Respiratory disease
Encyclopedia
Respiratory disease is a medical term that encompasses pathological
Pathology
Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....

 conditions affecting the organs and tissues that make gas exchange possible in higher organisms, and includes conditions of the upper respiratory tract
Upper respiratory tract
The upper respiratory tract or upper airway primarily refers to the parts of the respiratory system lying outside of the thorax or above the sternal angle. Another definition commomly used in medicine is the airway above the glottis or vocal cords...

, trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...

, bronchi, bronchioles, alveoli, pleura and pleural cavity
Pleural cavity
In human anatomy, the pleural cavity is the potential space between the two pleura of the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally...

, and the nerves and muscles of breathing
Breathing
Breathing is the process that moves air in and out of the lungs. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. Breathing is only one process that delivers oxygen to where it is needed in the body and...

. Respiratory diseases range from mild and self-limiting, such as the common cold
Common cold
The common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...

, to life-threatening entities like bacterial pneumonia
Bacterial pneumonia
Bacterial pneumonia is a type of pneumonia caused by bacterial infection.-Sign and symptoms:*Fever*Rigors*Cough*Dyspnea*Chest pain*Pneumococcal pneumonia can cause Hemoptysis-Gram positive:...

, pulmonary embolism
Pulmonary embolism
Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...

, and lung cancer
Lung cancer
Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...

.

The study of respiratory disease is known as pulmonology
Pulmonology
In medicine, pulmonology is the specialty that deals with diseases of the respiratory tract and respiratory disease. It is called chest medicine and respiratory medicine in some countries and areas...

. A doctor who specializes in respiratory disease is known as a pulmonologist, a chest medicine specialist, a respiratory medicine specialist, a respirologist or a thoracic medicine specialist.

Classification

Respiratory diseases can be classified in many different ways, including by the organ or tissue involved, by the type and pattern of associated signs and symptoms, or by the cause (etiology
Etiology
Etiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....

) of the disease.

Inflammatory lung disease

Characterised by a high neutrophil count, e.g. asthma, cystic fibrosis, emphysema, chronic obstructive pulmonary disorder or acute respiratory distress syndrome.

Allergic reactions
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...

 due to exposure to certain agents (i.e. foods) are a relatively common cause of acute respiratory disease. Some common examples include sea foods prawns, some fatty fish, radish, arrow root, lady's finger, lemon, moong dhal, peanuts, water content spinach, curd, bananas, grapes, pomegranates, berries, custard apple, ice creams, etc. In summer, bad weather condition mean sandy and dusty weather or some may affect in winter also.

Obstructive lung diseases

Obstructive lung disease
Obstructive lung disease
Obstructive lung disease is a category of respiratory disease characterized by airway obstruction. It is generally characterized by inflamed and easily collapsible airways, obstruction to airflow, and frequent office visits and hospitalizations. Types of obstructive lung disease include; Asthma,...

s are diseases of the lung where the airways (i.e. bronchi, bronchioles, alveoli) become reduced in volume or have free flow of gas impeded, making it more difficult to move air in and out of the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

.

Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...

 (COPD), which includes asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

 an example of an obstructive lung disease, is where the airways become damaged, causing them to narrow.

Asthma

Asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

 is another example of an obstructive lung disease, (and of an inflammatory lung disease).

Asthma attacks can be brought on by triggers, such as air pollution, tobacco smoke, factory fumes, cleaning solvents, infections, pollens, foods, cold air, exercise, chemicals and medications. Triggers are highly individual and may not be related to allergens. Many asthmatics are not allergic to common allergens such as mold, ragweed, dust or pollens.
Asthma is a difficulty in breathing causing wheezing due to inflammation of bronchi and bronchioles

Restrictive lung diseases

Restrictive lung disease
Restrictive lung disease
Restrictive lung diseases are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion, resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygenation...

s (also known as interstitial lung diseases) are a category of respiratory disease characterized by a loss of lung compliance
Pulmonary compliance
Pulmonary compliance can refer to either dynamic or static lung compliance. Static lung compliance is the change in volume for any given applied pressure...

