Why do you need to breathe?
All the cells in your body require oxygen. Without it, they couldn't move, build, reproduce, and turn food into energy. In fact, without oxygen, they and you would die! How do you get oxygen? From breathing in air which your blood circulates to all parts of the body.
How do you breathe?
You breathe with the help of your diaphragm and other muscles in your chest and abdomen. These muscles literally change the space and pressure inside your body to accomodate breathing. When your diaphragm pulls down, it not only leaves more space for the lungs to expand but also lowers the internal air pressure. Outside, where the air pressure is greater, you suck in air in an inhale. The air then expands your lungs like a pair of balloons. When your diaphragm relaxes, the cavity inside your body gets smaller again. Your muscles squeeze your rib cage and your lungs begin to collapse as the air is pushed up and out your body in an exhale.
So, it all starts at the nose?
Yup. About 20 times a minute, you breathe in. When you do, you inhale air and pass it through your nasal passages where the air is filtered, heated, moistened and enters the back of the throat. Interestingly enough, it's the esophagus or foodpipe which is located at the back of the throat and the windpipe for air which is located at the front. When we eat, a flap -- the epiglottis -- flops down to cover the windpipe so that food doesn't go down the windpipe.
So -- back to breathing -- the air has a long journey to get to your lungs. It flows down through the windpipe, past the voice box or vocal cords, to where the lowermost ribs meet the center of your chest. There, your windpipe divides into two tubes which lead to the two lungs which fill most of your ribcage. Inside each of your sponge-like lungs, tubes, called bronchi, branch into even smaller tubes much like the branches of a tree. At the end of these tubes are millions of tiny bubbles or sacs called aleoli. Spread out flat, all the air sacs in the lungs of an adult would cover an area about the third of a tennis court.
What do these sacs do?
They help perform an incredible magic act. Your air sacs bring new oxygen from air you've breathed to your bloodstream. They exchange it for waste products, like carbon dioxide, which the cells in your body have made and can't use.
How does this exchange work?
With the help of the red blood cells in your bloodstream. Your red blood cells are like box cars on train tracks. They show up at the sacs at just the right time, ready to trade in old carbon dioxide that your body's cells have made for some new oxygen you've just breathed in. In the process, these red blood cells turn from purple to that beautiful red color as they start carrying the oxygen to all the cells in your body.
But what happens to the carbon dioxide?
It goes through the lungs, back up your windpipe and out with every exhale. It's a remarkable feat, this chemical exchange and breathing in and out. You don't have to tell your lungs to keep working. Your brain does it automatically for you.
Factoids
•Your lungs contain almost 1500 miles of airways and over 300 million alveoli.
•Every minute you breathe in 13 pints of air.
•Plants are our partners in breathing. We breathe in air, use the oxygen in it, and release carbon dioxide. Plants take in carbon dioxide and release oxygen. Thank goodness!
•People tend to get more colds in the winter because we're indoors more often and in close proximity to other people. When people sneeze, cough and even breathe -- germs go flying!
Monday, July 27, 2009
Respiratory system Detail for Adults
This photo (courtesy of the Anatomical Institute, Bern) shows a rubber cast of human lungs.
The Human Respiratory System
The Pathway
•Air enters the nostrils
•passes through the nasopharynx,
•the oral pharynx
•through the glottis
•into the trachea
•into the right and left bronchi, which branches and rebranches into
•bronchioles, each of which terminates in a cluster of
•alveoli
Only in the alveoli does actual gas exchange takes place. There are some 300 million alveoli in two adult lungs. These provide a surface area of some 160 m2 (almost equal to the singles area of a tennis court and 80 times the area of our skin!).
Breathing
In mammals, the diaphragm divides the body cavity into the
•abdominal cavity, which contains the viscera (e.g., stomach and intestines) and the
•thoracic cavity, which contains the heart and lungs.
The inner surface of the thoracic cavity and the outer surface of the lungs are lined with pleural membranes which adhere to each other. If air is introduced between them, the adhesion is broken and the natural elasticity of the lung causes it to collapse. This can occur from trauma. And it is sometimes induced deliberately to allow the lung to rest. In either case, reinflation occurs as the air is gradually absorbed by the tissues.
Because of this adhesion, any action that increases the volume of the thoracic cavity causes the lungs to expand, drawing air into them.
•During inspiration (inhaling),
◦The external intercostal muscles contract, lifting the ribs up and out.
◦The diaphragm contracts, drawing it down .
•During expiration (exhaling), these processes are reversed and the natural elasticity of the lungs returns them to their normal volume. At rest, we breath 15-18 times a minute exchanging about 500 ml of air.
•In more vigorous expiration,
◦The internal intercostal muscles draw the ribs down and inward
◦The wall of the abdomen contracts pushing the stomach and liver upward.
Under these conditions, an average adult male can flush his lungs with about 4 liters of air at each breath. This is called the vital capacity. Even with maximum expiration, about 1200 ml of residual air remain.
The table shows what happens to the composition of air when it reaches the alveoli. Some of the oxygen dissolves in the film of moisture covering the epithelium of the alveoli. From here it diffuses into the blood in a nearby capillary. It enters a red blood cell and combines with the hemoglobin therein.
At the same time, some of the carbon dioxide in the blood diffuses into the alveoli from which it can be exhaled.
Link to discussion of gas transport in the blood.
Composition of atmospheric air and expired air in a typical subject.
Note that only a fraction of the oxygen inhaled is taken up by the lungs.
Component Atmospheric Air (%) Expired Air (%)
N2 (plus inert gases) 78.62 74.9
O2 20.85 15.3
CO2 0.03 3.6
H2O 0.5 6.2
100.0% 100.0%
The ease with which oxygen and carbon dioxide can pass between air and blood is clear from this electron micrograph of two alveoli (Air) and an adjacent capillary from the lung of a laboratory mouse. Note the thinness of the epithelial cells (EP) that line the alveoli and capillary (except where the nucleus is located). At the closest point, the surface of the red blood cell is only 0.7 µm away from the air in the alveolus. (Reproduced with permission from Keith R. Porter and Mary A. Bonneville, An Introduction to the Fine Structure of Cells and Tissues, 4th. ed., Lea & Febiger, 1973.)
Central Control of Breathing
The rate of cellular respiration (and hence oxygen consumption and carbon dioxide production) varies with level of activity. Vigorous exercise can increase by 20-25 times the demand of the tissues for oxygen. This is met by increasing the rate and depth of breathing.
