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PHGY350 - Respiratory
N/A
80
Physiology
Undergraduate 3
12/06/2011

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Cards

Term
What is the main cause of COPD?
Definition
Smoking
Term
Type of airway obstruction in COPD?
Definition
Partially reversible, but will NEVER normalize
Term
What are the 3 main pathologies associated with COPD?
Definition
Expiratory flow limitation
Air trapping
Hyperinflation of lungs
Term
Pathogenic mechanisms of COPD
Definition
Neutrophilia - enhances elastase and protease activity to cause destruction of parenchyma
a1-antitrypsin deficiency (genetic) - w/o inhibitor get increased protease activity & alveolar wall destruction (contributes to parenchymal breakdown)
Term
What are the 2 clinical identities of COPD?
Definition
Emphysema & chronic bronchitis
Term
COPD - Emphysema
Definition
Abnormal & permanent enlargement of airways distal to terminal bronchioles; aveolar & parenchymal destruction
Term
COPD - Chronic Bronchitis
Definition
Productive cough for > 3 months, in 2 consecutive years w/o alternative diagnosis
Term
Acinus
Definition
Functional unit of the lung; all structures distal to terminal bronchioles
= respiratory bronchioles, alveolar ducts & sacs, alveoli
Term
Types of tissue degeneration in COPD:
Definition
Panacinar - distal alveoli & acini
Centriobular - bronchiolar destruction
Term
What is the cellular pathology involved in hyperinflation of the lungs & air trapping?
Definition
Loss of elastic tissue due to parenchymal destruction (airways lose ability to recoil)
Term
Bullae
Definition
Outpouchings of the lung seen in smokers w/ hyperinflated alveoli; caused by loss of alveolar tissue
Term
Why does loss of alveoli cause airway closure/limited flow?
Definition
All alveoli are interconnected and interdependent; they are tethered together to keep the airways open
Loss of some alveoli, parenchymal attachments fall apart & airways collapse (limits flow)
Term
What are the pathophysiological impacts of COPD?
Definition
Loss of area for gas exchange (loss of alveoli)
Mismatch between ventilation/perfusion & diffusion - lose O2 diffusion capacity
Loss of elastic fibers - air trapping & hyperinflation
Term
What is the most preventable risk factor for COPD?
Definition
Smoking (tobacco)
Term
What has the greatest effect on reducing respiratory disease in adults?
Definition
Quitting smoking
Term
What is essential for COPD diagnosis?
Definition
Objective demonstration of airway obstruction by SPIROMETRY
Term
What is the purpose of spirometry?
Definition
To measure lung volumes as a measure of pulmonary function
Term
What is the FEV1/FVC ratio which indicates obstruction?
Definition
< 0.70; NEEDED for COPD diagnosis
Term
Tidal Volume
Definition
Normal amount of air entering lungs after normal breath = 500 mL
Term
Vital Capacity
Definition
Maximum amount of air that can be moved in/out of lungs = 4600 mL
Term
Residual Capacity
Definition
Amount left in lungs after maximal expiration = 1200 mL
Term
Total Lung Capacity
Definition
VC + RV = 5800 mL
Term
What are the two categories of respiratory disease? Where do asthma and COPD fall?
Definition
Restrictive
Obstructive - includes both COPD & asthma
Term
When is COPD treatable?
Definition
It is treatable at ANY stage
Term
MRC Dyspnea Scale
Definition
Mild = 1 or 2
Moderate = 3 or 4
Severe = 5
Term
Continuum of management strategies of COPD:
Definition
Start w/ smoking cessation & exercise
With progression, use SABD prn; may need LABD if necessary
More severe forms require ICS or LABA; possible O2 therapy/surgery with end-stage
Term
What is the most effective intervention for COPD?
Definition
SMOKING CESSATION
Term
5 A's in COPD
Definition
Ask, Advise, Assess, Assist, Arrange
Term
Guidelines for exercise therapy in respiratory disease
Definition
Frequency = 3-5 times per week
Moderate shortness of breath
30-45 minutes/session
Activities = running, cycling, swimming
Term
COPD Pharmacotherapy in MILD Cases:
Definition
SABA prn -> LAAC/LABA + SABA prn
Term
COPD Pharmacotherapy in MODERATE cases:
Definition
Infrequent AECOPD (<1/year)
LAAC/LABA + SABA prn -> LAAC + ICS/LABA + SABA
Term
COPD Pharmacotherapy in SEVERE cases:
Definition
Frequent AECOPD (>1/year)
Same as moderate + theophylline
Term
What is the normal function of ACh in the airways?
