Aspiration Pneumonia Imaging

Introduction:

Pneumonia is an infectious disease that results in inflammation of the lungs and the air sacs. The air sacs get filled with pus, resulting in a persistent cough, fever, and difficulty breathing. Pneumonia may be mild or severe; however, it can be fatal for infants and young kids, older adults over 65 years, or patients with a weakened immune system.

Pneumonia can be caused due to various factors, but more predominantly, it is considered to be a viral or bacterial infection. Pneumonia can also occur in people who have been hospitalized for a prolonged period. Certain lifestyle habits, such as smoking and drinking alcohol, can also raise the risk of developing pneumonia. However, pneumonia may also occur when substances such as food or drinks accidentally enter the lungs instead of being swallowed. This type is known as aspiration pneumonia.

What Is Aspiration Pneumonia?

Aspiration pneumonia is an infectious disease (pneumonia) affecting the lungs due to accidental inhalation of substances other than air. It can be caused by food, liquids, foreign objects, or regurgitation of contents from the stomach. Accidental drawing-in of food and drinks into the windpipe is common. The body, in response, stimulates a sudden cough to expel the aspirated materials. However, inhaling larger particles that cannot be coughed out may result in airway obstruction and infection and subsequently lead to aspiration pneumonia.

What Is the Difference Between Pneumonia and Pneumonitis?

The swelling of the lungs is known as pneumonitis. Pneumonia is a type of pneumonitis that is caused due to infection.

What Causes Aspiration Pneumonia?

Aspiration pneumonia may be caused by the aspiration of foreign substances such as food, water, liquids, foreign objects, bacteria from the saliva, or nasal secretions and contents regurgitating from the stomach. Certain factors increase the risk of aspirating the materials. They are as given below:

• Prolonged hospital stay for an illness.

• Patients who have received general anesthesia.

• Patients receiving dental treatments under anesthesia can have inhibitory swallowing reflexes.

• Patients with neurological diseases such as Parkinson's disease, Alzheimer's disease, and cerebral palsy have difficulty swallowing.

• Individuals who consume excessive alcohol, sedatives, or illegal drugs.

• Individuals suffering from gastroesophageal reflux disease (GERD) are more prone to aspirate gastric contents as they continue having acid reflux.

• Older adults.

• Individuals with a weakened or immature immune system.

• Patients with achalasia disorder where the nerves in the food pipe are injured, resulting in difficulty in swallowing food or liquids.

• Throat cancer patients.

What Are the Symptoms of Aspiration Pneumonia?

The symptoms of aspiration pneumonia are given below:

• Fever.

• Chest pain.

• Difficulty in breathing.

• Wheezing.

• Severe cough with sputum containing pus or blood and bad odor.

• Sputum may also be green in color.

• Profuse sweating.

• Tired and confused.

• Difficulty in swallowing.

• Severe cases may even have bluish discoloration on the skin.

What Are the Complications of Aspiration Pneumonia?

Aspiration pneumonia, if not diagnosed early, may lead to several complications which can be fatal. They are as mentioned below:

• Fluid accumulation in the lungs.

• Accumulation of pus in the lungs and airways resulting in lung abscess.

• A possibility of secondary infection despite treating the first one.

What Are the Ways to Diagnose Aspiration Pneumonia?

Aspiration pneumonia should be diagnosed as early as the symptoms occur. The diagnostic workup is as follows:

1. Physical Examination:

• A detailed history and physical examination is the first step in diagnosing aspiration pneumonia.

• Doctors would evaluate the symptoms and look for the typical crackling breath sound, characteristic of aspiration pneumonia.

2. Imaging Studies:

• Chest X-ray and computed tomography (CT) is most commonly used to evaluate patients with aspiration pneumonia.

• These imaging tests aid in assessing the complications associated with aspiration pneumonia.

• Bronchoscopy provides a direct view of the lungs and the airways. A bronchoscope is a device with a flexible tube and a camera attached to its end, inserted through the mouth or nose into the lungs. This would help to view the airways and assess any abnormalities.

3. Lab Tests:

• Lab tests can be done to support the diagnosis and assess the severity of the condition.

• Blood tests can be done to indicate the focus of infection.

• Sputum tests can be done to confirm the bacterial or viral presence.

