Respiratory and Airway Management — MCQs
On this page
Which of the following is contraindicated during endotracheal intubation?
What is the method to establish a safer airway in a patient with neck trauma and cricoid fracture, with a possibility of a difficult airway?
A 6-year-old patient, admitted for a dog bite on the face, developed anaphylaxis to a test dose of Augmentin, presenting with stridor requiring immediate intubation. As the sole physician available, and with a No. 3 curved blade laryngoscope ready, what is the appropriate internal diameter of the endotracheal tube to request?
What is the recommended dose of epinephrine for anaphylaxis?
During endotracheal intubation, unilateral breath sounds, no air heard entering the stomach, and no gastric distension are suggestive of entry of the endotracheal tube into which location?
Which of the following is NOT true about endotracheal intubation?
Which of the following is a fixed oxygen delivery device?
Which of the following ventilation modes reduces work of breathing by overcoming the resistance created by ventilator tubing?
Which of the following conditions are contraindications for both oral and nasal intubation?
Hypercarbia is characterized by:
Respiratory and Airway Management Indian Medical PG Practice Questions and MCQs
Question 121: Which of the following is contraindicated during endotracheal intubation?
- A. Head elevation
- B. Preoxygenation with 100% oxygen
- C. Introduction of blade toward the right side of oropharynx
- D. Neck flexion at atlanto-occipital joint (Correct Answer)
Explanation: To achieve a successful view of the glottis during endotracheal intubation, the oral, pharyngeal, and laryngeal axes must be aligned. This is best achieved through the **"Sniffing Position."** ### **Why Option D is Correct** The sniffing position requires **neck flexion at the lower cervical spine (C6-C7)** and **extension at the atlanto-occipital joint**. * **Neck flexion at the atlanto-occipital joint** (Option D) is contraindicated because it closes the airway and makes visualization of the larynx impossible. * Extension at this joint is what actually aligns the oral and pharyngeal axes. ### **Analysis of Incorrect Options** * **A. Head elevation:** Elevating the head (usually 5–10 cm with a pillow) is a standard maneuver to achieve the "sniffing position" by flexing the lower cervical spine. * **B. Preoxygenation with 100% oxygen:** This is mandatory to increase the functional residual capacity (FRC) and provide a "safety buffer" of apnea time before desaturation occurs. * **C. Introduction of blade toward the right side:** This is the standard technique for Macintosh (curved) blades. The blade is inserted on the right side of the mouth to sweep the tongue to the left, creating space for the endotracheal tube. ### **High-Yield NEET-PG Pearls** * **Sniffing Position:** Flexion of the neck + Extension of the head. * **3-3-2 Rule:** Used for predicting difficult airways (Mouth opening >3 fingers; Hyoid-mental distance >3 fingers; Thyroid-hyoid distance >2 fingers). * **Cormack-Lehane Classification:** Used to grade the view obtained during direct laryngoscopy (Grade 1 is full view; Grade 4 is no view of epiglottis). * **BURP Maneuver:** Backward, Upward, Rightward Pressure on the thyroid cartilage to improve the laryngeal view.
Question 122: What is the method to establish a safer airway in a patient with neck trauma and cricoid fracture, with a possibility of a difficult airway?
- A. Orotracheal intubation
- B. Cricothyroidotomy
- C. Emergency tracheostomy (Correct Answer)
- D. None of the above
Explanation: ### Explanation The management of a traumatic airway requires a balance between speed and the prevention of further injury. In this scenario, the presence of a **cricoid fracture** is the critical deciding factor. **Why Emergency Tracheostomy is the Correct Choice:** In the setting of laryngeal or tracheal trauma (specifically a cricoid fracture), the airway is structurally unstable. An **Emergency Tracheostomy** is the definitive and safest method because it secures the airway **below** the level of the injury. This avoids further disruption of the fractured laryngeal framework and bypasses potential obstructions caused by edema or hematoma at the glottic level. **Why Other Options are Incorrect:** * **Orotracheal Intubation:** This is generally contraindicated or used with extreme caution in suspected laryngeal fractures. Blind or forceful passage of an Endotracheal Tube (ETT) can lead to a "complete" transection of a partially injured trachea, create a false passage, or cause total airway collapse. * **Cricothyroidotomy:** This is typically the first-line emergency surgical airway. However, it is **absolutely contraindicated** in patients with laryngeal trauma or cricoid fractures. Performing a procedure directly through the site of injury (the cricothyroid membrane) can exacerbate the fracture, worsen subglottic stenosis, and fail to provide a secure airway if the injury is distal to the site. **High-Yield Clinical Pearls for NEET-PG:** 1. **Cricoid Fracture = Tracheostomy:** Always look for signs of laryngeal trauma (hoarseness, subcutaneous emphysema, palpable fracture). If present, avoid cricothyroidotomy. 2. **Cricothyroidotomy Contraindications:** Age < 10-12 years (due to risk of subglottic stenosis) and laryngeal/cricoid trauma. 3. **Awake Fiberoptic Intubation:** This is the gold standard for *anticipated* difficult airways, but in *acute trauma* with structural instability, a surgical airway is often prioritized.
