**Question:** Commonest sign of aspiration pneumonitis is:

A. Cough
B. Chest pain
C. Shortness of breath
D. Pleuritic pain

**Core Concept:**
Aspiration pneumonitis is a form of lung inflammation that occurs when foreign substances, such as food, liquids, or saliva, enter the respiratory tract and come into contact with the alveoli and surrounding tissues. This can lead to inflammation, edema, and damage to the lung parenchyma. The condition is commonly seen in patients with impaired swallowing function, gastroesophageal reflux, or compromised cough reflex.

**Why the Correct Answer is Right:**
The correct answer is **Cough** because it is the most common and earliest symptom of aspiration pneumonitis. Cough is an essential defense mechanism that helps clear foreign substances from the respiratory tract. In the setting of aspiration, the cough reflex becomes exaggerated as the body attempts to expel the irritant. While chest pain, shortness of breath, and pleuritic pain may occur as part of the clinical presentation, cough is the most likely sign to be present in the early stage of aspiration pneumonitis.

**Why Each Wrong Option is Incorrect:**
A. Chest pain is a late symptom of aspiration pneumonitis and may occur due to alveolar or pleural inflammation.
B. Shortness of breath can be a sign of lung inflammation and chest pain, but it is not the primary presenting symptom of aspiration pneumonitis.
D. Pleuritic pain is a specific type of chest pain that occurs due to inflammation of the pleura, but it is less likely to be the primary sign of aspiration pneumonitis due to its specificity for pleural irritation.

**Clinical Pearls:**
1. Aspiration pneumonitis is a clinical entity to be considered in patients with unexplained cough, especially when accompanied by respiratory symptoms like dyspnea or wheezing.
2. A thorough history and physical examination, including assessing the patient's swallowing ability and evaluating the presence of gastroesophageal reflux, is crucial to identify patients at risk for aspiration pneumonitis.
3. Prompt intervention, including airway clearance techniques, antacid therapy, and strengthening swallowing muscles, can help prevent further lung damage from aspiration.

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In conclusion, aspiration pneumonitis typically presents with a cough, which is a result of the exaggerated cough reflex to expel foreign substances from the respiratory tract. The cough may be accompanied by shortness of breath, chest pain, or wheezing, but the primary sign of aspiration pneumonitis is the patient's exaggerated cough. Assessing the patient's swallowing ability and gastroesophageal reflux is essential in identifying patients at risk for aspiration pneumonitis. Early intervention, including airway clearance techniques, antacid therapy, and muscle strengthening exercises, can help prevent further lung damage due to aspiration.