Respiratory Flashcards
Explain the characteristics of respiratory epithelium and how it differs between the conducting and respiratory airway
Pseudostratified columnar cells with cilia
Conducting epithelium - thick layer of cells to restrict gas exchange. Contains layers of cartilage to keep airway open and mucus producing goblet cells
Respiratory epithelium - single layer of cells
What levels of the airway are conducting and which are respiratory
Conducting - 1-14 (transitional bronchioles at 15)
Respiratory - 16-23
What muscles are used in inspiration
Accessory muscles - elevate ribs and sternum
Principle muscles - external intercostals and diagram
What muscles are used during active expiration
Internal intercostals and abs
What are the characteristics of conducting epithelium that has remodelled
thickening of smooth muscle and basement epithelium.
Thickening of sub mucosal layer that folds inwards into the lumen
Hyperpnea
Increased breathing that matched the metabolic need
Apnea
Absence of airflow due to lack of respiratory effort or airway obstruction (failure to breathe)
Dyspnea
Sensation of laboured breathing (shortness of breath)
What is the effect of neuromuscular control on the work of breathing
It changes the mechanical work of breathing by adapting to the information from the sensors
What areas of the brain are active in breathing - both subconsciously and conscious
Subconscious breathing is regulated in the brain stem - inspiration neurons are always active and expiration neurons become active during active breathing.
As soon as breathing become conscious it is controlled by higher centers in the brain.
What is the only area in the body that can respond to hypoxic blood condition
Carotid Bodies
How does the carotid bodies send information to the brain
Carotid body sensors are located to access the blood heading to the brain. Chemo and baroreceptors are sent to the brainstem via the carotid sinus nerve.
What are responsible for controlling acclimatization
Carotid Bodies
What causes hypocapnia
Hypoventilation
What results from alveolar hypoventilation
Respiratory acidosis
What results from alveolar hyperventialtion
Respiratory alkilosis
What site in the airway is most vulnerable for full obstruction during sleep
Pharynx
How many pharynx obstructions have to occur during sleep for it to be deemed clinical (likely to lead to pathology)
> 5
What occurs during sleep that causes OSAS and how does one overcome it
When neuromuscular control to the head and neck relaxes during sleep, the pharynx can collapse on itself, closing the airway.
Active breathing is required to overcome the obstruction, opening the pharynx.
Explain the difference in SPo2 levels of a patient with OSAS when they are awake and asleep
Awake - flat line
Asleep - oscillatory drops in pressure as airflow is obstructed
What are 3 anatomical and 3 non-anatomical contributors to OSAS
anatomical - narrow airway, crowded airway, collapsible airway
non-anatomical - ineffective pharyngeal dilatory muscle activity in sleep, low arousal threshold to airway narrowing, unstable control of breathing
What are the benefits of oscillometery compared to spirometry
Oscillometry is recorded during normal breathing, thus requires less patient compliance (can be good with children)
Before you begin testing with oscillometry, what recordings must you obtain first
3 artifact recordings with coeffiecnt of variability of <10% in adults and <15% in children
What frequency is used in oscillometry testing
5-50Hz, but typically 5-26Hz. Up to 35Hz can be useful in children.