It is a rising concentration of carbon dioxide — not a declining concentration of oxygen — that plays the major role in regulating the ventilation of the lungs. The concentration of CO2 is monitored by cells in the medulla oblongata. If the level rises, the medulla responds by increasing the activity of the motor nerves that control the intercostal muscles and diaphragm.
However, the carotid body in the carotid arteries does have receptors that respond to a drop in oxygen. Their activation is important in situations (e.g., at high altitude in the unpressurized cabin of an aircraft) where oxygen supply is inadequate but there has been no increase in the production of CO2.
Local Control of Breathing
The smooth muscle in the walls of the bronchioles is very sensitive to the concentration of carbon dioxide. A rising level of CO2 causes the bronchioles to dilate. This lowers the resistance in the airways and thus increases the flow of air in and out.
The Human Respiratory System
The Pathway
•Air enters the nostrils
•passes through the nasopharynx,
•the oral pharynx
•through the glottis
•into the trachea
•into the right and left bronchi, which branches and rebranches into
•bronchioles, each of which terminates in a cluster of
•alveoli
Only in the alveoli does actual gas exchange takes place. There are some 300 million alveoli in two adult lungs. These provide a surface area of some 160 m2 (almost equal to the singles area of a tennis court and 80 times the area of our skin!).
Breathing
In mammals, the diaphragm divides the body cavity into the
•abdominal cavity, which contains the viscera (e.g., stomach and intestines) and the
•thoracic cavity, which contains the heart and lungs.
The inner surface of the thoracic cavity and the outer surface of the lungs are lined with pleural membranes which adhere to each other. If air is introduced between them, the adhesion is broken and the natural elasticity of the lung causes it to collapse. This can occur from trauma. And it is sometimes induced deliberately to allow the lung to rest. In either case, reinflation occurs as the air is gradually absorbed by the tissues.
Because of this adhesion, any action that increases the volume of the thoracic cavity causes the lungs to expand, drawing air into them.
•During inspiration (inhaling),
◦The external intercostal muscles contract, lifting the ribs up and out.
◦The diaphragm contracts, drawing it down .
•During expiration (exhaling), these processes are reversed and the natural elasticity of the lungs returns them to their normal volume. At rest, we breath 15-18 times a minute exchanging about 500 ml of air.
•In more vigorous expiration,
◦The internal intercostal muscles draw the ribs down and inward
◦The wall of the abdomen contracts pushing the stomach and liver upward.
Under these conditions, an average adult male can flush his lungs with about 4 liters of air at each breath. This is called the vital capacity. Even with maximum expiration, about 1200 ml of residual air remain.
The table shows what happens to the composition of air when it reaches the alveoli. Some of the oxygen dissolves in the film of moisture covering the epithelium of the alveoli. From here it diffuses into the blood in a nearby capillary. It enters a red blood cell and combines with the hemoglobin therein.
At the same time, some of the carbon dioxide in the blood diffuses into the alveoli from which it can be exhaled.
Link to discussion of gas transport in the blood.
Composition of atmospheric air and expired air in a typical subject.
Note that only a fraction of the oxygen inhaled is taken up by the lungs.
Component Atmospheric Air (%) Expired Air (%)
N2 (plus inert gases) 78.62 74.9
O2 20.85 15.3
CO2 0.03 3.6
H2O 0.5 6.2
100.0% 100.0%
The ease with which oxygen and carbon dioxide can pass between air and blood is clear from this electron micrograph of two alveoli (Air) and an adjacent capillary from the lung of a laboratory mouse. Note the thinness of the epithelial cells (EP) that line the alveoli and capillary (except where the nucleus is located). At the closest point, the surface of the red blood cell is only 0.7 µm away from the air in the alveolus. (Reproduced with permission from Keith R. Porter and Mary A. Bonneville, An Introduction to the Fine Structure of Cells and Tissues, 4th. ed., Lea & Febiger, 1973.)
Central Control of Breathing
The rate of cellular respiration (and hence oxygen consumption and carbon dioxide production) varies with level of activity. Vigorous exercise can increase by 20-25 times the demand of the tissues for oxygen. This is met by increasing the rate and depth of breathing.
It is a rising concentration of carbon dioxide — not a declining concentration of oxygen — that plays the major role in regulating the ventilation of the lungs. The concentration of CO2 is monitored by cells in the medulla oblongata. If the level rises, the medulla responds by increasing the activity of the motor nerves that control the intercostal muscles and diaphragm.
However, the carotid body in the carotid arteries does have receptors that respond to a drop in oxygen. Their activation is important in situations (e.g., at high altitude in the unpressurized cabin of an aircraft) where oxygen supply is inadequate but there has been no increase in the production of CO2.
Local Control of Breathing
The smooth muscle in the walls of the bronchioles is very sensitive to the concentration of carbon dioxide. A rising level of CO2 causes the bronchioles to dilate. This lowers the resistance in the airways and thus increases the flow of air in and out.
Obstructive lung disease
Obstructive lung disease is a category of respiratory disease characterized by airway obstruction.
MeSH includes the following in this category:[1]
•Asthma
•Bronchitis
•Chronic obstructive pulmonary disease
Cystic fibrosis is sometimes also included in this category.[2]
FEV1/FVC ratio is usually decreased.
Following is an overview of the main obstructive lung diseases. Chronic obstructive pulmonary disease is mainly a combination of chronic bronchitis and emphysema, but may be more or less overlapping with all conditions.[3]
Condition Main site Major changes Causes Symptoms
Chronic bronchitis Bronchus Hyperplasia and hypersecretion of mucus glands Tobacco smoking and air pollutants Productive cough
Bronchiectasis Bronchus Dilation and scarring of airways Persistent severe infections Cough, purulent sputum and fever
Asthma Bronchus •Smooth muscle hyperplasia
•Excessive mucus
•Inflammation
Immunologic or idiopathic Episodic wheezing, cough and dyspnea
Emphysema Acinus Airspace enlargement and wall destruction Tobacco smoking Dyspnea
Bronchiolitis
(subgroup of chronic bronchitis) Bronchiole Inflammatory scarring and bronchiole obliteration Tobacco smoking and air pollutants Cough, dyspnea
Unless else specified in boxes then reference is [3]
Scope
[edit] Chronic obstructive pulmonary disease
Main article: Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive airways disease (COAD) or chronic airflow limitation (CAL), is a group of illnesses characterised by airflow limitation that is not fully reversible. The flow of air into and out of the lungs is impaired.[4] This can be measured with breathing devices such as a peak flow meter or by spirometry. The term COPD includes the conditions emphysema and chronic bronchitis although most patients with COPD have characteristics of both conditions to varying degrees. Asthma being a reversible obstruction of airways is often considered separately, but many COPD patients also have some degree of reversibility in their airways.