Definition
Causes smooth muscle contraction to NARROW the airways
Mediated by parasympathetic innervation to airways by CN X (vagus nerve)
Term
Function of AC drugs
Definition
Block ACh receptors in the airway to prevent airway narrowing from smooth muscle contraction
Term
Normal function of B2-adrenergics in airways:
Definition
Function as BRONCHODILATORS to relax airway smooth muscle
Term
How to B2-agonist drugs function:
Definition
Cause relaxation of all airway smooth muscle to prevent narrowing (counteract the effects of ACh induced airway narrowing)
Term
AECOPD
Definition
Sustained worsening of dyspnea, cough, or sputum production causing increased use of meds
Known as "heart attacks" of lung disease
Term
What is the most frequent cause of hospital visits & death in COPD patients?
Definition
AECOPD episodes
Term
What are related to the probability of surviving AECOPD episodes?
Definition
Age, length of exacerbation, frequency of exacerbations
Measured by Kaplan-Meier survival curve
Term
What is the basis of expiratory flow limitation; i.e. what is the principle behind it?
Definition
As you increase expiratory effort, expiratory flow increases to a maximum after which further efforts are not matched by increased flow
At a given point, expiratory flow becomes independent of effort
Term
Pulmonary volumes on the flow vs. volume curve of expiratory flow:
Definition
TLC on left side, RV on right side
Diameter of small circle = tidal volume
Entire length of curve = VC of lung
Term
What is the difference in flow between normal breathing and maximum expiration?
Definition
This is the expiratory flow reserve - present during quiet breathing; gives us the ability to increase breathing rate to increase expiratory flow
Term
What is the difference in expiratory flow reserve in a normal individual vs. one with emphysema (COPD)?
Definition
The flow reserve is greatly reduced in the COPD patient at ALL lung volumes, cannot increase their rates of respiration to increase flow
Term
What is the compensation mechanism to increase flow in COPD patients?
Definition
They HYPERINFLATE their lungs to increase tidal volume and thereby increase flow (increase TLC)
This increases the work of breathing though, and worsens dyspnea
Term
What causes expiratory flow limitations?
Definition
DYNAMIC COMPRESSION of the airways
Term
What is the physiology behind dynamic compression?
Definition
Chest wall exerts pressure on the lung to create a positive pleural pressure difference
As the airways move closer to the mouth, the pressure within them decreases as it is expended to overcome flow limitations
At a point the pressure outside the airways > pressure within airways - causes compression and limitation of flow
Term
Factors affective dynamic compression:
Definition
Increased peripheral resistance = increased pressure loss -> this moves the equal pressure point further w/in the periphery of the lung (seen in COPD); more limitation
Loss of tissue recoil from low lung volume or parenchymal loss
Airway stiffness/rigidity
Term
Asthma (Definition)
Definition
Inflammatory disorder of the airways chracterized by paroxysmal or persistent symptoms - dyspnea, tightness in chest, wheezing - associated with VARIABLE airflow limitation & hyperresponsiveness of the airways to certain stimuli (hypersensitivity response)
Term
Airflow limitation in COPD vs. ASTHMA
Definition
Asthma = VARIABLE limitation
COPD = persistent flow limitation
Term
What inflammatory cell types are involved in asthma?
Definition
Eosinophils (predominant), mast cells, neutrophils (acute episodes, smokers), T lymphocytes, macrophages, RTE
Term
Flow limitation and reversibility in COPD vs. asthma:
Definition
Asthma = variable limitation; spontaneously reversible often
COPD = fixed limtation; only partially reversible
Term
Gender ratios in asthma over time:
Definition
Childhood = 2:1 in favor of boys
Teenagers = more prevalent in girls
Adults = 1:1 ratio
Term
What is the primary immunohistological characteristic of asthma?
Definition
Inflammatory cell infiltration by eosinophils
Term
Effects of inflammation in asthma:
Definition
Local edema in mucosa
Bronchoconstriction of airway smooth muscle
Mucous secretion
ALL of the above contribute to a narrowing of the airways, with this being at least partially reversible
Term
What are the two types of asthma?