What does resistance and reactance tell us about the larger and peripheral airways
Resistance is the degree of obstruction in larger airways
Reactance is sensitive to changes in peripheral airway
On a ‘real axis’ for oscillometry:
- what does the length of the line represent
- what does the vertical position represent
- what does the angle between the two lines represent
- amplitude of the wave
- the line furthest ahead will peak first
- the angle determines the difference between the phases in the wave
On a ‘real axis’ in oscillometry:
- What is represented on the X axis
- What is represented on the Y axis
X axis is Resistance (Rrs)
Y axis is Reactance (Xrs)
What force is prevailing is the reactance in oscillometry is negative
Elastin
What force is prevailing is the reactance in oscillometry is postiive
inertance
Equation for impendance
pressure/flow
Explain the expected impendence graph of a healthy adult during an oscillometry test
reactance starts at negative number (dominated by elastin) and increases with increasing frequency and when it crosses the 0 line it starts acting with less elastin and more inertance. Resistance starts as positive and drops a little bit but never goes negative
Resonance frequency
When the reactance is 0 (occurs around 8-12Hz in adults)
What would we expect the impendance to look like in an individual with central airway obstruction
Reactance - same as healthy subject
Resistance - this will not decrease as the frequency increases
What would we expect the impendence to look like in an individual with peripheral airway obstruction
Reactance - this will remain low and likely not cross 0 until high frequencies
Resistance - will start very positive then drop to normal range as frequencies increase
What is the area of reactance in an impedance graph
Area under the curve until reactance = 0.
What does an increase in area of reactance suggest
change in peripheral airway
What are the 5 moments of hand washing
- before touching a patient
- before a procedure
after a procedure or bodily fluid risk
after touching a patient
after touch a patients surroundings
3 examples of obstructive airway disorder
Asthma, COPD, cystic fibrosis
What is the general approach to treating obstructive lung disease
reducing inflammation, relaxing airway muscles, improving lung function with lifestyle changes
What are 2 hallmark indicators of obstructive lung disease in spirometry testing
- Reduced FEV1/FVC% indicating significant difficult in expelling air from the lungs
- Peach expiratory flow significantly decreases
COPD
- Caused by
- What are the two primary conditioned associated with it
- Key symptom
- Caused by long term exposure to harmful irritants, commonly cigarettes
1. Chronic Bronchitis: inflammation and mucus buildup in airway
2. Emphysema: stretching of the alveolar - excessive mucus production which worsens overtime
How does emphysema reduce lung function
the destruction of the alveolar walls reduces the lungs natural recoil ability which normally helps push air out during exhalation. With an increased amount of air left in the lungs this further contributes to hyperinflation.
What chemical changes are associated with COPD
Hypecapnia
What is the effect of COPD on exercising individuals
Their increased work of breathing recruits more accessory muscles, so o they begin to fatigue quicker and the tolerance to exercise and everyday tasks becomes challenging.
What is the key identifying symptom of cystic fibrosis
Production of thick, sticky mucus
What is the genetic cause of cystic fibrosis
Destruction of the CFTR gene leads to dysfunctional Cl- transport into the cells causing water retention outside of the cells.
What are the effects of the FEV1, FVC and FEV1/FVC% on cystic fibrosis patients
FEV1 - reduced
FVC - reduced as exhalation becomes difficult
FEV1/FVC% - reduced
Asthma
Chronic inflammation of the bronchial wall, leading to mucus production and airway narrowing, reducing the efficiency of airflow
What are 4 tests/test markers used to diagnose Asthma
- Spirometry - FEV1/FVC% below lower limit of normal (<0.75)
- Peak expiratory flow - monitored over 2 week period and a variation of >20% is supportive of asthma
- Exhaled NO fraction - used when diagnosis isn’t made just off spirometry and challenge testing
- Bronchial challenge testing - bronchoconstrictor is administered then airway function is assessed after each incremental dose of bronchodilator.
What are common symptoms of restrictive lung disease
Dry cough, crackles on lung auscultation, clubbing of the finger, tachypnea
What are three examples of structural abnormalities that would lead to a restrictive lung disease
kyphoscoliosis, pectus excavatum, ankylosing spondylitis
How do structural changes in restricted lung change the work of breathing
the stiffness and restricted movement of the chest wall decreases compliance of the lungs, requiring more effect to breathe.
Leads to tachypnea and increased work of breathing as they try to compensate for the reduced lung volumes.
