Dyspnea: Difficult or labored breathing.Pulmonary Disease, Chronic Obstructive: A disease of chronic diffuse irreversible airflow obstruction. Subcategories of COPD include CHRONIC BRONCHITIS and PULMONARY EMPHYSEMA.Respiratory Function Tests: Measurement of the various processes involved in the act of respiration: inspiration, expiration, oxygen and carbon dioxide exchange, lung volume and compliance, etc.Exercise Tolerance: The exercise capacity of an individual as measured by endurance (maximal exercise duration and/or maximal attained work load) during an EXERCISE TEST.Dyspnea, Paroxysmal: 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.Forced Expiratory Volume: Measure of the maximum amount of air that can be expelled in a given number of seconds during a FORCED VITAL CAPACITY determination . It is usually given as FEV followed by a subscript indicating the number of seconds over which the measurement is made, although it is sometimes given as a percentage of forced vital capacity.Spirometry: Measurement of volume of air inhaled or exhaled by the lung.Vital Capacity: The volume of air that is exhaled by a maximal expiration following a maximal inspiration.Lung Diseases, Obstructive: Any disorder marked by obstruction of conducting airways of the lung. AIRWAY OBSTRUCTION may be acute, chronic, intermittent, or persistent.Exercise Test: Controlled physical activity which is performed in order to allow assessment of physiological functions, particularly cardiovascular and pulmonary, but also aerobic capacity. Maximal (most intense) exercise is usually required but submaximal exercise is also used.Respiratory Muscles: These include the muscles of the DIAPHRAGM and the INTERCOSTAL MUSCLES.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Cough: A sudden, audible expulsion of air from the lungs through a partially closed glottis, preceded by inhalation. It is a protective response that serves to clear the trachea, bronchi, and/or lungs of irritants and secretions, or to prevent aspiration of foreign materials into the lungs.Airway Obstruction: Any hindrance to the passage of air into and out of the lungs.Inspiratory Capacity: The maximum volume of air that can be inspired after reaching the end of a normal, quiet expiration. It is the sum of the TIDAL VOLUME and the INSPIRATORY RESERVE VOLUME. Common abbreviation is IC.Radiography, Thoracic: X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs.Breathing Exercises: Therapeutic exercises aimed to deepen inspiration or expiration or even to alter the rate and rhythm of respiration.Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Bronchodilator Agents: Agents that cause an increase in the expansion of a bronchus or bronchial tubes.Scopolamine Derivatives: Analogs or derivatives of scopolamine.Oxygen Inhalation Therapy: Inhalation of oxygen aimed at restoring toward normal any pathophysiologic alterations of gas exchange in the cardiopulmonary system, as by the use of a respirator, nasal catheter, tent, chamber, or mask. (From Dorland, 27th ed & Stedman, 25th ed)Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Fatal Outcome: Death resulting from the presence of a disease in an individual, as shown by a single case report or a limited number of patients. This should be differentiated from DEATH, the physiological cessation of life and from MORTALITY, an epidemiological or statistical concept.Lung Diseases, Interstitial: A diverse group of lung diseases that affect the lung parenchyma. They are characterized by an initial inflammation of PULMONARY ALVEOLI that extends to the interstitium and beyond leading to diffuse PULMONARY FIBROSIS. Interstitial lung diseases are classified by their etiology (known or unknown causes), and radiological-pathological features.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.Lung Diseases: Pathological processes involving any part of the LUNG.Lung Volume Measurements: Measurement of the amount of air that the lungs may contain at various points in the respiratory cycle.