Respiratory diseases, or lung diseases, are pathology conditions affecting the organs and tissues that make gas exchange difficult in Breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bronchioles, alveoli, pleurae, pleural cavity, the nerves and muscles of respiration. Respiratory diseases range from mild and self-limiting, such as the common cold, influenza, and pharyngitis to life-threatening such as bacterial pneumonia, pulmonary embolism, tuberculosis, Asthma, lung cancer, and severe acute respiratory syndromes, such as COVID-19. 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 of the disease.
The study of respiratory disease is known as pulmonology. A physician 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.
Epiglottitis is a bacterial infection of the larynx which causes life-threatening swelling of the epiglottis with a mortality rate of 7% in adults and 1% in children. Haemophilus influenzae is still the primary cause even with vaccinations. Also Streptococcus pyogenes can cause epiglottitis. Symptoms include drooling, stridor, difficulty breathing and swallowing, and a hoarse voice.
Croup (Laryngotracheobronchitis) is a viral infection of the vocal cords typically lasting five to six days. The main symptom is a barking cough and low-grade fever. On an X-ray, croup can be recognized by the "steeple sign", which is a narrowing of the trachea. It most commonly occurs in winter months in children between the ages of 3 months and 5 years. A severe form caused by bacteria is called bacterial tracheitis.
Tonsillitis is swelling of the tonsils by a bacterial or viral infection. This inflammation can lead to airway obstruction. From tonsillitis can come a peritonsillar abscess which is the most common upper airway infection and occurs primarily in young adults. It causes swelling in one of the tonsils, pushing the Palatine uvula to the unaffected side. Diagnosis is usually made based on the presentation and examination. Symptoms generally include fever, sore throat, trouble swallowing, and sounding like they have a "hot potato" in their mouth.
Poor oral care may be a contributing factor to lower respiratory disease, as bacteria from gum disease may travel through airways and into the lungs. There is also a co-occurrence between acute eosinophilic pneumonia, desquamative interstitial pneumonia and tobacco use.
The major histology types of respiratory system cancer are:
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 may invade directly through local spread, and through lymph node metastases. After metastasis to the liver cancer, colon cancer frequently metastasizes to the lung. Prostate cancer, germ cell cancer and renal cell carcinoma may also metastasize to the lung.
Treatment of respiratory system cancer depends on the type of cancer. Surgical removal of part of a lung (lobectomy, segmentectomy, or wedge resection) or of an entire lung (pneumonectomy), along with 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 to some extent on the histology, 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.
A collection of fluid in the pleural cavity is known as a pleural effusion. 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 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.
Infant respiratory distress syndrome most commonly occurs in less than six hours after birth in about 1% of all births in the United States. The main risk factor is prematurity with the likelihood of it occurring going up to 71% in infants under 750g. Other risk factors include infant of a diabetic mother (IDM), method of delivery, fetal asphyxia, genetics, prolonged rupture of membranes (PROM), maternal toxemia, chorioamnionitis, and male sex. The widely accepted pathophysiology of respiratory distress syndrome is it caused by insufficient surfactant production and immature lung and vascular development. The lack of surfactant makes the lungs Atelectasis causing a ventilation to perfusion mismatch, lowered compliance, and increased air resistance. This causes hypoxia and respiratory acidosis which can lead to pulmonary hypertension. It has a ground glass appearance on an x-ray. Symptoms can include tachypnea, nasal flaring, paradoxical chest movement, grunting, and subcostal retractions.
Bronchopulmonary Dysplasia is a condition that occurs after birth usually from mechanical ventilation and oxygen use. It happens almost exclusively in pre-mature infants and is characterized by the alveoli, and lung vasculature becoming inflamed and damaged. Complications from BPD can follow a patient into adulthood. As a child they may experience learning disabilities, pulmonary hypertension, and hearing problems. As an adult, there is an increased likelihood for asthma and exercise intolerance.
Meconium Aspiration Syndrome occurs in full term or post-term infants who aspirate meconium. Risk factors include a diabetic mother, fetal hypoxia, precipitous delivery, and maternal high blood pressure. Its diagnosis is based on meconium stained amniotic fluid at delivery and staining on the skin, nails, and umbilical cord. Aspiration can cause airway obstruction, air-trapping, pneumonia, lung inflammation, and inactivated surfactant. It presents as patchy atelectasis and hyperinflation on an x-ray with a pneumothorax of pneumomediastinum also possible.
Persistent Pulmonary Hypertension of the Newborn (PPHN) is a syndrome that occurs from an abnormal transition to extra-uterine life. It is marked by an elevated pulmonary vascular resistance and vasoconstriction causing a right-to-left shunt of the blood through the foramen ovale or ductus arteriosus. There are three main causes of PPHN are parenchymal diseases such as meconium aspiration syndrome, idiopathic, and hypoplastic vasculature like in a diaphragmatic hernia. It will eventually resolve in most infants. This is the only syndrome that inhaled nitric oxide is approved for by the FDA. Transient Tachypnea of the Newborn is caused by the retention of alveolar fluid in the lungs. It commonly occurs in infants who are delivered via caesarean section without the onset of labor because absorption of amniotic fluid in the lungs has not yet commenced. Other risk factors are male sex, macrosomia, multiple gestations, and maternal asthma. It usually presents with tachypnea and increased work of breathing. On an x-ray diffuse infiltrates, interlobar fissures, and sometimes can be seen. It is a diagnosis of exclusion because of its similarity to other diseases and frequently CPAP is used to help push the lung fluid into the pulmonary vasculature.
Pulmonary interstitial emphysema is the condition of air escaping overdistended alveoli into the pulmonary interstitium. It is a rare disease that occurs most often in premature infants, even though it is possible to appear in adults. It often presents as a slow deterioration with the need for increased ventilatory support. Chest x-ray is the standard for diagnosis where it is seen as linear or cystic translucencies extending to the edges of the lungs.
Bronchiolitis is the swelling and buildup of mucus in the bronchioles. It is usually caused by respiratory syncytial virus (RSV), which is spread when an infant touches the nose or throat fluids of someone infected. The virus infects the cells causing ciliary dysfunction and death. The debris, edema, and inflammation eventually leads to the symptoms. It is the most common reason for admission of children under the age of one year. It can present widely from a mild respiratory infection to respiratory failure. Since there is no medication to treat the disease, it is only managed supportively with fluids and oxygen.
In the UK, approximately 1 in 7 individuals are affected by some form of chronic lung disease, most commonly chronic obstructive pulmonary disease, which includes asthma, chronic bronchitis and emphysema. Respiratory diseases (including lung cancer) are responsible for over 10% of hospitalizations and over 16% of deaths in Canada.
In 2011, respiratory disease with ventilator support accounted for 93.3% of ICU utilization in the United States.
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