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Shortness of breath (SOB), also known as dyspnea (
BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codification of grammar and usage and is employed by a population ...
: dyspnoea), is a feeling of not being able to
breathe
breathe
well enough. The
American Thoracic Society The American Thoracic Society (ATS) is a nonprofit organization focused on improving care for pulmonary diseases, critical illnesses and sleep-related breathing disorders. It was established in 1905 as the American Sanatorium Association, and change ...
defines it as "a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity", and recommends evaluating dyspnea by assessing the intensity of the distinct sensations, the degree of distress involved, and its burden or impact on
activities of daily living Activities of daily living (ADLs or ADL) is a term used in healthcare to refer to people's daily self-care Self care is the individual practise of health management without the aid of a medical professional. In health care, self-care is an ...
. Distinct sensations include effort/work, chest tightness, and air hunger (the feeling of not enough oxygen). The
tripod position The tripod position is a physical stance often assumed by people experiencing respiratory distress (such as chronic obstructive pulmonary disease) or who are simply out of breath (such as a person who has just run a sprint). In tripod position, one ...
is often assumed. Dyspnea is a normal
symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality show ...
of heavy
exertion Exertion is the physical Physical may refer to: *Physical examination, a regular overall check-up with a doctor *Physical (album), ''Physical'' (album), a 1981 album by Olivia Newton-John **Physical (Olivia Newton-John song), "Physical" (Olivia New ...
but becomes
pathological Pathology is the study of the causesCauses, or causality, is the relationship between one event and another. It may also refer to: * Causes (band), an indie band based in the Netherlands * Causes (company), an online company See also * Cau ...
if it occurs in unexpected situations or light exertion. In 85% of cases it is due to
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
,
pneumonia Pneumonia is an inflammatory Inflammatory may refer to: * Inflammation, a biological response to harmful stimuli * The word ''inflammatory'' is also used to refer literally to fire and flammability, and figuratively in relation to comments t ...

pneumonia
,
cardiac ischemia Ischemia or ischaemia is a restriction in blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requ ...
,
interstitial lung disease Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue and space around the alveoli (air sacs)) of the lung The lungs are the primary organs ...
,
congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mos ...
,
chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease The lungs are the primary Organ (anatomy), organs of the respiratory system in humans and many other animals including a few fish and some snails. In mammal ...
, or
psychogenic A psychogenic effect is one that originates from the brain A brain is an organ (anatomy), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sens ...
causes, such as
panic disorder Panic disorder is a mental Mental may refer to: * of or relating to the mind Films * Mental (2012 film), ''Mental'' (2012 film), an Australian comedy-drama * Mental (2016 film), ''Mental'' (2016 film), a Bangladeshi romantic-action movie * ''Me ...
and
anxiety Anxiety is an emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or suffering, disp ...

anxiety
. The best treatment to relieve shortness of breath typically depends on the underlying cause.


Definition

Dyspnea, in medical terms, is “shortness of breath”. The
American Thoracic Society The American Thoracic Society (ATS) is a nonprofit organization focused on improving care for pulmonary diseases, critical illnesses and sleep-related breathing disorders. It was established in 1905 as the American Sanatorium Association, and change ...
defines dyspnea as: "A subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity." Other definitions describe it as "difficulty in breathing", "disordered or inadequate breathing", "uncomfortable awareness of breathing", and as the experience of "breathlessness" (which may be either acute or chronic).


Differential diagnosis

While shortness of breath is generally caused by disorders of the
cardiac The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as ...
or
respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network Network and networking may refer to: Arts, entertainment, and media * ''Network'' (1976 film), a 1976 Ame ...

respiratory system
, other systems such as
neurological Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is a branch of medicine Medicine is the Art (skill), art, science, and Praxis (process) , practice of caring for a patient and managing the d ...
,
musculoskeletal The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system An organ system is a biological system A biological system is a complex biological network, network which conne ...
,
endocrine The endocrine system is a messenger system comprising feedback loops of the hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Re ...

