Pharmacy and Medicine

Bronchitis is inflammation of the mucous membranes of the bronchi, the airways that carry airflow from the trachea into the lungs. Bronchitis can be classified into two categories, acute and chronic, each of which has unique etiologies, pathologies, and therapies.
Acute bronchitis is characterized by the development of a cough, with or without the production of sputum, mucus that is expectorated (coughed up) from the respiratory tract. Acute bronchitis often occurs during the course of an acute viral illness such as the common cold or influenza. Viruses cause about 90% of cases of acute bronchitis while bacteria account for less than 10%.
Chronic bronchitis, a type of chronic obstructive pulmonary disease, is characterized by the presence of a productive cough that lasts for 3 months or more per year for at least 2 years. Chronic bronchitis most often develops due to recurrent injury to the airways caused by inhaled irritants. Cigarette smoking is the most common cause, followed by air pollution and occupational exposure to irritants, and cold air.

Acute bronchitis:
Acute bronchitis is most often caused by viruses that infect the epithelium of the bronchi, resulting in inflammation and increased secretion of mucus. Cough, a common symptom of acute bronchitis, develops in an attempt to expel the excess mucus from the lungs. Other common symptoms include sore throat, runny nose, nasal congestion (coryza), low-grade fever, malaise, and the production of sputum.
Acute bronchitis often develops during the course of an upper respiratory infection (URI) such as the common cold or influenza. About 90% of cases of acute bronchitis are caused by viruses, including rhinoviruses, adenoviruses, and influenza. Bacteria, including Mycoplasma pneumoniae, Chlamydia pneumoniae, and Bordetella pertussis, account for about 10% of cases.

Treatment for acute bronchitis is primarily symptomatic. Non-steroidal anti-inflammatory drugs (NSAIDs) may be used to treat fever and sore throat. Decongestants can be useful in patients with nasal congestion, and expectorants may be used to loosen mucus and increase expulsion of sputum. Cough suppressants may be used if the cough interferes with sleep or is bothersome, although coughing may be useful in expelling sputum from the airways. Even with no treatment, most cases of acute bronchitis resolve quickly.
As most cases of acute bronchitis are caused by viruses, antibiotics should not be used since they are only effective against bacteria. Using antibiotics in patients who do not have bacterial infections promotes the development of antibiotic-resistant bacteria, which may lead to greater morbidity and mortality. Antibiotics should only be prescribed if microscopic examination of Gram stained sputum shows large numbers of bacteria present.

Chronic bronchitis:
Chronic bronchitis, a type of chronic obstructive pulmonary disease, is defined by a productive cough that lasts for 3 months or more per year for at least 2 years. Other symptoms may include wheezing and shortness of breath, especially upon exertion. The cough is often worst soon after awakening, and the sputum produced may have a yellow or green color and may be streaked with blood.
Chronic bronchitis is caused by recurring injury or irritation to the respiratory epithelium of the bronchi, resulting in chronic inflammation, edema (swelling), and increased production of mucus by goblet cells. Airflow into and out of the lungs is partly blocked because of the swelling and extra mucus in the bronchi or due to reversible bronchospasm.
Most cases of chronic bronchitis are caused by smoking cigarettes or other forms of tobacco. Chronic inhalation of irritating fumes or dust from occupational exposure or air pollution may also be causative. About 5% of the population has chronic bronchitis, and it is two times more common in males than females.
Chronic bronchitis is treated symptomatically. Inflammation and edema of the respiratory epithelium may be reduced with inhaled corticosteroids. Wheezing and shortness of breath can be treated by reducing bronchospasm (reversible narrowing of smaller bronchi due to constriction of the smooth muscle) with bronchodilators such as inhaled ß-Adrenergic agonists (e.g., albuterol) and inhaled anticholinergics (e.g., ipratropium bromide). Hypoxemia, too little oxygen in the blood, can be treated with supplemental oxygen. However, oxygen supplementation can result in decreased respiratory drive leading to increased blood levels of carbon dioxide and subsequent respiratory acidosis.
The most effective method of preventing chronic bronchitis and other forms of COPD is to avoid smoking cigarettes and other forms of tobacco.

On pulmonary tests, a bronchitic (bronchitis) may present a decreased FEV1 and FEV1/FVC. However, unlike the other common obstructive disorders, asthma and emphysema, bronchitis rarely causes a high residual volume. This is because the air flow obstruction found in bronchitis is due to increased resistance, which does not generally cause the airways to collapse prematurely and trap air in the lungs.