• Oxygen saturation tests can also be done to evaluate the oxygen level in the blood, thereby ascertaining the severity of the situation.

What Is the Role of Imaging Modalities in Aspiration Pneumonia?

Imaging modalities are an essential diagnostic tool to provide a confirmatory diagnosis of aspiration pneumonia. Various imaging modalities indicated in aspiration pneumonia are discussed below:

1. Chest X-Ray:

• Chest X-rays are the ideal first-line diagnostic tool for lung disorders. In addition, since X-rays are widely available, non-invasive, and quick to obtain, they are vital in emergency diagnosis.

• Posteroanterior or lateral X-rays are usually preferred in aspiration pneumonia. It is known as the posteroanterior view when X-rays are directed through the back of the chest and exit from the front side. Lateral X-rays refer to the sideways views.

• Chest X-rays are the gold standard in diagnosing aspiration pneumonia.

• The infection usually appears as well-defined, unilateral, or bilateral opacities.

• If the aspiration occurred when the patient was lying down or unconscious, the rear part of the upper lobe of the lung is usually involved.

• However, if the aspiration occurred when the patient was standing or sitting erect, the lower lobe of both lungs would be involved.

• Infection is evident by the presence of dense white spots throughout the lungs (infiltrates).

• These will be more often present in a bunch around the source of infection.

2. Computed Tomography (CT):

• CT is more sensitive in diagnosing aspiration pneumonia as well as the complications associated with it.

• CT is most commonly indicated to diagnose lung abscess, fluid accumulation, and secondary infection that may be associated with progressive disease.

• It can also identify esophageal or other structural abnormalities in the head and neck region, resulting in the aspiration of food materials.

• Aspirated material can also distinctly be seen on CT.

• High-resolution CT (HRCT) and multidetector CT (MDCT) are advanced procedures that are more specific and sensitive in evaluating aspiration pneumonia.

• CT can also guide procedures such as biopsy, pus drainage, or removal of foreign objects.

3. Magnetic Resonance Imaging (MRI):

• MRI though not routinely recommended, is more sensitive than conventional X-ray or CT.

• They can assess and evaluate the severity of complications associated with aspiration pneumonia, such as lung necrosis (infection resulting in tissue death), fluid accumulation around the lungs, abscess formation, and fibrosis (thickened lung tissues).

4. Nuclear Imaging:

• Nuclear imaging is most commonly indicated in children with neurological disorders.

• Radionuclide salivagram is a technique that uses radioactive material to demonstrate salivary aspirations that are a common cause of recurrent pneumonia.

5. Ultrasonography:

• Ultrasonography may be used when a chest X-ray or CT cannot be accomplished.

• Ultrasound is an excellent, on-the-spot screening tool to monitor and manage aspiration pneumonia.

6. Videofluoroscopic Swallow Study (VFSS):

• VFSS is the chosen diagnostic test to evaluate difficulty in swallowing.

• This study uses a device called fluoroscopy and a contrast agent to determine the swallowing process in the patients.

• The results can be viewed as real-time images, thus facilitating precise diagnosis.

How Is Aspiration Pneumonia Treated?

• Antibiotics are the first-line drugs used to treat aspiration pneumonia.

• Supportive measures such as oxygen or mechanical ventilators may be required to assist breathing.

• Fluid accumulation will have to be drained out by a procedure known as thoracentesis. A thin hollow needle will be inserted through the chest wall into the lungs to drain the fluid.

• Surgical intervention may be required if any structural abnormalities are associated with difficulty in swallowing.

Certain preventive measures can be taken to avoid aspiration pneumonia. They are as follows:

• Older adults will require extra care to ensure the food is not frequently aspirated while eating.

• Children should be advised to sit erect while eating and chew slowly and thoroughly before swallowing.

• Avoid smoking, drinking alcohol, or the use of illicit drugs.

Conclusion:

Aspiration pneumonia is a common condition affecting adults and children equally. The recovery and prognosis are excellent with prompt and timely treatment, yet any delay in diagnosis could prove fatal. Recurrent aspiration pneumonia suggests the probability of any underlying neurological or anatomical impairment that requires immediate intervention. Advanced imaging modalities ensure early diagnosis and, thereby, a favorable treatment.