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 A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sys ...
and
congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mos ...
while common pulmonary causes include
chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease The lungs are the primary Organ (anatomy), organs of the respiratory system in humans and many other animals including a few fish and some snails. In mammal ...
,
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
,
pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way ...

pneumothorax
, pulmonary edema and
pneumonia Pneumonia is an inflammatory Inflammatory may refer to: * Inflammation, a biological response to harmful stimuli * The word ''inflammatory'' is also used to refer literally to fire and flammability, and figuratively in relation to comments t ...

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. The tempo of onset and the duration of dyspnea are useful in knowing the etiology of dyspnea. Acute shortness of breath is usually connected with sudden physiological changes, such as
laryngeal edema Edema, also spelt oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area may fe ...
,
bronchospasm Bronchospasm or a bronchial spasm is a sudden bronchoconstriction, constriction of the muscles in the walls of the bronchioles. It is caused by the release (degranulation) of substances from mast cells or basophils under the influence of anaphylato ...
,
myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

myocardial infarction
,
pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain p ...

pulmonary embolism
, or
pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way ...

pneumothorax
. Patients with COPD and idiopathic pulmonary fibrosis (IPF) have a gradual progression of dyspnea on exertion, punctuated by acute exacerbations of shortness of breath. In contrast, most asthmatics do not have daily symptoms, but have intermittent episodes of dyspnea, cough, and chest tightness that are usually associated with specific triggers, such as an upper respiratory tract infection or exposure to allergens.


Acute coronary syndrome

Acute coronary syndrome Acute coronary syndrome (ACS) is a syndrome (a set of signs and symptoms) due to decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function properly or dies. The most common symptom is centrally l ...
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 Smoking is a practice in which a substance is burned and the resulting smoke Smoke is a collection of airborne and es emitted when a material undergoes or , together with the quantity of air that is or otherwise mixed into the ma ...

smoking
,
hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not ...

hypertension
,
hyperlipidemia Hyperlipidemia is abnormally elevated levels of any or all lipids (fats, cholesterol, or triglycerides) or lipoproteins in the blood. citing: and The term ''hyperlipidemia'' refers to the laboratory finding itself and is also used as an umbre ...
, and
diabetes Diabetes mellitus, commonly known as just diabetes, is a group of metabolic disorder A metabolic disorder is a disorder that negatively alters the body's processing and distribution of macronutrients such as proteins, fats, and carbohydrate ...

diabetes
. An
electrocardiogram Electrocardiography is the process of producing an electrocardiogram (ECG or EKG). It is a graph of voltage Voltage, electric potential difference, electromotive force emf, electric pressure or electric tension is the difference in elec ...

electrocardiogram
and
cardiac enzymes Cardiac markers are Biomarker (medicine), biomarkers measured to evaluate heart function. They can be useful in the early prediction or diagnosis of disease. Although they are often discussed in the context of myocardial infarction, other conditions ...
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.


COVID-19

People that have been infected by
COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease A contagious disease is a disease A disease is a particular abnormal condition that negatively affects the structure A structure is an arrangement and organization o ...
may have symptoms such as a fever, dry cough, loss of smell and taste, or shortness of breath.


Congestive heart failure

Congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mos ...
frequently presents with shortness of breath with exertion,
orthopnea Orthopnea or orthopnoea is shortness of breath Shortness of breath (SOB), also known as dyspnea (BrE: dyspnoea) is a feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breath ...
, and
paroxysmal nocturnal dyspnea Paroxysmal nocturnal dyspnea or paroxysmal nocturnal dyspnoea (PND) is an attack of severe shortness of breath Shortness of breath (SOB), also known as dyspnea (BrE: dyspnoea) is a feeling of not being able to breathe well enough. The American Th ...
. 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 Salt is a mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure fo ...

salt
intake, medication noncompliance, cardiac ischemia, abnormal heart rhythms,
kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys are functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may res ...
, pulmonary emboli,
hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not ...

hypertension
, and infections. Treatment efforts are directed towards decreasing lung congestion.