Pneumonia is an inflammatory illness of the lung. Frequently, it is described as lung parenchyma/alveolar inflammation and abnormal alveolar filling with fluid (consolidation and exudation).
The alveoli are microscopic air-filled sacs in the lungs responsible for absorbing oxygen. Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi, or parasites, and chemical or physical injury to the lungs. Its cause may also be officially described as idiopathic—that is, unknown—when infectious causes have been excluded.
Typical symptoms associated with pneumonia include cough, chest pain, fever, and difficulty in breathing. Diagnostic tools include x-rays and examination of the sputum. Treatment depends on the cause of pneumonia; bacterial pneumonia is treated with antibiotics.
Pneumonia is a common illness which occurs in all age groups, and is a leading cause of death among the elderly and people who are chronically and terminally ill. Additionally, it is the leading cause of death in children under five years old worldwide. to prevent certain types of pneumonia are available. The prognosis depends on the type of pneumonia, the appropriate treatment, any complications, and the person's underlying health.

Signs And Symptoms:
People with infectious pneumonia often have a cough producing greenish or yellow sputum, or phlegm and a high fever that may be accompanied by shaking chills. Shortness of breath is also common, as is pleuritic chest pain, a sharp or stabbing pain, either experienced during deep breaths or coughs or worsened by them. People with pneumonia may cough up blood, experience headaches, or develop sweaty and clammy skin. Other possible symptoms are loss of appetite, fatigue, blueness of the skin, nausea, vomiting, mood swings, and joint pains or muscle aches. Less common forms of pneumonia can cause other symptoms; for instance, pneumonia caused by Legionella may cause abdominal pain and diarrhea, while pneumonia caused by tuberculosis or Pneumocystis may cause only weight loss and night sweats. In elderly people manifestations of pneumonia may not be typical. They may develop a new or worsening confusion or may experience unsteadiness, leading to falls. Infants with pneumonia may have many of the symptoms above, but in many cases they are simply sleepy or have a decreased appetite.
Pneumonia fills the lung's alveoli with fluid, keeping oxygen from reaching the bloodstream. The alveolus on the left is normal, while the alveolus on the right is full of fluid from pneumonia.
Symptoms of pneumonia need immediate medical evaluation. Physical examination by a health care provider may reveal fever or sometimes low body temperature, an increased respiratory rate, low blood pressure, a high heart rate, or a low oxygen saturation, which is the amount of oxygen in the blood as indicated by either pulse oximetry or blood gas analysis. People who are struggling to breathe, who are confused, or who have cyanosis (blue-tinged skin) require immediate attention.Physical examination of the lungs may be normal, but often shows decreased expansion of the chest on the affected side, bronchial breathing on auscultation with a stethoscope (harsher sounds from the larger airways transmitted through the inflamed and consolidated lung), and rales (or crackles) heard over the affected area during inspiration. Percussion may be dulled over the affected lung, but increased rather than decreased vocal resonance (which distinguishes it from a pleural effusion). While these signs are relevant, they are insufficient to diagnose or rule out a pneumonia; moreover, in studies it has been shown that two doctors can arrive at different findings on the same patient.

Complications:
Sometimes pneumonia can lead to additional complications. Complications are more frequently associated with bacterial pneumonia than with viral pneumonia. The most important complications include:
Respiratory and circulatory failure
Because pneumonia affects the lungs, often people with pneumonia have difficulty breathing, and it may not be possible for them to breathe well enough to stay alive without support. Non-invasive breathing assistance may be helpful, such as with a bi-level positive airway pressure machine. In other cases, placement of an endotracheal tube (breathing tube) may be necessary, and a ventilator may be used to help the person breathe.
Pneumonia can also cause respiratory failure by triggering acute respiratory distress syndrome (ARDS), which results from a combination of infection and inflammatory response. The lungs quickly fill with fluid and become very stiff. This stiffness, combined with severe difficulties extracting oxygen due to the alveolar fluid, create a need for mechanical ventilation.
Pleural effusion. Chest x-ray showing a pleural effusion. The A arrow indicates "fluid layering" in the right chest. The B arrow indicates the width of the right lung. The volume of useful lung is reduced because of the collection of fluid around the lung.
Sepsis and septic shock are potential complications of pneumonia. Sepsis occurs when microorganisms enter the bloodstream and the immune system responds by secreting cytokines. Sepsis most often occurs with bacterial pneumonia; Streptococcus pneumoniae is the most common cause. Individuals with sepsis or septic shock need hospitalization in an intensive care unit. They often require intravenous fluids and medications to help keep their blood pressure from dropping too low. Sepsis can cause liver, kidney, and heart damage, among other problems, and it often causes death.
Pleural effusion, empyema, and abscess
Occasionally, microorganisms infecting the lung will cause fluid (a pleural effusion) to build up in the space that surrounds the lung (the pleural cavity). If the microorganisms themselves are present in the pleural cavity, the fluid collection is called an empyema. When pleural fluid is present in a person with pneumonia, the fluid can often be collected with a needle (thoracentesis) and examined. Depending on the results of this examination, complete drainage of the fluid may be necessary, often requiring a chest tube. In severe cases of empyema, surgery may be needed. If the fluid is not drained, the infection may persist, because antibiotics do not penetrate well into the pleural cavity.
Rarely, bacteria in the lung will form a pocket of infected fluid called an abscess. Lung abscesses can usually be seen with a chest x-ray or chest CT scan. Abscesses typically occur in aspiration pneumonia and often contain several types of bacteria. Antibiotics are usually adequate to treat a lung abscess, but sometimes the abscess must be drained by a surgeon or radiologist.