Definition
Extrinsic & intrinsic
Term
Extrinsic Asthma
Definition
Type I hypersensitivity (IgE); inhaled allergens
Familial history of atopy
Childhood onset
Term
Intrinsic Asthma
Definition
Stimuli target hyperresponsiveness of airways - cold air, stress, infection, drugs (aspirin)
Adult onset
Term
Symptoms suggestive of asthma:
Definition
Dyspnea, tight chest, wheezing, productive cough
Worse at night & early morning - chronobiological symptoms
Develops after exposure to irritant/allergen
Improves w/ bronchodilator or ICS
Term
What is the preferred PF criteria for asthma diagnosis?
Definition
Spirometry
Term
Spirometry criteria for asthma diagnosis:
Definition
Reduced FEV1/FVC - children < 0.8-0.9; adults < 0.75-0.8
Increased FEV1 w/ bronchodilator - children >12%; adults >12% + > 200 mL
Term
Alternative diagnostic measure for asthma diagnosis?
Definition
Peak expiratory flow (PEF) variability
Need to see PEF increase post-bronchodilator
Can use diurnal variation in ADULTS only
Term
What does methacholine mimic?
Definition
ACh
Term
Name one drug unique to asthma treatment and one drug unique to COPD treatment:
Definition
Asthma = LTRA
COPD = LAAC
Term
What becomes the main driving force for inspiration in emphysema?
Definition
The low pO2 (hypoxic drive)
Chronically elevated pCO2 downregulates central chemoreceptors, so peripheral receptors respond to hypoxia instead
Term
How does air trapping lead to hyperinflation in COPD?
Definition
Air trapping is due to loss of elastic fibers in walls of airways - leads to higher RV
Higher RV progressively leads to hyperinflation (increased TLC)
Term
When is COPD treatable?
Definition
AT ANY STAGE - never too late to stop smoking or start pharmacotherapeutic intervention
Term
Difference between moderate and severe COPD
Definition
Moderate = infrequent AECOPD
Severe = frequent AECOPD (>1/yr)
Term
Example of anti-cholinergic & example of B-agonist
Definition
AC = Triotropium Bromide
BA = Salbutamol
Term
What are AECOPD's also known as?
Definition
The "heart attacks of lung disease"
Term
How is the expiratory flow reserve used to increase expiratory flow?
Definition
Use it INCREASE RATE of breathing (increases flow)
Term
How do COPD patients try to increase expiratory flow?
Definition
Increase TLC (hyperinflate lungs) to try to increase expiratory flow, leads to severe dyspnea
Term
Why does the expiratory flow increase compensation mechanism lead to increased dyspnea?
Definition
Because the pt hyperinflates lungs to try and increase expiratory flow (increases tidal volume
However, this hyperinflation increases work of breathing, leading to worsening dyspnea
Term
What are all symptoms of asthma associated with?
Definition
Variable flow limitation (key aspect of pathology)
Term
Onset of intrinsic vs. extrinsic asthma?
Definition
Extrinsic = childhood (IgE mediated)
Intrinsic = adult (hyperresponsive airways are targeted)
Term
What 3 objective measures are needed for an asthma diagnosis?
Definition
Reversible airway obstruction (post-bronchodilator)
Variable flow limitation over time
Airway hyperresponsiveness
Term
Difference of dose-response curve in asthmatics vs. normal for methacholine challenge
Definition
Normal - sigmoidal decrease in FEV1, get plateau (maximum decrease)
Asthma - linear decrease; no plateau is seen - with increasing concentrations will always see further decrease
Term
What is the function of inhaled corticosteroids/LTRA?
Definition
Prevent bronchoconstriction of airways
Term
Difference between ICS & bronchodilator use in asthma vs. COPD:
Definition
ICS - essential for asthma, only helpful for AECOPD
BD - prn for asthma, regular for COPD
Term
Course of progression of asthma vs. COPD:
Definition
Asthma - stable course (w/ exacerbations)
COPD - progressively worsening (downward spiral)
Term
What is inflammation mediated by in asthma vs. COPD:
Definition
Asthma = EOSINOPHILS
COPD = NEUTROPHILS
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