Chronic obstructive pulmonary disease

People with
chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease The lungs are the primary Organ (anatomy), organs of the respiratory system in humans and many other animals including a few fish and some snails. In mammal ...
(COPD), most commonly
emphysema Emphysema, or pulmonary emphysema, is a lower respiratory tract disease, characterised by air-filled spaces ( pneumatoses) in the lung The lungs are the primary organs An organ is a group of tissues with similar functions. Plant lif ...
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 Sputum is mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body and covers the surface of internal organs. It consists o ...
production.
COPD Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease The lungs are the primary Organ (anatomy), organs of the respiratory system in humans and many other animals including a few fish and some snails. In mammal ...

COPD
is a risk factor for
pneumonia Pneumonia is an inflammatory Inflammatory may refer to: * Inflammation, a biological response to harmful stimuli * The word ''inflammatory'' is also used to refer literally to fire and flammability, and figuratively in relation to comments t ...

pneumonia
; thus this condition should be ruled out. In an acute exacerbation treatment is with a combination of
anticholinergics Anticholinergics (anticholinergic agent) are a group of substances that blocks the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central nervous system, central and peripheral nervous system. These agents inhibit t ...
, beta2-adrenoceptor agonists,
steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes which alter membrane fluidity; and ...
and possibly
positive pressure ventilation Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV), is the medical term for artificial ventil ...
.


Asthma

Asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

Asthma
is the most common reason for presenting to the emergency room 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 A wheeze is a continuous, coarse, whistling sound produced in the respiratory airways during breathing. For wheezes to occur, some part of the respiratory tree must be narrowed or obstructed (for example narrowing of the lower respiratory tract ...
, tightness in the chest, and a non productive cough. Inhaled corticosteroids are the preferred treatment for children, however these drugs can reduce the growth rate. Acute symptoms are treated with short-acting bronchodilators.


Pneumothorax

Pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way ...

Pneumothorax
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 The jugular venous pressure (JVP, sometimes referred to as ''jugular venous pulse'') is the indirectly observed pressure over the vein, venous system via visualization of the internal jugular vein. It can be useful in the differentiation of differe ...
, and tracheal deviation.


Pneumonia

The symptoms of
pneumonia Pneumonia is an inflammatory Inflammatory may refer to: * Inflammation, a biological response to harmful stimuli * The word ''inflammatory'' is also used to refer literally to fire and flammability, and figuratively in relation to comments t ...

pneumonia
are
fever Fever, also referred to as pyrexia, is defined as having a temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on th ...

fever
,
productive cough A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an o ...
, shortness of breath, and pleuritic chest pain. Inspiratory
crackles Crackles are the clicking, rattling, or crackling noise Crackling noise arises when a system is subject to an external force and it responds via events that appear very scale invariant, similar at many different scales. In a classical system t ...
may be heard on exam. A chest x-ray can be useful to differentiate pneumonia from
congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mos ...
. As the cause is usually a bacterial infection,
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, ...
are typically used for treatment.


Pulmonary embolism

Pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain p ...

Pulmonary embolism
classically presents with an acute onset of shortness of breath. Other presenting symptoms include pleuritic chest pain, cough,
hemoptysis Hemoptysis is the coughing up of blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow ( ...

hemoptysis
, and
fever Fever, also referred to as pyrexia, is defined as having a temperature Temperature ( ) is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy Thermal radiation in visible light can be seen on th ...

fever
. Risk factors include
deep vein thrombosis Deep vein thrombosis (DVT) is a type of venous thrombosis Venous thrombosis is blockage of a vein caused by a thrombus (blood clot). A common form of venous thrombosis is deep vein thrombosis (DVT), when a blood clot forms in the deep veins. ...
, recent surgery,
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biolo ...

cancer
, and previous
thromboembolism Thrombosis (from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: ...
. 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 and is often used to assess the clinical probability. Treatment, depending on severity of symptoms, typically starts with
anticoagulants Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in hematophagy, blood-eating animals such as leeches and mosquitoes, ...
; the presence of ominous signs (low blood pressure) may warrant the use of thrombolytic drugs.


