Dyspnea

Definition and Epidemiology

Definition

Dyspnea is the subjective sensation of breathing discomfort that derives from interactions among multiple physiologic, psychologic, social, and environmental factors. 

• Also referred to as chest tightness or shortness of breath
• Experienced and described differently among patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship depending on the cause
• Types:
  • Acute dyspnea: occurring within minutes of the triggering event
  • Chronic dyspnea: lasting longer than 1 month

Epidemiology

• Very common symptom, present in: 
  • 50% of inpatients
  • 25% of ambulatory patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
  • 9%–13% of the entire population
  • 37% of people aged ≥ 70 years
• In chronic obstructive pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis ( COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)) and other pathologic lung and heart conditions, dyspnea may be a better predictor of outcome than traditional assessments.

Etiology

There are 5 basic categories of causes that can lead to dyspnea. The causes can present individually or as a combination:

1. Respiratory conditions
2. Cardiac conditions
3. Neuromuscular conditions
4. Psychogenic conditions
5. Systemic illnesses

General causes of dyspnea

Acute dyspnea

Common causes per affected organ system:

• Conditions affecting the cardiovascular system:
  • Acute myocardial ischemia Myocardial ischemia A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (coronary artery disease), to obstruction by a thrombus (coronary thrombosis), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Coronary Heart Disease
  • Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
  • Cardiac tamponade Tamponade Pericardial effusion, usually of rapid onset, exceeding ventricular filling pressures and causing collapse of the heart with a markedly reduced cardiac output. Pericarditis
• Conditions affecting the respiratory system:
  • Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma 
  • Pulmonary infection/bronchitis
  • Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism
  • Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax
  • Upper airway obstruction Upper Airway Obstruction Airway Obstruction

Chronic or recurrent dyspnea

The 5 most common causes:

• Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma
• COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD)
• Interstitial lung disease ( ILD ILD Interstitial lung diseases are a heterogeneous group of disorders characterized by the inflammation and fibrosis of lung parenchyma, especially the pulmonary connective tissue in the alveolar walls. It may be idiopathic (e.g., idiopathic pulmonary fibrosis) or secondary to connective tissue diseases, medications, malignancies, occupational exposure, or allergens. Interstitial Lung Diseases)
• Myocardial dysfunction 
• Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity/physical deconditioning Deconditioning Psychotherapy 

Pulmonary causes of chronic dyspnea can originate from disturbances in any of the following:

• Central respiratory controller: the efferent signals from the brain to the ventilatory muscles, which produce “air hunger” when stimulated
• Ventilatory pump Pump ACES and RUSH: Resuscitation Ultrasound Protocols: the muscles, peripheral nerves Peripheral Nerves The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium. Nervous System: Histology, airways, and chest wall Chest wall The chest wall consists of skin, fat, muscles, bones, and cartilage. The bony structure of the chest wall is composed of the ribs, sternum, and thoracic vertebrae. The chest wall serves as armor for the vital intrathoracic organs and provides the stability necessary for the movement of the shoulders and arms. Chest Wall: Anatomy used to move air into and out of the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
• Gas exchange Gas exchange Human cells are primarily reliant on aerobic metabolism. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood. Gas Exchange: the alveolar membranes:
  • Affected in conditions with hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome +/- hypercapnia Hypercapnia A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood. Neonatal Respiratory Distress Syndrome
  • Leads to stimulation of the central controller

Extrapulmonary causes of chronic dyspnea:

• Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
• Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
• Physical deconditioning Deconditioning Psychotherapy