In COPD, there is an increase in airway resistance, shown by a decrease in the forced expiratory volume in 1 second (FEV1) measured by spirometry. COPD is defined as a forced expiratory volume in 1 second to forced vital capacity ratio (FEV1/FVC) that is less than 0.7[5]. The residual volume, the volume of air left in the lungs following full expiration, is often increased in COPD, as is the total lung capacity, while the vital capacity remains relatively normal. The increased total lung capacity (hyperinflation) can result in the clinical feature of a "barrel chest" - a chest with a large front-to-back diameter that occurs in some individuals with COPD. Hyperinflation can also be seen on a chest x-ray as a flattening of the diaphragm.
The most common cause of COPD is cigarette smoking. COPD is a gradually progressive condition and usually only develops after about 20 pack-years of smoking. COPD may also be caused by breathing in other particles and gases.
The disagnosis of COPD is established through spirometry although other pulmonary function tests can be helpful. A chest x-ray is often ordered to look for hyperinflation and rule out other lung conditions but the lung damage of COPD is not always visible on a chest x-ray. Emphysema, for example can only be seen on CT scan.
The main form of long term management involves the use of inhaled bronchodilators (specifically beta agonists and anticholinergics) and inhaled corticosteroids. Many patients eventually require oxygen supplementation at home. In severe cases that are difficult to control, chronic treatment with oral corticosteroids may be necessary, although this is fraught with significant side-effects.
COPD is generally irreversible although lung function can partially recover if the patient stops smoking. Smoking cessation is an essential aspect of treatment[6]. Pulmonary rehabilitation programmes involve intensive exercise training combined with education and are effective in improving shortness of breath. Severe emphysema has been treated with lung volume reduction surgery, with some success in carefully chosen cases. Lung transplantation is also performed for severe COPD in carefully chosen cases.
Alpha 1-antitrypsin deficiency is a fairly rare genetic condition that results in COPD (particularly emphysema) due to a lack of the antitrypsin protein which protects the fragile alveolar walls from protease enzymes released by inflammatory processes.
Asthma
Main article: Asthma
Asthma is an obstructive lung disease where the bronchial tubes (airways) are extra sensitive (hyperresponsive). The airways become inflamed and produce excess mucus and the muscles around the airways tighten making the airways narrower. Asthma is usually triggered by breathing in things in the air such as dust or pollen that produce an allergic reaction. It may be triggered by other things such as an upper respiratory tract infection, cold air, exercise or smoke. Asthma is a common condition and affects over 300 million people around the world[7]. Asthma causes recurring episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning.
Asthma is diagnosed by the characteristic pattern of symptoms. A peak flow meter can record variations in the severity of asthma over time. Spirometry, a measurement of lung function, can provide an assessment of the severity, reversibility, and variability of airflow limitation, and help confirm the diagnosis of asthma[7].
Asthma is treated by identifying and removing the triggers that set it off, if possible. The main form of long term management involves the use of inhaled corticosteroids. Inhaled bronchodilators, particularly beta agonists are used to relieve and control symptoms by reducing muscle spasm around the airways. An alternative way to control mild asthma is with a leukotriene antagonist tablet.
Other obstructive lung diseases
•Cystic fibrosis is an inherited disorder of the CFTR gene, a chloride ion channel. The lack of this channel causes reduced water content of secretions. This affects the mucus secreted as part of the lung's defence and creates sticky, viscous mucus. This makes the lungs more susceptible to infection, inflammation and mucous plugging.
•Bronchiectasis
•Bronchiolitis
•Allergic bronchopulmonary aspergillosis
In many parts of the world, the most common cause of obstructive lung disease is lung scarring after tuberculosis infection.
MeSH includes the following in this category:[1]
•Asthma
•Bronchitis
•Chronic obstructive pulmonary disease
Cystic fibrosis is sometimes also included in this category.[2]
FEV1/FVC ratio is usually decreased.
Following is an overview of the main obstructive lung diseases. Chronic obstructive pulmonary disease is mainly a combination of chronic bronchitis and emphysema, but may be more or less overlapping with all conditions.[3]
Condition Main site Major changes Causes Symptoms
Chronic bronchitis Bronchus Hyperplasia and hypersecretion of mucus glands Tobacco smoking and air pollutants Productive cough
Bronchiectasis Bronchus Dilation and scarring of airways Persistent severe infections Cough, purulent sputum and fever
Asthma Bronchus •Smooth muscle hyperplasia
•Excessive mucus
•Inflammation
Immunologic or idiopathic Episodic wheezing, cough and dyspnea
Emphysema Acinus Airspace enlargement and wall destruction Tobacco smoking Dyspnea
Bronchiolitis
(subgroup of chronic bronchitis) Bronchiole Inflammatory scarring and bronchiole obliteration Tobacco smoking and air pollutants Cough, dyspnea
Unless else specified in boxes then reference is [3]
Scope
[edit] Chronic obstructive pulmonary disease
Main article: Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive airways disease (COAD) or chronic airflow limitation (CAL), is a group of illnesses characterised by airflow limitation that is not fully reversible. The flow of air into and out of the lungs is impaired.[4] This can be measured with breathing devices such as a peak flow meter or by spirometry. The term COPD includes the conditions emphysema and chronic bronchitis although most patients with COPD have characteristics of both conditions to varying degrees. Asthma being a reversible obstruction of airways is often considered separately, but many COPD patients also have some degree of reversibility in their airways.
In COPD, there is an increase in airway resistance, shown by a decrease in the forced expiratory volume in 1 second (FEV1) measured by spirometry. COPD is defined as a forced expiratory volume in 1 second to forced vital capacity ratio (FEV1/FVC) that is less than 0.7[5]. The residual volume, the volume of air left in the lungs following full expiration, is often increased in COPD, as is the total lung capacity, while the vital capacity remains relatively normal. The increased total lung capacity (hyperinflation) can result in the clinical feature of a "barrel chest" - a chest with a large front-to-back diameter that occurs in some individuals with COPD. Hyperinflation can also be seen on a chest x-ray as a flattening of the diaphragm.