Anemia

Anemia Anemia (American and British English spelling differences#ae and oe, also spelled anaemia) is a decrease in the total amount of red blood cells (RBCs) or hemoglobin in the blood, or a lowered ability of the blood to carry oxygen. When anemia c ...

Anemia
that develops gradually usually presents with exertional dyspnea, fatigue, weakness, and
tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate Heart rate is the speed of the heartbeat Heartbeat or heartbeats may refer to: Physiology *Cardiac cycle, of the heart *Contraction of the cardiac muscle, muscles of the heart, or a per ...
. It may lead to
heart failure Heart failure (HF), also known as congestive heart failure (CHF) and (congestive) cardiac failure (CCF), is a set of manifestations caused by the failure of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in mo ...
. Anaemia is often a cause of dyspnea. Menstruation, particularly if excessive, can contribute to anaemia and to consequential dyspnea in women. Headaches are also a symptom of dyspnea in patients suffering from anaemia. Some patients report a numb sensation in their head, and others have reported blurred vision caused by hypotension behind the eye due to a lack of oxygen and pressure; these patients have also reported severe head pains, many of which lead to permanent brain damage. Symptoms can include loss of concentration, focus, fatigue, language faculty impairment and memory loss.


Cancer

Shortness of breath is common in people with cancer and may be caused by numerous different factors. In people with advanced cancer, acute shortness of periods of time with severe shortness of breath may occur, along with a more continuous feeling of breathlessness.


Other

Other important or common causes of shortness of breath include
cardiac tamponade Cardiac tamponade, also known as pericardial tamponade, is when fluid in the pericardium (the sac around the heart) builds up, resulting in compression of the heart. Onset may be rapid or gradual. Symptoms typically include those of cardiogenic sh ...
,
anaphylaxis Anaphylaxis is a serious allergic reaction Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable rea ...
,
interstitial lung disease Interstitial lung disease (ILD), or diffuse parenchymal lung disease (DPLD), is a group of respiratory diseases affecting the interstitium (the tissue and space around the alveoli (air sacs)) of the lung The lungs are the primary organs ...
,
panic attack Panic attacks are sudden periods of intense fear Fear is an intensely unpleasant emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feel ...

panic attack
s, and
pulmonary hypertension Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physics Physics is the natural science that studies matt ...
. Also, around 2/3 of women experience shortness of breath as a part of a normal
pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring In biology, offspring are the young creation of living organisms, produced either by a Asexual reproduction, single organism or, in the case of sexual repr ...

pregnancy
. Cardiac tamponade presents with dyspnea, tachycardia, elevated jugular venous pressure, and
pulsus paradoxus Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pre ...
. The gold standard for diagnosis is
ultrasound Ultrasound is sound wave In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, ...

ultrasound
. Anaphylaxis typically begins over a few minutes in a person with a previous history of the same. Other symptoms include
urticaria Hives, also known as urticaria, is a kind of skin rash A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin t ...

urticaria
, , and gastrointestinal upset. The primary treatment is
epinephrine Adrenaline, also known as epinephrine, is a hormone A hormone (from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a co ...
. 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 attacks typically present with
hyperventilation Hyperventilation occurs when the rate or tidal volume Tidal volume (symbol VT or TV) is the volume of air moved into or out of the lungs during a normal breath. In a healthy, young human adult, tidal volume is approximately 500 ml per i ...
, sweating, and
numbness Hypoesthesia or numbness is a common side effect of various medical conditions which manifests as a reduced sense of touch The somatosensory system is a part of the sensory nervous system. The somatosensory system is a complex system of sensory ...
. They are however a
diagnosis of exclusionA diagnosis of exclusion or by exclusion (''per exclusionem'') is a diagnosis Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic ...
. Neurological conditions such as spinal cord injury, phrenic nerve injuries,
Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness Muscle weakness is a lack of muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and ...
,
amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS; also known as Lou Gehrig's disease in Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the A ...
,
multiple sclerosis Multiple sclerosis (MS), also known as encephalomyelitis disseminata, is the most common demyelinating disease A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This damage impa ...
and
muscular dystrophy Muscular dystrophies (MD) are a genetically and clinically heterogeneous group of rare neuromuscular disease A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron A motor neuron (or motoneuron) is a n ...
can all cause an individual to experience shortness of breath. Shortness of breath can also occur as a result of
vocal cord dysfunction Vocal cord dysfunction (VCD), is a pathology affecting the vocal folds In humans, vocal cords, also known as vocal chords, vocal folds or voice reeds, are folds of tissue in the throat that are key in creating sounds through vocalization. The ...
(VCD).


