Respiratory and Airway Management — MCQs

Respiratory and Airway Management Indian Medical PG Practice Questions and MCQs

Question 351: All of the following are related to difficult intubation, except which of the following?

A. TMJ ankylosis
B. Micrognathia
C. Increased thyromental distance (Correct Answer)
D. Miller's sign

Explanation: ***Increased thyromental distance*** - An **increased thyromental distance** (greater than 6.5 cm) indicates more space between the mental protuberance and the thyroid cartilage, suggesting better laryngeal visualization and thus a **lower likelihood of difficult intubation**. - This measurement correlates with the adequacy of the submandibular space, which is crucial for achieving an optimal sniffing position for intubation. *Miller's sign* - **Miller's sign** refers to a prominent or anterior larynx, which can make it challenging to visualize the glottis during direct laryngoscopy. - This anatomical feature can obstruct the view of the vocal cords, thereby increasing the difficulty of intubation. *TMJ ankylosis* - **Temporomandibular joint (TMJ) ankylosis** significantly restricts mouth opening, which is essential for laryngoscope insertion and laryngeal visualization. - Limited mouth opening is a well-established predictor of **difficult intubation** because it prevents adequate alignment of the oral, pharyngeal, and laryngeal axes. *Micrognathia* - **Micrognathia**, or a small mandible, is associated with a posterior displacement of the tongue and a reduction in the space available for laryngoscope insertion. - This anatomical variation makes it difficult to achieve an adequate view of the glottis and can lead to **difficult or failed intubation**.

Question 352: Which anaesthetic agent is contraindicated in patients with emphysema?

A. Nitrous oxide (N2O) (Correct Answer)
B. Halothane
C. Diethyl ether
D. Isoflurane

Explanation: ***Nitrous oxide (N2O)*** - **Nitrous oxide** diffuses rapidly into air-filled cavities, such as **bullae** in emphysema, causing them to expand. - This expansion can lead to **pneumothorax** or worsen existing respiratory compromise by increasing the size of trapped gas. *Halothane* - While it can cause **bronchodilation**, its use in emphysema is limited due to its potential for **cardiac depression** and **hepatotoxicity**. - It is not specifically contraindicated due to its effect on bullae or air trapping. *Diethyl ether* - This agent is largely obsolete due to its **flammability** and high incidence of **postoperative nausea and vomiting**. - Its effects on emphysematous lungs are less of a concern than its general anesthetic properties and side effects. *Isoflurane* - **Isoflurane** is often preferred in patients with respiratory disease due to its potent **bronchodilating properties** and minimal cardiac depression. - It does not expand air-filled spaces and is considered relatively safe for patients with emphysema.

Question 353: In status asthmaticus, which anesthetic agent is used as a bronchodilator?

A. Morphine
B. Thiopentone sodium
C. Halothane
D. Ketamine (Correct Answer)

Explanation: ***Ketamine*** - Possesses **bronchodilatory** properties due to its sympathomimetic effects, making it useful in severe asthma or **status asthmaticus**. - It can cause **catecholamine release**, leading to relaxation of bronchial smooth muscle and improved airflow. *Morphine* - Can cause **histamine release**, which may lead to **bronchoconstriction** and worsen an asthmatic patient's condition. - It is a respiratory depressant that can further compromise breathing in a patient with severe airway obstruction. *Thiopentone sodium* - May induce **histamine release** and cause **bronchospasm**, which is contraindicated in asthma. - It is a potent depressant of the central nervous system and can cause respiratory depression, worsening the clinical picture of status asthmaticus. *Halothane* - Although it has some **bronchodilatory** properties, its use has largely been replaced by newer inhalational anesthetics due to concerns about myocardial sensitization to catecholamines and potential **hepatotoxicity**. - It is a potent inhalational agent but is less favored in modern anesthesia for asthma due to side effect profiles compared to other agents.

Question 354: All are indications for one-lung ventilation except which of the following?

A. Massive hemorrhage in one lung
B. Bronchopleural fistula
C. Video-assisted thoracoscopic surgery
D. General anesthesia without lung isolation (Correct Answer)

Explanation: ***General anesthesia without lung isolation*** - One-lung ventilation (OLV) is specifically performed to achieve **lung isolation**, which is the opposite of general anesthesia without lung isolation. - The goal of OLV is to collapse one lung to facilitate surgical access or prevent contamination, making general anesthesia without isolation a contraindication. *Bronchopleural fistula* - OLV is indicated in cases of **bronchopleural fistula** to prevent leakage of air from the affected lung into the intact lung. - This helps to maintain adequate ventilation and oxygenation in the healthy lung while the fistula can be managed or repaired. *Massive hemorrhage in one lung* - **Massive hemorrhage** in one lung is a critical indication for OLV to prevent the spread of blood to the contralateral healthy lung. - Isolating the bleeding lung protects the airway and facilitates surgical control of the hemorrhage. *Video-assisted thoracoscopic surgery* - **Video-assisted thoracoscopic surgery (VATS)** procedures frequently require OLV to collapse the operative lung. - This provides a clear surgical field and sufficient working space for the surgeon to perform the procedure without lung movement obstructing the view.