Question 123: A 6-year-old patient, admitted for a dog bite on the face, developed anaphylaxis to a test dose of Augmentin, presenting with stridor requiring immediate intubation. As the sole physician available, and with a No. 3 curved blade laryngoscope ready, what is the appropriate internal diameter of the endotracheal tube to request?
- A. 3.5mm
- B. 4.5mm
- C. 5.5mm (Correct Answer)
- D. 6.5mm
Explanation: **Explanation:** The selection of an endotracheal tube (ETT) size in pediatric patients is primarily based on age-related anatomical development. For children over 2 years of age, the standard formula used to calculate the internal diameter (ID) of an **uncuffed** ETT is: **Formula: (Age / 4) + 4** Applying this to the 6-year-old patient: $(6 / 4) + 4 = 1.5 + 4 = \mathbf{5.5\text{ mm}}$. **Analysis of Options:** * **5.5 mm (Correct):** This is the standard size for an uncuffed tube in a 6-year-old. In cases of upper airway edema (like anaphylaxis/stridor), clinicians might occasionally consider a 0.5 mm smaller tube to minimize trauma, but 5.5 mm remains the calculated baseline. * **3.5 mm (Incorrect):** This size is typically used for full-term neonates or infants up to 6 months. * **4.5 mm (Incorrect):** This is the calculated size for a 2-year-old child. * **6.5 mm (Incorrect):** This size is more appropriate for an older child (approx. 10 years) or a small adult female. **High-Yield Clinical Pearls for NEET-PG:** 1. **Cuffed vs. Uncuffed:** If using a **cuffed** ETT, the formula is **(Age / 4) + 3.5**. Cuffed tubes are increasingly preferred in modern practice to prevent leaks and reduce the risk of aspiration. 2. **Depth of Insertion:** A quick bedside formula for the length of ETT insertion (at the lip) is **(Age / 2) + 12** or simply **ID × 3**. 3. **Laryngoscope Blades:** For a 6-year-old, a **Macintosh (curved) size 2** is usually standard; however, the question mentions a No. 3, which is often used for older children/adults but may be used depending on the child's size. 4. **Narrowest Part of Airway:** In children, the **cricoid cartilage** is traditionally considered the narrowest point (funnel-shaped airway), unlike the glottis in adults.
Question 124: What is the recommended dose of epinephrine for anaphylaxis?
- A. 0.5 mg of 1:1000 solution intramuscularly (Correct Answer)
- B. 0.5 mg of 1:10,000 solution intramuscularly
- C. 0.5 mg of 1:500 solution intramuscularly
- D. 1 mg of 1:100 solution intramuscularly
Explanation: **Explanation:** **1. Why Option A is Correct:** Epinephrine is the first-line treatment for anaphylaxis. The standard adult dose is **0.5 mg** (or 0.3–0.5 mg) administered via the **Intramuscular (IM)** route in the mid-outer thigh (vastus lateralis). The concentration used for IM injection is **1:1000** (1 mg/mL), meaning 0.5 mL of this solution provides the required 0.5 mg dose. The IM route is preferred over subcutaneous or IV routes in initial management due to its superior safety profile and rapid peak plasma concentrations. **2. Why Other Options are Incorrect:** * **Option B:** 1:10,000 (0.1 mg/mL) is the concentration used for **Intravenous (IV)** administration during cardiac arrest or severe refractory shock. Using this concentration for an IM injection would require a large volume (5 mL) to achieve the 0.5 mg dose, which is impractical and delays absorption. * **Option C:** 1:500 is not a standard pharmaceutical preparation for epinephrine. * **Option D:** 1 mg is double the recommended initial dose for anaphylaxis and carries a high risk of inducing arrhythmias or severe hypertension. 1:100 is a highly concentrated form typically used for inhalation (nebulization) in specific airway pathologies, not for injection. **3. High-Yield Clinical Pearls for NEET-PG:** * **Pediatric Dose:** 0.01 mg/kg of 1:1000 IM (Max 0.3 mg). * **Site of Choice:** Mid-outer thigh (vastus lateralis) provides faster absorption than the deltoid. * **Mechanism:** $\alpha_1$ agonist (reduces mucosal edema/hypotension), $\beta_1$ (positive inotropy), and $\beta_2$ (bronchodilation and stabilization of mast cells). * **Refractory Cases:** If the patient is on **Beta-blockers** and unresponsive to epinephrine, the antidote/alternative is **Glucagon**.