Most cases of pneumonia can be treated without hospitalization. Typically, oral antibiotics, rest, fluids, and home care are sufficient for complete resolution. However, people with pneumonia who are having trouble breathing, people with other medical problems, and the elderly may need more advanced treatment. If the symptoms get worse, the pneumonia does not improve with home treatment, or complications occur, the person will often have to be hospitalized.

Bacterial pneumonia:
Antibiotics are used to treat bacterial pneumonia. In contrast, antibiotics are not useful for viral pneumonia, although they sometimes are used to treat or prevent bacterial infections that can occur in lungs damaged by a viral pneumonia.[citation needed] The antibiotic choice depends on the nature of the pneumonia, the most common microorganisms causing pneumonia in the local geographic area, and the immune status and underlying health of the individual. Treatment for pneumonia should ideally be based on the causative microorganism and its known antibiotic sensitivity. However, a specific cause for pneumonia is identified in only 50% of people, even after extensive evaluation.[citation needed] Because treatment should generally not be delayed in any person with a serious pneumonia, empiric treatment is usually started well before laboratory reports are available. In the United Kingdom, amoxicillin and clarithromycin or erythromycin are the antibiotics selected for most patients with community-acquired pneumonia; patients allergic to penicillins are given erythromycin instead of amoxicillin. In North America, where the "atypical" forms of community-acquired pneumonia are becoming more common, macrolides (such as azithromycin and clarithromycin), the fluoroquinolones, and doxycycline have displaced amoxicillin as first-line outpatient treatment for community-acquired pneumonia. The duration of treatment has traditionally been seven to ten days, but there is increasing evidence that shorter courses (as short as three days) are sufficient.
Antibiotics for hospital-acquired pneumonia include third- and fourth-generation cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and vancomycin. These antibiotics are usually given intravenously. Multiple antibiotics may be administered in combination in an attempt to treat all of the possible causative microorganisms. Antibiotic choices vary from hospital to hospital because of regional differences in the most likely microorganisms, and because of differences in the microorganisms' abilities to resist various antibiotic treatments.
People who have difficulty breathing due to pneumonia may require extra oxygen. Extremely sick individuals may require intensive care, often including endotracheal intubation and artificial ventilation.

Viral pneumonia:
Viral pneumonia caused by influenza A may be treated with rimantadine or amantadine, while viral pneumonia caused by influenza A or B may be treated with oseltamivir or zanamivir. These treatments are beneficial only if they are started within 48 hours of the onset of symptoms. Many strains of H5N1 influenza A, also known as avian influenza or "bird flu," have shown resistance to rimantadine and amantadine. There are no known effective treatments for viral pneumonias caused by the SARS coronavirus, adenovirus, hantavirus, or parainfluenza virus.

Aspiration pneumonia:
There is no evidence to support the use of antibiotics in chemical pneumonitis without bacterial infection. If infection is present in aspiration pneumonia, the choice of antibiotic will depend on several factors, including the suspected causative organism and whether pneumonia was acquired in the community or developed in a hospital setting. Common options include clindamycin, a combination of a beta-lactam antibiotic and metronidazole, or an aminoglycoside. Corticosteroids are commonly used in aspiration pneumonia, but there is no evidence to support their use either.