Pathophysiology

Different physiological pathways may lead to shortness of breath including via
ASIC An application-specific integrated circuit (ASIC ) is an integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit 200px, A circuit b ...
chemoreceptor A chemoreceptor, also known as chemosensor, is a specialized sensory receptor Sensory neurons, also known as afferent neurons, are neuron A neuron or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology) ...
s,
mechanoreceptor A mechanoreceptor, also called mechanoceptor, is a sensory receptor Sensory neurons, also known as afferent neurons, are neuron A neuron or nerve cell is an electrically excitable cell Cell most often refers to: * Cell (biology), the fu ...
s, and lung receptors. It is thought that three main components contribute to dyspnea: afferent signals, efferent signals, and central information processing. It is believed the central processing in the brain compares the afferent and efferent signals; and dyspnea results when a "mismatch" occurs between the two: such as when the need for ventilation (afferent signaling) is not being met by physical breathing (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 The carotid body is a small cluster of chemoreceptor cells, and supporting sustentacular cells. The carotid body is located in the adventitia, in the bifurcation (fork) of the common carotid artery, which runs along both sides of the neck. The ...
,
medulla Medulla or Medullary may refer to: Science * Medulla oblongata The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is ...

medulla
,
lungs The lungs are the primary organs of the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animal ...

lungs
, and
chest wall The thoracic wall or chest wall is the boundary of the thoracic cavity 250px, The picture displays the Mediastinum on sagittal plane, Thoracic diaphragm">sagittal_plane.html" ;"title="Mediastinum on sagittal plane">Mediastinum on sagittal pla ...
. 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 Muscle spindles are stretch receptors within the body of a muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed ...
in the chest wall signal the stretch and tension of the respiratory muscles. Thus, poor ventilation leading to
hypercapnia Hypercapnia (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10. ...
, left heart failure leading to interstitial edema (impairing gas exchange),
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

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 muscles of respiration are those muscle Muscle is a soft tissue found in most animals. Muscle cells contain protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residu ...
. The most important respiratory muscle is the
diaphragm Diaphragm may refer to: * Diaphragm (anatomy) or thoracic diaphragm, a thin sheet of muscle between the thorax and the abdomen * Diaphragm (optics), a stop in the light path of a lens, having an aperture that regulates the amount of light that pass ...
. Other respiratory muscles include the external and internal
intercostal muscles Intercostal muscles are many different groups of muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in ...
, 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. There is also a psychological component to dyspnea, as some people may become aware of their breathing in such circumstances but not experience the typical distress of dyspnea.


Diagnosis

The initial approach to evaluation begins by assessment of the airway, breathing, and circulation followed by a
medical history The medical history, case history, or anamnesis (from Greek: ἀνά, ''aná'', "open", and μνήσις, ''mnesis'', "memory") of a patient A patient is any recipient of health care services that are performed by Health professional, healthc ...
and
physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient A patient is any recipient of health care services that are performed by Health professional, healthcare professionals. The pati ...

