Obstructive and restrictive respiratory diseases

Lung volumes

Total Lung Capacity (TLC) - the total volume of the lung, the volume of air contained in the lung at the end of maximal inspiration Inspiratory Reserve Volume (IRV) - volume, which can be inspired beyond a restful inspiration Tidal Volume (TV) – volume of a single breath, usually at rest Functional Residual Capacity (FRC) - The amount of air left in the lungs after a tidal breath out, the amount of air that stays in the lungs during normal breathing Vital Capacity (VC) – maximum volume which can be ventilated in a single breath Inspiratory Capacity (IC) - the maximal volume that can be inspired following a normal expiration Expiratory Reserve Volume (ERV) – volume, which can be expired beyond a restful expiration Residual Volume (RV) – volume remaining in the lungs after a maximum expiration

Volumes Forced Vital Capacity (FVC) - the volume of air that can forcibly be blown out after full inspiration, measured in litres Forced Expiratory Volume in 1 Second (FEV1) - the maximum volume of air that can forcibly blow out in the first second during the FVC manoeuvre, measured in liters FEV1/FVC (FEV1%) - in healthy adults this should be approximately 75–80%. In obstructive diseases (asthma, COPD, chronic bronchitis, emphysema) FEV1 is decreased because of increased airway resistance to expiratory flow and the FVC may be increased (for instance by air trapping in emphysema). FEV1/FVC is decreased (<80%, often ~45%). In restrictive diseases (such as pulmonary fibrosis) the FEV1 and FVC are both reduced proportionally and the FEV1/FVC value may be normal or even increased as a result of decreased lung compliance

Obstructive lung diseases airway obstruction restricted expiration  FEV1,  FEV1/FVC  compliance, elasticity Chronic bronchitis Bronchiolitis Asthma Emphysema Bronchiectasia Cystic fibrosis normal Asthma COPD

Condition Major changes Causes Symptoms Chronic Hyperplasia Tobacco smoking Productive bronchitis and hypersecretion and air pollutants cough of mucus glands Bronchiectasis Dilation and scarring Persistent severe Cough, purulent of airways infections sputum and fever Asthma Smooth muscle Immunologic Episodic wheezing hyperplasia or idiopathic cough and dyspnea Excessive mucus Inflammation Emphysema Airspace enlargement Tobacco smoking Dyspnea Genetic and wall destruction

Restrictive lung diseases restricted lung expansion restricted inspiration + expiration  FEV1,  FVC, FEV1/FVC normal  compliance, elasticity Interstitial diseases – pneumonia Fibrosis of lungs – asbestosis, silicosis Restriction to breathing – pneumothorax, malformities, fracturae Signs dyspnea hypoxemia cor pulmonale

Flow volume curves

Spirogram in restriction Normal spirogram Spirogram in restriction Spirogram in obstruction Normal spirogram and lung volumes. ERV = FRC - RV; VC = TLC - RV; RV ~= 25% of TLC; FRC ~= 40% of TLC; FEV1 >= 75% of FVC. Spirogram and lung volumes in obstructive disease. RV and FRC are increased.TLC is also increased but to a lesser degree, so that VC is decreased. Expiration is prolonged. FEV1 <= 75% of FVC. Note the emphysematous notch.

Asthma Chronic inflamatory disease of bronchi leading to spasmatic occlusion and hyperproduction of viscous mucus Causes allergic allergens infection non-allergic neurogenic psychogenic

Asthma atack acute exacerbation of asthma Signs and symptoms dyspnea, wheezing, catching for air cough – viscous sputum cyanosis tachycardia chest pain

Chronic bronchitis chronic inflammation of bronchi Causes smoking air pollutions Signs and symptoms expectorating cough (productive cough, produces sputum) dyspnea, wheezing chest pain fever fatigue and malaise

Chronic bronchitis Smoking impairs ciliary movement inhibits function of alveoli macrophages hypertrophy and hyperplasia of mucus-secreting gland causes smooth muscle constriction Air pollutions ozone CO SO2

Emphysema Abnormal, permanent enlargement and destruction of theair spaces distal to the terminal bronchioles withou obvious fibrosis, progressively lose elasticity and eventual rupture of alveoli Panacinar (or panlobular) emphysema: The entire respiratory acinus, from respiratory bronchiole to alveoli, is expanded. Occurs more commonly in the lower lobes, especially basal segments, and anterior margins of the lungs.Typical for alpha-1-antitrypsin deficiency. Centroacinar (or centrilobular) emphysema: The respiratory bronchiole (proximal and central part of the acinus) is expanded. The distal acinus or alveoli are unchanged. Occurs more commonly in the upper lobes. Typical for smokers.

Emphysema Causes Inherited alpha 1-antitrypsin deficiency Acquired cigarette smoking air pollution Signs and symptoms Dyspnea upon exertion, wheezing, coughing Pursed lips to maximize ventilation Right heart failure Hypoxia, respiratory acidosis

Emphysema Alpha 1-antitrypsin deficiency (A1AD) inflammatory enzymes (such as elastase) destroy the alveolar tissue most A1AD patients do not develop clinically significant emphysema smoking and severely decreased A1AT levels (10-15%) can cause emphysema at a young age

Chronic obstructive pulmonary disease combination of chronic brnchitis + emphysema + asthma Cause Smoking Occupational exposures coal mining, gold mining, silicosis Air pollution Genetics alpha 1-antitrypsin deficiency Other risk factors a tendency to sudden airway constriction in response to inhaled irritants (asthma) repeated lung infections COPD as an autoimmune disease sustained inflammation mediated by autoantibodies and autoreactive T cells

Chronic obstructive pulmonary disease Signs and symptoms dyspnea, wheezing mucous sputum respiratory failure cyanosis cor pulmonale peripheral oedema (RV failure) tachypnea