEET-PG High-Yield Pearls:** * **Gold Standard for ETT placement:** Capnography. * **Gold Standard for ETT depth/position:** Chest X-ray. * **False Positives in Capnography:** Can occur if the patient recently consumed carbonated beverages (transient CO2 in the stomach). * **False Negatives in Capnography:** May occur during **Cardiac Arrest** or severe pulmonary embolism, where CO2 is not being delivered to the lungs due to lack of pulmonary blood flow. * **Colorimetric CO2 detectors:** Use pH-sensitive paper (turns from purple to yellow) and are useful in pre-hospital settings.

Q: Which is the anesthetic agent of choice in a case of status asthmaticus?

Ketamine. **Explanation:** **Ketamine** is the induction agent of choice in status asthmaticus due to its potent **bronchodilatory properties**. It works through two primary mechanisms: 1. **Sympathomimetic effect:** It increases the release of endogenous catecholamines, which stimulate $\beta_2$ receptors, leading to smooth muscle relaxation. 2. **Direct action:** It exerts a direct relaxant effect on the bronchial smooth muscles and inhibits vagal pathways. This makes it ideal for patients with reactive airway disease where intubation is necessary. **Analysis of Incorrect Options:** * **Thiopentone:** It is generally avoided in asthmatics because it can cause **histamine release**, which may trigger or worsen bronchospasm. It also does not suppress airway reflexes as effectively as other agents. * **Ether:** While Ether is a potent bronchodilator, it is an **irritant to the respiratory mucosa**, leading to increased secretions and a high incidence of laryngospasm during induction. It is also flammable and largely obsolete in modern practice. * **Nitrous Oxide:** It is a relatively inert gas with no significant bronchodilatory or bronchoconstrictive properties. It is not used as a primary induction agent for managing status asthmaticus. **High-Yield Clinical Pearls for NEET-PG:** * **Inhalational Agent of Choice:** **Sevoflurane** is preferred for mask induction in asthmatics as it is non-pungent and a potent bronchodilator (Halothane is also a bronchodilator but sensitizes the myocardium to catecholamines). * **Muscle Relaxant to Avoid:** **Atracurium** and **Mivacurium** should be avoided due to histamine release. **Vecuronium** or **Rocuronium** are preferred. * **Pre-medication:** Glycopyrrolate is often used to reduce secretions and provide mild bronchodilation via its anticholinergic effect.

Q: What is the maximum fraction of inspired oxygen (FiO2) that can be delivered via a nasal oxygen catheter?

0.44. **Explanation:** The fraction of inspired oxygen (FiO2) delivered via a **nasal cannula (or catheter)** is determined by the flow rate and the patient’s inspiratory flow. In a normal adult, the baseline FiO2 of room air is 0.21 (21%). For every **1 liter per minute (L/min)** of supplemental oxygen added, the FiO2 increases by approximately **4% (0.04)**. The maximum effective flow rate for a nasal cannula is **6 L/min**. Beyond this, the nasal mucosa becomes irritated/dried, and the anatomical reservoir (nasopharynx) is saturated, leading to a plateau in FiO2. * **Calculation:** $21\% + (6\text{ L/min} \times 4\%) = 21\% + 24\% = 45\%$. * In clinical practice and standard textbooks, this maximum value is rounded to **0.44 (44%)**. **Analysis of Options:** * **A (1.0):** Achievable only with a closed circuit (ventilator), a tight-fitting non-rebreather mask (NRBM) with high flow, or high-flow nasal cannula (HFNC) systems. * **B (0.6):** This is the typical maximum for a **simple face mask** (at 6–10 L/min). * **C (0.2):** This represents room air (0.21) without any supplemental oxygen. **High-Yield Clinical Pearls for NEET-PG:** * **Flow Rates:** Nasal cannula flow is typically 1–6 L/min. If >4 L/min is used, humidification is required to prevent epistaxis and mucosal crusting. * **Variable Performance:** The nasal cannula is a **low-flow/variable performance device**; the actual FiO2 varies if the patient’s minute ventilation or inspiratory flow rate changes. * **Dead Space:** Nasal catheters/cannulae do not increase dead space, unlike certain masks. * **Simple Face Mask:** Minimum flow must be **5 L/min** to flush out exhaled $CO_2$ from the mask and prevent rebreathing.

