Module 4: Disorders of Pulmonary System Flashcards
Define hypercapnia
Increased PaCO2 in arterial blood defined as > 45 mmHg
What causes hypercapnia?
- Hypoventilation of the alveoli
- Suppressions of respiration centers
- -> DRG and VRG - Large airway obstructions (tumors or sleep apnea)
- Damage to alveoli (emphysema)
- Respiratory acidosis
** Anything that impairs the nervous system or mechanical work of breathing
Respiratory Acidosis
any condition which lungs can’t effectively remove all CO2 from blood
Tissue Hypoxia
Decreased O2 in any tissue that could be caused by any number of causes, some of which include hypoxemia or ischemia
Hypoxemia
Decreased PaO2 in arterial blood
Defined as < 60 mmHg in arterial blood
What are the 5 major causes of hypoxemia?
- Decreased PO2 of inspired air
- -> either from altitude or suffocation - Hypoventilation
- -> meds that depress resp. centers (DRG & VRG) - Diffusion abnormality of alveolocapillary membrane
- -> emphysema, fibrosis, or edema
4 and 5. Altered V/Q perfusion ratio (low or high V/Q)
–> MC cause!
What causes low V/Q?
Pulmonary “right to left shunting”
What is “right to left shunting”?
When blood travels from right heart to left without receiving O2…so poor O2 returns to left side of heart
Blood may pass through alveoli that are damaged/filled with fluid/debris
BOTTOM LINE:
Blood can get there, but lung tissue can’t deliver O2
Examples of right to left shunting
Asthma Chronic bronchitis Pneumonia ARDS Respiratory distress syndrom of infants
What causes high V/Q?
Inadequate blood flow in area of well ventilated lung
BOTTOM LINE:
lung tissue can deliver O2 but blood can’t get there
Name an example that causes high V/Q
pulmonary embolism
Describe the difference between low V/Q and high V/Q hypoxemia
Low V/Q means that the blood can get there but the lung tissue can’t deliver O2
High V/Q means that the lung tissue CAN deliver O2 but blood can’t get there
Aspiration
Entry of fluid or solids into trachea and lungs
What are risk factors for aspiration?
Neurological conditions
Medicines
Decreased level of consciousness
Pulmonary edema
Excess fluid in lungs
What is the most common cause of pulmonary edema?
heart disease (increased left sided pressures)
What are the 4 types of Atelectasis?
- Compressive Atelectasis
- Absorptive Atelectasis
- Surfactant Impairment
- Post-operative Atelectasis
Compressive Atelectasis
external pressure compresses lung
Caused by:
- Tumor
- Fluid or air in pleural space
- Abdominal distention
Absorptive Atelectasis
Air from blocked or hypoventilated alveoli gets absorbed into system
Surfactant Impairment
Lack of surfactant results in increased surface tension which makes lung prone to collapse
Post-Operative atelectasis
Most common form of atelectasis
How to prevent post-op atelectasis?
- Post surgical deep breathing exercise
- Patient positioning
- Early ambulation
Do surfactant impairment and post-op atelectasis cause compressive or absorptive atelectasis?
Absorptive Atelectasis
Pneumothorax
Air accumulation within pleural cavity (pleural space)
Three “types” of pneumothorax:
- Open pneumothorax
- Tension pneumothorax
- Spontaneous pneumothorax
Open Pneumothorax
Air enters pleural cavity during inspiration and exits during expiration
This causes air pressure in pleural space to = barometric air pressure
Tension Pneumothorax
Air enters pleural cavity during inspiration but DOES NOT EXIT during expiration
This gradual buildup of air pressure collapses lung and compresses or displaces other structures (heart, vessels, etc)
EMERGENCY condition
Spontaneous Pneumothorax
An UNEXPECTED rupture of pleura common in 20-40 yo males
Air escapes from lung into pleural space and it may or may not develop into tension penumothorax
What is pleural effusion?