What is the effect of structural abnormalities causing restrictive lung disease on the FEV1/FVC%
FEV1 low
FVC low
FEV1/FVC% can remain the same or be elevated
How does neuromuscular disease lead to restrictive lung disease
Progressive weakness of breathing muscles impair ventilation
What is the effect on the FEV1/FVC% in people with restrictive lung diseases caused by neuromuscular disease
FCV1 - remains the same
FVC - decreases
FEV1/FVC% - can remain the same or be elevated
How does pleural effusion lead to restrictive lung disease
Fluid accumulates in the pleural space compresses lung tissue
What mechanical and chemical changes occur during restrictive lung disease due to pleural effusion
Compression of the lung increases the work of breathing and causes dyspnea
Hypoxia due to inefficient gas exchange
How does a pneumothorax cause restrcitive lung disease
Air in the pleural space during a pneumothorax disrupts negative pressure to keep the lung inflated leading to lung collapse and impaired ventilation
What lung volumes are particularly effected during a pneumothorax
TLC and VC drop significantly as the lung is unable to expand
Interstitial lung disease
- what is is characterised by
- risk factors
- management
characterised by inflammation and scarring of the lung interstitial, affecting the space around the alveoli
risk factors: exposure to drugs, autoimmune or idiopathic
anti-inflammatory, immunosuppressants, anti-fibrotic treatments
What effects to the FEV1/FVC% does interstitial lung disease have
FFEV1/FVC% may be the same or elevated depending on how much FVC drops
Idiopathic pulmonary fibrosis
- characterised by
- effect on FEV1/FVC%
- mechanical work of breathing
Characterised by progressive scarring of the lung interstitial, the tissue between the alveoli, which impairs gas exchange and lung elasticity
FEV1/FVC% could remain constant or elevate depending on how much FVC changes
Work of breathing increases due to stiffening of lungs and reduced compliance
What is idiopathic pulmonary fibrosis driven by on the cellular level
abnormal activation of fibroblasts, which proliferate and produce excessive collagen, leading to the formation of fibrotic tissue in the lungs
Hypersensitivity pneumonititis
- characterised by
- triggered by
- effect on FEV1/FVC%
Characterised by inflammation in the lungs due to repeated inhalation of organic particles, leading to an immune-mediated reaction in the alveoli and bronchioles
FEV1/FVC% can be the same or elevated depending on how much FVC drops
Sarcoidosis
- characterised by
- which symptom of sarcoidosis isn’t present in other restrictive lung diseases
- chemical changes
Characterised by the formation of granulomas in the lung parenchyma, leading to reduced lung compliance
Enlargement of lymph nodes are common in sarcoidosis
Hypoxia due to reduced diffusion capacity of alveoli
Tidal Volume
volume of gas entering the lung in each breath during quiet breathing
Forced Vital Capacity (FVC)
maximal expiration followed by maximal inspiration
Total lung capacity
volume of gas in the lung after one breath
Expiratory reserve volume (ERV)
volume of gas that can be expired from the end expiratory lung volume (EELV)
Inspiratory reserve volume (IRV)
volume that can be inspired from end inspiratory volume volume (EILV)
Vital capacity
volume of gas from maximum inspiration to maximum expiration
What happens to the pressure inside the alveolar as the lung inflates
The pressure in the alveolar sacs (originally 0) becomes negative causing flow of air into the lungs
Functional residual capacity
Volume of gas remaining in the lung upon relaxation of the lung/passive exhalation
What is the alveolar pressure and pleural pressure when at functional residual capacity
Alveolar = atmospheric
Pleural = -5cmH2O
What occurs to FRC when sitting and in obesity
Sitting - abdominal contents displaces towards the chest wall, reducing FRC
Obesity - reduced FRC
What is the most important muscle during expiration in exercise
Abdominals - these raise intra-abdominal pressure pushing the diaphragm upwards
What two tests have to be used to measure FRC, RV and TLC
Helium Dilution and body plethysmography
How does helium dilution work
Subject is asked to inhale and exhale in a closed-circuit spirometer containing a known concentration of helium and oxygen.