, causing incomplete lung expansion and increased lung stiffness. E.g. in infant respiratory distress syndrome (IRDS).

Respiratory tract infections

Infections can affect any part of the respiratory system. They are traditionally divided into upper respiratory tract infections and lower respiratory tract infections.

Upper respiratory tract infection

The most common upper respiratory tract infection
Upper respiratory tract infection
Upper respiratory tract infections are the illnesses caused by an acute infection which involves the upper respiratory tract: nose, sinuses, pharynx or larynx...

 is the common cold
Common cold
The common cold is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever...

 however, infections of specific organs of the upper respiratory tract such as sinusitis
Sinusitis
Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...

, tonsillitis
Tonsillitis
Tonsillitis is an inflammation of the tonsils most commonly caused by viral or bacterial infection. Symptoms of tonsillitis include sore throat and fever. While no treatment has been found to shorten the duration of viral tonsillitis, bacterial causes are treatable with antibiotics...

, otitis media
Otitis media
Otitis media is inflammation of the middle ear, or a middle ear infection.It occurs in the area between the tympanic membrane and the inner ear, including a duct known as the eustachian tube. It is one of the two categories of ear inflammation that can underlie what is commonly called an earache,...

, pharyngitis
Pharyngitis
Pharyngitis is an inflammation of the throat or pharynx. In most cases it is quite painful, and is the most common cause of a sore throat.Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic....

 and laryngitis
Laryngitis
Laryngitis is an inflammation of the larynx. It causes hoarse voice or the complete loss of the voice because of irritation to the vocal folds . Dysphonia is the medical term for a vocal disorder, of which laryngitis is one cause....

 are also considered upper respiratory tract infections.

Lower respiratory tract infection

The most common lower respiratory tract infection in is pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...

, a lung infection. Pneumonia is usually caused by bacteria, particularly Streptococcus pneumoniae
Streptococcus pneumoniae
Streptococcus pneumoniae, or pneumococcus, is Gram-positive, alpha-hemolytic, aerotolerant anaerobic member of the genus Streptococcus. A significant human pathogenic bacterium, S...

 in Western countries. Worldwide, tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 is an important cause of pneumonia. Other pathogens such as viruses and fungi can cause pneumonia for example severe acute respiratory syndrome
Severe acute respiratory syndrome
Severe Acute Respiratory Syndrome is a respiratory disease in humans which is caused by the SARS coronavirus . Between November 2002 and July 2003 an outbreak of SARS in Hong Kong nearly became a pandemic, with 8,422 cases and 916 deaths worldwide according to the WHO...

 and pneumocystis pneumonia
Pneumocystis pneumonia
Pneumocystis pneumonia or pneumocystosis is a form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii...

. A pneumonia may develop complications such as a lung abscess, a round cavity in the lung caused by the infection, or may spread to the pleural cavity
Pleural cavity
In human anatomy, the pleural cavity is the potential space between the two pleura of the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally...

.

Malignant tumors

Malignant tumors, or cancers of the respiratory system, particularly lung cancers, are a major health problem responsible for 15% of all cancer diagnoses and 29% of all cancer deaths. The majority of respiratory system cancers are attributable to smoking tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...

.

The major types of respiratory system cancer are:
  • Small cell lung cancer
  • Non-small cell lung cancer
    • Adenocarcinoma
    • Large cell undifferentiated carcinoma
  • Other lung cancers (carcinoid
    Carcinoid
    Carcinoid is a slow-growing type of neuroendocrine tumor, originating in the cells of the neuroendocrine system.In 2000, the World Health Organization redefined "carcinoid", but this new definition has not been accepted by all practitioners. This has led to some complexity in distinguishing...

    , Kaposi’s sarcoma, melanoma
    Melanoma
    Melanoma is a malignant tumor of melanocytes. Melanocytes are cells that produce the dark pigment, melanin, which is responsible for the color of skin. They predominantly occur in skin, but are also found in other parts of the body, including the bowel and the eye...

    )
  • Lymphoma
    Lymphoma
    Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...