Question 125: During endotracheal intubation, unilateral breath sounds, no air heard entering the stomach, and no gastric distension are suggestive of entry of the endotracheal tube into which location?
- A. Right main bronchus (Correct Answer)
- B. Oesophagus
- C. Mid-trachea
- D. Left main bronchus
Explanation: ### Explanation The correct answer is **A. Right main bronchus**. **1. Why the Correct Answer is Right:** Endobronchial intubation occurs when the endotracheal tube (ETT) is advanced too far beyond the carina. The **right main bronchus** is the most common site for this because it is **shorter, wider, and more vertical** (at an angle of approximately 25°) compared to the left main bronchus (approx. 45°). * **Unilateral breath sounds:** Air enters only one lung (usually the right), leading to absent or diminished breath sounds on the contralateral side (left). * **No air in stomach/No gastric distension:** These findings specifically rule out esophageal intubation, confirming the tube is within the tracheobronchial tree. **2. Why Incorrect Options are Wrong:** * **B. Oesophagus:** Esophageal intubation would present with gurgling sounds over the epigastrium, gastric distension, and a lack of bilateral breath sounds. * **C. Mid-trachea:** Correct placement in the mid-trachea results in **equal, bilateral breath sounds** and no gastric air entry. * **D. Left main bronchus:** While possible, it is anatomically less likely than right-sided entry due to the more acute angle and narrower diameter of the left bronchus. **3. High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for ETT placement:** Persistent **End-tidal CO2 (EtCO2)** detection (capnography). * **Average ETT depth:** Usually 21 cm for females and 23 cm for males (measured at the incisors). * **The "Murphy Eye":** A side hole at the distal end of the ETT that allows ventilation even if the main tip is occluded. * **Immediate Action:** If endobronchial intubation is suspected, the tube should be withdrawn slowly while auscultating until breath sounds become bilateral.
Question 126: Which of the following is NOT true about endotracheal intubation?
- A. Hypertension and tachycardia
- B. Raised intraocular pressure
- C. Raised intracranial pressure
- D. Increased esophageal peristalsis (Correct Answer)
Explanation: ### Explanation Endotracheal intubation is a potent stimulus that triggers a significant sympathetic (stress) response and various physiological changes due to the manipulation of the airway. **Why Option D is Correct:** **Increased esophageal peristalsis** is **NOT** a physiological response to intubation. In fact, the pharmacological agents used during the induction of anesthesia (such as neuromuscular blockers and induction agents) typically **decrease** esophageal sphincter tone and motility. Furthermore, the presence of an endotracheal tube does not stimulate peristalsis; rather, the primary concern regarding the esophagus during intubation is the risk of aspiration or accidental esophageal intubation. **Why the other options are incorrect (Physiological effects of intubation):** * **A. Hypertension and tachycardia:** Laryngoscopy and intubation stimulate the epipharynx and laryngopharynx, leading to a reflex sympathetic discharge (the "pressor response"). This results in a transient rise in heart rate and blood pressure. * **B. Raised intraocular pressure (IOP):** The sympathetic surge and the mechanical stimulation of the airway cause a transient increase in IOP. This is clinically significant in patients with penetrating eye injuries or glaucoma. * **C. Raised intracranial pressure (ICP):** Intubation increases ICP through both the sympathetic response and the transient increase in intrathoracic pressure (if coughing/bucking occurs). This is a critical consideration in neurosurgery. **High-Yield Clinical Pearls for NEET-PG:** * **The Pressor Response:** Peak physiological changes occur approximately 1–2 minutes after intubation and usually subside within 5–10 minutes. * **Blunting the Response:** To prevent the rise in BP, HR, IOP, and ICP, clinicians use "adjuvants" such as **Intravenous Lidocaine (1.5 mg/kg)**, Fentanyl, Esmolol, or Magnesium Sulfate 3–5 minutes before intubation. * **Gold Standard:** The most reliable sign of correct endotracheal tube placement is **End-tidal CO2 (EtCO2) monitoring** (Capnography).
