Respiratory and Airway Management Practice Questions

Q: Positive end-expiratory pressure causes an increase in which respiratory parameter?

All of the above. **Explanation:** Positive End-Expiratory Pressure (PEEP) is a pressure applied at the end of expiration to prevent the alveolar pressure from falling to zero. Its primary physiological effect is the recruitment of collapsed alveoli and the prevention of atelectasis. 1. **Functional Residual Capacity (FRC):** This is the most significant effect of PEEP. By maintaining positive pressure at the end of expiration, PEEP keeps the small airways and alveoli open, effectively increasing the volume of air remaining in the lungs at the end of a normal breath. 2. **Lung Compliance:** Compliance is defined as the change in volume per unit change in pressure ($C = \Delta V / \Delta P$). In many pathological states (like ARDS), alveoli are collapsed or fluid-filled, placing the lung on the "flat" (non-compliant) portion of the pressure-volume curve. By recruiting these alveoli and moving the lung to a more favorable part of the curve, PEEP increases overall lung compliance. 3. **Tidal Volume:** In a pressure-controlled ventilation setting, an increase in lung compliance (due to PEEP) results in a larger delivered tidal volume for the same set inspiratory pressure. **Conclusion:** Since PEEP increases FRC and improves compliance, which in turn can facilitate better tidal volume delivery, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Indication:** PEEP is the gold standard for managing hypoxemia in **ARDS** by improving ventilation-perfusion ($V/Q$) matching. * **Hemodynamic Impact:** High levels of PEEP increase intrathoracic pressure, which **decreases venous return (preload)** and can lead to hypotension. * **Barotrauma:** Excessive PEEP increases the risk of pneumothorax and alveolar overdistension. * **Physiological PEEP:** In intubated patients, a "physiological PEEP" of **5 cm $H_2O$** is usually applied to compensate for the loss of the glottic closure reflex.

Q: Sellick's maneuver is:

Both A and B. **Explanation:** **Sellick’s Maneuver**, also known as **Cricoid Pressure**, is a fundamental technique used during Rapid Sequence Induction (RSI) to prevent pulmonary aspiration of gastric contents. 1. **Mechanism (Option A):** The maneuver involves applying firm downward pressure on the **cricoid cartilage** (the only complete cartilaginous ring in the airway). This pressure compresses the underlying esophagus against the body of the fifth or sixth cervical vertebra, effectively occluding the esophageal lumen. 2. **Function during Ventilation (Option B):** Beyond preventing regurgitation, Sellick’s maneuver is clinically used during bag-mask ventilation to prevent **gastric insufflation**. By occluding the esophagus, it ensures that the positive pressure airflow is directed into the trachea rather than the stomach, thereby reducing the risk of gastric distension and subsequent vomiting. Since both the anatomical mechanism (Option A) and the functional benefit during ventilation (Option B) are accurate descriptions of the maneuver's purpose, **Option C** is the correct answer. **Why other options are incorrect:** * **Option D** is incorrect because both A and B are standard medical definitions of the maneuver’s utility. **High-Yield Clinical Pearls for NEET-PG:** * **Pressure Required:** Approximately **10 Newtons (1kg)** when the patient is awake and **30 Newtons (3kg)** once consciousness is lost. * **Indication:** Primarily used in "Full Stomach" cases (e.g., intestinal obstruction, emergency trauma, pregnancy). * **Contraindications:** Active vomiting (risk of esophageal rupture), unstable cervical spine fractures, or laryngeal trauma. * **BURP Maneuver vs. Sellick’s:** Do not confuse Sellick's with the **BURP** maneuver (Backward, Upward, Rightward Pressure), which is applied to the *thyroid* cartilage to improve the laryngeal view during intubation.

Q: Armored endotracheal tube is used in which type of surgery?

Neurosurgery. **Explanation:** **Armored (Reinforced) Endotracheal Tubes (ETTs)** are specialized tubes containing a wire coil embedded within the silicone or PVC wall. This design makes the tube **kink-resistant**, ensuring that the airway remains patent even when the tube is bent at acute angles. **Why Neurosurgery is the Correct Answer:** In neurosurgical procedures, the patient is often placed in unconventional positions (e.g., prone, sitting, or lateral) with the head acutely flexed or rotated. Furthermore, the surgical team often works near the airway, increasing the risk of accidental tube compression or kinking. An armored tube is used because it maintains its internal diameter and prevents airway obstruction despite these extreme head positions or external pressure. **Analysis of Incorrect Options:** * **B, C, and D (Cardiac, Liver, and Intestinal Surgery):** These surgeries are typically performed in the **supine position** with the head in a neutral "sniffing" position. In these cases, a standard PVC (Murphy) ETT is sufficient, as there is minimal risk of the tube kinking due to head positioning. **High-Yield Clinical Pearls for NEET-PG:** * **The "No-Cut" Rule:** Never cut an armored tube to shorten it. If you cut it, the wire coil can unravel, or the connector may not fit securely, leading to potential airway disaster. * **Stylet Requirement:** Because armored tubes are very flexible (floppy), a **stylet** is mandatory during intubation to provide the necessary rigidity to guide the tube into the larynx. * **Biting Risk:** If a patient bites an armored tube, the wire coil can permanently deform and occlude the lumen. Therefore, a **bite block** must always be used. * **Other Indications:** Armored tubes are also frequently used in **Head and Neck surgeries** (e.g., Thyroidectomy, Parotidectomy) where the head is manipulated intraoperatively.

