Forced Expiratory Flow Rates: The rate of airflow measured during a FORCED VITAL CAPACITY determination.Peak Expiratory Flow Rate: Measurement of the maximum rate of airflow attained during a FORCED VITAL CAPACITY determination. Common abbreviations are PEFR and PFR.Maximal Expiratory Flow Rate: The airflow rate measured during the first liter expired after the first 200 ml have been exhausted during a FORCED VITAL CAPACITY determination. Common abbreviations are MEFR, FEF 200-1200, and FEF 0.2-1.2.Maximal Midexpiratory Flow Rate: Measurement of rate of airflow over the middle half of a FORCED VITAL CAPACITY determination (from the 25 percent level to the 75 percent level). Common abbreviations are MMFR and FEF 25%-75%.Vital Capacity: The volume of air that is exhaled by a maximal expiration following a maximal inspiration.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.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.Asthma: 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).Spirometry: Measurement of volume of air inhaled or exhaled by the lung.Pulmonary Ventilation: The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.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.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.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.Bronchodilator Agents: Agents that cause an increase in the expansion of a bronchus or bronchial tubes.Airway Obstruction: Any hindrance to the passage of air into and out of the lungs.Airway 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.Lung Volume Measurements: Measurement of the amount of air that the lungs may contain at various points in the respiratory cycle.Functional Residual Capacity: The volume of air remaining in the LUNGS at the end of a normal, quiet expiration. It is the sum of the RESIDUAL VOLUME and the EXPIRATORY RESERVE VOLUME. Common abbreviation is FRC.Administration, Inhalation: The administration of drugs by the respiratory route. It includes insufflation into the respiratory tract.Respiration Disorders: Diseases of the respiratory system in general or unspecified or for a specific respiratory disease not available.Maximal Expiratory Flow-Volume Curves: Curves depicting MAXIMAL EXPIRATORY FLOW RATE, in liters/second, versus lung inflation, in liters or percentage of lung capacity, during a FORCED VITAL CAPACITY determination. Common abbreviation is MEFV.Lung Diseases, Obstructive: Any disorder marked by obstruction of conducting airways of the lung. AIRWAY OBSTRUCTION may be acute, chronic, intermittent, or persistent.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.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.Respiratory Sounds: Noises, normal and abnormal, heard on auscultation over any part of the RESPIRATORY TRACT.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).Ipratropium: A muscarinic antagonist structurally related to ATROPINE but often considered safer and more effective for inhalation use. It is used for various bronchial disorders, in rhinitis, and as an antiarrhythmic.Beclomethasone: An anti-inflammatory, synthetic glucocorticoid. It is used topically as an anti-inflammatory agent and in aerosol form for the treatment of ASTHMA.Nebulizers and Vaporizers: Devices that cause a liquid or solid to be converted into an aerosol (spray) or a vapor. It is used in drug administration by inhalation, humidification of ambient air, and in certain analytical instruments.Atropine Derivatives: Analogs and derivatives of atropine.Lung Diseases: Pathological processes involving any part of the LUNG.Asthma, Exercise-Induced: Asthma attacks following a period of exercise. Usually the induced attack is short-lived and regresses spontaneously. The magnitude of postexertional airway obstruction is strongly influenced by the environment in which exercise is performed (i.e. inhalation of cold air during physical exertion markedly augments the severity of the airway obstruction; conversely, warm humid air blunts or abolishes it).Occupational Diseases: Diseases caused by factors involved in one's employment.Aerosols: Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents.