Dyspnea
Encyclopedia
Dyspnea shortness of breath (SOB), or air hunger, is the subjective symptom of breathlessness.
It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations. In 85% of cases it is due to either asthma
, pneumonia
, cardiac ischemia, interstitial lung disease, congestive heart failure
, chronic obstructive pulmonary disease
, or psychogenic causes. Treatment typically depends on the underlying cause.
as the "subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. The experience derives from interactions among multiple physiological, psychological, social, and environmental factors, and may induce secondary physiological and behavioral responses." Other definitions of dyspnea include "difficulty in breathing", "disordered or inadequate breathing", "uncomfortable awareness of breathing", or simple "breathlessness". Acute breathlessness is defined as severe shortness of breath that develops over minutes to hours. Chronic breathlessness on the other hand comes on over weeks or months. Dyspnea is distinct from labored breathing
, which is rather a common physical presentation of respiratory distress.
, other systems such as neurological, musculoskeletal
, endocrine
, hematologic, and psychiatric may be the cause. DiagnosisPro
, an online medical expert system, listed 497 distinct causes in October 2010. The most common cardiovascular causes are acute myocardial infarction and congestive heart failure
while common pulmonary causes include chronic obstructive pulmonary disease
, asthma
, pneumothorax
, and pneumonia
. On a pathophysiological basis the causes can be divided into: (1) an increased awareness of normal breathing such as during an anxiety attack, (2) an increase in the work of breathing and (3) an abnormality in the ventilatory system.
frequently presents with retrosternal chest discomfort
and difficulty catching the breath. It however may atypically present with shortness of breath alone. Risk factors include old age, smoking
, hypertension
, hyperlipidemia
, and diabetes. An electrocardiogram
and cardiac enzymes are important both for diagnosis and directing treatment. Treatment involves measures to decrease the oxygen requirement of the heart and efforts to increase blood flow.
frequently presents with SOB with exertion, orthopnea, and paroxysmal nocturnal dyspnea. It affects between 1-2% of the general United States population and occurs in 10% of those over 65 years old. Risk factors for acute decompensation
include high dietary salt
intake, medication noncompliance, cardiac ischemia, dysrhythmias
, renal failure
, pulmonary emboli, hypertension
, and infections. Treatment efforts are directed towards decreasing lung congestion.
(COPD), most commonly emphysema
or chronic bronchitis
, frequently have chronic shortness of breath and a chronic productive cough. An acute exacerbation
presents with increased shortness of breath and sputum
production. COPD is a risk factor for pneumothorax
; thus this condition should be ruled out. In an acute exacerbation treatment is with a combination of anticholinergics, beta2-adrenoceptor agonists, steroids and possibly positive pressure ventilation.
is the most common reason for presenting to the emergency with shortness of breath. It is the most common lung disease in both developing and developed countries affecting about 5% of the population. Other symptoms include wheezing, tightness in the chest, and a non productive cough. Inhaled beta2-adrenergic agonist (salbutamol) are first line therapy and usually lead to prompt improvement.
presents typically with pleuritic chest pain of acute onset and shortness of breath not improved with oxygen. Physical findings may include absent breath sounds on one side of the chest, jugular venous distension, and tracheal deviation.
are fever
, productive cough, shortness of breath, and pleuritic chest pain. Inspiratory crackles may be heard on exam. A chest x-ray can be useful to differential pneumonia from congestive heart failure. As the cause is usually a bacterial infections antibiotics are typically used for treatment.
classically presents with an acute onset of shortness of breath. Other presenting symptoms include pleuritic chest pain, cough, hemoptysis
, and fever
. Risk factors include deep vein thrombosis
, recent surgery, cancer
, and previous thromboembolism. It must always be considered in those with acute onset of shortness of breath owing to its high risk of mortality. Diagnosis however may be difficult. Treatment is typically with anticoagulants.