Pathophysiology

• Dyspnea is a poorly understood phenomenon. 
• Appears to be a mismatch of afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology and efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology signaling between the respiratory and central nervous system Central nervous system The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges. Nervous System: Anatomy, Structure, and Classification (CNS) (“neuromechanical uncoupling”): 
  • Afferent Afferent Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology signals from:
    • Chemoreceptors activated by hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome, hypercapnia Hypercapnia A clinical manifestation of abnormal increase in the amount of carbon dioxide in arterial blood. Neonatal Respiratory Distress Syndrome, and acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis
    • Mechano-, biochemical, and irritant receptors Irritant receptors Respiratory Regulation
  • Efferent Efferent Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology signals from the CNS ( motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology cortex, brainstem) to the following: 
    • Respiratory muscles
    • Sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology cortex (by corollary discharge), which cause sensation of work of breathing Work of breathing Respiratory muscle contraction during inhalation. The work is accomplished in three phases: lung compliance work, that required to expand the lungs against its elastic forces; tissue resistance work, that required to overcome the viscosity of the lung and chest wall structures; and airway resistance work, that required to overcome airway resistance during the movement of air into the lungs. Work of breathing does not refer to expiration, which is entirely a passive process caused by elastic recoil of the lung and chest cage. Pulmonary Examination and air hunger 
  • Autonomic input by fear and anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder contribute to the dyspneic state.
• Changes in lung physiology can also contribute to the sensation of dyspnea:
  • Increased airway Airway ABCDE Assessment resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing
  • Increased dead space Dead space That part of the respiratory tract or the air within the respiratory tract that does not exchange oxygen and carbon dioxide with pulmonary capillary blood. Ventilation: Mechanics of Breathing
  • Ventilation-perfusion mismatch
  • Decrease in lung/ chest wall compliance Chest wall compliance Respiratory Acidosis
  • Impaired oxygen delivery/utilization:
    • Reduced oxygen-carrying capacity of the blood
    • Physical deconditioning Deconditioning Psychotherapy

Diagnosis

Important elements in the clinical history

• Features of the dyspnea:
  • Duration
  • Onset
  • Severity
  • Progression
• Triggers Triggers Hereditary Angioedema (C1 Esterase Inhibitor Deficiency):
  • Exertion
  • Body position
  • Cold air
  • Allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction to animal dander or other allergens
  • Stress/ anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder
• Associated symptoms:
  • Cough
  • Sputum production
  • Orthopnea Orthopnea Pulmonary Edema
  • Paroxysmal nocturnal dyspnea Paroxysmal nocturnal dyspnea A disorder characterized by sudden attacks of respiratory distress in at rest patients with heart failure and pulmonary edema. It usually occurs at night after several hours of sleep in a reclining position. Patients awaken with a feeling of suffocation, coughing, a cold sweat, and tachycardia. When there is significant wheezing, it is called cardiac asthma. Pulmonary Edema
  • Chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
  • Peripheral edema Peripheral edema Peripheral edema is the swelling of the lower extremities, namely, legs, feet, and ankles. Edema
  • Palpitations Palpitations Ebstein’s Anomaly
• Effects of medications (e.g., albuterol Albuterol A short-acting beta-2 adrenergic agonist that is primarily used as a bronchodilator agent to treat asthma. Sympathomimetic Drugs, beta blockers)
• Tobacco history
• Thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus risk factors

Labs

• Complete blood count and basic metabolic profile, especially if patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, sputum production, or anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
• Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification natriuretic peptide ( BNP BNP A peptide that is secreted by the brain and the heart atria, stored mainly in cardiac ventricular myocardium. It can cause natriuresis; diuresis; vasodilation; and inhibits secretion of renin and aldosterone. It improves heart function. It contains 32 amino acids. Renal Sodium and Water Regulation) levels to assist in the diagnosis of heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) 
• D-dimer D-dimer Deep Vein Thrombosis, in conjunction with Well’s criteria, to evaluate for pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism
• Troponin to assist in the diagnosis of MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction
• Arterial blood gas Arterial blood gas Respiratory Alkalosis

Imaging and other tests

• Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests to evaluate the presence of cardiopulmonary disease (e.g., congestive heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR), COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD), cor pulmonale Cor Pulmonale Cor pulmonale is right ventricular (RV) dysfunction caused by lung disease that results in pulmonary artery hypertension. The most common cause of cor pulmonale is chronic obstructive pulmonary disease. Dyspnea is the usual presenting symptom. Cor Pulmonale, pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension)
• Lateral neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess radiography and direct visualization by endoscopy Endoscopy Procedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body. Gastroesophageal Reflux Disease (GERD), if upper airway obstruction Upper Airway Obstruction Airway Obstruction is suspected 
• Electrocardiogram Electrocardiogram An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) ( ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG)) may detect ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage/infarction, arrhythmia, or ventricular hypertrophy Ventricular Hypertrophy Tetralogy of Fallot.
• Computed tomography (CT) pulmonary angiogram or ventilation-perfusion (VQ) lung scan if pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism is suspected 
• Spirometry Spirometry Measurement of volume of air inhaled or exhaled by the lung. Pulmonary Function Tests can differentiate the following:
  • Obstructive versus restrictive lung disease
  • Upper versus lower airway obstruction Lower Airway Obstruction Airway Obstruction
  • Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma versus COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD), if used with a bronchodilator 
• Echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA) and cardiac stress testing if cardiac conditions are suspected (e.g., MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction, heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR))

