Respiratory and Airway Management Practice Questions

Q: Mendelson's syndrome refers to what?

Aspiration of gastric content. **Explanation:** **Mendelson’s Syndrome** is a chemical pneumonitis caused by the aspiration of acidic gastric contents, typically occurring during general anesthesia. It was first described by Curtis Mendelson in 1946 in obstetric patients. The syndrome is characterized by the rapid onset of bronchospasm, cyanosis, tachycardia, and dyspnea, often leading to pulmonary edema or respiratory failure. **Why Option A is Correct:** The pathophysiology depends on the **pH and volume** of the aspirate. For Mendelson’s syndrome to occur, the gastric aspirate must typically have: 1. A **pH 0.4 ml/kg** (approx. 25 ml in an average adult). The acid causes immediate chemical burning of the alveolar-capillary membrane, leading to an inflammatory response rather than a bacterial infection. **Why Other Options are Incorrect:** * **Option B:** Rupture of a bronchial tuberculoma leads to endobronchial tuberculosis or localized inflammation, not the acute chemical pneumonitis described by Mendelson. * **Option C:** Transient pneumonitis of allergic origin refers to **Löffler’s syndrome**, characterized by eosinophilic pulmonary infiltrates, often due to parasites. * **Option D:** Tracheal compression due to nodal enlargement is a mechanical airway obstruction (e.g., seen in lymphomas or sarcoidosis), not an aspiration event. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis:** Use of H2 blockers (Ranitidine), Proton Pump Inhibitors (Pantoprazole), or non-particulate antacids (Sodium Citrate) to increase gastric pH. * **Management:** Immediate suctioning, supplemental oxygen, and supportive ventilation. **Antibiotics and Steroids** are generally not indicated unless secondary infection or specific complications arise. * **Risk Factors:** Pregnancy (due to increased intra-abdominal pressure and relaxed lower esophageal sphincter), obesity, and emergency surgeries ("Full Stomach").

Q: All are true regarding endotracheal intubation except?

Saturation falls to not more than 90% after 2 minutes. **Explanation** In the context of endotracheal intubation, the goal is to confirm correct placement and ensure patient safety. Option **A** is the correct answer because it is a **false statement**. In an apneic patient (even after pre-oxygenation), oxygen saturation ($SpO_2$) does not remain above 90% for a fixed duration of 2 minutes for everyone. The rate of desaturation depends on the patient's Functional Residual Capacity (FRC) and metabolic rate. For example, in obese patients, children, or pregnant women, $SpO_2$ can fall below 90% in less than 1 minute. **Analysis of other options:** * **Option B (Presence of $CO_2$ in expired air):** This is the **Gold Standard** for confirming tracheal intubation. Detection of $CO_2$ via capnography for at least 5–6 breaths confirms the tube is in the airway and not the esophagus. * **Option C (Inserted under direct vision):** During conventional laryngoscopy, the primary goal is to visualize the vocal cords (glottis) and pass the tube through them to ensure tracheal placement. * **Option D (Bilateral chest movement):** This is a clinical sign of successful intubation. Observing symmetrical chest rise and auscultating bilateral breath sounds helps rule out esophageal intubation and endobronchial (one-sided) intubation. **Clinical Pearls for NEET-PG:** * **Gold Standard Confirmation:** Capnography (ETCO2). * **Most reliable clinical sign:** Visualizing the tube passing through the vocal cords. * **Pre-oxygenation:** Aim is to replace nitrogen in the FRC with oxygen ("Denitrogenation"), providing a safety buffer of apnea time. * **First sign of esophageal intubation:** Absence of $CO_2$ waveforms on capnography and gurgling sounds over the epigastrium.

Q: Which of the following should be the ventilator settings for tidal volume in a patient with ARDS?

