Week 4 Flashcards
What are the forces that affect the work of breathing?
- Elastic recoil of the lungs and chest wall
* Airway resistance
What are the components of the elastic recoil of the lungs and chest wall that affects the work of breathing?
Static lung compliance is the change in volume for any given applied pressure
• Compliance = change in volume/change in pressure
• Increases with age and COPD
• Decreases with RLD
What are the components of the airway resistance that affects the work of breathing?
- Bronchoconstriction
- Mucous plugs
- Airway Thickening
How do we assess lung function?
• Lung Volume/Capacity - PFT • Gas Exchange - DLCO - ABG • Imaging - CXR, - CT Scan, - Perfusion Scan • Function - 6MWT - ETT
What does Diffusion capacity of the lung for carbon dioxide (DLCO) do?
It infuses a known volume of carbon monoxide, and assess the amount of inspired and expired gases
What are the normal conditions of a DLCO?
80-100% of predicted uptake occurs
What is considered pulmonary pathology in a DLCO?
< 80% of predicted uptake occurs
What are the factors that DLCO is dependent upon?
- Volume inspired (ventilation)
- Pulmonary blood flow (perfusion)
- Alveolar capillary surface area
- Hemoglobin
- Thickness of alveolar capillary membrane
What are the factors that cause a general reduce of DLCO?
Emphysema, and restriction, normal in asthmatics
What is the common sequelae of Chronic Lung Disease?
- Pulmonary Hypertension
- Right Heart failure (cor pulmonale)
- Atrial Fibrillation (Especially COPD)
- Obstructive Sleep Apnea (Especially COPD)
_____ is the most common cause of clubbing
Lung cancer is the most common cause of clubbing
When does clubbing occur?
In heart and lung diseases that reduce the amount of oxygen in the blood, however may not always be present.
What is pulmonary hypertension due to?
If there are issues with the oxygenation of the lungs, the removal of CO2 can change the vasculature/vascular tone in the lungs.
What is the role of CO2 in the periphery?
It is a vasodilator
What is the role of CO2 in the pulmonary arteries?
It is a vasoconstrictor
What is the primary issue of obstructive pulmonary disease?
Problems with getting “air out”
What is our normal FEV1(maximal amount of air you can forcefully exhale in one second)?
80%
What is the FEV1/FVC ( the total amount of air exhaled during the FEV test) ratio seen in patients with obstructive pulmonary disease?
FEV1/FVC ratio
What is obstructive pulmonary disease?
A common preventable and treatable disease, characterized by persistent
progressive airflow limitation and is associated with an enhanced chronic inflammatory response to noxious particles or gases
What is the most common risk factor for COPD worldwide?
Tobacco smoking
What are the types of Chronic Obstructive Pulmonary
Disease (COPD)?
- Chronic Bronchitis
- Emphysema
- Alpha 1 antitrypsin deficiency
- Asthma
What are the other types of obstructive pulmonary diseases?
- Bronchiectasis
* Cystic Fibrosis (in later stages)
What is chronic bronchitis?
Cough and sputum production, especially during the winter, not due to specific or localized disease, present on most days for at least 3 months per year for 2 consecutive years
What is emphysema?
Loss of alveolar walls associated with increase in the size of the acinar airways of the upper lobe segments in a Centrilobular “centriacinar” pattern
What is alpha-antitrypsin 1 deficiency?
Genetic deficiency, where people develop pancinar emphysema: lower
regions of the lungs are typically first affected.
What is asthma?
A disorder characterized by reversible bronchospasm with wheezing, the symptoms occurring in short lived episodes, manifests early in life
What is alpha-antitrypsin 1?
A chemical in the body that allow our lungs to repair when they are exposed to a noxious stimulus
What is the pathophysiology of COPD?
You inhale some sort of noxious gas/particles, which leads to overtaxing of the macrophages, which may rupture protolytic enzymes, breakdown the alveolar walls, which will signal mucus production, and some of the antibodies released from the macrophages and WBC facilitate mucus hypersecretion, often leading to hypertrophy of the mucosal glands, may also see fibrosis(flimsy, prone to collapsing). We see weakening of the cartilage that supports the airways and destruction of the alveolar walls
What is a feature of the pathophysiolgy of COPD?
They can usually take in air, but when they start to try to exhale, they have trouble and the airway can collapse, and the presence of the air in the lungs, leads to vasodilation
What are the classic signs of COPD?
Air trapping. Issues removing air, because the walls are so flimsy they collapse
What are the muscle pathophysiological changes we see in patients with COPD?
• Metabolic inefficiency
- Fiber type shift in some skeletal muscle from type I to type II
• Reduced Fat Free Mass FFM (especially in quadriceps)
• Increased resting energy expenditure (REE), 15–20% above predicted values
due to the increased work of breathing.
• Impaired Mitochondrial function and decreased density
• Multiple suspected causes
What are some of the suspected causes of the muscle pathophysiological changes we see in patients with COPD?
- Disuse atrophy
* Mitophagy: mitochondrial autophagy (pre-programmed cell death), which leads to skeletal muscle dysfunction
Why does the resting energy expenditure in patients with COPD increase?
Their diaphragm is over-worked due to some adaptation, which makes it work harder
What are the diaphragmatic adaptations we see in patients with COPD?