Question 127: Which of the following is a fixed oxygen delivery device?
- A. Venturi mask (Correct Answer)
- B. Nasal cannula
- C. Nasal mask
- D. Non-rebreather mask
Explanation: ### Explanation Oxygen delivery devices are classified into two categories: **Variable Performance (Low-flow)** and **Fixed Performance (High-flow)** systems. **1. Why Venturi Mask is Correct:** The **Venturi mask** is a high-flow device that works on the **Bernoulli principle** and the **Venturi effect**. It delivers a constant, precise Fraction of Inspired Oxygen ($FiO_2$) regardless of the patient’s inspiratory flow rate or respiratory pattern. Oxygen under pressure passes through a narrow orifice, creating a vacuum that draws in a specific amount of room air. Because the total flow provided by the device exceeds the patient's peak inspiratory flow, the $FiO_2$ remains "fixed." **2. Why the Other Options are Incorrect:** * **Nasal Cannula & Nasal Mask:** These are low-flow systems. The $FiO_2$ delivered (typically 24–44%) is **variable** because it depends on the patient’s tidal volume and respiratory rate. If a patient breathes deeply or quickly, they entrain more room air, thereby diluting the oxygen and lowering the $FiO_2$. * **Non-rebreather Mask (NRM):** Although it can deliver high concentrations of oxygen (up to 60–90%), it is still considered a **variable performance** device. The $FiO_2$ fluctuates based on the mask's seal and the patient's inspiratory demands. **Clinical Pearls for NEET-PG:** * **Best for COPD:** The Venturi mask is the gold standard for patients with Type II Respiratory Failure (COPD) to prevent suppressing their hypoxic respiratory drive. * **Color Coding:** Venturi valves are color-coded for specific $FiO_2$ (e.g., Blue = 24%, White = 28%, Orange = 31%, Yellow = 35%, Red = 40%, Green = 60%). * **Flow Rate Rule:** For a nasal cannula, $FiO_2$ increases by approximately **4% for every 1 L/min** increase in oxygen flow.
Question 128: Which of the following ventilation modes reduces work of breathing by overcoming the resistance created by ventilator tubing?
- A. Controlled mandatory ventilation
- B. Synchronized intermittent mandatory breath
- C. Assist control mode
- D. Pressure support mode (Correct Answer)
Explanation: **Explanation:** **Pressure Support Ventilation (PSV)** is a spontaneous mode of ventilation where the ventilator provides a preset level of positive pressure once the patient triggers a breath. The primary physiological goal of PSV is to **overcome the resistive work of breathing (WOB)** imposed by the endotracheal tube, the breathing circuit, and the demand valves. Because the patient determines the respiratory rate, inspiratory flow, and inspiratory time, it is highly comfortable and is the mainstay for weaning patients from mechanical ventilation. **Analysis of Incorrect Options:** * **Controlled Mandatory Ventilation (CMV):** The ventilator delivers a set tidal volume or pressure at a fixed rate regardless of patient effort. The machine does all the work; it does not "assist" the patient in overcoming tubing resistance during spontaneous efforts. * **Assist Control (AC) Mode:** Every breath (whether patient-triggered or machine-timed) receives the full preset tidal volume or pressure. While it supports the patient, it is not specifically designed to titrate against circuit resistance; rather, it provides full ventilatory support. * **Synchronized Intermittent Mandatory Ventilation (SIMV):** This mode delivers a set number of mandatory breaths while allowing spontaneous breaths in between. Without added pressure support, those spontaneous breaths must overcome the circuit resistance entirely on their own, actually *increasing* the work of breathing compared to PSV. **Clinical Pearls for NEET-PG:** * **Trigger:** PSV is always **patient-triggered** (usually by flow or pressure). * **Cycling:** PSV is **flow-cycled** (inspiration ends when the inspiratory flow drops to a certain percentage of the peak flow, usually 25%). * **High-Yield Fact:** PSV is the preferred mode for the **Spontaneous Breathing Trial (SBT)** during the weaning process to assess if a patient can maintain adequate ventilation post-extubation.
Question 129: Which of the following conditions are contraindications for both oral and nasal intubation?