, anemia
, anaphylaxis
, interstitial lung disease, panic attack
s, and pulmonary hypertension
. Cardiac tamponade
presents with dyspnea, tachycardia, elevated jugular venous pressure, and pulsus paradoxus
. The gold standard for diagnosis is ultrasound
. Anemia
, that develops gradually, usually presents with exertional dyspnea, fatigue, weakness, and tachycardia. It may lead to heart failure. Anaphylaxis
typically begins over a few minutes in a person with a previous history of the same. Other symptoms include urticaria
, throat swelling
, and gastrointestinal upset. The primary treatment is epinephrine
. Interstitial lung disease presents with gradual onset of shortness of breath typically with a history of a predisposing environmental exposure. Shortness of breath is often the only symptom in those with tachydysrhythmias. Panic attack
s typically present with hyperventilation
, sweating, and numbness
. They are however a diagnosis of exclusion
. Around 2/3 of women experience shortness of breath as a part of a normal pregnancy
. Neurological conditions such as spinal cord injury, phrenic nerve injuries, Guillain-Barre syndrome
, amyotrophic lateral sclerosis
, multiple sclerosis
and muscular dystrophy
can all cause an individual to experience shortness of breath.
s, and lung receptor
s.
It is currently thought that there are three main components that contribute to dyspnea: afferent signals, efferent signals, and central information processing. It is believed that the central processing in the brain compares the afferent and efferent signals, and that a "mismatch" results in the sensation of dyspnea. In other words, dyspnea may result when the need for ventilation (afferent signaling) is not being met by the physical breathing that is occurring (efferent signaling). Afferent signals are sensory neuronal signals that ascend to the brain. Afferent neurons significant in dyspnea arise from a large number of sources including the carotid bodies, medulla
, lungs, and chest wall. Chemoreceptors in the carotid bodies and medulla supply information regarding the blood gas levels of O2, CO2 and H+. In the lungs, juxtacapillary (J) receptors
are sensitive to pulmonary interstitial edema, while stretch receptors signal bronchoconstriction. Muscle spindles in the chest wall signal the stretch and tension of the respiratory muscles. Thus, poor ventilation leading to hypercapnia
, left heart failure leading to interstitial edema (impairing gas exchange), asthma
causing bronchoconstriction (limiting airflow) and muscle fatigue leading to ineffective respiratory muscle action could all contribute to a feeling of dyspnea.
Efferent signals are the motor neuronal signals descending to the respiratory muscles
. The most important respiratory muscle is the diaphragm
. Other respiratory muscles include the external and internal intercostal muscles, the abdominal muscles and the accessory breathing muscles.
As the brain receives its plentiful supply of afferent information relating to ventilation, it is able to compare it to the current level of respiration as determined by the efferent signals. If the level of respiration is inappropriate for the body's status then dyspnea might occur. It is worth noting that there is a psychological component of dyspnea as well, as some people may become aware of their breathing in such circumstances but not experience the distress typical of dyspnea.
The initial approach to evaluation begins by assessment of the airway, breathing, and circulation followed by a medical history
and physical examination
. Signs that represent significant severity include hypotension
, hypoxemia
, tracheal deviation, altered mental status, unstable dysrhythmia
, stridor
, intercostal indrawing, cyanosis
, and absent breath sounds.
A number of scales may be used to quantify the degree of shortness of breath. It may be subjectively rated on a scale from 1 to 10 with descriptors associated with the number (The Modified Borg Scale). Alternatively a scale such as the MRC Breathlessness Scale might be used - it suggests five different grades of dyspnea based on the circumstances in which it arises.
while useful to rule out a pulmonary embolism in those who are at low risk is not of much value if it is positive as it may be positive in a number of conditions that lead to shortness of breath. A low level of brain natriuretic peptide
is useful in ruling out congestive heart failure however a high level while supportive of the diagnosis could also be due to advanced age, renal failure
, acute coronary syndrome, or a large pulmonary embolism.
is useful to confirm or rule out a pneumothorax, pulmonary edema
, or pneumonia. Spiral computed tomography
with intravenousradiocontrast
is the imaging study of choice to evaluate for pulmonary embolism.
is effective in those with hypoxia
however has no effect in those with normal blood oxygen saturation
s even in those with who are palliative.
interventions. Persons with neurological/neuromuscular abnormalities may have breathing difficulties due to weak or paralyzed intercostal, abdominal and/or other muscles needed for ventilation
. Some physical therapy interventions for this population include active assisted cough
techniques, volume augmentation such as breath stacking, education about body position and ventilation patterns and movement strategies to facilitate breathing.