Management

• Symptomatic relief can be achieved with supplemental oxygen Supplemental Oxygen Respiratory Failure, but one must identify and correct the underlying condition for long-term treatment:
  • Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma:
    • Inhaled bronchodilators Bronchodilators Asthma Drugs, corticosteroids Corticosteroids Chorioretinitis, other medications
    • 5-step treatment strategy from the Global Initiative for Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma Group
  • COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD) exacerbations: 
    • Bronchodilator therapy and a course of oral glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids
    • Possible oral antibiotics (antivirals if there is evidence of influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza)
    • Supplemental oxygen Supplemental Oxygen Respiratory Failure if hypoxic and pulmonary rehabilitation program
  • Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR): 
    • Treatment depends on the type of heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) and severity.
    • Follow published guidelines for treatment.
    • Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) and angina medication Angina medication Angina is defined as chest pain or discomfort resulting from myocardial ischemia. Therapy for angina is targeted at limiting platelet aggregation and adhesion (with antiplatelet agents), reducing O2 demand (with beta-blockers), reducing preload (with nitrates), and preventing the progression of atherosclerotic disease (using statin therapy), along with the management of comorbidities. Heart Failure and Angina Medication
  • Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia/ infectious Infectious Febrile Infant causes: 
    • Use the appropriate antibiotic for the causative pathogen.
  • Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism:
    • Thrombolytics Thrombolytics Thrombolytics, also known as fibrinolytics, include recombinant tissue plasminogen activator (TPa) (i.e., alteplase, reteplase, and tenecteplase), urokinase, and streptokinase. The agents promote the breakdown of a blood clot by converting plasminogen to plasmin, which then degrades fibrin. Thrombolytics ( anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants and antiplatelet agents Antiplatelet agents Antiplatelet agents are medications that inhibit platelet aggregation, a critical step in the formation of the initial platelet plug. Abnormal, or inappropriate, platelet aggregation is a key step in the pathophysiology of arterial ischemic events. The primary categories of antiplatelet agents include aspirin, ADP inhibitors, phosphodiesterase/adenosine uptake inhibitors, and glycoprotein IIb/IIIa inhibitors. Antiplatelet Drugs)
    • Embolectomy and/or a vena cava filter if thrombolytics Thrombolytics Thrombolytics, also known as fibrinolytics, include recombinant tissue plasminogen activator (TPa) (i.e., alteplase, reteplase, and tenecteplase), urokinase, and streptokinase. The agents promote the breakdown of a blood clot by converting plasminogen to plasmin, which then degrades fibrin. Thrombolytics are contraindicated
• If complete relief of dyspnea is not possible, then attempts at lessening the intensity of dyspnea should follow with other therapy:
  • Oxygen supplementation if O₂ saturation O₂ saturation Gas Exchange < 88% at rest, with activity, or while sleeping
  • Opioids Opioids Opiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates. Opioid Analgesics can reduce air hunger, but one must:
    • Consider the risk-benefit profile.
    • Monitor the patient carefully because of opioids Opioids Opiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates. Opioid Analgesics‘ ability to cause respiratory depression. 
  • Inhaled furosemide Furosemide A benzoic-sulfonamide-furan. It is a diuretic with fast onset and short duration that is used for edema and chronic renal insufficiency. Loop Diuretics appears to be effective (large-scale studies are pending).

Clinical Relevance

The following conditions are the most common causes of dyspnea by organ system:

Cardiovascular conditions

• Acute MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction: ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage of the myocardial tissue due to a complete obstruction or drastic constriction of the coronary artery Coronary Artery Truncus Arteriosus. Acute MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction is usually accompanied by an increase in cardiac enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes, typical ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) changes, and chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways. 
• Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR): the inability of the heart to supply the body with normal cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics to meet metabolic needs. Risk factors include hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension, diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus mellitus, and coronary artery Coronary Artery Truncus Arteriosus disease. Echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA) can confirm the reduced EF EF Cardiac Cycle. 
• Cardiac tamponade Tamponade Pericardial effusion, usually of rapid onset, exceeding ventricular filling pressures and causing collapse of the heart with a markedly reduced cardiac output. Pericarditis: the condition of having an abnormal amount of fluid in the pericardial cavity Pericardial cavity Heart: Anatomy of the heart that restricts cardiac filling and leads to acute heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR). Treated by pericardiocentesis Pericardiocentesis Puncture and aspiration of fluid from the pericardium. Cardiac Surgery, removing the fluid with a needle.