The amount of helium in the exhaled breath is compared to that of the inhaled breath
What does body plethysmography measure
total lung volume including residual volume and dead space
How does body plethysmography work
When teh patients breathes in, the volume of air in the lungs increases, causing a drop in pressure within the box (because the total volume remains constant).
Conversely, when the patient exhales, the volume decreases, causing an increase in pressure.
Boyles Law states that pressure x volume is constant
Definition of ventilation
total volume of gas exchanged from athmosphe and lungs in 1 minute
Definition of alveolar ventilation
minute volume of gas entering the alveolar region
Equation for alveolar ventilation
total ventilation (VE) - Dead space (VD)
Where does the entire concentration of CO2 in expired gas come from
Only comes from the alveolar, so the alveolar volume would determine the amount of CO2 in expired air
In healthy subjects what are the PCO2 of alveolar gas and arterial blood and what does this allow
They should be virtually identical allowing for PaCO2 to estimate alveolar ventilation
What is the relationships between CO2 production, alveolar ventilation and PaCO2
If CO2 production remain constant and alveolar ventilation halves, PaCO2 doubles
(alveolar ventilation and PaCO2 are inversely proportional)
As work rate increase throughout exercise what is the primary contributor to the increase in ventilation
Tidal Volume increases
During exercise in healthy subjects, as tidal volume reaches the critical lung volume, what is modified to allow for the increase in work rate and ventilation
Predominately from an increase in respiratory rate and associated shortness of expiration and inspiration duration
As work rate peaks during exercise and ventilation increases what can then occur to the tidal volume
As ventilation increases, disproportate increase in respiratory rate can cause tidal volume to decrease
In healthy subjects during exercise what does their compliance curve look like
Lung expansion occurs over a near-linear region of the compliance curve, decreasing the elastic work of breathing
What occurs to the EELV in healthy subjects during exercise and how is this advantagous
EEVL decreases
Allows the recoil of the compressed thoracic cage to ‘assist’ the inspiratory muscles during the subsequent inhalation
What occurs to EELV in patients exercising with COPD
When VE demand become exceptionally high, the time of expiration required to accommodate the increase in respiratory rate can predispose to expiratory flow limitation and ‘dynamic hyperinflation’ so EELV increases
In COPD patients who are exercising, their EIVL changes, what is the results of this change
EILV increases (less inhalation time due to respiratory rate increase)
Increase in EILV towards limiting levels, compromising the inspiratory muscles and reducing the scope of tidal volume increase by encroaching on the flatter upper regions of the compliance curve
In COPD what is dynamic hyperinflation attributed to (3)
- Lower expiratory flows from decreased lung recoil
- Higher airway resistance
- Insufficient time to complete expiration before the next inspiration when the respiratory rate increases during exercise
What factors related to tidal volume result in dynamic hyperinflation in patients with ILD during exercise
- Inability to expand tidal volume appropriately die to thoracic restriction during the increased metabolic demand of exercise
- High tidal volume and the plateau of this early in exercise
What is the effect on respiratory rate of dynamic hyperinflation in ILD patients
Respiratory rate increases early and very steeply
Where on the compliance cure does ventilation operate in patients with ILD
Operates in the flat region due to static lung compliance
What is the effect on transfer factor of carbon monoxide in ILD and why
Disruption of the pulmonary microvasculature and the alveolar-capillary interface causing impaired gas exchange and decreased TLCO
What occurs to the oxygen levels in the blood during exercise in ILD patients
arterial hypoxemia is common during exercise and can occur early in ILD