, nebulised opioids, the use of gas mixtures, or cognitive-behavioral therapy.
in the United States. Of these approximately 51% are admitted to hospital and 13% are dead within a year. Some studies have suggested that up to 27% of people suffer from dyspnea, while in dying patients 75% will experience it. Acute shortness of breath is the most common reason people who are palliative visit an emergency department.
dyspnoia from dyspnoos) literally means disordered breathing.
It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations. In 85% of cases it is due to either 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...
, 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...
, cardiac ischemia, interstitial lung disease, congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
, 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...
, or psychogenic causes. Treatment typically depends on the underlying cause.
Definition
Dyspnea does not have a well-defined or universally accepted definition. It is defined by the American Thoracic SocietyAmerican Thoracic Society
American Thoracic Society , established in 1905, is an independently incorporated, international, educational and scientific society, serving its 18,000 members worldwide who are dedicated in respiratory and critical care medicine...
as the "subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. The experience derives from interactions among multiple physiological, psychological, social, and environmental factors, and may induce secondary physiological and behavioral responses." Other definitions of dyspnea include "difficulty in breathing", "disordered or inadequate breathing", "uncomfortable awareness of breathing", or simple "breathlessness". Acute breathlessness is defined as severe shortness of breath that develops over minutes to hours. Chronic breathlessness on the other hand comes on over weeks or months. Dyspnea is distinct from labored breathing
Labored breathing
Labored respiration or labored breathing is an abnormal respiration characterized by evidence of increased effort to breathe, including the use of accessory muscles of respiration, stridor, grunting, or nasal flaring.-Classification:...
, which is rather a common physical presentation of respiratory distress.
Differential diagnosis
While shortness of breath is generally caused by disorders of the cardiac or respiratory systemRespiratory system
The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...
, other systems such as neurological, musculoskeletal
Musculoskeletal system
A musculoskeletal system is an organ system that gives animals the ability to move using the muscular and skeletal systems...
, endocrine
Endocrine system
In physiology, the endocrine system is a system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. The endocrine system is in contrast to the exocrine system, which secretes its chemicals using ducts. It derives from the Greek words "endo"...
, hematologic, and psychiatric may be the cause. DiagnosisPro
DiagnosisPro
DiagnosisPro is a medical expert system. It provides exhaustive diagnostic possibilities for 11,000 diseases and 30,000 findings. It is supposed to give the most appropriate differential however this is not always the case. Between Oct 2008 and Oct 2009 the site averaged 61,000 visits per month....
, an online medical expert system, listed 497 distinct causes in October 2010. The most common cardiovascular causes are acute myocardial infarction and congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
while common pulmonary causes include 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...
, 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...
, 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...
, and 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...
. On a pathophysiological basis the causes can be divided into: (1) an increased awareness of normal breathing such as during an anxiety attack, (2) an increase in the work of breathing and (3) an abnormality in the ventilatory system.
Acute coronary syndrome
Acute coronary syndromeAcute coronary syndrome
Acute coronary syndrome is usually one of three diseases involving the coronary arteries: ST elevation myocardial infarction , non ST elevation myocardial infarction , or unstable angina ....
frequently presents with retrosternal chest discomfort
Chest pain
Chest pain may be a symptom of a number of serious conditions and is generally considered a medical emergency. Even though it may be determined that the pain is non-cardiac in origin, this is often a diagnosis of exclusion made after ruling out more serious causes of the pain.-Differential...
and difficulty catching the breath. It however may atypically present with shortness of breath alone. Risk factors include old age, smoking
Smoking
Smoking is a practice in which a substance, most commonly tobacco or cannabis, is burned and the smoke is tasted or inhaled. This is primarily practised as a route of administration for recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them...
, hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
, hyperlipidemia
Hyperlipidemia
Hyperlipidemia, hyperlipoproteinemia, or hyperlipidaemia is the condition of abnormally elevated levels of any or all lipids and/or lipoproteins in the blood...
, and diabetes. An electrocardiogram
Electrocardiogram
Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
and cardiac enzymes are important both for diagnosis and directing treatment. Treatment involves measures to decrease the oxygen requirement of the heart and efforts to increase blood flow.
Congestive heart failure
Congestive heart failureCongestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
frequently presents with SOB with exertion, orthopnea, and paroxysmal nocturnal dyspnea. It affects between 1-2% of the general United States population and occurs in 10% of those over 65 years old. Risk factors for acute decompensation
Acute decompensated heart failure
Acute decompensated heart failure is a common and potentially serious cause of acute respiratory distress.-Causes:Chronic stable heart failure may easily decompensate...
include high dietary salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
intake, medication noncompliance, cardiac ischemia, dysrhythmias
Cardiac dysrhythmia
Cardiac dysrhythmia is any of a large and heterogeneous group of conditions in which there is abnormal electrical activity in the heart. The heart beat may be too fast or too slow, and may be regular or irregular.Some arrhythmias are life-threatening medical emergencies that can result in cardiac...
, renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
, pulmonary emboli, hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
, and infections. Treatment efforts are directed towards decreasing lung congestion.
Chronic obstructive pulmonary disease
People with chronic obstructive pulmonary diseaseChronic 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), most commonly 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...
or 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...
, frequently have chronic shortness of breath and a chronic productive cough. An acute exacerbation
Acute exacerbation of chronic obstructive pulmonary disease
An acute exacerbation of COPD is a sudden worsening of COPD symptoms that typically lasts for several days. It may be triggered by an infection with bacteria or viruses or by environmental pollutants...
presents with increased shortness of breath and sputum
Sputum
Sputum is mucus that is coughed up from the lower airways. It is usually used for microbiological investigations of respiratory infections....
production. COPD is a risk factor for 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...
; thus this condition should be ruled out. In an acute exacerbation treatment is with a combination of anticholinergics, beta2-adrenoceptor agonists, steroids and possibly positive pressure ventilation.
Asthma
AsthmaAsthma
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 the most common reason for presenting to the emergency with shortness of breath. It is the most common lung disease in both developing and developed countries affecting about 5% of the population. Other symptoms include wheezing, tightness in the chest, and a non productive cough. Inhaled beta2-adrenergic agonist (salbutamol) are first line therapy and usually lead to prompt improvement.
Pneumothorax
PneumothoraxPneumothorax
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...
presents typically with pleuritic chest pain of acute onset and shortness of breath not improved with oxygen. Physical findings may include absent breath sounds on one side of the chest, jugular venous distension, and tracheal deviation.
Pneumonia
The symptoms of pneumoniaPneumonia
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...
are fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, productive cough, shortness of breath, and pleuritic chest pain. Inspiratory crackles may be heard on exam. A chest x-ray can be useful to differential pneumonia from congestive heart failure. As the cause is usually a bacterial infections antibiotics are typically used for treatment.
Pulmonary embolism
Pulmonary embolismPulmonary 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...
classically presents with an acute onset of shortness of breath. Other presenting symptoms include pleuritic chest pain, cough, hemoptysis
Hemoptysis
Hemoptysis or haemoptysis is the expectoration of blood or of blood-stained sputum from the bronchi, larynx, trachea, or lungs Hemoptysis or haemoptysis is the expectoration (coughing up) of blood or of blood-stained sputum from the bronchi, larynx, trachea, or lungs Hemoptysis or haemoptysis ...
, and fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
. Risk factors include deep vein thrombosis
Deep vein thrombosis
Deep vein thrombosis is the formation of a blood clot in a deep vein. Deep vein thrombosis commonly affects the leg veins or the deep veins of the pelvis. Occasionally the veins of the arm are affected...