Question 355: IPPV can cause all of the following complications except:

A. Barotrauma
B. Pneumonia
C. Hypotension
D. Pulmonary embolism (Correct Answer)

Explanation: **Pulmonary embolism** - **Mechanical ventilation**, particularly intermittent positive pressure ventilation (IPPV), is not a direct cause of pulmonary embolism. - While prolonged immobility and venous stasis in critically ill patients can increase the risk of deep vein thrombosis (DVT) and subsequent PE, IPPV itself does not directly induce thrombus formation. *Barotrauma* - **High inspiratory pressures** and large tidal volumes used during IPPV can overdistend alveoli, leading to rupture and air leaks. - This can result in conditions like **pneumothorax**, **pneumomediastinum**, and **subcutaneous emphysema**. *Pneumonia* - IPPV is a significant risk factor for **ventilator-associated pneumonia (VAP)** due to the presence of an endotracheal tube. - The tube bypasses natural airway defenses, facilitating bacterial colonization and aspiration of secretions. *Hypotension* - Positive pressure applied during IPPV can increase **intrathoracic pressure**, which in turn reduces venous return to the heart. - This decrease in preload directly leads to a **reduction in cardiac output** and systemic blood pressure, causing hypotension.

Question 356: In infants, the narrowest part of the larynx is at the cricoid level. In administering anesthesia, which of the following is NOT a potential complication of using a smaller size endotracheal tube?

A. Increased risk of airway obstruction
B. Trauma to the subglottic region
C. Choosing a smaller size endotracheal tube (Correct Answer)
D. Choosing an inappropriate size endotracheal tube

Explanation: ***Choosing a smaller size endotracheal tube*** - This option incorrectly states that *choosing a smaller size endotracheal tube* is a complication. It is a decision or action, not a direct complication of the tube itself. - While an *appropriately* sized smaller tube can be beneficial, the act of *choosing* it isn't inherently a complication. *Trauma to the subglottic region* - Using an **overly *large* endotracheal tube** can cause trauma to the **subglottic region**, which is the narrowest part of an infant's airway. - Trauma can lead to **edema**, **ulceration**, or even **scarring**, potentially resulting in **subglottic stenosis**. *Increased risk of airway obstruction* - An **endotracheal tube (ETT) that is too *small*** for the child can lead to various issues, including an **increased risk of obstruction** due to secretions or kinking. - A tube that is too small also offers higher resistance to airflow, making adequate ventilation more challenging and potentially requiring higher pressures. *Choosing an inappropriate size endotracheal tube* - *Choosing an inappropriate size endotracheal tube*, whether too large or too small, is a **patient safety concern** that can lead to various complications. - An **incorrectly sized tube** can result in complications ranging from air leak and inadequate ventilation (if too small) to direct airway trauma and post-extubation stridor (if too large).

Question 357: The most common cause of hypoxia during one-lung ventilation is:

A. Increased shunt fraction
B. Collapse of one lung
C. Soiling of lung by secretions
D. Malposition of the double-lumen tube (Correct Answer)

Explanation: ***Malposition of the double-lumen tube*** - **Malposition** of the double-lumen tube can lead to **obstruction of airflow** to the ventilated lung or incomplete isolation of the non-ventilated lung, resulting in significant **ventilation-perfusion mismatch** and **hypoxia**. - Incorrect placement is a common and often immediate cause of hypoxemia during one-lung ventilation because it directly interferes with the intended strategy of isolating and ventilating one lung while collapsing the other. *Increased shunt fraction* - While an **increased shunt fraction** is the physiological mechanism explaining hypoxia during one-lung ventilation, it is the *result* of various causes, not the primary cause itself. - The shunt fraction increases naturally due to blood flow through the non-ventilated lung, but a *pathological* increase causing severe hypoxia suggests another underlying problem like inadequate hypoxic pulmonary vasoconstriction or malposition of the tube. *Collapse of one lung* - The **collapse of one lung** is an *intended outcome* of one-lung ventilation to facilitate surgical access, and by itself, it is not the most common *cause* of hypoxia. - While collapse contributes to shunt, the body normally compensates through **hypoxic pulmonary vasoconstriction**; severe hypoxia typically points to a failure of this compensation or other issues. *Soiling of lung by secretions* - **Soiling of the lung by secretions** can certainly cause hypoxia by obstructing airways and increasing shunt but is **less common** than issues related to tube placement. - This typically causes **sudden deterioration** and requires immediate suctioning, but malposition is a more frequent initial problem during setup or with patient movement.