physical examination
. Signs that represent significant severity include
hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the Systole, systolic blood pressure (the top number) and ...
,
hypoxemia Hypoxemia is an abnormally low level of oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, a highly Chemic ...
, tracheal deviation, altered mental status, unstable dysrhythmia,
stridor Stridor (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Re ...
, intercostal indrawing,
cyanosis Cyanosis is the change of body Tissue (biology), tissue color to a bluish-purple hue as a result of having decreased amounts of oxygen bound to the hemoglobin in the Red blood cell, red blood cells of the capillary bed. Body tissues that reflect ...
,
tripod position The tripod position is a physical stance often assumed by people experiencing respiratory distress (such as chronic obstructive pulmonary disease) or who are simply out of breath (such as a person who has just run a sprint). In tripod position, one ...
ing, pronounced use of accessory muscles (
sternocleidomastoid The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion Motion Image:Leaving Yongsan Station.jpg, 300px, Motion invo ...
,
scalenes The scalene muscles are a group of three pairs of muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist i ...
) 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 In sports and particularly exercise testing, the rating of perceived exertion (RPE), as measured by the ''Borg rating of perceived exertion scale'' (RPE scale), is a frequently used quantitative measure of perceived exertion during physical activity ...
). The
MRC MRC may refer to: Government * Medical Research Council (United Kingdom) The Medical Research Council (MRC) is responsible for co-coordinating and funding medical research in the United Kingdom. It is part of United Kingdom Research and Inno ...
breathlessness scale suggests five grades of dyspnea based on the circumstances in which it arises.


Blood tests

A number of labs may be helpful in determining the cause of shortness of breath.
D-dimer D-dimer (or D dimer) is a fibrin degradation product Principles of D-dimer testing Fibrin degradation products (FDPs), also known as fibrin split products, are components of the blood produced by clot degeneration. Clotting, also called coagulation ...

D-dimer
, 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 Ventricular natriuretic peptide or brain natriuretic peptide (BNP), also known as B-type natriuretic peptide, is a hormone secreted by cardiomyocytes in the Ventricle (heart), heart ventricles in response to stretching caused by increased ventricu ...
is useful in ruling out congestive heart failure; however, a high level, while supportive of the diagnosis, could also be due to advanced age,
kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys are functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may res ...
, acute coronary syndrome, or a large pulmonary embolism.


Imaging

A
chest x-ray A chest radiograph, called a chest X-ray (CXR), or chest film, is a Projectional radiography, projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most ...

chest x-ray
is useful to confirm or rule out a pneumothorax,
pulmonary edema Pulmonary edema (PE), also known as pulmonary congestion, is liquid accumulation in the tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a ...

pulmonary edema
, or pneumonia. Spiral
computed tomography A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of ...

computed tomography
with intravenous
radiocontrast Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation In physics Physics is ...
is the imaging study of choice to evaluate for pulmonary embolism.


Treatment

The primary treatment of shortness of breath is directed at its underlying cause. Extra
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
is effective in those with hypoxia; however, this has no effect in those with normal blood oxygen saturations.


Physiotherapy

Individuals can benefit from a variety of
physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions Allied health professions are health care Health care, health-care, or healthcare is the maintenance or improvement of health via the preventive h ...

physical therapy
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 may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a mac ...
. Some physical therapy interventions for this population include active assisted
cough A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, ...
techniques, volume augmentation such as breath stacking, education about body position and ventilation patterns and movement strategies to facilitate breathing.
Pulmonary rehabilitation Pulmonary rehabilitation, also known as respiratory rehabilitation, is an important part of the management and health maintenance of people with chronic respiratory disease who remain symptomatic or continue to have decreased function despite standa ...
may alleviate symptoms in some people, such as those with COPD, but will not cure the underlying disease. Fan therapy to the face has been shown to relieve shortness of breath in patients with a variety of advanced illnesses including cancer. The mechanism of action is thought to be stimulation of the trigeminal nerve.


Palliative medicine

Systemic immediate release
opioids Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...

opioids
are beneficial in emergently reducing the symptom of shortness of breath due to both cancer and non cancer causes; long-acting/sustained-release opioids are also used to prevent/continue treatment of dyspnea in palliative setting. There is a lack of evidence to recommend
midazolam Midazolam, sold under the brand name Versed, among others, is a benzodiazepine Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of psychoactive drug A psychoactive drug, psychopharmaceutical, or psychotropic drug is ...

midazolam
, nebulised opioids, the use of gas mixtures, or
cognitive-behavioral therapy Cognitive behavioral therapy (CBT) is a psycho-social intervention that aims to improve mental health Mental health, defined by the World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the U ...
.


