pulmonary pathology: obstructive lung diseases

Question 1

shunt

Answer 1

• Q > V
• blood/capillaries go to better ventilated alvoeli
• hypoxic vasoconstriction (R heart failure)

Question 2

obstructive lung disease

Answer 2

• can’t get air out
• restrictive lung disease: stuff lungs, low compliance, problems in and out

Question 3

definition of COPD

Answer 3

• the most common, preventable and treatable disease that is characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases
• symptoms: SOB, coughing, wheezing, fatigue
• exposure: smoking, asbestos, work exposure

Question 4

COPD is a combination of

Answer 4

• chronic bronchitis (coughing)
• asthma
• ehmpysema

produces airflow obstruction and COPD

Question 5

risk factors for COPD

Answer 5

• external: cigarette smoke, occupational dust and chemicals, environmental tobacco smoke (ETS), indoor and outdoor air pollution
• internal: nutrition, infection, SES, age
• overall prevalence has declined but increases in women and with age
  
  • more rapid declines in men
• exacerbations and comorbidities contribute to overall severity in individual patients
  
  • comorbidities: CV disease, DM, low BMI, MSK involvement

Question 6

FEV1 goes down _____ per year after age 30

Answer 6

• 25-30 ml
  
  • smokers have an increased rate of FEV1 decline
    
    • cessation of smoking decreases rate of FEV1 decline towards “normal”

Question 7

COPD pulmonary function testing (PFT)

Answer 7

• decreased airflow during forced expiration
  
  • reduced FEV 1 and FEV1/FVC ration
  • normal FEV1/FVC > 80%
    
    • < 80% is obstruction
• increased FRC and RV: hyperinflation (barrel chest deformity seen in emphysema)
• disproportionate reduction in FEV1 compared to FVC reflected in ratio - hallmark of obstructuive lung disease

Question 8

factors of expiratory airflow obstruction in COPD

Answer 8

• airway narrowing
  
  • bronchostriction: asthma, emphysema
  • inflammation: asthma, chronic bronchitis, emphysema
  • mucus hypersecretion: asthma, chronic bronchitis, CF, bronchiectasis
• los of elastic recoil of the lung: emphysema

Question 9

COPD clinical presentation

Answer 9

• impaired gas exchange
  
  • hypoxemia: low PaO2, decrease SpO2
  • hypercapnia: high PaCO2, possible respiratory acidosis (low pH)
    
    • if CO2 retention is chronic, HCO3- increases so pH remains normal
• simplified Henderson-Hasselbach
  
  • pH ~ HCO₃^-/PaCO₂
• chest radiographys: lungs hyperlucent (black), diaphragm flattened, increased AP diameter
  
  • signifies hyperinflation

Question 10

simplified Henderson-Hasselbalch

Answer 10

• pH ~ HCO₃^-/PaCO₂
• HCO₃^- increases with CO2 retention:
  
  • CO2 goes up, so pH goes down - acidosis
  • bicarb buffers so pH will regulate and stay the same

Question 11

COPD physical exam

Answer 11

• clinical signs
  
  • DOE with decreased exercise capacity: progressive difficulty with ADL’s
  • desaturation with activity (decrease SpO2)
  • hyperinflation/barrel chest deformity
  • abnormal breathing pattern
  • hypertrophy of accessory muscle of breathing
  • clubbing of digits
  • wheezing
  • weight loss

Question 12

emphysema

Answer 12

permanent, destructive abnormal enlargement of air spaces distal to terminal bronchiole with destruction of alveolar walls without obvious fibrosis

• upper lobe predominance

Question 13

emphysema presentation

Answer 13

• tripod position: when winded, allows abdominal viscera to get out of the way, diaphragm can descend further to inflate lungs

Question 14

emphysema pathology

Answer 14

• inflammatory mediators chew up elastin that causes lung recoil
  
  • stays expanded
• cigarette smoke blocks protease inhibitors
  
  • macrophage/neutrophil proteases exit alveoli and destory elastin fibers
  • alveoli wall damage

Question 15

emphysema airway collapse

Answer 15

• loss of mechanical tethering
• with no elastin, pleural pressure collapses airways to alveoli, causes decreased alveolar pressure
• “floppy” airways no longer supported by alveolar tissue
  
  • causes wheezing

Question 16

chronic bronchitis definition

Answer 16

• persistent cough with sputum production for at least 3 months in at least 2 consecutive years
• smoking leads to
  
  • muco-ciliary dysfunction
  • direct airway epithelium damage
  • inhibits bronchiolar and alveolar leukocytes to clear bacteria
• more and larger mucous secreting glands

Question 17

cystic fibrosis

Answer 17

• genetic alteration in chormosome 7
  
  • autosomal recessive disorder
  • leads to alterations in cystic fibrosis transmembrane conductance regulator (CFTR) - chloride channel
    
    • important for mucus, sweat, and digestive enzyme production
    • also affects pancreas, GI, MSK
  • 80% of CTFR dysfunction related deaths are related to pulmonary dysfunction

Question 18

cystic fibrosis and bronchiectasis

Answer 18

• mucus hypersecretion and plugging combined with repeated infections leading to widening of airways (bronchiectasis), repeated infection, progressive airway obstruction

Question 19

CF and airway surface liquid

Answer 19

• sol layer smaller, gel layer bigger
• cilia don’t operate as well (ciliary dyskinesia)

Question 20

asthma

Answer 20

• characterized by chronic airway inflammation and bronchospasm
• defined by history of respiratory symptoms such as wheeze, SOB, chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow limitation

Question 21

asthma prevalence

Answer 21

• increased for all races
• Black people are more likely to have asthma compared to white people and Hispanic people
  
  • genetics, SES, inner city, exposure to mites/roaches, healthcare/medication access and efficacy
• CDC: Black children are twice as likely to have asthma as white children, and 10 times more likely to die of complications

Question 22

triggers for atopic/allergen asthma

Answer 22

• allergens
  
  • animal dander, cockroach droppings, dust mites, mold, pollen
• irritants
  
  • environmental tobacco smoke or secondhand smoke, air pollution, chemicals and strong smells
• additional
  
  • cold air, exercise, upper respiratory infections, strong emotions

Question 23

other factors in persisant asthma that further limit airflow

Answer 23

• bronchoconstriction: bronchial smooth muscle contraciton causing airways to narrow in response to exposure to stimuli (allergens, irritants)
  
  • dominant physiological event leading to symptoms
• airway edema: swelling (an abnormal infiltration and excess accumulation of fluid)
• airway remodeling: permanent structural chagnes that occur in the airway, associated with progressive loss of lung function

also edema, inflammation, mucus hypersecretion, mucus plugs, hypertrophy/hyperplasia of smooth muscle