An Overview of Lung Diseases in Pulmonology—Respiratory Diseases and Obstructive Lung Disease

The lungs are organs located in the chest cavity that are responsible for respiration. The human lungs consist of two lung lobes. The left lung consists of two lobes. The right lung (also known as the right lobe) consists of three lobes.

Since the lungs themselves have no muscles, air is inhaled by the diaphragm and the rib muscles.

The expansion of the chest creates negative pressure, which draws air into the lungs (inhalation). Exhalation (expiration) is usually passive, as the chest contracts again and pushes air out of the lungs.

The lungs are connected to the trachea via the bronchi (airways). The trachea and bronchi serve to transport air. Gas exchange takes place in the alveoli (air sacs). There, the blood absorbs oxygen from the inhaled air and releases carbon dioxide into the exhaled air.

Bronchial asthma, often simply referred to as asthma, is a chronic, inflammatory disease of the airways. The inflammation can lead to episodic shortness of breath due to narrowing of the airways (bronchial obstruction). This causes increased mucus production, the bronchial muscles to spasm, and edema of the bronchial mucosa.

An asthma attack can last from a few seconds to several hours. In Germany, about ten percent of children and five percent of adults suffer from bronchial asthma. The airways of people with asthma react with increased sensitivity to certain, mostly harmless triggers (e.g., psychological stress, overexertion). They constrict spasmodically.

Triggers can include:

• Allergens
• Respiratory tract infections
• Cold
• Medications and
• Polluted air

Asthma can be diagnosed based on medical history, a physical examination, and lung function and allergy tests. Treatment for allergic asthma involves avoiding the allergen. During an acute asthma attack, an asthma inhaler relieves symptoms. The active ingredients include, for example, beta-2 sympathomimetics, cortisone, or antileukotrienes. In severe attacks, the doctor administers the medication directly into a vein.

Pulmonary Fibrosis

Over 100 different lung diseases can lead to pulmonary fibrosis. In pulmonary fibrosis, an inflammatory reaction causes excessive connective tissue to form between the alveoli and the blood vessels. As a result, less oxygen enters the bloodstream. The stiffening of the lungs makes breathing more difficult. This leads to reduced physical endurance and shortness of breath. Doctors classify pulmonary fibrosis into conditions with known causes and those with unknown causes (idiopathic pulmonary fibrosis).

Known causes include, for example:

• Inhalation of asbestos 
• Inhalation of certain organic substances (e.g., protein components of hay dust or components of pigeon droppings)

Diagnosis involves computed tomography (CT), pulmonary function tests, and bronchoscopy. If the cause is known, the patient must avoid contact with the triggering substance. Doctors treat the inflammation with anti-inflammatory medications (e.g., cortisone, azathioprine). Depending on the cause, additional treatments may be necessary.

Bronchial Carcinoma and Lung Cancer (Lung Carcinoma)

Experts refer to cancer of the lung or the bronchi as lung cancer (lung carcinoma) or bronchial cancer. Lung carcinoma is the third most common form of cancer in Germany. Smoking is considered the main risk factor for developing lung cancer. Cigarette smoke is the primary cause in 80 to 90% of male lung cancer patients and in 30 to 60% of female lung cancer patients.

Other risk factors include:

• Inhaled dust and fumes in the workplace (e.g., asbestos, quartz dust, arsenic, chromates, nickel, and aromatic hydrocarbons)
• Environmental factors (the radioactive noble gas radon, high levels of air pollution)
• Genetic predisposition

Lung cancer often does not become apparent until very late in its development.

Symptoms are often nonspecific, such as:

• Cough
• Shortness of breath or
• Weight loss

If a tumor in the lung is suspected, doctors will perform a chest X-ray. This is often followed by a CT scan and bronchoscopy.

Treatment generally consists of:

• Removal of the tumor
• Chemotherapy or
• Radiation therapy

A combination of these options is usually used.

Pulmonary Emphysema

Pulmonary emphysema is a form of chronic obstructive pulmonary disease in which the alveoli are irreversibly dilated and destroyed. As the walls of the alveoli break down due to enzymatic action, large air pockets form in which air becomes trapped. Although the lungs contain air, shortness of breath occurs. As a result, the body does not receive enough oxygen. In some cases, this can lead to organ damage. Smoking is considered the primary cause of pulmonary emphysema.

