4Lung disease Obstructive lung disease Restrictive lung disease … is any disease or disorder characterized byimpaired Lung functionThere are 3 major physiologic categories of lung diseases:Obstructive lung diseaseRestrictive lung disease
5Step 1. Look at the FVC, to see if it is within normal limits. Step 2. Look at the FEV1, determine if it is within normal limits.Step 3. If both FVC and FEV1 are normal,then you do not have to go any further…the patient has a normal PFT testStep 4. If FVC and / or FEV1 are low,…then the presence of disease is highly likelyStep 5. If Step 4 indicates that there is disease !!!?then you need to go to the %predicted for FEV1 / FVC If the %predicted for FEV1 / FVC is 90% or higher,then the patient has a restricted lung disease If the %predicted for FEV1 / FVC is 69% or lower,then the patient has an obstructed lung disease
6Interpreting Spirometry Results …determine the “severity of disease”Normal PFT Outcomes: > 85 % of predicted valuesMild Disease: > 65 % but < 85 % of predicted valuesModerate Disease: > 50 % but < 65 % of predicted valuesSevere Disease: < 50 % of predicted values
12Cross-section of well-distended bronchioles Cross-section of well-distended bronchioles. The wall of the terminal bronchiole (TB) is constructed of ciliated, cuboidal epithelium, thin discontinuous bands of smooth muscle, and submucosal connective tissue. In the respiratory bronchiole (RB) there is abrupt transition (arrows) from cuboidal epithelium to alveolar epithelium. (Human lung surgical specimen, 10-mum-thick paraffin section, light microscopy.
13The terminal respiratory unit (the physiologist's alveolus) consists of the alveoli (A) and alveolar ducts (AD) arising from a respiratory bronchiole (RB). Each unit is roughly spherical, as suggested by the dashed outline. Pulmonary venous vessels (PV) are peripherally located. TB identifies a terminal bronchiole. PA identifies a pulmonary artery. (Normal sheep lung, somewhat underinflated, 1-mum-thick glycol methacrylate section, light microscopy.A, Centriacinar emphysema shows distention of respiratory bronchioles (RB), while alveolar ducts (AD) and alveoli (A) remain normal in size. TB, terminal bronchiole. B, Panacinar emphysema shows destruction of both proximal and distal portions of the lung acinus, resulting in enlarged air spaces that cannot be easily identified as respiratory bronchioles, alveolar ducts, or alveolar sacs. TB, terminal bronchiole. C, Distal acinar emphysema shows enlarged subpleural acini and associated fine fibrosis (open arrows). Closed arrow, visceral pleura. (All are stained with hematoxylin and eosin; A and B, original magnification ×30; C, original magnification ×19.) part of the thoracic cavity in combination with an acquired or congenital abnormality of the lung parenchyma further alters the distal acinus. Irregular emphysema is associated with scarring from other diseases and therefore is frequently found in the lung at autopsy.
16Dynamic Compression of Airway and Equal Pressure Point
17Volume-Time and Flow-Volume Relationship Flow (liter/sec)TLCFVCRVsecondsTLCRVFVCIn the graph of volume versus time, the slope of the curve at any point is equal to the flow at that point (flow = volume/ time)The expiratory flow is greatest at the beginning of the expiratory maneuver and then gradually declines until residual volume is reached
18Flow-Volume Curve in Obstructive Disease PEFThe scooped-out appearanceReduced Peak expiratory flow (PEF),Vmax50% and Vmax75%