The most common cause of COPD is cigarette smoking. COPD is a gradually progressive condition and usually only develops after about 20 pack-years of smoking. COPD may also be caused by breathing in other particles and gases.
The disagnosis of COPD is established through spirometry although other pulmonary function tests can be helpful. A chest x-ray is often ordered to look for hyperinflation and rule out other lung conditions but the lung damage of COPD is not always visible on a chest x-ray. Emphysema, for example can only be seen on CT scan.
The main form of long term management involves the use of inhaled bronchodilators (specifically beta agonists and anticholinergics) and inhaled corticosteroids. Many patients eventually require oxygen supplementation at home. In severe cases that are difficult to control, chronic treatment with oral corticosteroids may be necessary, although this is fraught with significant side-effects.
COPD is generally irreversible although lung function can partially recover if the patient stops smoking. Smoking cessation is an essential aspect of treatment[6]. Pulmonary rehabilitation programmes involve intensive exercise training combined with education and are effective in improving shortness of breath. Severe emphysema has been treated with lung volume reduction surgery, with some success in carefully chosen cases. Lung transplantation is also performed for severe COPD in carefully chosen cases.
Alpha 1-antitrypsin deficiency is a fairly rare genetic condition that results in COPD (particularly emphysema) due to a lack of the antitrypsin protein which protects the fragile alveolar walls from protease enzymes released by inflammatory processes.
Asthma
Main article: Asthma
Asthma is an obstructive lung disease where the bronchial tubes (airways) are extra sensitive (hyperresponsive). The airways become inflamed and produce excess mucus and the muscles around the airways tighten making the airways narrower. Asthma is usually triggered by breathing in things in the air such as dust or pollen that produce an allergic reaction. It may be triggered by other things such as an upper respiratory tract infection, cold air, exercise or smoke. Asthma is a common condition and affects over 300 million people around the world[7]. Asthma causes recurring episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning.
Asthma is diagnosed by the characteristic pattern of symptoms. A peak flow meter can record variations in the severity of asthma over time. Spirometry, a measurement of lung function, can provide an assessment of the severity, reversibility, and variability of airflow limitation, and help confirm the diagnosis of asthma[7].
Asthma is treated by identifying and removing the triggers that set it off, if possible. The main form of long term management involves the use of inhaled corticosteroids. Inhaled bronchodilators, particularly beta agonists are used to relieve and control symptoms by reducing muscle spasm around the airways. An alternative way to control mild asthma is with a leukotriene antagonist tablet.
Other obstructive lung diseases
•Cystic fibrosis is an inherited disorder of the CFTR gene, a chloride ion channel. The lack of this channel causes reduced water content of secretions. This affects the mucus secreted as part of the lung's defence and creates sticky, viscous mucus. This makes the lungs more susceptible to infection, inflammation and mucous plugging.
•Bronchiectasis
•Bronchiolitis
•Allergic bronchopulmonary aspergillosis
In many parts of the world, the most common cause of obstructive lung disease is lung scarring after tuberculosis infection.
Restrictive lung diseases
Restrictive lung diseases are a category of respiratory disease characterised by a loss of lung compliance,[1] causing incomplete lung expansion and increased lung stiffness.
Pathophysiology
The underlying process is usually pulmonary fibrosis (scarring of the lung). As the disease progresses, the normal lung tissue is gradually replaced by scar tissue interspersed with pockets of air. This can lead to parts of the lung having a honeycomb-like appearance.
Presentation
The main symptoms are shortness of breath and cough.
Diagnosis
In restrictive lung disease, both the FEV1 and FVC are reduced so the FEV1/FVC ratio is normal or even increased in contrast to obstructive lung disease where this ratio is reduced. The values for residual volume and total lung capacity are generally decreased in restrictive lung disease[2].
One definition requires a total lung capacity which is 80% or less of the expected value.[3]
Causes and classification
Restrictive lung diseases may be due to specific causes which can be intrinsic to the parenchyma of the lung, or extrinsic to it.
Intrinsic
•Asbestosis caused by long-term exposure to asbestos dust.
•Radiation fibrosis, usually from the radiation given for cancer treatment.
•Certain drugs such as amiodarone, bleomycin and methotrexate.
•As a consequence of another disease such as rheumatoid arthritis.
•Hypersensitivity pneumonitis due to an allergic reaction to inhaled particles.
•Acute respiratory distress syndrome (ARDS), a severe lung condition occurring in response to a critical illness or injury.
•Infant respiratory distress syndrome due to a deficiency of surfactant in the lungs of a baby born prematurely.
Many cases of restrictive lung disease are idiopathic (have no known cause). Examples are:
•Idiopathic pulmonary fibrosis
•Idiopathic interstitial pneumonia, of which there are several types
•Sarcoidosis
•Eosinophilic pneumonia
•Lymphangioleiomyomatosis
•Pulmonary Langerhan’s cell histiocytosis
•Pulmonary alveolar proteinosis
Conditions specifically affecting the interstitium are called interstitial lung diseases.
Extrinsic
Quadriplegia can be a cause of restrictive lung disease.
Pathophysiology
The underlying process is usually pulmonary fibrosis (scarring of the lung). As the disease progresses, the normal lung tissue is gradually replaced by scar tissue interspersed with pockets of air. This can lead to parts of the lung having a honeycomb-like appearance.
Presentation
The main symptoms are shortness of breath and cough.
Diagnosis
In restrictive lung disease, both the FEV1 and FVC are reduced so the FEV1/FVC ratio is normal or even increased in contrast to obstructive lung disease where this ratio is reduced. The values for residual volume and total lung capacity are generally decreased in restrictive lung disease[2].
One definition requires a total lung capacity which is 80% or less of the expected value.[3]
Causes and classification
Restrictive lung diseases may be due to specific causes which can be intrinsic to the parenchyma of the lung, or extrinsic to it.
Intrinsic
•Asbestosis caused by long-term exposure to asbestos dust.
•Radiation fibrosis, usually from the radiation given for cancer treatment.
•Certain drugs such as amiodarone, bleomycin and methotrexate.
