COPD

Question 1

List the major COPD states and why they fit under this category

Answer 1

1. emphysema (destruction and enlargement of lung alveoli)
2. chronic bronchitis (chronic cough and phelgm)
   * note: without chronic airflow obstruction, chronic bronchitis is not included within COPD)*
3. small airway disease (small bronchioles are narrowed)

**all conditions cause obstruction to getting air out of lung **

Question 2

explain the airway hyperresponsiveness and COPD

Answer 2

-increased bronchoconstriction in response to exogenous stimuli (like metacholine and histamine)

metacholine acts in parasympathetic nervous system, so would constrict the bronchioles

-Dutch hypothesis says both asthma AND COPD share this feature

Question 3

explain the following changes you expect to see in COPD of the following:

• Forced expiratory flow rates:
• Residual volume:
• residual volume/total lung capacity ratio:
• ventilation distribution:
• V/Q:
• FEV1/FVC

Answer 3

• Forced expiratory flow rates: decreased
• Residual volume: increased
• residual volume/total lung capacity ratio: increased
• ventilation distribution: nonuniform
• V/Q: mismatch
• FEV1/FVC: decreases

Question 4

airflow during forced exhalation is the result of the balance between these two factors:

Answer 4

• elastic recoil = promotes flow
• resistance of airways = limits flow

Question 5

Why does maximal expiratory flow diminish as the lungs empty? Does this happen in normal and/or COPD pts?

Answer 5

-lung parenchyma provides progressively less elastic recoil and cross sectional area of airway falls, raising the resistance to airflow

occurs in lungs affected by COPD and normal lungs

Question 6

What happens to lung volumes in COPD? How does this affect maximum expiratory airflow?

Answer 6

“air trapping”

increased RV and RV/TLC

progressive hyperinflation (increased TLC)

-hyperinflation of the thorax during tidal breathing actually helps to preserve max exp airflow: as lung volume increases, elastic pressure increases, and airways enlarge so that airway resistance decreases

Question 7

While hyperinflamation is a way to help expiration, how does it effect inspiration?

Answer 7

Overall,compromises inspiration in 3 ways:

less effective positive abdominal pressure –> hinders rib cage movement –> impaired inspiration

bigger lung volume flattens diaphgram –> shorter muscle fibers –> **less capable of generating inspiratory pressures **

diaphagram must generate greater tension to develop the transpulmonary pressure needed to produce tidal breathing, also inspiratory muscles must do more work to overcome the resistance of the thoracic cage (since chest wall isnt helping with its natural recoil outward towards resting volume)

Question 9

cigarette smoke causes different responses whether there are changes in large airways or small airways and alveoli. Explain

Answer 9

large airways: cause cough and sputum <– mucous gland enlargement and goble cell hyperplasia

these define chronic bronchitis, but not related to airflow limitation

small airways and alveoli: physiologic alterations <–luminal narrowing by fibrosis, excess mucus, edema, and cellular infiltration, mucus secreting cells replace surfactant secreting, which may increase surface tension, increased airway narrowing or collapse

Question 10

What characterizes emphysema

Answer 10

destruction of gas-exchanging air spaces (respiratory bronchioles, alveolar ducts, and alveoli)

small distinct airspaces –> abnormal large ones

macrophages are >95% of total cell count

Question 11

Centriacinar vs. panacinar emphysema

Answer 11

centriacinar = associated w cigarette smoke = bigger air spaces foudn intiially in association with respiratory bronchioles, usually in upper lobes

panacinar = a1AT deficiency = large air spaces evenly distrbuted across acinar units, usually lower lobes

Question 12

what causes the cell death in emphysema?

Answer 12

increased oxidant stress both directly from cigarette smoke and from inflammation

Question 13

3 most common symptoms in COPD

Answer 13

cough, sputum, exertional dyspnea

Question 14

physical findings of COPD

Answer 14

barrel chest, expiratory wheezing, prolonged expiratory phase, cyanosis may develop\

“pink puffers” (stay pink, pursed lips and prolonged expiration to overcome obstruction

blue bloaters are associateed with chronic bronchitis, but really you see elements of both in each type of patient

Question 15

change in pH with PCO2 for acute and chronic state

PCO2 level for classification of ventilatory failure

Answer 15

0.08 units/10 mmHg acutely and 0.03 units/10 mmHg in the chronic state

pCO2>45 mmHg

Question 16

the only three interventions that influence natural history of pts with COPD

Answer 16

smoking cessation, oxygen therapy in chronically hypoxemic pts, and lung volume reduction surgery

Question 17

6 pharmacotherapy options

Answer 17

1. bronchodilators
2. anticholinergic agents
3. beta agonists
4. inhalted (or oral, but not reccommended) glucocorticoids
5. methylxanthines (theophylline)
6. N-acetyl cysteine