Respiratory and Airway Management — MCQs

Respiratory and Airway Management Indian Medical PG Practice Questions and MCQs

Question 271: Which of the following is NOT an indication for endotracheal intubation?

A. Maintenance of a patent airway
B. To provide positive pressure ventilation
C. Pulmonary toilet
D. Pneumothorax (Correct Answer)

Explanation: ### Explanation The primary goal of endotracheal intubation is to secure the airway, protect the lungs from aspiration, and facilitate mechanical ventilation. **Why Pneumothorax is the Correct Answer:** Pneumothorax is a clinical condition characterized by air in the pleural space, leading to lung collapse. The definitive management for a pneumothorax is **intercostal drainage (chest tube insertion)**, not intubation. In fact, initiating positive pressure ventilation (via intubation) in a patient with an untreated pneumothorax can rapidly convert it into a life-threatening **tension pneumothorax**, as the positive pressure forces more air into the pleural space with no way to escape. **Analysis of Incorrect Options:** * **A. Maintenance of a patent airway:** This is a primary indication, especially in patients with a low GCS (<8), upper airway obstruction (e.g., angioedema, trauma), or loss of protective airway reflexes. * **B. To provide positive pressure ventilation:** Intubation is required when a patient cannot ventilate or oxygenate adequately on their own, such as in respiratory failure, ARDS, or during general anesthesia with muscle relaxants. * **C. Pulmonary toilet:** Intubation allows for deep tracheal suctioning in patients who cannot clear secretions effectively (e.g., neuromuscular weakness or thick, copious secretions), preventing atelectasis and pneumonia. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for confirming ETT placement:** Capnography (EtCO2). * **Most common complication of intubation:** Sore throat; however, the most serious immediate complication is **unrecognized esophageal intubation**. * **Cormack-Lehane Classification:** Used to grade the view obtained during direct laryngoscopy. * **Indication for "Rapid Sequence Induction" (RSI):** Full stomach, pregnancy, or acute intestinal obstruction to prevent aspiration.

Question 272: What is the proper technique for endotracheal intubation?

A. Flexion of neck
B. Flexion of the neck and extension of the atlantooccipital joint (Correct Answer)
C. Extension of the neck
D. Extension of the neck and flexion of the atlantooccipital joint

Explanation: To achieve a clear view of the glottis during direct laryngoscopy, the three anatomical axes—**Oral, Pharyngeal, and Laryngeal**—must be brought into near-alignment. This is best achieved through the **"Sniffing Position."** ### Why Option B is Correct The sniffing position consists of two distinct components: 1. **Flexion of the lower cervical spine (C6-C7):** This is usually achieved by placing a 5–10 cm pillow or firm pad under the patient's occiput. This elevates the head and aligns the pharyngeal and laryngeal axes. 2. **Extension of the atlanto-occipital joint (C1-Occiput):** This tilts the head back, aligning the oral axis with the already aligned pharyngeal and laryngeal axes. ### Why Other Options are Incorrect * **Option A (Flexion only):** Simple flexion of the neck without head extension keeps the oral axis perpendicular to the pharyngeal axis, making the larynx impossible to visualize. * **Option C (Extension only):** Pure extension of the neck (the "Rose position") is used for certain ENT surgeries (like tonsillectomy) but makes intubation difficult as it pushes the larynx more anteriorly. * **Option D (Extension of neck/Flexion of AO joint):** This is the opposite of the required mechanics and would result in the chin being tucked toward the chest, completely obstructing the view. ### High-Yield Clinical Pearls for NEET-PG * **The Sniffing Position** is the "Gold Standard" for intubation in non-obese adults. * **In Morbidly Obese patients:** The sniffing position is insufficient. Use the **"Ramped Position"** (elevating the head, neck, and shoulders) until the external auditory meatus is at the same horizontal level as the sternal notch. * **In Pediatrics:** Infants have a large occiput; therefore, they naturally assume a sniffing position. Placing a pad under the *shoulders* (not the head) is often required to prevent airway obstruction. * **Contraindication:** Avoid the sniffing position in suspected **cervical spine injuries**; use Manual In-Line Stabilization (MILS) and a jaw thrust instead.

Question 273: Which of the following inhalational anesthetic agents demonstrates the most potent bronchodilating effect?