Fluid in pleural space
What can pleural effusion cause?
compressive atelectasis
5 causes of pleural effusion:
- Transudate
- Exudates
- Pus
- Blood
- Lymph fluid
What is the difference between pleural effusion and pulmonary edema?
Pleural effusion has fluid in pleural space and pulmonary edema has fluid in lung tissue itself
Pleural effusion contains dull or decreased breath sounds while pulmonary edema has crackles, rales sounds
Name the 4 main Pulmonary Disorders:
- ARDS
- Obstructive pulmonary disease
- Restrictive pulmonary diseases
- Pulmonary embolism
ARDS (acute respiratory distress syndrome)
Respiratory failure due to acute inflammation and alveolar damage
What is the most common cause of ARDS?
Infection or multiple trauma
Describe Phase I of ARDS
- Initial injury to lung (damages alveolar & vascular endothelium)
- MASSIVE INFLAMMATORY RESPONSE
- Surfactant is inactivated
- Alveoli collapse d/t less compliance and filling of inflammatory fluid
Describe Phase II of ARDS
- Hyaline membrane forms into fibrous mass coating alveoli and bronchioles
Describe Phase III of ARDS
- End result is respiratory failure
- Inflammatory mediators can cause secondary inflammation and damage other organs which can cause death
Obstructive Pulmonary Disease
Airway obstruction that is worse with expiration
Can get air in but can’t breath out = wheezing
What are the 3 most common obstructive pulmonary diseases?
- Chronic bronchitis
- Emphysema
- Asthma
Name 6 common clinical characteristics of obstructive pulmonary disease
- Dyspnea - perceived difficulty breathing
- SOB or pain
- Increased WOB
- Wheezing
- Decreased FEV1/FEV ( b/c blood can get there but lungs can’t deliver O2
What co-existing conditions are referred to as COPD (chronic obstructive pulmonary disease)
Chronic bronchitis
Emphysema
What is the primary cause of COPD?
Smoking
Describe the pathophysiology of chronic bronchitis
The bronchial tubes are narrowed
Excess mucous production which decreases airways and increases risk of infection and inflammation
Describe the alveolar ventilation and V/Q ratio in Chronic Bronchitis
Decreased alveolar ventilation
Low V/Q
Hypoxemia and Hypercapnia occur in ______.
Chronic Bronchitis
What is car pulmonale and what is it a result of?
Car pulmonale: a change in structure and function of the right ventricle of the heart as a result of pulmonary hypertension
Pulmonary hypertension can stem from polycythemia, or increased amounts of RBCs
Signs and symptoms of chronic bronchitis
- Productive and persistent couch; “smokers cough”
- Recurrent pulmonary infections
- Reduced flow rates (dec. FEV1/FVC) - prolonged expiration
- Static lung volumes (decreased FVC and Increased RV)
Treatments of Chronic Bronchitis
- Expectorants
- Bronchodilators
- Physical Therapy
- Antibiotics and steroids
- Low flow O2 for severe hypoxemia
What is the challenge with giving low flow O2 to patients with chronic bronchitis?
The potential adverse effect is respiratory depression because the peripheral receptors that are sensitive to O2 take over and depress ventilation.
The challenge is to provide low flow O2 w/o increasing PaO2 above 60 mmHg
Emphysema
pathological accumulation of air in the lungs
Enlargement of gas exchange airways (acini)
What are the 2 forms of emphysema?
- Centriacinar (centrilobar)
2. Panacinar (panlobular)
Centriaacinar Emphysema
Destruction of the bronchioles and alveolar ducts
Alveolar sac remains intact
This is more common in chronic smoker
Panacinar Emphysema
Destruction of entire acinus (bronchiole, alveolar duct, and alveoli)
This is more common in elderly
Describe how smoking causes emphysema (the pathophysiology)
Proteases and free radicals destroy elastin in lungs.
Smoking inhibits a protease inhibitor (alpha1-antitrypsin)
This promotes release of elastase, which is an enzyme that destroys elastic tissue in lung
**Smoking also favors recruitment of WBC’s
What two things are uncommonly seen in a pt. with Emphysema?