Tidal volume 5-7 ml/kg. **Explanation:** The primary goal in managing a patient with **Acute Respiratory Distress Syndrome (ARDS)** is to prevent **Ventilator-Induced Lung Injury (VILI)**. The correct answer is **C (5-7 ml/kg)** because it adheres to the principles of **Lung Protective Ventilation**. **1. Why 5-7 ml/kg is correct:** In ARDS, the functional lung volume is significantly reduced due to edema and alveolar collapse (often called the **"Baby Lung" concept**). Using traditional tidal volumes can lead to **volutrauma** (overdistension of alveoli) and **barotrauma**. The ARDSNet protocol recommends a low tidal volume strategy, typically starting at 6 ml/kg of **Predicted Body Weight (PBW)**, to minimize alveolar stretch and reduce mortality. The range of 5-7 ml/kg aligns with this evidence-based practice. **2. Why other options are incorrect:** * **Options A & B (8-12 ml/kg):** These represent traditional tidal volumes used in healthy lungs. In ARDS, these high volumes cause excessive plateau pressures, leading to alveolar rupture and systemic inflammatory release (biotrauma). * **Option D (4 ml/kg):** While ultra-low tidal volumes are sometimes used in research or with ECMO, 4 ml/kg is generally too low for standard management as it can lead to severe permissive hypercapnia and significant atelectasis unless specialized rescue therapies are in place. **High-Yield Clinical Pearls for NEET-PG:** * **Calculation Base:** Always use **Predicted Body Weight (PBW)** based on height and sex, NOT actual body weight, to calculate tidal volume. * **Plateau Pressure:** The goal is to keep Plateau Pressure (**Pplat**) **< 30 cm H₂O**. * **Permissive Hypercapnia:** It is often acceptable to allow PaCO₂ to rise (and pH to drop to ~7.25) to maintain low-volume ventilation. * **Driving Pressure:** (Pplat - PEEP) is a strong predictor of survival; the goal is usually **< 15 cm H₂O**.

Q: Muscle rigidity caused by fentanyl is primarily due to its action on which opioid receptor?

Mu (μ). **Explanation:** **Muscle rigidity** (specifically "Wooden Chest Syndrome") is a well-known side effect of rapid, high-dose intravenous administration of potent synthetic opioids like **fentanyl**, sufentanil, and remifentanil. 1. **Why Mu (μ) is correct:** The mechanism is primarily mediated by **Mu-opioid receptors** located in the **striatum** (basal ganglia) and the **substantia nigra**. Activation of these receptors inhibits GABAergic neurons, leading to a decrease in GABA release. This results in the disinhibition of central dopaminergic pathways, causing increased motor outflow and intense skeletal muscle contraction, particularly in the thoracic and abdominal muscles. This rigidity can make bag-mask ventilation nearly impossible. 2. **Why other options are incorrect:** * **Kappa (κ):** These receptors are primarily associated with spinal analgesia, sedation, and dysphoria/hallucinations. They do not play a significant role in opioid-induced muscle rigidity. * **Delta (δ):** These receptors contribute to supraspinal/spinal analgesia and modulation of Mu-receptor activity but are not the primary mediators of motor rigidity. * **Sigma (σ):** Formerly classified as an opioid receptor, it is now considered a non-opioid receptor. It is associated with antitussive effects and psychotomimetic effects (like those seen with ketamine), not muscle rigidity. **Clinical Pearls for NEET-PG:** * **Management:** The definitive treatment for fentanyl-induced chest wall rigidity is the administration of a **muscle relaxant** (e.g., Succinylcholine) and endotracheal intubation. Opioid antagonists like **Naloxone** can reverse it but will also abolish analgesia. * **Prevention:** Administer fentanyl slowly and in lower doses. * **High-Yield Fact:** Rigidity is most common with **lipophilic** opioids that rapidly cross the blood-brain barrier.

Q: Which statement best describes high air flow oxygen enriched (HiAFOE) devices?