Q: A patient under anesthesia is found to be in a “cannot intubate, cannot ventilate” (CICV) scenario. What is the next best step in management?

Perform a cricothyroidotomy. ***Perform a cricothyroidotomy*** - In a “cannot intubate, cannot ventilate” (**CICV**) scenario, immediate establishment of a surgical airway is life-saving to prevent **hypoxic brain injury** and death. - A **cricothyroidotomy** is the fastest and most definitive emergency procedure to secure the airway by making an incision through the **cricothyroid membrane** into the trachea, bypassing any upper airway obstruction. *Insert nasopharyngeal airway* - A nasopharyngeal airway is a basic airway adjunct designed to relieve soft tissue obstruction at the level of the pharynx. It does not provide a definitive airway for ventilation. - In a **CICV** situation, basic maneuvers and adjuncts like this have already been attempted and failed; it is an inadequate intervention for this life-threatening emergency. *Insert a laryngeal mask airway* - A laryngeal mask airway (**LMA**) is a supraglottic airway device. A **CICV** scenario is declared only after attempts to secure the airway with both an endotracheal tube and a supraglottic device have failed. - Wasting further time attempting to insert an LMA is inappropriate when ventilation is not possible and a surgical airway is urgently needed. *Perform a tracheostomy* - A **tracheostomy** is a formal, time-consuming surgical procedure that is more complex and has a higher complication rate in an emergency setting compared to a cricothyroidotomy. - While it is a definitive airway, it is not the procedure of choice for a time-critical airway emergency. A cricothyroidotomy is the standard emergent surgical airway.

Q: What is the primary function of the inflatable cuff of the endotracheal tube shown in the image?

Prevention of air leakage and aspiration. ***Prevention of air leakage and aspiration*** - When inflated, the cuff creates a seal against the wall of the **trachea**. This prevents air delivered during **positive pressure ventilation** from escaping around the tube, ensuring adequate tidal volume delivery to the lungs. - The seal also protects the airway by preventing oropharyngeal and gastric secretions from entering the lungs, thus reducing the risk of **aspiration pneumonia**. *Facilitation of vocal cord visualization* - Vocal cord visualization is achieved using a **laryngoscope** during the intubation procedure *before* the cuff is inflated. - The endotracheal tube cuff is positioned *below* the vocal cords; its inflation would not aid in their visualization. *Monitoring airway pressure* - Airway pressure (e.g., peak inspiratory pressure) is monitored through the **ventilator circuit**, not the cuff. The pressure within the cuff is monitored separately via the **pilot balloon** using a manometer. - While maintaining appropriate **cuff pressure** (typically 20-30 cm H2O) is vital to prevent tracheal injury, the cuff's primary function is sealing, not monitoring overall airway pressure. *Suctioning of lower respiratory tract secretions* - Suctioning is performed by passing a sterile **suction catheter** through the lumen of the endotracheal tube to clear secretions from the lower airways. - The cuff itself has no suctioning capability, although some specialized tubes have a separate **subglottic suction port** located above the cuff to remove pooled secretions.

Q: A patient undergoing general anesthesia develops left lung collapse following intubation. On auscultation, breath sounds are heard only on the right side. What is the most likely cause of this condition?

Right endobronchial intubation. ***Right endobronchial intubation***- This is the most common cause of unilateral lung collapse *immediately* following intubation, as the endotracheal tube (ETT) is usually advanced too far into the **right main bronchus (RMB)**, which is wider and less acutely angled than the left.- When the ETT is solely in the RMB, air ventilates the right lung exclusively, resulting in **absent breath sounds** and subsequent **atelectasis** (collapse) of the non-ventilated left lung.*Mucus secretions obstructing the endotracheal tube*- Significant obstruction of the ETT by mucus would typically lead to **bilateral loss of breath sounds** or severely impaired ventilation (high peak inspiratory pressures), affecting both lungs equally.- The specific finding of unilateral breath sounds (only on the right) excludes a primary blockage of the ETT itself.*Pneumothorax on the left side due to positive pressure ventilation*- While a left **pneumothorax** can cause absent breath sounds on the left, it would involve air accumulation in the pleural space, often requiring significant barotrauma, and is a less frequent and less immediate cause than mainstem intubation following successful intubation.- The clinical picture of immediate unilateral absence of breath sounds following intubation is overwhelmingly attributed to ETT malposition, which causes obstructive **atelectasis** (collapse), not tension pneumothorax.*Bronchospasm*- **Bronchospasm** is characterized by diffuse airway narrowing, typically presenting with high **peak inspiratory pressures** and **wheezing** heard over both lung fields.- It impairs air entry bilaterally and would not result in the complete unilateral absence of breath sounds and lung collapse described, which is indicative of complete airway obstruction to the non-ventilated lung.

Q: Which of the following is the use of the Mallampatti classification?

Endotracheal intubation. ***Correct Option C: Endotracheal intubation*** - The Mallampati classification assesses the visibility of the soft palate, uvula, and tonsillar pillars, which directly correlates with the ease of achieving a satisfactory view during **direct laryngoscopy** - It is a critical component of the **pre-anesthetic airway assessment** used alongside thyromental distance and mouth opening to predict difficult airway management and guide intubation strategy - Classes I-IV predict increasing difficulty in intubation, with Class III-IV indicating potentially difficult airways *Incorrect Option A: To evaluate the fitness of the patient* - Patient fitness evaluation involves holistic assessment of **cardiopulmonary reserve** and functional capacity, ensuring the patient can safely tolerate the physiological stress of surgery and anesthesia - Fitness relies on optimizing chronic medical conditions and functional capacity, not just anatomical classification of the airway opening *Incorrect Option B: To evaluate the pros and cons of surgery* - This evaluation is a clinical and ethical judgment based on the patient's **disease severity**, anticipated benefits, potential complications, and mortality associated with the procedure - The Mallampati score does not directly contribute to weighing the overall risk-benefit ratio of the surgical procedure itself *Incorrect Option D: To evaluate the risk of surgery* - Surgical risk is determined using tools like the **ASA physical status classification** (P1-P6), comorbidities, and type of surgery - While a predicted difficult airway (Mallampati class III or IV) increases the **anesthesia-related risk**, it does not comprehensively define the overall surgical risk profile

Q: A patient in the ICU with an endotracheal tube now needs a tracheostomy tube. Which type of tube will you use?

Cuffed tracheostomy tube. ***Cuffed tracheostomy tube*** - A **cuffed tracheostomy tube** is mandatory in the ICU setting, especially when transitioning from an endotracheal tube, because it provides a seal necessary for **positive pressure ventilation** (PPCV). - The cuff also provides crucial protection against the aspiration of **oral secretions** and **gastric contents**, which is a high risk in critically ill, often sedated, ICU patients. *Uncuffed tracheostomy tube* - *Uncuffed tubes* are inadequate for patients requiring mechanical ventilation as they cannot create the necessary sealed circuit to deliver **tidal volume**. - These tubes are generally reserved for stable patients who require a chronic airway, are not on ventilation, and have a low risk of **aspiration**. *Metallic tracheostomy tube.* - **Metallic tracheostomy tubes** (like those used historically or specific specialized tubes) are typically uncuffed and are not suitable for patients requiring mandatory **mechanical ventilation** or aspiration protection in the acute ICU setting. - They are primarily used for *long-term placement* in ambulatory patients who require a stable, durable airway and often need their tube removed and cleaned frequently. *Endotracheal tube* - An **endotracheal tube (ETT)** is the device currently in use and is being *replaced* by a tracheostomy, making this option incorrect. - While the ETT provides airway management, a tracheostomy tube offers advantages for **long-term airway maintenance** (e.g., improved comfort, easier weaning, better oral hygiene).

Q: Which of the following airway devices helps maintain Fio2 of 0.25-0.60, irrespective of the patient's breathing effort?