What occurs to the work of breathing during exercise in ILD patients and why
Work of breathing increases dramatically in order to overcome the high elastic load of the stiff lungs while breathing close to TLC
What are the 3 main classes of bronchodilators used to treat asthma
Beta-2 agonists
Anticholinergics
Methylxanthines
What are the 3 main anti-inflammatory methods for asthma treatment
Corticosteroids
Biolics
Leukotriene Modifiers
What are 3 Biologics for Asthma and what to they each target
Omalizumab (anti-IgE)
Anti IL-5 monoclonal antibodies
Dupilumas (anti IL-4)
Cystic fibrosis monotherapy targets what type of mutations + example
Targets class 3 and 4 CFTR mutation (there is a protein but it doesn’t function)
E.g Ivacaftor
Cystic Fibrosis triple therapy targets what CFTR mutation and what is an example of this
Targets class 2 mutation (CFTR protein gets degraded before it reaches the surface)
E.g elexacaftor/tezacadtor/ivacaftor
What 4 factors determine the reference range for spirometry results
age, height, weight, ethnicity
What spirometry results must you get before concluding the test
Have to of conducted it a minimum of 3 times with at least two FVC readings with 5% or 150ml of each other
What three measurements does a spirometry trace measure
volume, time and flow
What would be the pathological interpretation for the following spirometry outcomes
1. FCV normal, FEV1 normals, ratio normal
2. FCV low or normal, FEV1 low, ratio low
3. FCV low, FEV1 low, ratio normal
4. FCV low, FEV1 low, ratio low
- Normal
- Airway obstruction
- Lung restriction
- Combination of obstruction and restriction
What airway, proximal or distal, determine airflow resistance at large lung volumes and drive the FEV1/FVC ratio
Proximal
What airway, proximal or distal, determines the airflow resistance at small lung volumes and drive the measurements later in maximal exhalation
Distal
Airway obstruction impairs lung emptying, what other two factors are usually associated with it
air trapping and hyperinflation that may reduce the FVC but more directly assessed by the residual volume measurement
Explain the shape of the spirometry curve for a normal, obstructive and restrictive lung
Normal - steep rise to FEV1
Obstructive - shallow rise so doesn’t match FEV1 of normal, but does release the same amount of gas (FVC is the same)
Restrictive - very small curve, doesn’t match FEV1 or FVC
According to the GIL, what z scores are associated with different severity of disease
Greater than -2.5 = mild
-2.5 - -4.0 = moderate
less than -4.0 = severe
According to GIL, what FEV1 is associated with different levels of severity
More than 70% = mild
50%-70% = moderate
35%-50% = severe
less than 35% = very severe
Is someone has a reduced FEV1 this tells you they likely have which category of disease
Obstructive
What results are required in a bronchodilator response test to be indicative of asthma
There needs to be at least a 10% change in dilation upon administering the bronchodilator
What can a bronchodilator test aid in differentiating between
COPD and asthma
Salbutamol, terbualine and ipratroium are all typs of what
bronchdilators
Explain the morphology of the flow volume loop in in normal, obstructive and restrictive conditions
Normal - Rapid increase and stead decrease exhalation. Peak volume 6L, broad and deep inspiration
Obstructive - think shark fin. Volume could be normal or reduced. In general smaller on all aspects
Restrictive - Much more similar in shape to normal curve, but smaller in all values.
Adverse effects to doing spirometry
Respiratory alkalosis as a result of hyperinflation
Lightheadedness/fainters
Headache
Coughing
What are some absolute contraindications of spirometry
Heamodynamic instability
Recent MI
Respiratory infection, pneumothorax, pulmonary embolism
Retinal detatchment
What are some relative contraindication to spirometry
Patient cant follow instructions
Patient can hold the mouthpiece
Recent abdominal surgeries
Hypertension
What does DLCO measure
The surface area of the lung available for has exchange
How do they perform DLCO. What gas is used and why
Carbon monoxide is used as it has a high affinity to Hb similar to oxygen.