They deliver constant concentrations of oxygen.. ### Explanation **High Air Flow Oxygen Enriched (HiAFOE)** devices, most commonly represented by the **Venturi mask**, are classified as **fixed performance devices**. **1. Why Option B is Correct:** The core principle of HiAFOE devices is that they provide a **total gas flow** (oxygen + entrained room air) that meets or exceeds the patient’s peak inspiratory flow rate (typically >30 L/min). Because the device provides the entire inspired atmosphere, the fraction of inspired oxygen (**FiO₂**) remains **constant and predictable**, regardless of the patient’s respiratory rate, tidal volume, or inspiratory flow pattern. **2. Why the Other Options are Incorrect:** * **Option A:** Variable performance devices (e.g., nasal cannulas, simple face masks) deliver FiO₂ that fluctuates based on the patient's breathing pattern. HiAFOE devices are the opposite; they are **fixed performance**. * **Option C:** These devices utilize **air entrainment** (Bernoulli’s principle/Venturi effect) where high-velocity oxygen draws in room air. They do not "entrain oxygen"; they entrain air to dilute a pure oxygen source to a specific concentration. * **Option D:** They require **open (loose-fitting) masks** with large exhalation ports. Since the device provides the total flow required, a tight seal is unnecessary and would interfere with the washout of expired CO₂. **High-Yield Clinical Pearls for NEET-PG:** * **Bernoulli Principle:** The pressure drop across a narrowing allows for air entrainment. * **COPD Patients:** HiAFOE/Venturi masks are the **gold standard** for patients with Type 2 Respiratory Failure (COPD) because they prevent the delivery of excessive oxygen, which could otherwise abolish the hypoxic respiratory drive. * **Color Coding:** Venturi valves are color-coded for specific FiO₂ (e.g., Blue = 24%, White = 28%, Yellow = 35%, Red = 40%, Green = 60%).

Question 1

Mendelson's syndrome refers to what?

Accepted Answer

Aspiration of gastric content

Answer

Rupture of bronchial tuberculoma

Answer

Transient pneumonitis of allergic origin

Answer

Tracheal compression due to nodal enlargement

Question 2

All are true regarding endotracheal intubation except?

Accepted Answer

Saturation falls to not more than 90% after 2 minutes

Answer

Presence of CO2 in expired air

Answer

Endotracheal tube is inserted under direct vision of the glottis

Answer

Bilateral chest movement is observed

Question 3

Which of the following should be the ventilator settings for tidal volume in a patient with ARDS?

Accepted Answer

Tidal volume 5-7 ml/kg

Answer

Tidal volume 10-12 ml/kg

Answer

Tidal volume 8-10 ml/kg

Answer

Tidal volume 4 ml/kg

Question 4

When wheezing occurs intraoperatively, which of the following measures is NOT appropriate?

Accepted Answer

Intratracheal administration of mucolytic agents

Answer

Use of a volatile anesthetic agent (e.g., halothane)

Answer

Rechecking breath sounds bilaterally

Answer

Intravenous hydrocortisone

Question 5

A patient with a head injury presents with a Glasgow Coma Scale of 8, a mid-face fracture, cyanosis, decreased breathing with frequent apnea, and hypoxia. What is the most appropriate method for airway maintenance?

Accepted Answer

Cricothyrotomy

Answer

Oropharyngeal airway

Answer

Orotracheal airway

Answer

Nasotracheal airway

Question 6

Muscle rigidity caused by fentanyl is primarily due to its action on which opioid receptor?

Accepted Answer

Mu (μ)

Answer

Kappa (κ)

Answer

Delta (δ)

Answer

Sigma (σ)

Question 7

With a fixed performance mask such as a Venturi mask, which of the following is true?

Accepted Answer

Total gas flow is higher than the patient’s peak inspiratory flow.

Answer

Rebreathing is possible.

Answer

Plugging the side holes increases the oxygen concentration.

Answer

There is high equipment dead space.

Question 8

Blind nasal intubation is not indicated in which of the following conditions?

Accepted Answer

Basilar skull fracture

Answer

Temporomandibular joint ankylosis

Answer

Impossible laryngoscopy

Answer

Cerebrospinal fluid otorrhea

Question 9

Which statement best describes high air flow oxygen enriched (HiAFOE) devices?

Accepted Answer

They deliver constant concentrations of oxygen.

Answer

They are variable performance devices.

Answer

They require oxygen entrainment.

Answer

They require closed face masks.

Question 10

Intermittent Positive Pressure Ventilation (IPPV) can cause which of the following?

Accepted Answer

Barotrauma

Answer

Pleural effusion

Answer

Pulmonary edema

Answer

None of the above

Respiratory and Airway Management — MCQs

Respiratory and Airway Management — MCQs

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