•As a consequence of another disease such as rheumatoid arthritis.
•Hypersensitivity pneumonitis due to an allergic reaction to inhaled particles.
•Acute respiratory distress syndrome (ARDS), a severe lung condition occurring in response to a critical illness or injury.
•Infant respiratory distress syndrome due to a deficiency of surfactant in the lungs of a baby born prematurely.
Many cases of restrictive lung disease are idiopathic (have no known cause). Examples are:
•Idiopathic pulmonary fibrosis
•Idiopathic interstitial pneumonia, of which there are several types
•Sarcoidosis
•Eosinophilic pneumonia
•Lymphangioleiomyomatosis
•Pulmonary Langerhan’s cell histiocytosis
•Pulmonary alveolar proteinosis
Conditions specifically affecting the interstitium are called interstitial lung diseases.
Extrinsic
Quadriplegia can be a cause of restrictive lung disease.
Upper respiratory tract infection
Upper respiratory tract infections, (URTI or URI), are the illnesses caused by an acute infection which involves the upper respiratory tract: nose, sinuses, pharynx or larynx.
Signs and symptoms
Acute upper respiratory tract infections include rhino-sinusitis (Common cold), sinusitis, pharyngitis/tonsillitis,ear infection, laryngitis and sometimes bronchitis. Symptoms of URTI's commonly include nasal congestion, cough, running nose, sore throat, fever, facial pressure and sneezing. Onset of the symptoms usually begins after 1-3 days after exposure to a microbial pathogen, most commonly a virus. The duration of the symptoms is typically 7 to 10 days but may persist longer.
Up to 15% of acute pharyngitis cases may be caused by bacteria, commonly Group A streptococcus in Streptococcal pharyngitis ("Strep Throat"). Generally, patients with strep throat start with a sore throat as their first symptom and usually do not have runny nose or cough or sneezing.
Pain and pressure of the ear caused by a middle ear infection (Otitis media) and the reddening of the eye caused by Viral Conjunctivitis are often associated with upper respiratory infections.
Influenza (the flu) is a more systemic illness which can also involve the upper respiratory tract.
Treatment
Judicious use of antibiotics can decrease unnecessary adverse effects of antibiotics as well as out-of-pocket costs to the patient. But more importantly, decreased antibiotic usage will prevent the rise of drug resistant bacteria, which is now a growing problem in the world. Health authorities have been strongly encouraging physicians to decrease the prescribing of antibiotics to treat common upper respiratory tract infections because antibiotic usage does not significantly reduce recovery time for these viral illnesses.
Some have advocated a delayed antibiotic approach to treating URIs which seeks to reduce the consumption of antibiotics while attempting to maintain patient satisfaction. Most studies show no difference in improvement of symptoms between those treated with antibiotics right away and those with delayed prescriptions. Most studies also show no difference in patient satisfaction, patient complications, symptoms between delayed and no antibiotics. It should be noted that a strategy of "no antibiotics" results in even less antibiotic use than a strategy of "delayed antibiotics". Until more effective treatments are available to treat the common respiratory viruses responsible for the majority of cases, treatment of URIs with rest, increased fluids, and symptomatic care with over-the-counter medications will remain the treatment of choice. However, in certain higher risk patients with underlying lung disease, such as chronic obstructive pulmonary disease (COPD), evidence does exist to support the treatment of URIs with antibiotics to shorten the course of illness and decrease treatment failure.
The use of Vitamin C in the prevention and treatment of upper respiratory infections has been suggested since the initial isolation of vitamin C in the 1930s. Several studies have failed to demonstrate that vitamin C supplementation reduces the incidence of colds in the normal healthy population, indicating that routine large dose prophylaxis with Vitamin C is not beneficial in widespread community usage. Some evidence exists to indicate that it could be justified in persons exposed to brief periods of severe physical exercise and/or cold environments. The evidence does not support the use of Vitamin C at the onset of colds as effective therapy.
Signs and symptoms
Acute upper respiratory tract infections include rhino-sinusitis (Common cold), sinusitis, pharyngitis/tonsillitis,ear infection, laryngitis and sometimes bronchitis. Symptoms of URTI's commonly include nasal congestion, cough, running nose, sore throat, fever, facial pressure and sneezing. Onset of the symptoms usually begins after 1-3 days after exposure to a microbial pathogen, most commonly a virus. The duration of the symptoms is typically 7 to 10 days but may persist longer.
Up to 15% of acute pharyngitis cases may be caused by bacteria, commonly Group A streptococcus in Streptococcal pharyngitis ("Strep Throat"). Generally, patients with strep throat start with a sore throat as their first symptom and usually do not have runny nose or cough or sneezing.
Pain and pressure of the ear caused by a middle ear infection (Otitis media) and the reddening of the eye caused by Viral Conjunctivitis are often associated with upper respiratory infections.
Influenza (the flu) is a more systemic illness which can also involve the upper respiratory tract.
Treatment
Judicious use of antibiotics can decrease unnecessary adverse effects of antibiotics as well as out-of-pocket costs to the patient. But more importantly, decreased antibiotic usage will prevent the rise of drug resistant bacteria, which is now a growing problem in the world. Health authorities have been strongly encouraging physicians to decrease the prescribing of antibiotics to treat common upper respiratory tract infections because antibiotic usage does not significantly reduce recovery time for these viral illnesses.
Some have advocated a delayed antibiotic approach to treating URIs which seeks to reduce the consumption of antibiotics while attempting to maintain patient satisfaction. Most studies show no difference in improvement of symptoms between those treated with antibiotics right away and those with delayed prescriptions. Most studies also show no difference in patient satisfaction, patient complications, symptoms between delayed and no antibiotics. It should be noted that a strategy of "no antibiotics" results in even less antibiotic use than a strategy of "delayed antibiotics". Until more effective treatments are available to treat the common respiratory viruses responsible for the majority of cases, treatment of URIs with rest, increased fluids, and symptomatic care with over-the-counter medications will remain the treatment of choice. However, in certain higher risk patients with underlying lung disease, such as chronic obstructive pulmonary disease (COPD), evidence does exist to support the treatment of URIs with antibiotics to shorten the course of illness and decrease treatment failure.