  • Head and neck cancer
    Head and neck cancer
    Head and neck cancer refers to a group of biologically similar cancers that start in the upper aerodigestive tract, including the lip, oral cavity , nasal cavity , paranasal sinuses, pharynx, and larynx. 90% of head and neck cancers are squamous cell carcinomas , originating from the mucosal lining...

  • Pleural Mesothelioma, almost always caused by exposure to asbestos
    Asbestos
    Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...

     dust.


In addition, since many cancers spread via the bloodstream and the entire cardiac output passes through the lungs, it is common for cancer metastases to occur within the lung. Breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

  may invade directly through local spread, and through lymph node metastases. After metastasis to the liver
Liver cancer
Liver tumors or hepatic tumors are tumors or growths on or in the liver . Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. These growths can be benign or malignant...

, colon cancer frequently metastasizes to the lung. Prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

, germ cell cancer and renal cell carcinoma
Renal cell carcinoma
Renal cell carcinoma is a kidney cancer that originates in the lining of the proximal convoluted tubule, the very small tubes in the kidney that filter the blood and remove waste products. RCC is the most common type of kidney cancer in adults, responsible for approximately 80% of cases...

 may also metastasize to the lung.

Treatment of respiratory system cancer depends on the type of cancer. Surgery (usually removal of part of the lung, a lobectomy
Lobectomy
Lobectomy means surgical excision of a lobe. This may refer to a lobe of the lung, a lobe of the thyroid , or a lobe of the brain ....

 or an entire lung, a pneumonectomy
Pneumonectomy
A pneumonectomy is a surgical procedure to remove a lung. Removal of just one lobe of the lung is specifically referred to as a lobectomy, and that of a segment of the lung as a wedge resection .-Indications:...

), chemotherapy and radiotherapy are all used. The chance of surviving lung cancer depends on the cancer stage at the time the cancer is diagnosed and is only about 14-17% overall. In the case of metastases to the lung, treatment can occasionally be curative but only in certain, rare circumstances.

Benign tumors

Benign tumors are relatively rare causes of respiratory disease. Examples of benign tumors are:
  • Pulmonary hamartoma
    Hamartoma
    A hamartoma is a benign, focal malformation that resembles a neoplasm in the tissue of its origin. This is not a malignant tumor, and it grows at the same rate as the surrounding tissues. It is composed of tissue elements normally found at that site, but which are growing in a disorganized mass...

  • Congenital malformations such as pulmonary sequestration
    Pulmonary sequestration
    A pulmonary sequestration, also known as a bronchopulmonary sequestration or a cystic lung lesion, is a medical condition where a piece of tissue that develops into lung tissue is not attached to the pulmonary arterial blood supply and does not communicate with the other...

     and congenital cystic adenomatoid malformation
    Congenital cystic adenomatoid malformation
    Congenital cystic adenomatoid malformation is a congenital disorder similar to bronchopulmonary sequestration. In CCAM, usually an entire lobe of lung is replaced by a non-working cystic piece of abnormal lung tissue. This abnormal tissue will never function as normal lung tissue.In most cases the...

     (CCAM).

Pleural cavity diseases

Pleural cavity diseases include emphysema
Emphysema
Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...

 and pleural mesothelioma which are mentioned above.

A collection of fluid in the pleural cavity is known as a pleural effusion
Pleural effusion
Pleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...

. This may be due to fluid shifting from the bloodstream into the pleural cavity due to conditions such as congestive heart failure and cirrhosis. It may also be due to inflammation of the pleura itself as can occur with infection, pulmonary embolus, tuberculosis, mesothelioma and other conditions.

A pneumothorax
Pneumothorax
Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...

 is a hole in the pleura covering the lung allowing air in the lung to escape into the pleural cavity. The affected lung “collapses” like a deflated balloon. A tension pneumothorax is a particularly severe form of this condition where the air in the pleural cavity cannot escape, so the pneumothorax keeps getting bigger until it compresses the heart and blood vessels, leading to a life threatening situation.