A. Isoflurane
B. Sevoflurane
C. Halothane (Correct Answer)
D. Desflurane

Explanation: **Explanation:** The correct answer is **Halothane (Option C)**. **1. Why Halothane is Correct:** Inhalational anesthetics generally cause bronchodilation by decreasing intracellular calcium in airway smooth muscle and inhibiting vagal pathways. Among all volatile agents, **Halothane** is considered the most potent bronchodilator. It is highly effective at reversing bronchospasm, making it historically the "gold standard" for managing patients with active wheezing or status asthmaticus in the operating room. **2. Analysis of Incorrect Options:** * **Sevoflurane (Option B):** While Sevoflurane is an excellent bronchodilator and is the **agent of choice** for inhalation induction due to its non-pungency and lack of airway irritation, its absolute bronchodilatory potency is slightly less than that of Halothane. * **Isoflurane (Option A):** Isoflurane possesses bronchodilatory properties but is also a mild airway irritant. It can cause coughing or breath-holding during induction, making it less ideal than Sevoflurane or Halothane for reactive airways. * **Desflurane (Option D):** This is the most pungent agent. In concentrations above 1 MAC, it can actually cause **bronchoconstriction** and increased airway resistance due to sympathetic stimulation and airway irritation. It is generally avoided in patients with asthma or reactive airway disease. **3. High-Yield Clinical Pearls for NEET-PG:** * **Agent of Choice for Induction in Asthma:** Sevoflurane (due to its pleasant odor and lack of pungency). * **Most Potent Bronchodilator:** Halothane. * **Agent to Avoid in Asthma:** Desflurane (due to pungency and risk of bronchospasm). * **Mechanism:** Volatile agents relax bronchial smooth muscle by direct action and by inhibiting the release of inflammatory mediators like histamine. * **Note:** Halothane is less commonly used today due to risks of "Halothane Hepatitis" and sensitization of the myocardium to catecholamines (arrhythmias), but it remains the correct answer for potency in bronchodilation.

Question 274: Which of the following statements about the infant airway compared to the adult airway is FALSE?

A. The relatively large size of the tongue
B. The epiglottis is omega shaped
C. The larynx is funnel shaped
D. All of the above are true statements about the infant airway (Correct Answer)

Explanation: The pediatric airway is not merely a smaller version of the adult airway; it possesses distinct anatomical characteristics that are high-yield for NEET-PG. **Explanation of the Correct Answer:** Option D is correct because all the listed features accurately describe the infant airway. These anatomical differences make pediatric intubation more challenging and necessitate specific equipment (like straight Miller blades). * **Large Tongue (Option A):** Relative to the oral cavity, the infant tongue is much larger. This makes it more likely to cause airway obstruction during sedation and obscures the view of the glottis during laryngoscopy. * **Omega-shaped Epiglottis (Option B):** The infant epiglottis is longer, stiffer, and narrower (U-shaped or Omega-shaped) compared to the flat, flexible adult epiglottis. It projects more posteriorly, often requiring direct lifting with a straight blade. * **Funnel-shaped Larynx (Option C):** In infants, the larynx is funnel-shaped, with the narrowest portion being the **subglottic region at the level of the cricoid cartilage**. In contrast, the adult larynx is cylindrical, with the narrowest point at the vocal cords (glottis). **Clinical Pearls for NEET-PG:** 1. **Position of Larynx:** The infant larynx is more cephalad/superior (located at **C3-C4**) compared to the adult larynx (**C4-C5**). 2. **Occiput:** Infants have a large occiput, which causes neck flexion when supine. A shoulder roll (not a head ring) is often needed to align the axes for intubation. 3. **Poiseuille’s Law:** Because the airway is narrow, even 1mm of edema significantly increases airway resistance (inversely proportional to the 4th power of the radius).

Question 275: Which of the following characterizes Mallampati class 3?

A. Only hard palate visible
B. Both hard palate and soft palate visible (Correct Answer)
C. Hard palate, soft palate, uvula and faucial pillars visible
D. None of the above

Explanation: The **Mallampati Classification** is a clinical tool used to predict the ease of endotracheal intubation by assessing the relationship between the size of the tongue and the oral cavity. It is performed with the patient sitting upright, head in a neutral position, mouth wide open, and tongue protruded without phonation. ### **Explanation of Options** * **Correct Answer (B):** In **Class 3**, the clinician can visualize the **hard palate and the soft palate**. The base of the uvula may occasionally be seen, but the pillars and the majority of the uvula are obscured by the tongue. This indicates a potentially difficult airway. * **Option A:** This describes **Class 4**, where only the hard palate is visible. This is a strong predictor of a difficult airway. * **Option C:** This describes **Class 1**, where the soft palate, fauces, entire uvula, and anterior/posterior tonsillar pillars are all clearly visible. This usually indicates an easy intubation. ### **The Mallampati Scale Summary** * **Class 1:** Soft palate, fauces, uvula, pillars visible. * **Class 2:** Soft palate, fauces, portion of uvula visible. * **Class 3:** Soft palate and hard palate visible. * **Class 4:** Only hard palate visible. ### **High-Yield Clinical Pearls for NEET-PG** * **Samsoon and Young Modification:** The original Mallampati classification had 3 classes; the 4th class was added later by Samsoon and Young. * **Predictive Value:** Classes 3 and 4 are clinically significant predictors of **difficult laryngoscopy** (Cormack-Lehane Grade 3 or 4). * **Gold Standard:** While Mallampati is a common screening tool, the "gold standard" for assessing the glottic view is the **Cormack-Lehane classification**, performed during direct laryngoscopy. * **Mnemonic:** Remember **PUSH** (Pillars, Uvula, Soft palate, Hard palate) to recall what is visible in descending order from Class 1 to 4.