Coughing and wheezing
What are some “clinical pearls” of Emphysema?
Barrel chest (chronic expansion)
Classic sit and lean forward with arms extended breathing position
What is the end stage of emphysema?
SAME AS CHRONIC BRONCHITIS
Pulmonary HTN and cor pulmonale
Treatment for acute emphysema:
- O2 therapy (positive pressure or mechanical ventilation)
- Bronchodilators
- Corticosteroids and antibiotics
Treatment for chronic emphysema:
- QUIT SMOKING
- Pulmonary rehab and pt. education
- O2 therapy if necessary
- Beta agonist or anticholinergic meds
Asthma
Reversible obstructive lung disease caused by increased reaction of airways to various stimuli (hypersensitive)
What are the 3 things that result from inflammation and epithelial damage that occurs in asthma?
- Bronchial smooth muscle spasm
- Mucus production (impairs cilia function)
- Vascular Congestion
What triggers exercise induced asthma?
Dry, cold air
Classic Fall weather
What are 4 characteristics of Restrictive Pulmonary Conditions?
- Short shallow breathing patterns
- Flow rates: increased or no change (FEV1/FVC (>90%))
- Static Volumes: Decreased FVC, RV and TLC
- DOE progress to dyspnea at rest
Sarcoidosis
Inflammation that produces tiny lumps of cells in various organs throughout the body
What are the 4 Restrictive-Parenchymal Conditions?
- Sarcoidosis
- Idiopathic pulmonary fibrosis
- Pneumoconiosis
- Drug- or radiation-induced interstitial lung disease
What are the 7 Restrictive-Extraparenchymal Conditions?
- Myasthenia gravis
- Guillain-Barre syndrome
- Muscular dystrophies
- Cervical spine injury
- Kyphoscoliosis
- Obesity
- Ankylosing spondylitis
Pulmonary Fibrosis
Excessive fibrosis proliferation in lung
What are 3 causes of pulmonary fibrosis?
- Secondary complication from disease (TB, ARDS)
- Inhalation of environmental hazards (pneumoconiosis)
- Idiopathic pulmonary fibrosis
Why is their excessive fibrosis proliferation in pulmonary fibrosis?
Chronic inflammation.
Alveoli are invaded by fibroblasts
Pneumoconiosis
Lung pathology due to inhalation of inorganic environmental hazards (often long term exposure)
What are some common pathologies of pneumoconiosis?
- Silica (common in mining)
- Asbestos
- “Coal miner lung” (coal, silica, and quartz)
Tuberculosis (TB)
Infection from mycobacterium tuberculosis
How is TB transmitted?
Through airborne particles/droplets
–> VERY contagious
What is the pathology of TB?
Inflammatory process secondary to bacteria
Immune response leads to formation of granulomatous lesions known as tubercle
Tissue within tubercle becomes necrotic
Scar tissue surrounds tubercle
Remains dormant unless disrupted or if immune system is comprimised
–> HIV greatest risk to reactivate TB
A positive PPD (purified protein derivative) means…
Pt either had disease or was vaccinated
What do chest films show in pts with TB?
Calcifications
Nodes observed in upper lobes
Pulmonary Embolism
Occlusion of pulmonary vascular/capillary supply
What is the V/Q ratio of pulmonary embolism?
Lung CAN deliver O2 but blood can’t get there so…
High V/Q ratio
What is the most common cause of pulmonary embolism?
Most common via DVT - Deep Vein Thrombosis
What are risk factors for a pulmonary embolism caused by venous stasis?
- immobility (post surgery, long travel)
- Pregnancy
- Congestive heart failure
What are risk factors for a pulmonary embolism caused by hypercoagulation?
Genetics
OCPs
Malignancy
What are risk factors for a pulmonary embolism caused by damage to endothelium of blood vessels?
Trauma or surgical
CVA (stroke)