The use of Vitamin C in the prevention and treatment of upper respiratory infections has been suggested since the initial isolation of vitamin C in the 1930s. Several studies have failed to demonstrate that vitamin C supplementation reduces the incidence of colds in the normal healthy population, indicating that routine large dose prophylaxis with Vitamin C is not beneficial in widespread community usage. Some evidence exists to indicate that it could be justified in persons exposed to brief periods of severe physical exercise and/or cold environments. The evidence does not support the use of Vitamin C at the onset of colds as effective therapy.
Lower respiratory tract infection
While often used as a synonym for pneumonia, the rubric of lower respiratory tract infection can also be applied to other types of infection including lung abscess, acute bronchitis, and emphysema. Symptoms include shortness of breath, weakness, high fever, coughing and fatigue.
Lower respiratory tract infections place a considerable strain on the health budget and are generally more serious than upper respiratory infections. Since 1993 there has been a slight reduction in the total number of deaths from lower respiratory tract infection. However in 2002 they were still the leading cause of deaths among all infectious diseases, and they accounted for 3.9 million deaths worldwide and 6.9% of all deaths that year.
There are a number of acute and chronic infections that can affect the lower respiratory tract. The two most common infections are bronchitis and pneumonia. Influenza affects both the upper and lower respiratory tracts. Antibiotics are often thought to be the first line treatment in lower respiratory tract infections; however, these are not indicated in viral infections. It is important to use appropriate antibiotic selection based on the infecting organism and to ensure this therapy changes with the evolving nature of these infections and the emerging resistance to conventional therapies. H. influenzae and M. catarrhalis are of increasing importance in both community acquired pneumonia (CAP) and acute exacerbation of chronic bronchitis (AECB) while the importance of S. pneumoniae is declining. It has also become apparent the importance of atypical pathogens such as C. pneumoniae, M. pneumoniae and L. pneumophila, in CAP.
Bronchitis
Bronchitis can be classified as either acute or chronic. Acute bronchitis can be defined as acute bacterial or viral infection of the larger airways in healthy patients with no history of recurrent disease. It affects over 40 adults per 1000 each year and consists of transient inflammation of the major bronchi and trachea. Most often it is caused by viral infection and hence antibiotic therapy is not indicated in immunocompetent individuals. There are no effective therapies for viral bronchitis. Treatment of acute bronchitis with antibiotics is common but controversial as their use has only moderate benefit weighted against potential side effects (nausea and vomiting), increased resistance, and cost of treatment in a self-limiting condition. Beta2 agonists are sometimes used to relieve the cough associated with acute bronchitis. In a recent systematic review it was found there was no evidence to support their use.
Acute Exacerbations of Chronic Bronchitis (AECB) are frequently due to non-infective causes along with viral ones. 50% of patients are colonised with Haemophilus influenzae, Streptococcus pneumoniae or Moraxella catarrhalis. Antibiotics have only been shown to be effective if all three of the following symptoms are present:- increased dyspnoea, increased sputum volume and purulence. In these cases 500mg of Amoxycillin orally, every 8 hours for 5 days or 100mg doxycycline orally for 5 days should be used.
Pneumonia
Pneumonia is a serious infection of the small bronchioles and alveoli that can involve the pleura. It occurs in a variety of situations and treatment must vary according to the situation. It is classified as either community or hospital acquired depending on where the patient contracted the infection. It is very life-threatening in the elderly or people with illnesses that affect the immune system. The most common treatment is antibiotics and these vary in their adverse effects and their effectiveness. Pneumonia is also the leading cause of death in children less than five years of age. The most common cause of pneumonia is pneumococcal bacteria, Streptococcus pneumoniae accounts for 2/3 of bacteremic pneumonias. A dangerous type of lung infection with a mortality rate of around 25%. For optimal management of a pneumonia patient the following must be assessed;- pneumonia severity (including where to treat eg. Home, hospital or intensive care), identification of causative organism, analgesia of chest pain, the need for supplemental oxygen, physiotherapy, Hydration, bronchodilators and possible complications of emphysema or lung abscess.
For community acquired respiratory infections the appropriate use of fluoroquinolones is a therapeutic option. These have been demonstrated to have targeted in vitro activity against both the typical and atypical pathogens of interest. The newer fluoroquinolones (eg, moxifloxacin or gatifloxacin) have extended gram +ve activity and once daily dosing and hence are potential first line in the treatment of lower respiratory tract infections. However it is clinical response that is the best indicators of efficacy and moxifloxacin or gatifloxacin have been proven to be effective against community acquired respiratory tract infections clinically.
Antibiotic Choice
With increased development of drug resistance, traditional empirical treatments are becoming less effective, hence it is important to base antibiotic choice on isolated bacteria and sensitivity tests. According to the Cochrane review of antibiotic use in CAP in adults, the current evidence from RCTs is insufficient in order to make evidenced based decisions on the antibiotic of choice. Further studies are required to make these decisions. For children they found amoxicillin or procaine penicillin to have greater effect than co-trimoxazole for the treatment of CAP. In hospital settings, penicillin and gentamicin was found to be more effective than chloramphenicol, with oral amoxicillin giving similar results to injectable penicillins. In another review of children with severe pneumonia, oral antibiotics were found to be as effective as injectable ones without the side effects of pain, risk of infection, or high cost. Also in a Cochrane review azithromycin has been shown to be no better than Amoxycillin or Amoxycillin with clavulanic acid in the treatment of lower respiratory infections. The AMH list Amoxycillin as first line of AECB and community acquired pneumonia where as IV azithromycin is first line if high risk of death. If severe hospital acquired pneumonia it recommends IV gentamicin and ticarcillin with clavulanic acid.
Non-Pharmacological Treatments
In 2003 very high quality, published research was done about the risk of hospitalization due to respiratory illness and type of infant feeding in developed countries. It involved 3,201 breastfed babies and 1,324 non –breastfed babies. It showed an overall 72 % reduction in the risk of hospitalization in infants who exclusively breastfed for 4 or more months compared to those who were formula-fed. Therefore, exclusive breastfeeding for 4 or more months is associated with a reduction in the risk of hospitalization secondary to lower respiratory tract diseases. Citation:Ip S, Chung M, et al. Breastfeeding and Maternal and Infant Health Outcomes in Developed Countries. Evidence Report/Technology Assessment No. 153 (prepared by Tufts-New England Medical Center Evidence-Based Practice Center, under Contract No. 290-02-0022). AHRQ Publication No. 07-E007. Rockville, MD: Agency for Health Care Research and Quality. April 2007
The main stay of non pharmacological treatment for many years has been rest and increased fluid intake. Although it is common for doctors and other health professional to recommend extra fluid intake a Cochrane systematic review could find no evidence for or against increased fluid intake. Although the idea of replacing fluids lost through fever and rapid breathing was sound, some observational studies reported harmful effects such as dilution of blood sodium concentration leading to headache, confusion or possibly seizures. Rest will allow the body to conserve energy to fight off the infection. Physiotherapy is indicated in some types of pneumonia and should be encouraged where appropriate.