Question 358: What is the medical procedure that involves the insertion of a tube directly into the trachea to secure the airway and ensure adequate ventilation?

A. Oral suction
B. Oropharyngeal suction
C. Endotracheal tube insertion (Correct Answer)
D. Nasogastric tube insertion

Explanation: ***Endotracheal tube insertion*** - This procedure involves placing a tube directly into the **trachea** to maintain an open airway and facilitate **mechanical ventilation**. - It is critical for patients who cannot protect their airway or require ventilatory support, ensuring direct access for gas exchange. *Oral suction* - **Oral suction** involves removing secretions from the mouth and pharynx but does not secure the airway to prevent aspiration or provide direct ventilatory support. - It is a superficial procedure, used for clearing the oral cavity, not for managing the trachea. *Oropharyngeal suction* - Similar to oral suction, **oropharyngeal suction** clears the back of the throat but does not involve insertion into the trachea to secure the airway. - This method is used for removing secretions from the upper airway and preventing aspiration into the larynx, but it doesn't establish a definitive airway. *Nasogastric tube insertion* - **Nasogastric tube insertion** involves placing a tube through the nose into the stomach, primarily for feeding or gastric decompression. - This procedure is unrelated to airway management and has no role in securing the trachea for ventilation.

Question 359: In which of the following conditions is Positive end-expiratory pressure (PEEP) beneficial?

A. Pneumonia
B. Pulmonary edema
C. Chronic Obstructive Pulmonary Disease (COPD)
D. Acute Respiratory Distress Syndrome (ARDS) (Correct Answer)

Explanation: ***Acute Respiratory Distress Syndrome (ARDS)*** - PEEP is crucial in ARDS to prevent **alveolar collapse** at end-expiration, improving oxygenation and reducing the risk of **ventilator-induced lung injury**. - It helps by **recruiting collapsed alveoli** and maintaining them open, thus increasing the functional residual capacity. *Pneumonia* - While pneumonia can cause hypoxemia, PEEP's benefit is less pronounced unless it progresses to **ARDS** or causes significant **atelectasis**. - Excessive PEEP can lead to barotrauma if lung compliance is relatively normal or if only a limited portion of the lung is affected. *Pulmonary edema* - PEEP can be helpful in **cardiogenic pulmonary edema** by reducing venous return and thus **preload**, as well as improving oxygenation. - However, it's not the primary or most universally beneficial intervention compared to its role in ARDS. *Chronic Obstructive Pulmonary Disease (COPD)* - PEEP must be used cautiously in COPD due to the risk of **dynamic hyperinflation** and **auto-PEEP**, which can increase air trapping. - While it might be cautiously applied to improve oxygenation or reduce work of breathing, it's generally not considered broadly beneficial and can be detrimental if not carefully managed.

Question 360: What is the intubation dose of pancuronium?

A. 0.02 mg/Kg
B. 0.04 mg/Kg
C. 0.06 mg/Kg
D. 0.08 mg/Kg (Correct Answer)

Explanation: ***0.08 mg/Kg*** - The standard **intubating dose** of pancuronium is typically **0.08-0.1 mg/kg intravenously**. - This dose provides adequate **neuromuscular blockade** for endotracheal intubation. *0.02 mg/Kg* - This dose is too low and would likely result in **insufficient neuromuscular blockade** for successful intubation. - Sub-therapeutic doses would lead to **incomplete muscle relaxation**, making intubation difficult and risky. *0.04 mg/Kg* - While higher than 0.02 mg/kg, this dose is still generally considered **sub-optimal** for intubation with pancuronium. - It may prolong the onset of action or provide **inadequate depth of block** for optimal intubating conditions. *0.06 mg/Kg* - This dose is approaching the lower end of an effective range for some neuromuscular blocking agents, but it is typically **not sufficient** for reliable intubation with pancuronium. - It might lead to a longer **onset time** and compromised intubating conditions compared to the recommended dose.

Practice by Chapter

Respiratory Physiology

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Airway Anatomy

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Preoxygenation Techniques

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Mask Ventilation

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Supraglottic Airway Devices

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Direct Laryngoscopy

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Video Laryngoscopy

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Fiberoptic Intubation

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Surgical Airway Management

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One-Lung Ventilation Techniques

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Ventilation Strategies During Anesthesia

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Extubation Criteria and Techniques

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