, recent surgery, cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, and previous thromboembolism. It must always be considered in those with acute onset of shortness of breath owing to its high risk of mortality. Diagnosis however may be difficult. Treatment is typically with anticoagulants.
Other
Other important or common causes of shortness of breath include cardiac tamponadeCardiac tamponade
Cardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....
, anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, anaphylaxis
Anaphylaxis
Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...
, interstitial lung disease, panic attack
Panic attack
Panic attacks are periods of intense fear or apprehension that are of sudden onset and of relatively brief duration. Panic attacks usually begin abruptly, reach a peak within 10 minutes, and subside over the next several hours...
s, and pulmonary hypertension
Pulmonary hypertension
In medicine, pulmonary hypertension is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion...
. Cardiac tamponade
Cardiac tamponade
Cardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....
presents with dyspnea, tachycardia, elevated jugular venous pressure, and pulsus paradoxus
Pulsus paradoxus
In medicine, a pulsus paradoxus , also paradoxic pulse or paradoxical pulse, is defined as an exaggeration of the normal variation during the inspiratory phase of respiration, in which the blood pressure declines as one inhales and increases as one exhales...
. The gold standard for diagnosis is ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
. Anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, that develops gradually, usually presents with exertional dyspnea, fatigue, weakness, and tachycardia. It may lead to heart failure. Anaphylaxis
Anaphylaxis
Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...
typically begins over a few minutes in a person with a previous history of the same. Other symptoms include urticaria
Urticaria
Urticaria is a kind of skin rash notable for pale red, raised, itchy bumps. Hives is frequently caused by allergic reactions; however, there are many non-allergic causes...
, throat swelling
Angioedema
Angioedema or Quincke's edema is the rapid swelling of the dermis, subcutaneous tissue, mucosa and submucosal tissues. It is very similar to urticaria, but urticaria, commonly known as hives, occurs in the upper dermis...
, and gastrointestinal upset. The primary treatment is epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
. Interstitial lung disease presents with gradual onset of shortness of breath typically with a history of a predisposing environmental exposure. Shortness of breath is often the only symptom in those with tachydysrhythmias. Panic attack
Panic attack
Panic attacks are periods of intense fear or apprehension that are of sudden onset and of relatively brief duration. Panic attacks usually begin abruptly, reach a peak within 10 minutes, and subside over the next several hours...
s typically present with hyperventilation
Hyperventilation
Hyperventilation or overbreathing is the state of breathing faster or deeper than normal, causing excessive expulsion of circulating carbon dioxide. It can result from a psychological state such as a panic attack, from a physiological condition such as metabolic acidosis, can be brought about by...
, sweating, and numbness
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
. They are however a diagnosis of exclusion
Diagnosis of exclusion
A diagnosis of exclusion is a medical condition reached by a process of elimination, which may be necessary if presence cannot be established with complete confidence from examination or testing...
. Around 2/3 of women experience shortness of breath as a part of a normal pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
. Neurological conditions such as spinal cord injury, phrenic nerve injuries, Guillain-Barre syndrome
Guillain-Barré syndrome
Guillain–Barré syndrome , sometimes called Landry's paralysis, is an acute inflammatory demyelinating polyneuropathy , a disorder affecting the peripheral nervous system. Ascending paralysis, weakness beginning in the feet and hands and migrating towards the trunk, is the most typical symptom...
, amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis , also referred to as Lou Gehrig's disease, is a form of motor neuron disease caused by the degeneration of upper and lower neurons, located in the ventral horn of the spinal cord and the cortical neurons that provide their efferent input...
, multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
and muscular dystrophy
Muscular dystrophy
Muscular dystrophy is a group of muscle diseases that weaken the musculoskeletal system and hamper locomotion. Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue.In the 1860s, descriptions of boys who...
can all cause an individual to experience shortness of breath.
Pathophysiology
A number of different physiological pathway may lead to shortness of breath including via chemoreceptors, mechanoreceptorMechanoreceptor
A mechanoreceptor is a sensory receptor that responds to mechanical pressure or distortion. There are four main types in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles...
s, and lung receptor
Lung receptor
Lung receptors sense irritation or inflammation in the bronchi and alveoli....
s.