Complementary Therapies
Chickweed taken orally has been used for many years to reduce fever and phlegm associated with bronchitis. It is believed to act as an expectorant and although the pharmacological actions of several constituents suggest it may be useful, controlled studies are not available to confirm its effectiveness.
A systematic review of Chinese herbs used in the treatment of acute bronchitis found that there was weak evidence for their use, but there were insufficient quality data to recommend them. The benefit found may be due to study design or publication bias. Hence they should be used carefully because their safety is largely unknown.
Thyme is approved by commission E in the treatment of bronchitis and there are encouraging data for its use in chronic bronchitis when used in combination with other herbs, however there is no stand-alone data.
The use of Vitamin C is commonly thought to act to prevent colds and other respiratory infections. However according to a recent Cochrane review the evidence is too weak to support its widespread use as a prophylactic in preventing pneumonia in the general population. It may be reasonable to use in high risk patients with low plasma levels of vitamin C due to its low cost and risk associated with is use. Vitamin C used as an orthomolecular antibiotic, is most effective when used in the same way; i.e., on timetable dosages.
Vitamin A has been successfully used to reduce the mortality and severity of respiratory infection with measles. However in a review of non-measles pneumonia it was not found to have any benefit or harmful effects.
Used by native healers for millennia, garlic contains allicin, a powerful anti-fungal and antibiotic compound. Native American tribes have used garlic to treat coughs and croup. British herbalists use garlic for hoarseness and coughs. Louis Pasteur studied garlic's antibacterial properties. During both World Wars, Allium sativum was used as an antiseptic.
For the treatment of pneumonia baical skullcap was shown to be as effective as piperacillin after one treatment. The piperacillin group resulted in 4 of 30 patients with fungal infections while there were none in the baical skullcap group.
The Future
It is likely that the future treatment of lower respiratory tract infections will consist of new antibiotics aimed at facing the problems associated with the constant emergence of antibiotic resistance. With resistance evolving so rapidly future treatments may include the use of vaccines to prevent these infections. Although a Cochrane systematic review of a polysaccharide pneumococcal vaccine didn’t reduce the pneumonia or their related deaths in adults, but was able to reduce incidence of more specific outcomes such as pneumococcal disease in the elderly. So it is hoped with further developments these will become more effective against pneumonia.
Vaccination of patients with AECB in the autumn months is thought to have a positive effect in reducing the severity and number of exacerbations over winter. The oral vaccine described in this review was able to decrease the carriage or non-typeable Haemophilus influenzae that is a common cause of exacerbations to chronic bronchitis. With good planning and further research these types of vaccines may reduce the burden associated with lower respiratory diseases.
There are few treatments available for viral forms of bronchitis and pneumonia. Respiratory syncytial virus (RSV), the main cause of these in children, could be potentially treated using a new monoclonal antibody (mAb) Motavizumab. In animal trials it reduced antibody titres 100 lower than the only drug currently available to treat the condition. This holds great promise for future treatments of LRTI
Lower respiratory tract infections place a considerable strain on the health budget and are generally more serious than upper respiratory infections. Since 1993 there has been a slight reduction in the total number of deaths from lower respiratory tract infection. However in 2002 they were still the leading cause of deaths among all infectious diseases, and they accounted for 3.9 million deaths worldwide and 6.9% of all deaths that year.
There are a number of acute and chronic infections that can affect the lower respiratory tract. The two most common infections are bronchitis and pneumonia. Influenza affects both the upper and lower respiratory tracts. Antibiotics are often thought to be the first line treatment in lower respiratory tract infections; however, these are not indicated in viral infections. It is important to use appropriate antibiotic selection based on the infecting organism and to ensure this therapy changes with the evolving nature of these infections and the emerging resistance to conventional therapies. H. influenzae and M. catarrhalis are of increasing importance in both community acquired pneumonia (CAP) and acute exacerbation of chronic bronchitis (AECB) while the importance of S. pneumoniae is declining. It has also become apparent the importance of atypical pathogens such as C. pneumoniae, M. pneumoniae and L. pneumophila, in CAP.
Bronchitis
Bronchitis can be classified as either acute or chronic. Acute bronchitis can be defined as acute bacterial or viral infection of the larger airways in healthy patients with no history of recurrent disease. It affects over 40 adults per 1000 each year and consists of transient inflammation of the major bronchi and trachea. Most often it is caused by viral infection and hence antibiotic therapy is not indicated in immunocompetent individuals. There are no effective therapies for viral bronchitis. Treatment of acute bronchitis with antibiotics is common but controversial as their use has only moderate benefit weighted against potential side effects (nausea and vomiting), increased resistance, and cost of treatment in a self-limiting condition. Beta2 agonists are sometimes used to relieve the cough associated with acute bronchitis. In a recent systematic review it was found there was no evidence to support their use.
Acute Exacerbations of Chronic Bronchitis (AECB) are frequently due to non-infective causes along with viral ones. 50% of patients are colonised with Haemophilus influenzae, Streptococcus pneumoniae or Moraxella catarrhalis. Antibiotics have only been shown to be effective if all three of the following symptoms are present:- increased dyspnoea, increased sputum volume and purulence. In these cases 500mg of Amoxycillin orally, every 8 hours for 5 days or 100mg doxycycline orally for 5 days should be used.
Pneumonia
Pneumonia is a serious infection of the small bronchioles and alveoli that can involve the pleura. It occurs in a variety of situations and treatment must vary according to the situation. It is classified as either community or hospital acquired depending on where the patient contracted the infection. It is very life-threatening in the elderly or people with illnesses that affect the immune system. The most common treatment is antibiotics and these vary in their adverse effects and their effectiveness. Pneumonia is also the leading cause of death in children less than five years of age. The most common cause of pneumonia is pneumococcal bacteria, Streptococcus pneumoniae accounts for 2/3 of bacteremic pneumonias. A dangerous type of lung infection with a mortality rate of around 25%. For optimal management of a pneumonia patient the following must be assessed;- pneumonia severity (including where to treat eg. Home, hospital or intensive care), identification of causative organism, analgesia of chest pain, the need for supplemental oxygen, physiotherapy, Hydration, bronchodilators and possible complications of emphysema or lung abscess.