Pulmonary vascular diseases

Pulmonary vascular diseases are conditions that affect the pulmonary circulation
Pulmonary circulation
Pulmonary circulation is the half portion of the cardiovascular system which carries Oxygen-depleted Blood away from the heart, to the Lungs, and returns oxygenated blood back to the heart. Encyclopedic description and discovery of the pulmonary circulation is widely attributed to Doctor Ibn...

. Examples of these conditions are
  • Pulmonary embolism
    Pulmonary embolism
    Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...

    , a blood clot
    Thrombosis
    Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...

     that forms in a vein, breaks free, travels through the heart and lodges in the lungs (thromboembolism). Large pulmonary emboli are fatal, causing sudden death. A number of other substances can also embolise (travel through the blood stream) to the lungs but they are much more rare: fat embolism
    Fat embolism
    A fat embolism is a type of embolism that is often caused by physical trauma such as fracture of long bones, soft tissue trauma and burns.-Presentation:...

     (particularly after bony injury), amniotic fluid embolism (with complications of labour and delivery), air embolism
    Air embolism
    An air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...

     (iatrogenic - caused by invasive medical procedures).
  • Pulmonary arterial hypertension, elevated pressure in the pulmonary arteries. Most commonly it is idiopathic
    Idiopathic
    Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...

     (i.e. of unknown cause) but it can be due to the effects of another disease, particularly COPD. This can lead to strain on the right side of the heart, a condition known as cor pulmonale
    Cor pulmonale
    Cor pulmonale or pulmonary heart disease is enlargement of the right ventricle of the heart as a response to increased resistance or high blood pressure in the lungs ....

    .
  • Pulmonary edema
    Pulmonary edema
    Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...

    , leakage of fluid from capillaries of the lung into the alveoli (or air spaces). It is usually due to congestive heart failure.
  • Pulmonary hemorrhage, inflammation and damage to capillaries in the lung resulting in blood leaking into the alveoli. This may cause blood to be coughed up. Pulmonary hemorrhage can be due to auto-immune disorders such as Wegener's Granulomatosis
    Wegener's granulomatosis
    Wegener's granulomatosis , more recently granulomatosis with polyangiitis , is an incurable form of vasculitis that affects the nose, lungs, kidneys and other organs. Due to its end-organ damage, it is life-threatening and requires long-term immunosuppression...

     and Goodpasture's syndrome
    Goodpasture's syndrome
    Goodpasture’s syndrome is a rare disease characterized by glomerulonephritis and hemorrhaging of the lungs...

    .

Diagnosis

Respiratory diseases may be investigated by performing one or more of the following tests
  • Chest x-ray
    Chest X-ray
    In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...

  • Pulmonary function test
  • Computed tomography scan
  • Culture of microorganisms
    Microbiological culture
    A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...

     from secretions such as sputum
  • Bronchoscopy
    Bronchoscopy
    Bronchoscopy is a technique of visualizing the inside of the airways for diagnostic and therapeutic purposes. An instrument is inserted into the airways, usually through the nose or mouth, or occasionally through a tracheostomy. This allows the practitioner to examine the patient's airways for...

  • Biopsy
    Biopsy
    A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

     of the lung or pleura
  • Ventilation - perfusion scan
    Ventilation/perfusion scan
    A ventilation/perfusion lung scan, also called a V/Q lung scan, is a type of medical imaging using scintigraphy and medical isotopes to evaluate the circulation of air and blood within a patient's lungs, in order to determine the ventilation/perfusion ratio...

  • Ultrasound
    Medical ultrasonography
    Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...

     scanning can be useful to detect fluid such as pleural effusion
    Pleural effusion
    Pleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...


Epidemiology

Respiratory disease is a common and important cause of illness and death around the world. In the US, approximately 1 billion "common colds" occur each year. In the UK, approximately 1 in 7 individuals are affected by some form of chronic lung disease, most commonly chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...

, which includes asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

, chronic bronchitis
Chronic bronchitis
Chronic bronchitis is a chronic inflammation of the bronchi in the lungs. It is generally considered one of the two forms of chronic obstructive pulmonary disease...

 and emphysema
Emphysema
Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...

. Respiratory diseases (including lung cancer) are responsible for over 10% of hospitalizations and over 16% of deaths in Canada.
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