It is currently thought that there are three main components that contribute to dyspnea: afferent signals, efferent signals, and central information processing. It is believed that the central processing in the brain compares the afferent and efferent signals, and that a "mismatch" results in the sensation of dyspnea. In other words, dyspnea may result when the need for ventilation (afferent signaling) is not being met by the physical breathing that is occurring (efferent signaling). Afferent signals are sensory neuronal signals that ascend to the brain. Afferent neurons significant in dyspnea arise from a large number of sources including the carotid bodies, medulla
Medulla oblongata
The medulla oblongata is the lower half of the brainstem. In discussions of neurology and similar contexts where no ambiguity will result, it is often referred to as simply the medulla...
, lungs, and chest wall. Chemoreceptors in the carotid bodies and medulla supply information regarding the blood gas levels of O2, CO2 and H+. In the lungs, juxtacapillary (J) receptors
Juxtacapillary (J) receptors
J-receptors are nerves innervating into the body of the lung. They are present in the alveolar interstitium and are innervated by fibers of the vagus nerve. J-receptors respond to events such as pulmonary edema, pulmonary emboli, pneumonia, and barotrauma, which cause a decrease in oxygenation ...
are sensitive to pulmonary interstitial edema, while stretch receptors signal bronchoconstriction. Muscle spindles in the chest wall signal the stretch and tension of the respiratory muscles. Thus, poor ventilation leading to hypercapnia
Hypercapnia
Hypercapnia or hypercapnea , also known as hypercarbia, is a condition where there is too much carbon dioxide in the blood...
, left heart failure leading to interstitial edema (impairing gas exchange), 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...
causing bronchoconstriction (limiting airflow) and muscle fatigue leading to ineffective respiratory muscle action could all contribute to a feeling of dyspnea.
Efferent signals are the motor neuronal signals descending to the respiratory muscles
Muscles of respiration
The various muscles of respiration aid in both inspiration and expiration, which require changes in the pressure within the thoracic cavity. The respiratory muscles work to achieve this by changing the dimensions of the thoracic cavity....
. The most important respiratory muscle is the diaphragm
Thoracic diaphragm
In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...
. Other respiratory muscles include the external and internal intercostal muscles, the abdominal muscles and the accessory breathing muscles.
As the brain receives its plentiful supply of afferent information relating to ventilation, it is able to compare it to the current level of respiration as determined by the efferent signals. If the level of respiration is inappropriate for the body's status then dyspnea might occur. It is worth noting that there is a psychological component of dyspnea as well, as some people may become aware of their breathing in such circumstances but not experience the distress typical of dyspnea.
Evaluation
| Grade | Degree of dyspnea |
|---|---|
| 0 | no dyspnea except with strenuous exercise |
| 1 | dyspnea when walking up an incline or hurrying on the level |
| 2 | walks slower than most on the level, or stops after 15 minutes of walking on the level |
| 3 | stops after a few minutes of walking on the level |
| 4 | with minimal activity such as getting dressed, too dyspneic to leave the house |
The initial approach to evaluation begins by assessment of the airway, breathing, and circulation followed by a medical history
Medical history
The medical history or anamnesis of a patient is information gained by a physician by asking specific questions, either of the patient or of other people who know the person and can give suitable information , with the aim of obtaining information useful in formulating a diagnosis and providing...
and physical examination
Physical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
. Signs that represent significant severity include hypotension
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
, hypoxemia
Hypoxemia
Hypoxemia is generally defined as decreased partial pressure of oxygen in blood, sometimes specifically as less than or causing hemoglobin oxygen saturation of less than 90%.-Distinction from anemia and hypoxia:...
, tracheal deviation, altered mental status, unstable dysrhythmia
Dysrhythmia
Dysrhythmia is an American instrumental progressive metal band formed in Philadelphia, Pennsylvania in 1998. The band's music combines avant-garde elements of progressive rock and jazz with heavy metal...
