Patho: collection of lower airway disorders that interfere with airflow and gas exchange.
Two disorders that fall under the umbrella of COPD is emphysema and chronic bronchitis.
Emphysema: destroys the wall of the air sac (alveoli) in the lung. The wall of the alveoli loses their
elasticity and get bigger which lead to hyperinflation.
These changes is the alveoli results in dyspnea with reduced gas exchange and the need to
increased respiratory rate
The main cause of emphysema is smoking.
Cigarette smoking trigger increased synthesis of protease enzymes to higher than
normal levels, which than damages the alveoli and small airways by breaking down
elastin and over time, alveolar sacs lose their elasticity and the small airways either
collapse or narrow and the alveoli either are destroyed or become flabby and large
leaving less area for gas exchange
Increased amount of air is trapped in the lungs due to loss of elastic recoil in the
alveolar walls, over stretching and enlargement of the alveoli into air filled spaces
called bulla, collapse of small bronchioles. These changes greatly increase the work
of breathing and interfere with airflow to the lungs.
The hyperinflated lungs flatten the diaphragm thus making the diaphragm weaker
thus causing the patients with emphysema to use accessory muscles in the neck,
chest wall, and abdomen to inhale and exhale.
With the accessory muscles being used this cause increases the need for oxygen
making the patient “Air hunger”
, Inhalation start before exhalation in completed, resulting in uncoordinated
breathing patterns.
Gas Exchange: is affected by the increased work breathing and loss of alveolar tissue.
Patient adjusts by increasing their respiratory rate and thus causing changes in ABGs values
but it shows in lab results later on in advanced disease
CO2 is produced faster than it can be eliminated, resulting CO2 retention leading to
respiratory acidosis.
Patient with late-stage emphysema also has a low arterial oxygen (PaO2) level because it is
difficult for oxygen to move from diseased alveoli into the blood.
Emphysema is mostly associated with tobacco smoking , marijuana, chronic inhaled particulate
matter exposure such as wood smoke biomass fuel.
Chronic Bronchitis: is an inflammation of the bronchi and bronchioles caused by exposure to
irritants, especially cigarette smoking
The irritants trigger inflammation, vasodilation, mucosal edema, congestion and
bronchospasm
Bronchitis effects only the airway not the alveoli
Chronic inflammation increase the number and size of mucus secreting glands, which
produces large amount of thick mucus
The bronchial wall thickens and impair airflow.
The increased mucus causes breeding ground for organisms and leads to chronic infection
, Chronic bronchitis impairs airflow and gas exchange thus resulting in the PaO2 to decreases
(hypoxemia) and PaCO2 increase (respiratory acidosis)
Etiology and genetic risk factors:
Cigarette smoking: the inhaled smoke triggers the release of excessive protease in the lungs.
These enzymes breakdown elastin, the major components of the alveoli. Smoking also
impairs the action of the cilia by inhibiting the cilia from clearing the bronchi of mucus,
cellular debris and fluid.
Alpha antitrypsin deficiency:
Asthma can also be a risk factor for COPD (ASTHMA -COPD overlap syndrome)
Complication:
Affects gas exchange and the oxygenation of all tissue.
Hypoxia, acidosis, respiratory infection, cardiac failure, dysrhythmias, and respiratory
failure
Respiratory infection: because of increased mucus and poor gas exchange, bacterial
infection are common and make COPD symptoms worsen by increasing inflammation and
mucus production and inducing more bronchospasm thus leading to airflow to become
more limited and the work of breathing increases and dyspnea results
Cardiac failure: cor pulmonale ( right sided heart failure caused by pulmonary disease) ; air
trapping, airway collapse, and stiff alveolar walls increase the lung tissue pressure and
narrow lung blood vessels, making blood flow more difficult. The increased pressure creates