Pulmonology focuses on diagnosing and treating lung and airway conditions such as asthma, COPD, and pneumonia, as well as overall respiratory health.

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Lung Infection: Diagnosis and Evaluation

To diagnose a lung infection, doctors use a mix of physical exams, imaging tests, and lab work. Because the symptoms can look like other problems, such as heart failure or blood clots in the lungs, getting the diagnosis right is very important. At Liv Hospital, we use advanced tests to confirm the infection and find out exactly which germ is causing it. This helps us choose the best treatment and use antibiotics responsibly.

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Clinical History and Physical Examination

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The diagnostic journey begins with the physician.

  • History Taking: The doctor will ask about the duration of symptoms, the nature of the cough, and the characteristics of the sputum. Travel history is essential to rule out endemic fungal infections or exotic pathogens. Occupational history helps identify exposure to specific dusts or animals (zoonotic diseases).
  • Auscultation: Listening to the lungs with a stethoscope is fundamental. Crackles (rales) suggest fluid in the alveoli (pneumonia). Wheezing suggests airway narrowing (e.g., bronchitis or a viral infection). Decreased breath sounds may indicate a pleural effusion (fluid around the lung) or severe consolidation.
  • Observation: The doctor looks for signs of respiratory distress, such as the use of accessory muscles to breathe, a rapid breathing rate, or cyanosis (a bluish tint to lips/fingernails).
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Radiological Imaging

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Imaging provides a visual confirmation of the infection and helps determine its extent.

  • Chest X-ray: The primary tool for diagnosing pneumonia. It can show consolidation (white patches indicating fluid-filled alveoli), infiltrates, or pleural effusions. It helps distinguish between pneumonia (alveolar) and bronchitis (airway), as bronchitis typically has a normal chest X-ray.
  • Computed Tomography (CT) Scan: A CT scan provides much greater detail. It is used when the X-ray is unclear, when the patient is not responding to treatment, or to detect complications such as lung abscesses or cavitation. It is beneficial for visualizing interstitial infections or fungal infection in the lungs, which may present as nodules or “halo signs.”
  • Ultrasound: Bedside lung ultrasound is increasingly used to detect consolidation and pleural effusions quickly without radiation.

Laboratory Blood Tests

Blood tests provide systemic evidence of infection and organ function.

  • Complete Blood Count (CBC): An elevated white blood cell count (leukocytosis) usually signals a bacterial infection. A normal or low count might suggest a viral etiology or overwhelming infection in a frail host.
  • Inflammatory Markers: C-reactive protein (CRP) and Procalcitonin levels are measured. High procalcitonin levels are particular for bacterial infections and help guide antibiotic decisions for lung infections.
  • Blood Cultures: These are drawn to detect whether bacteria have spread from the lungs into the bloodstream (bacteremia/sepsis), which alters the severity and treatment duration.
  • Arterial Blood Gas (ABG): This measures oxygen and carbon dioxide levels in the blood to assess the severity of respiratory failure and the need for supplemental oxygen.
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Microbiological Identification

Identifying the specific bug is the key to targeted therapy.

  • Sputum Culture: Patients are asked to cough up deep mucus (not saliva). The lab stains and cultures this to grow the bacteria. This helps determine which antibiotics will work (sensitivity testing).
  • Viral PCR Panels: Nasopharyngeal swabs are tested by Polymerase Chain Reaction (PCR) to rapidly detect respiratory viruses such as Influenza, RSV, and COVID-19.
  • Urinary Antigen Tests: Urine tests can quickly detect antigens for Pneumococcus and Legionella, two common causes of severe pneumonia.
  • Fungal Testing: Blood tests for fungal antigens (such as galactomannan for Aspergillus) or fungal cultures of sputum are used when a fungal lung infection is suspected.

Invasive Diagnostic Procedures

When non-invasive tests fail to provide a diagnosis, especially in immunocompromised patients or those who are deteriorating, invasive methods are needed.

  • Bronchoscopy: A flexible tube with a camera is passed into the lungs. The doctor can visualize the airways and collect samples directly from the infected area (Bronchoalveolar Lavage – BAL). This is the gold standard for diagnosing complex infections such as Pneumocystis or Mycobacterium avium lung infections.
  • Thoracentesis: If fluid is present in the pleural space, a needle is inserted to obtain a sample. Analyzing this fluid helps distinguish between a simple fluid reaction and an infected empyema that requires drainage.
  • Lung Biopsy: Rarely, a small piece of lung tissue is surgically removed to differentiate between chronic infection (e.g., fungal or mycobacterial) and non-infectious causes (e.g., autoimmune disease or cancer).

Evaluating Severity and Triage

Doctors use scoring systems such as CURB-65 or the Pneumonia Severity Index (PSI) to determine whether a patient can be treated at home or requires hospitalization. These scores take into account factors such as confusion, urea levels, respiratory rate, blood pressure, and age.

  • Low Risk: Patients with mild symptoms and stable vitals are often treated as outpatients with oral antibiotics.
  • Moderate to High Risk: Patients with unstable vitals, low oxygen, or significant comorbidities are admitted for intravenous treatment and monitoring.

Differential Diagnosis

It is crucial to differentiate lung infections from other conditions that mimic them.

  • Pulmonary Embolism: A blood clot in the lung can cause chest pain and shortness of breath, symptoms similar to those of pneumonia.
  • Heart Failure: Fluid backup in the lungs (pulmonary edema) can look like pneumonia on an X-ray.
  • Lung Cancer: A tumor blocking an airway can cause a recurrent “post-obstructive” pneumonia.
  • Vasculitis or Interstitial Lung Disease: Autoimmune conditions can cause lung inflammation that mimics infection.

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Assoc. Prof. MD. Engin Aynacı Assoc. Prof. MD. Engin Aynacı Pulmonology Overview and Definition
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FREQUENTLY ASKED QUESTIONS

Why do doctors listen to my back when I have a cough?

The lungs are located in the back as well as the front of the chest; listening to the back allows the doctor to hear the lower lobes of the lungs, where fluid from infections often accumulates.

A good sputum culture requires mucus coughed up from deep in the lungs, which contains the pathogen, whereas spit is mostly saliva from the mouth and contains oral bacteria that can confuse the results.

If a chest X-ray is inconclusive or if complications like an abscess or cavity are suspected, a CT scan provides detailed 3D images to guide accurate diagnosis and treatment.

White blood cells are the body’s infection fighters; a high count usually indicates that the immune system is actively fighting a bacterial infection.

Doctors use severity scores (like CURB-65) that look at your confusion, blood pressure, breathing rate, and age to determine if it is safe for you to recover at home or if you need hospital care.

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