Respiratory conditions

• Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma: a chronic inflammatory condition characterized by reversible obstruction to airflow in the lower airways. Presents with intermittent or persistent wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing, cough, and dyspnea. Diagnosis is confirmed with pulmonary function testing Pulmonary Function Testing Pulmonary Function Tests that shows a reversible obstructive pattern. 
• Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia: acute or chronic inflammation Chronic Inflammation Inflammation of lung tissue caused by infection with bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology, viruses Viruses Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells. Virology, or fungi Fungi A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including mushrooms; yeasts; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies. Mycology. Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia can also be due to toxic triggers Triggers Hereditary Angioedema (C1 Esterase Inhibitor Deficiency) through inhalation of toxic substances, immunologic processes, or radiotherapy.
• Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism: a potentially fatal clinical condition that occurs as a result of mechanical obstruction Mechanical Obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Imaging of the Intestines of the pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy or its branches by a thrombus, air, or fat. Diagnosis is established by CT pulmonary angiogram CT pulmonary angiogram Pulmonary Function Tests.
• Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax: a collection of air in the pleural space Pleural space The thin serous membrane enveloping the lungs (lung) and lining the thoracic cavity. Pleura consist of two layers, the inner visceral pleura lying next to the pulmonary parenchyma and the outer parietal pleura. Between the two layers is the pleural cavity which contains a thin film of liquid. Pleuritis that causes the lung to collapse due to the loss of negative pressure. Presents with pleuritic chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, dyspnea, tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children, and reduced breath sounds on the ipsilateral side.
• Airway Airway ABCDE Assessment obstruction: a partial or complete blockage of airflow in the respiratory tract, which can be classified into upper or lower airway Airway ABCDE Assessment obstructions. Usually associated with foreign body Foreign Body Foreign Body Aspiration aspirations, but can be caused by other conditions including mucous plug, epiglottitis Epiglottitis Epiglottitis (or “supraglottitis”) is an inflammation of the epiglottis and adjacent supraglottic structures. The majority of cases are caused by bacterial infection. Symptoms are rapid in onset and severe. Epiglottitis, infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, smoke inhalation Smoke Inhalation Carbon Monoxide Poisoning, goiter Goiter A goiter is a chronic enlargement of the thyroid gland due to nonneoplastic growth occurring in the setting of hypothyroidism, hyperthyroidism, or euthyroidism. Morphologically, thyroid enlargement can be diffuse (smooth consistency) or nodular (uninodular or multinodular). Goiter, etc ETC The electron transport chain (ETC) sends electrons through a series of proteins, which generate an electrochemical proton gradient that produces energy in the form of adenosine triphosphate (ATP). Electron Transport Chain (ETC).
• COPD COPD Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by progressive, largely irreversible airflow obstruction. The condition usually presents in middle-aged or elderly persons with a history of cigarette smoking. Signs and symptoms include prolonged expiration, wheezing, diminished breath sounds, progressive dyspnea, and chronic cough. Chronic Obstructive Pulmonary Disease (COPD): a spectrum of conditions characterized by irreversible airflow limitation correlated to smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases. Results from obstructive inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the small airways as well as changes in the lung parenchyma and pulmonary vasculature. 
• ILD ILD Interstitial lung diseases are a heterogeneous group of disorders characterized by the inflammation and fibrosis of lung parenchyma, especially the pulmonary connective tissue in the alveolar walls. It may be idiopathic (e.g., idiopathic pulmonary fibrosis) or secondary to connective tissue diseases, medications, malignancies, occupational exposure, or allergens. Interstitial Lung Diseases: a heterogeneous group of disorders characterized by the inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation and fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans of the lung parenchyma, especially the pulmonary connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology in the alveolar walls. May be idiopathic Idiopathic Dermatomyositis or secondary to connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue: Histology diseases, medications, malignancies, occupational exposure, or allergens.