Non-pharmacological techniques

Non-pharmacological interventions provide key tools for the management of breathlessness. Potentially beneficial approaches include active management of
psychosocial The psychosocial approach looks at individuals in the context of the combined influence that psychological Psychology is the scientific Science () is a systematic enterprise that Scientific method, builds and organizes knowledge i ...
issues (
anxiety Anxiety is an emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or suffering, disp ...

anxiety
,
depression Depression may refer to: Mental health * Depression (mood), a state of low mood and aversion to activity * Mood disorders characterized by depression are commonly referred to as simply ''depression'', including: ** Dysthymia ** Major depressive ...
, etc.), and implementation of self-management strategies, such as physical and mental
relaxation technique A relaxation technique (also known as relaxation training) is any method, process, procedure, or activity that helps a person to relax; to attain a state of increased calmness Calmness is the mental state of peace of mind being free from agitat ...
s, pacing techniques, energy conservation techniques, learning exercises to control breathing, and
education Education is the process of facilitating learning, or the acquisition of knowledge, skills, value (ethics), values, morals, beliefs, habits, and personal development. Educational methods include teaching, training, storytelling, discussion ...

education
. The use of a fan may also be beneficial.
Cognitive behavioural therapy Cognitive behavioral therapy (CBT) is a Psychosocial, psycho-social intervention that aims to improve mental health. CBT focuses on challenging and changing cognitive distortions (e.g. thoughts, beliefs, and attitudes) and behaviors, improving e ...
may also be helpful.


Pharmacological treatment

For people with severe, chronic, or uncontrollable breathlessness, non-pharmacological approaches to treating breathlessness may be combined with medication. For people who have cancer that is causing the breathlessness, medications that have been suggested include opioids, benzodiazepines, oxygen, and steroids. Results of recent systematic reviews and meta-analyses found opioids were not necessarily associated with more effectiveness in treatment for patients with advanced cancer. Ensuring that the balance between side effects and adverse effects from medications and potential improvements from medications needs to be carefully considered before prescribing medication. The use of systematic corticosteriods in palliative care for people with cancer is common, however the effectiveness and potential adverse effects of this approach in adults with cancer has not been well studied.


Epidemiology

Shortness of breath is the primary reason 3.5% of people present to the
emergency department An emergency department (ED), also known as an accident & emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine #REDIRECT Emergency medici ...
in the United States. Of these individuals, approximately 51% are admitted to the hospital and 13% are dead within a year. Some studies have suggested that up to 27% of people suffer from dyspnea,Murray and Nadel's Textbook of Respiratory Medicine, 4th Ed. Robert J. Mason, John F. Murray, Jay A. Nadel, 2005, Elsevier while in dying patients 75% will experience it.Harrison's Principles of Internal Medicine (Kasper DL, Fauci AS, Longo DL, et al. (eds)) (16th ed.). New York: McGraw-Hill. Acute shortness of breath is the most common reason people requiring
palliative Palliative care (derived from the Latin root ''palliare, or'' "to cloak") is an interdisciplinary medical caregiving approach aimed at optimizing quality of life Quality of life (QOL), according to Britannica, is the degree to which an indivi ...
care visit an emergency department. Up to 70% of adults with advanced cancer experience dyspnoea.


Etymology and pronunciation

English ''dyspnea'' comes from
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became ...
''dyspnoea'', from
Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as of ...
''dyspnoia'', from ''dyspnoos'', which literally means "disordered breathing". Its
combining form Combining may refer to: * Combine harvester use in agriculture * Combining capacity, in chemistry * Combining character, in digital typography * Combining form, in linguistics * Combining grapheme joiner, Unicode character that has no visible glyph ...
s (''
dys- {{Short pages monitor