Q: What is the ideal duration for preoxygenation?

3-5 minutes. **Explanation:** Preoxygenation (denitrogenation) is the process of replacing the nitrogen in the functional residual capacity (FRC) of the lungs with oxygen. This creates an oxygen reservoir that delays the onset of hemoglobin desaturation during periods of apnea, such as during endotracheal intubation. **Why 3–5 minutes is correct:** Under normal circumstances, breathing 100% oxygen at a normal tidal volume for **3 to 5 minutes** is the gold standard. This duration is sufficient to wash out approximately 95% of the nitrogen from the FRC. In a healthy adult, this provides approximately 8 minutes of "safe apnea time" (time until saturation drops below 90%), compared to only 1–2 minutes when breathing room air. **Analysis of incorrect options:** * **1–3 minutes & 2–3 minutes:** These durations are generally insufficient to achieve complete denitrogenation of the FRC in all patients. While 4-8 deep breaths over 30–60 seconds (vital capacity breaths) can be used in emergencies, they are not considered the "ideal" duration for elective scenarios. * **5–8 minutes:** While not harmful, extending preoxygenation beyond 5 minutes offers diminishing returns. By 5 minutes, the FRC is already maximally saturated with oxygen; further time does not significantly increase the oxygen reservoir but may delay the surgical workflow. **High-Yield Clinical Pearls for NEET-PG:** * **The Goal:** To replace Nitrogen (approx. 79% of FRC) with Oxygen. * **FRC:** The FRC acts as the primary oxygen reservoir during apnea. Conditions that decrease FRC (obesity, pregnancy, ascites) lead to faster desaturation despite adequate preoxygenation. * **Alternative Technique:** If time is limited, **8 vital capacity breaths over 60 seconds** is an acceptable alternative to 3 minutes of tidal breathing. * **Indicator of Adequacy:** Monitoring **End-tidal Oxygen (EtO2)**; a value >90% (or 0.9) indicates successful denitrogenation.

Q: What is the major advantage of volume control ventilation?

Constant tidal volume. In **Volume Control Ventilation (VCV)**, the clinician sets a specific tidal volume ($V_T$) and respiratory rate. The ventilator delivers this fixed volume regardless of changes in the patient’s lung mechanics (compliance or resistance). ### Why "Constant Tidal Volume" is Correct: The primary goal and major advantage of VCV is the **guaranteed delivery of a preset tidal volume**. This ensures a predictable **Minute Ventilation** ($V_E = V_T \times RR$), which is crucial for precise control of arterial $CO_2$ levels. In patients with fluctuating lung compliance (e.g., during laparoscopic surgery with pneumoperitoneum), VCV ensures the lungs do not hypoventilate. ### Why Other Options are Incorrect: * **B. Variable minute ventilation:** This is incorrect because VCV aims for a *stable* minute ventilation. Variable minute ventilation is more characteristic of pressure-supported modes where $V_T$ fluctuates based on patient effort and lung compliance. * **C. Improved patient comfort:** VCV is often associated with *decreased* patient comfort compared to Pressure Control Ventilation (PCV). In VCV, the flow rate is fixed; if a conscious patient demands more flow than the machine provides, it leads to "flow starvation" and patient-ventilator dyssynchrony. ### High-Yield Clinical Pearls for NEET-PG: * **The Trade-off:** While $V_T$ is constant in VCV, the **Peak Inspiratory Pressure (PIP)** is variable. If lung compliance decreases (e.g., bronchospasm or ARDS), PIP can rise dangerously, increasing the risk of barotrauma. * **VCV vs. PCV:** In PCV, pressure is constant but $V_T$ is variable. PCV is often preferred in ARDS to limit barotrauma and in pediatric anesthesia due to the uncuffed tubes used previously. * **Monitoring:** When using VCV, always set high-pressure alarms to prevent lung injury.

Q: Murphy's eye is a part of which of the following devices?

Endotracheal tube. **Explanation:** **Murphy’s eye** is a small oval opening or side-hole located on the side wall of an **Endotracheal Tube (ETT)**, near its distal tip. **Why Option A is correct:** The primary function of Murphy’s eye is to act as an **alternate pathway for gas exchange**. If the main distal orifice of the ETT becomes obstructed by secretions, blood clots, or if the tip abuts against the tracheal wall (carina), Murphy’s eye ensures that ventilation can still occur. Tubes featuring this opening are specifically called "Murphy-type" tubes, whereas those without it are known as "Magill-type" tubes. **Why other options are incorrect:** * **B. Laryngeal Mask Airway (LMA):** This is a supraglottic airway device. It consists of a mask and a tube but does not feature a Murphy’s eye; instead, it has aperture bars to prevent the epiglottis from obstructing the lumen. * **C. Anesthesia Face Mask:** These are used for non-invasive ventilation and do not have internal safety orifices like the ETT. * **D. Mapleson Circuit:** This is a breathing system (tubing and valves) used to deliver anesthetic gases; it does not contain an ETT-specific anatomical feature like Murphy's eye. **High-Yield Clinical Pearls for NEET-PG:** 1. **Right Mainstem Intubation:** If an ETT is inserted too deeply into the right main bronchus, Murphy’s eye may occasionally allow some ventilation to the **Right Upper Lobe**, which might otherwise be collapsed. 2. **Bevel:** The distal end of an ETT is beveled (usually to the left) to improve visualization of the vocal cords during intubation. 3. **Vocal Cord Guide:** A black line often present above the cuff to ensure correct depth of insertion. 4. **Standard Connector:** The proximal end of the ETT has a universal **15 mm connector**.