Venturi mask. ***Venturi mask***- This device utilizes the **Bernoulli principle** to mix a specific flow of 100% oxygen with a fixed volume of **room air** via interchangeable jet adapters, achieving a precise FIO2 (0.24-0.60).- Because the total gas flow delivered to the patient (O2 + entrained air) greatly exceeds the patient's peak inspiratory flow, the delivered FIO2 is **independent of the patient's breathing effort** (rate and depth).*Nasal cannula*- The actual FIO2 delivered is highly **variable** and dependent on the patient's **inspiratory flow rate** and pattern, as the device primarily provides supplemental oxygen flow into the pharynx.- It typically provides a maximum FIO2 of about 0.44 at flow rates up to 6 L/min, which is insufficient for predictable FIO2 control in the moderate range.*Simple face mask*- The FIO2 delivered is variable (typically 0.35–0.50) because a significant amount of **room air is entrained** through the ports and the seal around the mask, highly dependent on the patient’s ventilation pattern.- It requires a flow rate of at least 5 L/min to flush out the volume in the mask and prevent the risk of **carbon dioxide ($ ext{CO}_2$) rebreathing** from the mask's dead space.*Non-rebreathing mask*- Offers the **highest FIO2 available** non-invasively (up to 0.90–0.95); however, its primary purpose is maximizing oxygen delivery, not maintaining a precise, lower concentration (0.25-0.60).- While a valve prevents exhaled air from entering the reservoir bag, the exact FIO2 delivered still requires a tight seal and is generally used when high concentrations are needed, making it unsuitable for precise intermediate FIO2.

Question 1

When gases flow through an orifice, which factor is least likely to affect turbulence?

Accepted Answer

Pressure of gas

Answer

Density of gas

Answer

Viscosity of gas

Answer

Diameter of orifice

Question 2

An infant with respiratory distress was intubated. What is the fastest and most accurate method to confirm endotracheal tube placement?

Accepted Answer

Capnography

Answer

Clinical assessment by auscultation

Answer

Chest radiography

Answer

Airway pressure measurement

Question 3

Which is the anesthetic agent of choice in a case of status asthmaticus?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Ether

Answer

Nitrous Oxide

Question 4

What is the maximum fraction of inspired oxygen (FiO2) that can be delivered via a nasal oxygen catheter?

Accepted Answer

0.44

Answer

1.0

Answer

0.6

Answer

0.2

Question 5

A patient under anesthesia is found to be in a “cannot intubate, cannot ventilate” (CICV) scenario. What is the next best step in management?

Accepted Answer

Perform a cricothyroidotomy

Answer

Insert a laryngeal mask airway

Answer

Insert nasopharyngeal airway

Answer

Perform a tracheostomy

Question 6

What is the primary function of the inflatable cuff of the endotracheal tube shown in the image?

Accepted Answer

Prevention of air leakage and aspiration

Answer

Suctioning of lower respiratory tract secretions

Answer

Facilitation of vocal cord visualization

Answer

Monitoring airway pressure

Question 7

A patient undergoing general anesthesia develops left lung collapse following intubation. On auscultation, breath sounds are heard only on the right side. What is the most likely cause of this condition?

Accepted Answer

Right endobronchial intubation

Answer

Pneumothorax on the left side due to positive pressure ventilation

Answer

Bronchospasm

Answer

Mucus secretions obstructing the endotracheal tube

Question 8

Which of the following is the use of the Mallampatti classification?

Accepted Answer

Endotracheal intubation

Answer

To evaluate the fitness of the patient

Answer

To evaluate the pros and cons of surgery

Answer

To evaluate the risk of surgery

Question 9

A patient in the ICU with an endotracheal tube now needs a tracheostomy tube. Which type of tube will you use?

Accepted Answer

Cuffed tracheostomy tube

Answer

Metallic tracheostomy tube

Answer

Endotracheal tube

Answer

Uncuffed tracheostomy tube

Question 10

Which of the following airway devices helps maintain Fio2 of 0.25-0.60, irrespective of the patient's breathing effort?

Accepted Answer

Venturi mask

Answer

Simple face mask

Answer

Non-rebreathing mask

Answer

Nasal cannula

Respiratory and Airway Management — MCQs

Respiratory and Airway Management — MCQs

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