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Bronchial DiseasesHemoptysis: Expectoration or spitting of blood originating from any part of the RESPIRATORY TRACT, usually from hemorrhage in the lung parenchyma (PULMONARY ALVEOLI) and the BRONCHIAL ARTERIES.Respiratory Mechanics: The physical or mechanical action of the LUNGS; DIAPHRAGM; RIBS; and CHEST WALL during respiration. It includes airflow, lung volume, neural and reflex controls, mechanoreceptors, breathing patterns, etc.Heart Neoplasms: Tumors in any part of the heart. They include primary cardiac tumors and metastatic tumors to the heart. Their interference with normal cardiac functions can cause a wide variety of symptoms including HEART FAILURE; CARDIAC ARRHYTHMIAS; or EMBOLISM.Tracheal NeoplasmsAsthma: A form of bronchial disorder with three distinct components: airway hyper-responsiveness (RESPIRATORY HYPERSENSITIVITY), airway INFLAMMATION, and intermittent AIRWAY OBSTRUCTION. It is characterized by spasmodic contraction of airway smooth muscle, WHEEZING, and dyspnea (DYSPNEA, PAROXYSMAL).Tracheal DiseasesAcute Disease: Disease having a short and relatively severe course.Inhalation: The act of BREATHING in.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. (Guyton, Textbook of Medical Physiology, 8th ed, p406)Bronchoscopy: Endoscopic examination, therapy or surgery of the bronchi.Natriuretic Peptide, Brain: 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.Maximal Voluntary Ventilation: Measure of the maximum amount of air that can be breathed in and blown out over a sustained interval such as 15 or 20 seconds. Common abbreviations are MVV and MBC.Pulmonary Diffusing Capacity: The amount of a gas taken up, by the pulmonary capillary blood from the alveolar gas, per minute per unit of average pressure of the gradient of the gas across the BLOOD-AIR BARRIER.Residual Volume: The volume of air remaining in the LUNGS at the end of a maximal expiration. Common abbreviation is RV.Pulmonary Emphysema: Enlargement of air spaces distal to the TERMINAL BRONCHIOLES where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions.Palliative Care: Care alleviating symptoms without curing the underlying disease. (Stedman, 25th ed)Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Albuterol: A short-acting beta-2 adrenergic agonist that is primarily used as a bronchodilator agent to treat ASTHMA. Albuterol is prepared as a racemic mixture of R(-) and S(+) stereoisomers. The stereospecific preparation of R(-) isomer of albuterol is referred to as levalbuterol.Pericardial Effusion: Fluid accumulation within the PERICARDIUM. Serous effusions are associated with pericardial diseases. Hemopericardium is associated with trauma. Lipid-containing effusion (chylopericardium) results from leakage of THORACIC DUCT. Severe cases can lead to CARDIAC TAMPONADE.Pulmonary Embolism: Blocking of the PULMONARY ARTERY or one of its branches by an EMBOLUS.Respiration: The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Walking: An activity in which the body advances at a slow to moderate pace by moving the feet in a coordinated fashion. This includes recreational walking, walking for fitness, and competitive race-walking.Total Lung Capacity: The volume of air contained in the lungs at the end of a maximal inspiration. It is the equivalent to each of the following sums: VITAL CAPACITY plus RESIDUAL VOLUME; INSPIRATORY CAPACITY plus FUNCTIONAL RESIDUAL CAPACITY; TIDAL VOLUME plus INSPIRATORY RESERVE VOLUME plus functional residual capacity; or tidal volume plus inspiratory reserve volume plus EXPIRATORY RESERVE VOLUME plus residual volume.Bronchial Provocation Tests: Tests involving inhalation of allergens (nebulized or in dust form), nebulized pharmacologically active solutions (e.g., histamine, methacholine), or control solutions, followed by assessment of respiratory function. These tests are used in the diagnosis of asthma.Natriuretic Agents: Endogenous or exogenous chemicals that regulate the WATER-ELECTROLYTE BALANCE in the body. They consist of peptides and non-peptide compounds.Expiratory Reserve Volume: The extra volume of air that can be expired with maximum effort beyond the level reached at the end of a normal, quiet expiration. Common abbreviation is ERV.Cryptogenic Organizing Pneumonia: An interstitial lung disease of unknown etiology, occurring between 21-80 years of age. It is characterized by a dramatic onset of a "pneumonia-like" illness with cough, fever, malaise, fatigue, and weight loss. Pathological features include prominent interstitial inflammation without collagen fibrosis, diffuse fibroblastic foci, and no microscopic honeycomb change. There is excessive proliferation of granulation tissue within small airways and alveolar ducts.Tracheal StenosisChest Pain: Pressure, burning, or numbness in the chest.