Lung Volumes 4 Volumes 4 Capacities Sum of 2 or more lung volumes IRV TV ERV RV IC FRC VC TLC RV
Relative Contraindications to Performing Spirometry Hemoptysis of unknown origin Pneumothorax Unstable cardiovascular status or recent myocardial infarction or pulmonary embolus Thoracic, abdominal, or cerebral aneurysms Recent eye surgery Presence of an acute disease process that might interfere with test performance (eg, nausea, vomiting) Recent surgery of thorax or abdomen Patients with a history of syncope associated with forced exhalation
Standards for Testing Technical Requirements for Good Quality Full inhalation before start of test Satisfactory start of exhalation Evidence of maximal effort No hesitation No cough or glottic closure during first second Duration of test 3-6 seconds Up to 10 seconds in patients with obstruction No evidence of leak No evidence of obstruction of mouthpiece
Obstructive Flow Volume Loop RV TLC FRC Flow Ex. In Vol......... Note the Concave Expiratory Flow Loop.
Obstructive Disorders Characterized by reduction in exp flow rates not attributable to decreased lung volumes FEV1/FVC TLC is N or if lung elastic recoil is decreased (as in emphysema) FRC and RV are typically (may be N) FVC may be by large increase in RV
Flow-volume loops and upper airway obstruction Extrathoracic obstruction – vocal cord dysfunction, goiter, cause flattening of inspiratory limb of flow/volume loop Intrathoracic obstruction – bronchogenic cancer in right mainstem bronchus, flattening of expiratory limb of flow/volume loop
Variable Intrathoracic Obstruction Localized tumors of the lower trachea or mainstem bronchus Tracheomalacia Airway changes associated with polychondritis
Fixed Airway Obstruction RV TLC FRC Flow Ex. In Vol......... Note that both inspiratory flow and expiratory flow are “flat” due to decreased flow.
Fixed Upper Airway Obstruction Goiters Endotracheal neoplasms Stenosis of both main bronchi Postintubation stenosis Performance of the test through a tracheostomy tube or other fixed orifice device.
ActualPredicted% Predicted FVC4.04.588 FEV13.34.281 FEV1/FVC8382101 FEF25-751.73.548 Small Airways Defect
Bronchodilator Response: Response to inhaled bronchodilators: Typical in asthma; some patients with COPD and CF have reversibility also “Real response”: consists of a change in FEV1 by at least 12% (and 200cc) after inhalation of albuterol
Restrictive Disorders Volume of air within the lung by: Space-occupying abnormalities in the thorax (effusion, tumor) Parenchymal infiltration (fibrosis, fluid, inflam.) Alveolar collapse Respiratory muscle weakness Abnormal recoil or deformity of the chest wall RV (but if there is exp muscle weakness) FRC (but N if resp muscle weakness) FEV1/FVC is N or
Restrictive Lung Disease Characterized by diminished lung volume due to: change in alteration in lung parenchyma (interstitial lung disease) disease of pleura, chest wall (e.g. scoliosis), or neuromuscular apparatus (e.g. muscular dystrophy) Decreased TLC, FVC Normal or increased: FEV 1 /FVC ratio