For community acquired respiratory infections the appropriate use of fluoroquinolones is a therapeutic option. These have been demonstrated to have targeted in vitro activity against both the typical and atypical pathogens of interest. The newer fluoroquinolones (eg, moxifloxacin or gatifloxacin) have extended gram +ve activity and once daily dosing and hence are potential first line in the treatment of lower respiratory tract infections. However it is clinical response that is the best indicators of efficacy and moxifloxacin or gatifloxacin have been proven to be effective against community acquired respiratory tract infections clinically.
Antibiotic Choice
With increased development of drug resistance, traditional empirical treatments are becoming less effective, hence it is important to base antibiotic choice on isolated bacteria and sensitivity tests. According to the Cochrane review of antibiotic use in CAP in adults, the current evidence from RCTs is insufficient in order to make evidenced based decisions on the antibiotic of choice. Further studies are required to make these decisions. For children they found amoxicillin or procaine penicillin to have greater effect than co-trimoxazole for the treatment of CAP. In hospital settings, penicillin and gentamicin was found to be more effective than chloramphenicol, with oral amoxicillin giving similar results to injectable penicillins. In another review of children with severe pneumonia, oral antibiotics were found to be as effective as injectable ones without the side effects of pain, risk of infection, or high cost. Also in a Cochrane review azithromycin has been shown to be no better than Amoxycillin or Amoxycillin with clavulanic acid in the treatment of lower respiratory infections. The AMH list Amoxycillin as first line of AECB and community acquired pneumonia where as IV azithromycin is first line if high risk of death. If severe hospital acquired pneumonia it recommends IV gentamicin and ticarcillin with clavulanic acid.
Non-Pharmacological Treatments
In 2003 very high quality, published research was done about the risk of hospitalization due to respiratory illness and type of infant feeding in developed countries. It involved 3,201 breastfed babies and 1,324 non –breastfed babies. It showed an overall 72 % reduction in the risk of hospitalization in infants who exclusively breastfed for 4 or more months compared to those who were formula-fed. Therefore, exclusive breastfeeding for 4 or more months is associated with a reduction in the risk of hospitalization secondary to lower respiratory tract diseases. Citation:Ip S, Chung M, et al. Breastfeeding and Maternal and Infant Health Outcomes in Developed Countries. Evidence Report/Technology Assessment No. 153 (prepared by Tufts-New England Medical Center Evidence-Based Practice Center, under Contract No. 290-02-0022). AHRQ Publication No. 07-E007. Rockville, MD: Agency for Health Care Research and Quality. April 2007
The main stay of non pharmacological treatment for many years has been rest and increased fluid intake. Although it is common for doctors and other health professional to recommend extra fluid intake a Cochrane systematic review could find no evidence for or against increased fluid intake. Although the idea of replacing fluids lost through fever and rapid breathing was sound, some observational studies reported harmful effects such as dilution of blood sodium concentration leading to headache, confusion or possibly seizures. Rest will allow the body to conserve energy to fight off the infection. Physiotherapy is indicated in some types of pneumonia and should be encouraged where appropriate.
Complementary Therapies
Chickweed taken orally has been used for many years to reduce fever and phlegm associated with bronchitis. It is believed to act as an expectorant and although the pharmacological actions of several constituents suggest it may be useful, controlled studies are not available to confirm its effectiveness.
A systematic review of Chinese herbs used in the treatment of acute bronchitis found that there was weak evidence for their use, but there were insufficient quality data to recommend them. The benefit found may be due to study design or publication bias. Hence they should be used carefully because their safety is largely unknown.
Thyme is approved by commission E in the treatment of bronchitis and there are encouraging data for its use in chronic bronchitis when used in combination with other herbs, however there is no stand-alone data.
The use of Vitamin C is commonly thought to act to prevent colds and other respiratory infections. However according to a recent Cochrane review the evidence is too weak to support its widespread use as a prophylactic in preventing pneumonia in the general population. It may be reasonable to use in high risk patients with low plasma levels of vitamin C due to its low cost and risk associated with is use. Vitamin C used as an orthomolecular antibiotic, is most effective when used in the same way; i.e., on timetable dosages.
Vitamin A has been successfully used to reduce the mortality and severity of respiratory infection with measles. However in a review of non-measles pneumonia it was not found to have any benefit or harmful effects.
Used by native healers for millennia, garlic contains allicin, a powerful anti-fungal and antibiotic compound. Native American tribes have used garlic to treat coughs and croup. British herbalists use garlic for hoarseness and coughs. Louis Pasteur studied garlic's antibacterial properties. During both World Wars, Allium sativum was used as an antiseptic.
For the treatment of pneumonia baical skullcap was shown to be as effective as piperacillin after one treatment. The piperacillin group resulted in 4 of 30 patients with fungal infections while there were none in the baical skullcap group.
The Future
It is likely that the future treatment of lower respiratory tract infections will consist of new antibiotics aimed at facing the problems associated with the constant emergence of antibiotic resistance. With resistance evolving so rapidly future treatments may include the use of vaccines to prevent these infections. Although a Cochrane systematic review of a polysaccharide pneumococcal vaccine didn’t reduce the pneumonia or their related deaths in adults, but was able to reduce incidence of more specific outcomes such as pneumococcal disease in the elderly. So it is hoped with further developments these will become more effective against pneumonia.
Vaccination of patients with AECB in the autumn months is thought to have a positive effect in reducing the severity and number of exacerbations over winter. The oral vaccine described in this review was able to decrease the carriage or non-typeable Haemophilus influenzae that is a common cause of exacerbations to chronic bronchitis. With good planning and further research these types of vaccines may reduce the burden associated with lower respiratory diseases.
There are few treatments available for viral forms of bronchitis and pneumonia. Respiratory syncytial virus (RSV), the main cause of these in children, could be potentially treated using a new monoclonal antibody (mAb) Motavizumab. In animal trials it reduced antibody titres 100 lower than the only drug currently available to treat the condition. This holds great promise for future treatments of LRTI
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