Other risk factors include:

• Indoor air pollution
• Open fires
• Inhalation of gases and dust in the workplace
• Genetic predisposition
• Frequent respiratory infections

Pulmonary emphysema is diagnosed through:

• Lung function tests (e.g., spirometry)
• Blood gas analysis and
• Imaging tests (e.g., chest X-ray)

In addition to quitting smoking immediately and avoiding other triggering factors, surgery may be necessary. This procedure reduces the size of the lungs and prevents the formation of particularly large alveoli. In extreme cases, a lung transplant or a single-lung transplant may also be necessary.

Pulmonary hypertension

This condition is characterized by elevated blood pressure in the pulmonary circulation. This leads to shortness of breath, reduced oxygen supply to the body, and decreased physical performance.

It can also cause chest pain and leg swelling. The causes of pulmonary hypertension are not yet fully understood. There is evidence that pulmonary hypertension frequently occurs in the following cases:

• HIV infection
• Certain autoimmune diseases and
• Certain medications (e.g., appetite suppressants, psychostimulants)

Experts also discuss a genetic predisposition. Based on the symptoms, electrocardiograms (ECGs), chest X-rays, and pulmonary function tests are frequently performed.

However, only transthoracic echocardiography—an ultrasound examination performed externally through the chest—provides evidence of pulmonary hypertension. Physicians measure blood pressure in the pulmonary circulation using a cardiopulmonary catheter (right heart catheter). Treatment for pulmonary hypertension primarily involves medication.

Bronchitis

Bronchitis is an inflammation of the mucous membrane lining the bronchi of the lungs. It can be acute or chronic. Chronic bronchitis is characterized by a cough and sputum production on most days for three months in two consecutive years. Chronic bronchitis is not caused by pathogens, but rather by cigarette smoke (or its constituents) or other inhaled irritants.

In contrast, a newly developed inflammation of the bronchial mucous membrane accompanied by coughing, mucus production, fever, and other nonspecific symptoms is called acute bronchitis. This lung disease is usually triggered by viruses and, in rare cases, by bacteria. Therefore, acute bronchitis usually resolves on its own without medication. Antibiotics are effective only when the cause is bacterial.

To prevent acute bronchitis from becoming chronic, the patient must avoid the triggering irritants (dust, gases, or vapors). There are several medications that alleviate the symptoms of chronic bronchitis.

Pneumonia

Pneumonia is an acute or chronic inflammation of the lung tissue. It is usually caused by an infection with bacteria (most commonly Streptococcus pneumoniae), viruses, or fungi.

The inflammation can affect the alveoli, the lung tissue between the alveoli, or the blood vessels. Older adults, infants, and young children, as well as immunocompromised individuals, are particularly at risk.

Doctors often make a preliminary diagnosis based on a physical examination and the clinical presentation. In most cases, the doctor will order a chest X-ray to confirm the diagnosis. They may also collect a sputum sample to identify the pathogen. Treatment usually involves antibiotics.

Interstitial Lung Diseases

Interstitial lung diseases encompass various lung conditions and are relatively rare. They affect the connective tissue (interstitium) of the lungs or the alveoli.

Examples of interstitial lung diseases include:

• Pulmonary fibrosis (abnormal proliferation and scarring of lung tissue)
• Sarcoidosis (formation of small connective tissue nodules in the lungs)
• Tuberculosis

Tuberculosis is an infectious disease caused by bacteria that primarily affects the lungs. In the majority of people infected with tuberculosis, the disease does not cause any noticeable symptoms.

The lung disease asthma can be caused by allergic reactions on the one hand, and by respiratory tract infections, smoking, or medications on the other. Smoking is the main cause of chronic lung diseases such as COPD, pulmonary emphysema, pulmonary hypertension, or lung cancer.

The effects of tobacco smoke on the lungs are far-reaching. The toxic substances contained in tobacco smoke cause lasting damage to and destruction of the lungs. It has now been proven that about nine out of ten lung cancer patients are smokers. The situation is similar with the lung disease COPD.

Auscultation of the lungs

Pneumologists define auscultation as listening to the lungs and heart with a stethoscope. It is part of the physical examination performed by a doctor.

During auscultation of the lungs, the doctor examines whether breathing sounds are normal or pathologically altered. The doctor listens for abnormal breathing sounds (rales and crackles). Auscultation is an essential component of diagnosis in pulmonology.