During a 10 second breath-hold, DLCO measures uptake of carbon monoxide
What factors can influence the alveolar membrane gas diffusion efficiency and what law defines this
Fick’s Law
- Surface area
- Thickness
- Pressure
- Solubility of the gas
How does the single breath technique work in DLCO measurements
patient is asked to full exhale to RV then to rapidly inhale the gas. They hold their breath for 10 seconds at TLC and exhales the gas.
The exhaled gas is collected for analysis
How does the intrabath technique work for DLCO measurements
They CO is measured during different phases of exhalation to measure the gas diffusion capacity at different lung volumes
How does the rebreathing technique work for DLCO measurements
Patient takes multiple breaths in a closed circuit and the amount of CO absorbed it measured
In what diseases is DLCO useful for aiding in diagnosis
Parenchymal and non-parenchymal lung disease
What percentage of DLCO is associated with differing levels of severity
> 75% Normal
60% of LLN Mild
40%-60% Moderate
<40% Severe
What disease can primarily affect DLCO testing
Anaemia
What is the equation for DLCO
DLCO = Va x Kco
Va = number of contributing alveolar unnits measured by tracer gas (helium)
Kco - amount of CO absorbed over unit time
What diseases would we expect for there to be a decreased DLCO
Emphysema - due to alveolar destruction
Smoking
Interstitial Lung Disease - pulmonary fibrosis and thickening of the membrane
What diseases would we expect with a normal DLCO and restictive pattern on the PFT
A normal DLCO with a restrictive pattern on spirometry would suggest neuromuscular or chest wall disorder
What diseases would we expect for there to be a decreased DLCO and normal spiromoetry
In dyspnoea cases with unknown ethology, normal spirometry with low DLCO increases the likelihood of pulmonary vascular disease
Obestity, asthma, good pasture syndrome, lupus
Why would you perform a muscle strength test
Someone is suspected of a neuromuscular disease
Lung function test show reduced C or and increase DLCO with unknown eteology
What three measurements are taken during a muscle stregnth test
Maximal Inspiratory Pressure
Maximal Expiraotry Pressure
Sniff Nasal Inspiratory Pressure
In muscle strength testing, what values of inspiratory pressure and SNIP are clinically significant of muscle weakness in men and woman
MIP - >80cmH2O men, >70cmH2O women
SNIP - >70 cmH2O men, >60cmH2O women
What values of FVC, VC, MIP, MEP and SNIP are indication of needing non-invasive ventilation
FVC - <50% predicted
VC <60% predicted
MIP <60cmH2O
MEP <40cmH2O
SNIP <40cmH2O
What two issues is arterial blood gas analysis good for identifying
potential respiratory derangements or metabolic derangements
What is the normal PaO2
11-13.5kPa
Normal PaCO2
4.5-6kPa
Normal pH of blood
7.35-7.45
Normal SaO2
95%-100%
What PaO2 would be indicative of needing long term oxygen in chronic lung patients
<7.3kPa
Explain the morphology of a flow-volume loop of someone with variable extra thoracic obstruction
Give some examples of extra thoracic obstruction
Expiratory phase is normal but the inspiratory phase is flattened (this is hallmark of someone struggling to keep their upper airway open during inspiration)
usually involves obstruction in the upper airway - vocal cord dysfunction, vocal cord paralysis, tracheomalacia
Describe the morphology of a flow-volume loop for a patient with variable intrathoracic obstruction and give examples of these diseases
Inspiratory phase is normal, but expiratory phase is truncated in height
intrathoracic tumours and bronchial compression from masses
What does capnography measure
measures the concentration of end tidal volume of carbon dioxide in exhaled breath, providing continuous, real time assessment
In capnography, what levels are considered normal, elevated and low and what can cause these
35-45mmHg normal
>45mmHg elevated - hypoventilation, respiratory depression, increased CO2 production
<35mmHg low - hyperventilation, decreased cardiac output, pulmonary embolism
How do exhaled nitric oxide fractions differ between children and adults