Question 276: During laryngoscopy and intubation procedure, all of these are true, except:

A. A slight pressure may be applied at the cricoid cartilage.
B. The laryngoscope is held in the right hand and introduced from the right side of the patient.
C. The neck is flexed with extension at the atlanto-occipital joint.
D. After insertion of the laryngoscope, it is levered on the upper incisors to pull up the tongue and visualize the vocal cords. (Correct Answer)

Explanation: **Explanation:** The goal of direct laryngoscopy is to create a straight line of sight from the operator’s eye to the glottic opening. This requires specific maneuvers and precautions to ensure patient safety and successful intubation. **Why Option D is the Correct Answer (The Incorrect Statement):** Levering the laryngoscope on the upper incisors is a **major technical error**. Using the teeth as a fulcrum can lead to dental trauma (chipped or dislodged teeth) and limits the space available for tube passage. Instead, the laryngoscope should be lifted **upward and forward** (at a 45-degree angle away from the patient) to displace the tongue and soft tissues without touching the teeth. **Analysis of Other Options:** * **Option A:** Applying slight pressure at the cricoid cartilage (Sellick’s maneuver) or the thyroid cartilage (BURP maneuver—Backward, Upward, Rightward Pressure) is often used to improve the view of the larynx or prevent aspiration. * **Option B:** Standard laryngoscopes are designed for the **left hand**. They are introduced from the right side of the mouth to sweep the tongue to the left, clearing the midline for visualization. * **Option C:** This describes the **"Sniffing Position,"** which aligns the oral, pharyngeal, and laryngeal axes. It is achieved by flexing the lower cervical spine (using a pillow) and extending the atlanto-occipital joint. **High-Yield Clinical Pearls for NEET-PG:** * **Sniffing Position:** Flexion of the neck (C6-C7) + Extension of the head (C1-C2). * **Cormack-Lehane Classification:** Used to grade the view obtained during laryngoscopy (Grade I is full view; Grade IV is no epiglottis seen). * **Macintosh Blade:** Curved blade, tip placed in the **vallecula**. * **Miller Blade:** Straight blade, tip used to **directly lift the epiglottis**.

Question 277: The Sellick maneuver is used to prevent which of the following?

A. Alveolar collapse
B. Hypertension
C. Aspiration of gastric content (Correct Answer)
D. Bradycardia

Explanation: **Explanation:** The **Sellick maneuver**, also known as **cricoid pressure**, is a technique used during Rapid Sequence Induction (RSI) to prevent the passive regurgitation and subsequent **aspiration of gastric contents** into the lungs. **Why Option C is correct:** The maneuver involves applying firm downward pressure on the **cricoid cartilage** (the only complete cartilaginous ring in the larynx). This pressure compresses the flexible esophagus against the body of the sixth cervical vertebra (C6), effectively occluding the esophageal lumen and preventing stomach contents from reaching the pharynx during the period between loss of consciousness and successful tracheal intubation. **Why the other options are incorrect:** * **A. Alveolar collapse:** This is prevented by PEEP (Positive End-Expiratory Pressure) or recruitment maneuvers, not by external laryngeal pressure. * **B. Hypertension:** Laryngoscopy and intubation typically cause a sympathetic surge leading to hypertension. The Sellick maneuver does not prevent this; in fact, if applied poorly, it can make intubation more difficult, potentially worsening the hypertensive response. * **C. Bradycardia:** Bradycardia is a common side effect of the maneuver, especially in children, due to stimulation of the vagus nerve (vasovagal response). It is not a preventive measure for it. **High-Yield Clinical Pearls for NEET-PG:** * **Force required:** Approximately **10 Newtons (1kg)** when awake and **30 Newtons (3kg)** once the patient is unconscious. * **Contraindications:** Active vomiting (risk of esophageal rupture/Boerhaave syndrome), unstable cervical spine fractures, and laryngeal trauma. * **BURP Maneuver vs. Sellick:** Do not confuse Sellick with the **BURP maneuver** (Backward, Upward, Rightward Pressure), which is used to improve the *view* of the glottis during laryngoscopy, not to prevent aspiration.

Question 278: An infant with respiratory distress was intubated. What is the fastest and most accurate method to confirm endotracheal tube placement?

A. Capnography (Correct Answer)
B. Clinical assessment by auscultation
C. Chest radiography
D. Airway pressure measurement

Explanation: **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.

Question 279: Which is the anesthetic agent of choice in a case of status asthmaticus?

A. Ketamine (Correct Answer)
B. Thiopentone
C. Ether
D. Nitrous Oxide

Explanation: **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.

Question 280: What is the maximum fraction of inspired oxygen (FiO2) that can be delivered via a nasal oxygen catheter?

A. 1.0
B. 0.6
C. 0.2
D. 0.44 (Correct Answer)

Explanation: **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.

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Preoxygenation Techniques

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Video Laryngoscopy

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Fiberoptic Intubation

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Surgical Airway Management

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Extubation Criteria and Techniques

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