• Patients with severe COPD generate 60% of normal max trans-diaphragmatic pressure
• Changes at the cellular and molecular level in the muscle can fully account for the reduced diaphragm strength.
• Similowski et al suggested that weakness of the diaphragm could also be explained by
hyperinflation-induced diaphragm shortening.
What are the changes at the cellular and molecular level in the muscle that can fully account for the reduced diaphragm strength?
- Fiber type “switch” to type 1 to compensate for increased diaphragmatic loading
- Reduction of max force generated by COPD diaphragm fibers was associated with an approximate 30% loss of heavy chain myosin content.
- These physiological changes are present in both mild and moderate cases
What does hyperinflation-induced diaphragm shortening do?
Places the diaphragm on a suboptimal position on its pressure–length relationship.
What are the signs and symptoms of COPD found upon physical exam?
- Chronic Cough
- Sputum production
- Exertional dyspnea
- Barrel Chest
- Paradoxical Chest wall movements
- Decreased breath sounds
- Crackles (atelectasis)
- Early satiety and difficulty eating
- Balance and strength deficits
- Body weight changes*
- Cyanosis (severe cases)
- Get full fast
What are the signs and symptoms of COPD found upon diagnostic testing?
• Impaired FEV1/FVC Ratio (
What are the common impairments of COPD?
• Reduced Functional capacity - 6MWD - Or other ETT • Decreased strength • Impaired balance (LE muscles lose a lot) - Increased Fall risk and mortality/morbidity • Dyspnea with minimal activity • Reduced Gait speed • Altered cardiorespiratory response to exercise • Back pain and chronic pain
What do we see in patients with COPD during pulmonary function testing?
Expiratory scooping. When inspiration is pretty normal, but during the 1st sec of expiration where we are supposed to be getting most of our volume out, patient with COPD get compression and flow reduction happens much sooner than it is supposed to
What is the cause of dyspnea in patients with COPD?
Due to air trapping and flimsy airways, as they begin to work harder and breathe faster, they hold more and more air in, because the respiratory rate is increasing to maintain oxygenation. Their issue is not having enough time
What are the skeletal muscle changes we see in patients with COPD?
- Barrel chasting
- Hyper kyphosis
What are the diffusion and blood gas changes seen in COPD?
• Hypoxemia develops with mild to moderate COPD
• Hypoxemia and hypercapnea
develops in more severe cases when FEV1 <1L or 50%
- CO2 retainers (becomes more reliant on oxygen)
- May down-regulate chemoreceptor response to [CO2]
What does DLCO do?
Measures the diffusing capacity of CO through the alveolar membrane to hemoglobin
Why do we see reductions in DLCO in patients with COPD?
• Damage to alveolar capillary membrane or vasculature will reduce it. • Often adjusted by the alveolar volume (VA) for severe COPD • Generally reduced in reduced with most obstructive and restrictive diseases, - Normal in patients with asthma
What is considered mild COPD according to the COPD- Gold classification?
FEV1 >/= 80%
What is considered moderate COPD according to the COPD- Gold classification?
FEV1: 50-80%
What is considered severe COPD according to the COPD- Gold classification?
FEV1: 30-50%
What is considered very severe COPD according to the COPD- Gold classification?
FEV1 < 30%
According to the Bode index, what are the domains taken into consideration in the assessment of 4 year survival of COPD?
- Disease severity on FEV1
- Distance on 6MWT
- Score on MMRC dyspnea scale
- BMI
What is the general minimum distance covered on the 6MWT that patients with COPD must achieve?
Minimum of 200 meters
What is the FEV1 predicted scale used in the Bode index?
- > 65% (0 points)
- 50-64% (1 point)
- 36%-49% (2 points)
- < 35% (3 points)
What is the 6 MWT scale used in the Bode index?
- > 1150 feet (0 points)
- 820-1150 feet (1 point)
- 490- 820 feet (2 points)
- < 490 feet (3 points)
What is the MMRC dyspnea scale used in the Bode index?
- 0: dyspnea with strenuous exercise (0 points)
- 1: dyspnea with walking on a slight hill (0 points)
- 2: dyspnea with walking on level ground, must stop d/t SOB (1 point)
- 3: must stop d/t SOB after 100 yards (2 points)
- 4: dyspnea with dressing ADL (3 points)
What is the BMI scale used in the Bode index?
- > 21 (0 points)
- < 21 (1 point)
What is the score and 4 year survival scale used by the Bode index?
- Score: 0-2, 4yr survival: 80%
- Score: 3-4, 4yr survival: 67%
- Score: 5-6, 4yr survival: 57%
- Score: 7-10, 4yr survival: 18%
What are the highlights of emphysema?
• Increased airway compliance. - Air trapping/Hyperinflation • Decreased surface area of alveoli for gaseous exchange. - (V/Q) mismatch. • Reduced expiratory flow - Reduced elastic recoil pressure - Narrow & poorly supported airways - Increased airflow resistance • “Pink Puffer
What are the presentations of emphysema?
- Barrel chesting
- Potential compression of the abdominal contents
- Impairments of the diaphragm, because it is flattened out
- Pursing of lips to help slow the respiration cycle
- Arms resting on chairs o help ribcage take in more air
How is chronic bronchitis primarily identified?
By submucosal gland hypertrophy in bronchioles producing increased thickness resulting from exposure to smoking or other irritants.