Children will have a decreased FeNO exhaled
For an obstruction to be considered apnea, what percentage of the airway needs to be blocked and for how long
> 90% needs to be blocked for longer than 10 seconds
What does the AHI measure
Number of apneas and hypopneas per hour of sleep
What is hypopnea
This is a >30% obstruction in the airflow that lasts for longer then 10 seconds
What is ODI
number of oximetry decreases in an hour
What is the Mallampati Score
This measures the risk of obstructive sleep apnae by looking at the gap at the back of the mouth when someone sticks out their tounge
central vs obstructive sleep apnea
Central sleep apnea occurs because the brain doesn’t send proper signals to the muscles that control breathing. This condition is different from obstructive sleep apnea, in which breathing stops because the throat muscles relax and block the airway
What are the broad difference between the 4 different types of respiratory tests done during sleep
Type I - full tests + scientist observation (>7 channels)
Type II - full test, no observation (>7 channels)
Type III - >4 channels
Type IV - >1 channel
What disease are they likely looking for if they are performing a type I respiratory sleep test
neuromuscular sleep disorders
What is the normal REM latancy
90 Minutes
How many delta waves are required to move from stage 2 sleep to stage 3
20% of the waves need to be delta to move onto stage 3
Stage 1 sleep waveforms
Beta and alpha waves
What occurs to the chemoreceptiveness of the brain during sleep
The sensitivity to CO2 and PaO2 is decreased
Stage 2 sleep wave forms
Theta wave with K complexes
What are K complexes in sleep
sharp negative monophasic or polyphasic waves followed by a slower positive wave
they must persist for 0.5 seconds
Could also see sleep spindles
REM sleep waveforms
resemble Beta waves
no K complexes or sleep spindles
Stage 3 sleep waveforms
Delta waves
What does a CPAP do
Provides positive pressure during expiration to avoid the airway from collapsing
What does an ASV do
This adapts pressures during someone sleeping as their minute ventilation decreases
What neurotransmitter is used in the somatic nervous sytem
Ach
What neurotransmitter is used in the autonomous nervous system
SNS - noradrenaline
PNS - Ach
What are the two receptors that the sympathetic nervous system act on
Alpha 1 - muscle contraction
Alpha 2 - inhibits adrenergic responses
Beta 1 - vasocontraction
Beta 2 - Dilation in airway
What are the three types of beta-2-agonoists
SABA - short acting (e.g salbutamol)
LABA - long acting (e.g salmeterol)
ULABAs - ultra long acting (e.g indacterol)
What two receptors does Ach primarily act on in the parasympathetic nervous system and what are the effects of both of these receptors
M2 - inhibits relaxation of smooth muscle
M3 - bronchocontriction
What type of bronchodilators are commonly used in COPD
Anticholinergic bronchodilators
What are two types of anticholenergic bronchodilators used to treat COPD
SAMA - short acting (e,g ipratropum bromide)
LAMA - lasts 24 hours (e.g tiotropium)
What is the key factor in making a diagnosis of obstructed airway disease when performing bronchodilation test
The FEV1/FVC ratio must drop less than 0/7 to confirm the presence of persistent airflow limitation
What type of disease would be suggested if a patient had a normal DLCO with a restrictive pattern on PFT
neuromuscular or chest wall disorder
What can cause a decrease in DLCO
COPD, emphysema, smoking, ILD, pulmonary fibrosis
What can cause an increase in DLCO
obesity, asthma, which are characterised by large lung volumes
What is radial traction
Elastic fibres of the surrounding alveoli pull on the walls of small airways and hold them open.
The higher the elastic recoil of the lungs, the greater the radial traction will be.
Radial traction helps to prevent airway collapse in expiration.
What is normal breathing rate
20 breaths per minute
What is hypersomnolence
An inability to stay awake & alert during major waking episodes, resulting in periods of irrepressible need for sleep / unintended lapses into drowsiness or sleep
What sort of sensor is a carotid body
Chemoreceptor