, stridor
Stridor
Stridor is a high pitched wheezing sound resulting from turbulent air flow in the upper airway. Stridor is a physical sign which is produced by narrow or obstructed airway path. It can be inspiratory, expiratory or biphasic . Inspiratory stridor is common...
, intercostal indrawing, cyanosis
Cyanosis
Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...
, and absent breath sounds.
A number of scales may be used to quantify the degree of shortness of breath. It may be subjectively rated on a scale from 1 to 10 with descriptors associated with the number (The Modified Borg Scale). Alternatively a scale such as the MRC Breathlessness Scale might be used - it suggests five different grades of dyspnea based on the circumstances in which it arises.
Blood tests
A number of labs maybe helpful in determining the cause of shortness of breath. D-dimerD-dimer
D-dimer is a fibrin degradation product , a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. It is so named because it contains two crosslinked D fragments of the fibrinogen protein....
while useful to rule out a pulmonary embolism in those who are at low risk is not of much value if it is positive as it may be positive in a number of conditions that lead to shortness of breath. A low level of brain natriuretic peptide
Brain natriuretic peptide
Brain natriuretic peptide , now known as B-type natriuretic peptide or GC-B, is a 32 amino acid polypeptide secreted by the ventricles of the heart in response to excessive stretching of heart muscle cells...
is useful in ruling out congestive heart failure however a high level while supportive of the diagnosis could also be due to advanced age, renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
, acute coronary syndrome, or a large pulmonary embolism.
Imaging
A chest x-rayChest 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...
is useful to confirm or rule out a pneumothorax, 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...
, or pneumonia. Spiral computed tomography
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
with intravenousradiocontrast
Radiocontrast
Radiocontrast agents are a type of medical contrast medium used to improve the visibility of internal bodily structures in an X-ray based imaging techniques such as computed tomography or radiography...
is the imaging study of choice to evaluate for pulmonary embolism.
Treatment
In those who are not palliative the primary treatment of shortness of breath is directed at its underlying cause. Extra oxygenOxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
is effective in those with hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
however has no effect in those with normal blood oxygen saturation
Oxygen saturation
Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...
s even in those with who are palliative.
Physiotherapy
Individuals can benefit from a variety of physical therapyPhysical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...
interventions. Persons with neurological/neuromuscular abnormalities may have breathing difficulties due to weak or paralyzed intercostal, abdominal and/or other muscles needed for ventilation
Ventilation
Ventilation is movement of air in and out of an enclosed space, including a body. It is used in the following contexts:* Ventilation * Ventilation * Ventilation * Ventilation * Ventilation...
. Some physical therapy interventions for this population include active assisted cough
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
techniques, volume augmentation such as breath stacking, education about body position and ventilation patterns and movement strategies to facilitate breathing.
Palliative
Along with the measure above, systemic immediate release opioids are beneficial in reducing the symptom of shortness of breath due to both cancer and non cancer causes. There is a lack of evidence to recommend midazolamMidazolam
Midazolam is a short-acting drug in the benzodiazepine class developed by Hoffmann-La Roche in the 1970s. The drug is used for treatment of acute seizures, moderate to severe insomnia, and for inducing sedation and amnesia before medical procedures. It possesses profoundly potent anxiolytic,...
, nebulised opioids, the use of gas mixtures, or cognitive-behavioral therapy.
Epidemiology
Shortness of breath is the primary reason 3.5% of people present to the emergency departmentEmergency department
An emergency department , also known as accident & emergency , emergency room , emergency ward , or casualty department is a medical treatment facility specialising in acute care of patients who present without prior appointment, either by their own means or by ambulance...
in the United States. Of these approximately 51% are admitted to hospital and 13% are dead within a year. Some studies have suggested that up to 27% of people suffer from dyspnea, while in dying patients 75% will experience it. Acute shortness of breath is the most common reason people who are palliative visit an emergency department.
Etymology
Dyspnea (icon ; from Latin dyspnoea, from GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
dyspnoia from dyspnoos) literally means disordered breathing.