Q: A supraglottic airway device is contraindicated for all of the following patients except:

Patient under general anesthesia. **Explanation:** Supraglottic Airway Devices (SADs), such as the Laryngeal Mask Airway (LMA), are designed to sit above the glottis to maintain a patent airway. **1. Why "Patient under general anesthesia" is correct:** General anesthesia is the primary **indication** for using a SAD, not a contraindication. SADs are frequently used for elective surgical procedures under general anesthesia where tracheal intubation is not mandatory. They provide a less invasive alternative to endotracheal tubes, reducing hemodynamic stress and postoperative sore throat. **2. Why the other options are Contraindications:** * **Risk of Aspiration (Option A):** SADs do not provide a definitive seal for the trachea. In patients with a full stomach, hiatal hernia, or morbid obesity, they cannot prevent the aspiration of gastric contents. * **Poor Lung Compliance (Option B):** SADs are "low-pressure" seals. In patients with stiff lungs (e.g., ARDS, restrictive lung disease), high peak inspiratory pressures are required for ventilation. These pressures often exceed the seal pressure of the SAD, leading to significant air leaks and gastric insufflation. * **Limited Mouth Opening (Option C):** Insertion of a SAD requires adequate space to maneuver the device into the oropharynx. A patient with severe trismus or limited mouth opening (e.g., <2 cm) presents a physical barrier to successful placement. **Clinical Pearls for NEET-PG:** * **Gold Standard for Airway:** The Endotracheal Tube (ETT) remains the gold standard for protecting against aspiration. * **Difficult Airway Algorithm:** SADs (specifically the ILMA or Fastrach) play a crucial role as "rescue devices" in "cannot intubate, can ventilate" scenarios. * **Nerve Injury:** Excessive cuff inflation in an LMA can lead to pressure-induced injury of the **lingual, hypoglossal, or recurrent laryngeal nerves.**

Question 1

Positive end-expiratory pressure causes an increase in which respiratory parameter?

Accepted Answer

All of the above

Answer

Lung compliance

Answer

Functional residual capacity (FRC)

Answer

Tidal volume

Question 2

Which of the following conditions necessitates emergency endotracheal intubation?

Accepted Answer

Glasgow Coma Scale (GCS) less than 7

Answer

Tension pneumothorax

Answer

Cardiac tamponade

Answer

Bleeding gastric ulcer

Question 3

What type of ventilation is typically required for a patient with bronchial asthma on artificial ventilation?

Accepted Answer

An IE ratio of 1:2.5

Answer

A low respiratory flow

Answer

An equal inspiratory to expiratory (IE) ratio of 1:1

Answer

Inverse ratio ventilation

Question 4

Sellick's maneuver is:

Accepted Answer

Both A and B

Answer

Application of pressure over cricoid cartilage to occlude the esophagus

Answer

Aims at avoiding oxygen entry into the esophagus during mask ventilation

Answer

Neither A nor B

Question 5

Armored endotracheal tube is used in which type of surgery?

Accepted Answer

Neurosurgery

Answer

Cardiac surgery

Answer

Liver surgery

Answer

Intestinal surgery

Question 6

What is the ideal duration for preoxygenation?

Accepted Answer

3-5 minutes

Answer

1-3 minutes

Answer

5-8 minutes

Answer

2-3 minutes

Question 7

What is the major advantage of volume control ventilation?

Accepted Answer

Constant tidal volume

Answer

Variable minute ventilation

Answer

Improved patient comfort

Answer

All of the above

Question 8

A lightly anaesthetized patient is placed in the lithotomy position and is spontaneously breathing. Which of the following is true?

Accepted Answer

Residual volume and closing volume are equal

Answer

Marked reduction in vital capacity

Answer

Increased FRC

Answer

Normal alveolar ventilation

Question 9

Murphy's eye is a part of which of the following devices?

Accepted Answer

Endotracheal tube

Answer

Laryngeal mask airway

Answer

Anesthesia face mask

Answer

Mapleson circuit

Question 10

A supraglottic airway device is contraindicated for all of the following patients except:

Accepted Answer

Patient under general anesthesia

Answer

Patient with a risk of aspiration

Answer

Patient with poor lung compliance

Answer

Patient with limited mouth opening

Respiratory and Airway Management — MCQs

Respiratory and Airway Management — MCQs

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