- A. Laryngeal edema
- B. Cerebrospinal fluid (CSF) rhinorrhea
- C. Comatose patient
- D. Acute tracheo-laryngo-bronchitis (Correct Answer)
Explanation: **Explanation:** The correct answer is **Acute tracheo-laryngo-bronchitis (Croup)**. In patients with acute tracheo-laryngo-bronchitis, the airway is severely inflamed, edematous, and highly irritable. Attempting either oral or nasal intubation can trigger catastrophic **laryngospasm** or worsen the subglottic edema, leading to complete airway obstruction. In such cases, the preferred management is conservative (oxygen, racemic epinephrine, steroids); if the airway must be secured, it is often done via tracheostomy or in a highly controlled surgical setting to avoid trauma to the friable mucosa. **Analysis of Incorrect Options:** * **Laryngeal edema:** While it makes intubation difficult, it is not an absolute contraindication for both routes. If the edema is supraglottic, a skilled clinician may still perform oral intubation, though a surgical airway may be required if the glottis is obscured. * **CSF Rhinorrhea:** This is a classic contraindication for **nasal** intubation (due to the risk of meningitis or intracranial tube placement via a fractured cribriform plate), but **oral** intubation remains the safe and preferred route. * **Comatose patient:** Coma is an **indication** for intubation (to protect the airway from aspiration), not a contraindication. **High-Yield Clinical Pearls for NEET-PG:** * **Absolute Contraindication for Nasal Intubation:** Base of skull fractures (CSF rhinorrhea/raccoon eyes), coagulopathy, and nasal polyps. * **Epiglottitis vs. Croup:** In Epiglottitis (cherry-red epiglottis), intubation is usually performed in the OR under GA; in Croup (steeple sign), intubation is avoided unless respiratory failure is imminent. * **Gold Standard for Airway:** Endotracheal intubation is the gold standard for protecting the airway against aspiration.
Question 130: Hypercarbia is characterized by:
- A. Miosis
- B. Cool extremities
- C. Bradycardia
- D. Hypertension (Correct Answer)
Explanation: ### Explanation **Hypercarbia (Hypercapnia)** refers to an elevation in the partial pressure of carbon dioxide ($PaCO_2$) in the blood. The physiological response to hypercarbia is primarily driven by the stimulation of the **sympathoadrenal system**. **1. Why Hypertension is Correct:** Hypercarbia causes a dual effect: a direct local vasodilator effect and a central sympathetic stimulant effect. In a conscious or lightly anesthetized patient, the **sympathetic stimulation** predominates, leading to the release of catecholamines. This results in **hypertension** and **tachycardia**. Additionally, $CO_2$ acts as a potent cerebral vasodilator, increasing cerebral blood flow. **2. Why Other Options are Incorrect:** * **Miosis:** Hypercarbia typically causes **mydriasis** (pupillary dilation) due to the massive sympathetic surge and increased adrenaline levels. Miosis (pinpoint pupils) is more characteristic of opioid overdose. * **Cool Extremities:** Because hypercarbia causes peripheral vasodilation (direct effect of $CO_2$ on vascular smooth muscle), the skin usually appears **flushed, warm, and sweaty** (diaphoretic), rather than cool. * **Bradycardia:** The initial and most common response to hypercarbia is **tachycardia** due to sympathetic activation. Bradycardia only occurs as a terminal event or in cases of severe, acute acidosis that depresses the myocardium. **Clinical Pearls for NEET-PG:** * **The "CO2 Narcosis" Zone:** $PaCO_2$ levels above 90–100 mmHg can lead to CNS depression, coma, and respiratory arrest. * **Arrhythmias:** Hypercarbia sensitizes the myocardium to catecholamines, increasing the risk of ventricular arrhythmias (especially when using halothane). * **Signs of Hypercarbia under Anesthesia:** Rising blood pressure, tachycardia, and increased oozing at the surgical site (due to vasodilation).
Practice by Chapter
Respiratory Physiology
Practice Questions
Airway Anatomy
Practice Questions
Preoxygenation Techniques
Practice Questions
Mask Ventilation
Practice Questions
Supraglottic Airway Devices
Practice Questions
Direct Laryngoscopy
Practice Questions
Video Laryngoscopy
Practice Questions
Fiberoptic Intubation
Practice Questions
Surgical Airway Management
Practice Questions
One-Lung Ventilation Techniques
Practice Questions
Ventilation Strategies During Anesthesia
Practice Questions
Extubation Criteria and Techniques
Practice Questions
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free