Blood gas analysis

Blood gas analysis determines the gas distribution (partial pressure) of oxygen and carbon dioxide, as well as the pH level and acid-base balance in the blood. It allows doctors to monitor patients with lung disease, respiratory disorders, or oxygen deficiency (e.g., in COPD).

Body plethysmography (whole-body plethysmography, large-volume lung function)

Body plethysmography (whole-body plethysmography, large-volume pulmonary function testing) is a procedure used to determine lung and respiratory parameters.

Examples of lung and respiratory parameters include:

• Respiratory resistance
• Residual volume
• Total lung capacity

Since this method of lung function testing is relatively complex, it is typically performed only by hospitals and specialists. During the test, the patient lies in a special chamber that measures the parameters as the pressure inside the chamber changes.

Body plethysmography is used to monitor the course of the disease and treatment in asthma and COPD.

Bronchoscopy (examination of the bronchi, lung endoscopy)

During bronchoscopy, the doctor inserts a bronchoscope (endoscope) through the mouth or nose into the bronchi. A bronchoscope is a soft, flexible, very thin tube with a camera and a light source at its tip.

The camera allows the doctor to view the patient’s airways on a monitor. In addition, the bronchoscope can be used to remove tissue samples (biopsies) or foreign objects. Doctors can also use it to inject and suction out fluid (e.g., thick mucus). A very small ultrasound transducer can produce an ultrasound image of the area surrounding the airways.

Bronchoscopy is also used to diagnose lung disease. This may be necessary when there are unclear changes visible on an X-ray. It is also useful for bronchial tumors and respiratory tract infections, as well as for persistent, unexplained coughs or coughing up blood.

Lung Scintigraphy

Lung scintigraphy is a diagnostic method used to assess ventilation (ventilation scintigraphy) and blood flow (perfusion, lung perfusion scintigraphy) in the lungs.

In lung perfusion scintigraphy, radioactively labeled protein particles accumulate in the lungs to varying degrees depending on blood flow.

A special camera (gamma camera) makes this visible. During ventilation scintigraphy, the patient inhales a radioactive noble gas or aerosol. Doctors use multiple images from the gamma camera to assess the distribution of the gas in the lungs.

Pleural puncture

During a pleural puncture, doctors withdraw fluid from the pleural cavity (pleural space). This is done using a hollow needle that the doctor inserts into the pleural space. The pleural space is the area between the pleura and the costal pleura, as well as between the pleura and the diaphragm.

Pleural puncture is used for:

• Diagnostic purposes (e.g., pleural effusion, lung tumors, pneumonia),
• Therapeutic purposes (e.g., treatment of a pneumothorax, draining the entire pleural effusion)

Spiroergometry

Spiroergometry (ergospirometry or ergospirography) is a diagnostic procedure. 

It assesses:

• Lung diseases 
• Function of the heart, circulatory system, respiration, and muscular metabolism

During the test, doctors first measure respiratory gases at rest and then during physical exertion.

During the test, the patient stands on a treadmill ergometer or sits on a bicycle ergometer. They wear a tight-fitting breathing mask equipped with a flowmeter.

The following are measured:

• Respiratory volumes
• Oxygen and carbon dioxide concentrations
• Heart rate
• Blood pressure

Spiroergometry is often used to diagnose exercise-induced shortness of breath.

Spirometry

In pulmonology, spirometry (spirography) measures lung and respiratory volumes as well as airflow parameters to assess lung function.

Lung and respiratory volumes include, for example:

• Vital capacity
• Tidal volume
• inspiratory and 
• expiratory reserve volume

Airflow parameters include, for example:

• One-second capacity
• Peak flow

During the examination, the patient wears a nose clip and breathes into a closed container through a mouthpiece. It is the most commonly used procedure in pulmonology.

Thoracoscopy

Thoracoscopy is an endoscopic examination of the chest cavity (thorax) and the pleura. During the procedure, doctors examine the chest cavity using a thin tube (laparoscope). The laparoscope is equipped with a small camera, a light source, and often a device for irrigation and suction. 

Thoracoscopy allows doctors to examine the chest cavity from the inside. Additionally, surgical instruments can be inserted to take biopsies or perform surgeries. Doctors can also administer medications through the laparoscope.