RESP Flashcards
What is FEV1?
The force expiratory volume in 1 second (Max inspiration followed by max exparation)
How much of the vital capacity can healthy individuals expire in 1 seconds?
80% of vital capacity
What is vital capacity?
The maximal volume of air that can be expired following maximum inspiration
What is inspiratory reserve volume?
The amount of air that can be inhaled above tidal volume during a forceful breath in.
What is tidal volume?
The amount of air that moves in and out of the lungs with each respiratory cycle
What is functional residual capacity?
The amount of air remianing in the lungs at the end of a normal exhalation
What is residual volume?
The volume of air remaining in the lungs after maximum forceful expiration
What is expiratory reserve volume?
The volume of air, above normal tidal volume that can be exhaled during a forceful breath out
What is vital lung capacity?
The maximum amount of air you can forcibly exhale after fully inhaling.
What is the average tidal volume?
500ml male
400ml female
What is FVC?
Forced vital capacity–> The total amount of air forcibly expired.
What is an FEV1 or FVC result compared with?
The predicted value for that patient: if it’s 80% or greater than the predicted value then the result is normal.
What is the different between the FEV1 and FVC test?
FEV1 is the forced expiratory volume in 1 second, whereas FVC is the full amount of air that can be exhaled in a complete breath
Which test is better (FEV1/ FVC) and why?
FEV1 is more reproducible
What does a low FVC indicate?
Airways restriction
What is the FEV1/ FVC ratio?
The proportion of FVC exhaled in the 1st second
What does it indicate the if the FEV1/ FVC ratio is below 0.7?
Airways obstruction
Why does a low FEV1/FVC ratio indicate airway obstruction?
The FEV1 is reduced due to the obstruction but the overall capacity doesn’t change
What does a normal/ high FEV1/FVC ratio with low FVC (and FEV1) percentages (<80%) indicate?
Airways restriction
Why does a high FEV1/ FVC ratio indicate airway restriction?
Easy for them to breathe out quickly but low FVC as they can’t exhale fully
Which of inspiration and expiration is an active process?
Inspiration
What structures does air move through to get to the lungs and what are the two zones?
Conducting airway:
Trachea–> Main bronchi–> Lobar bronchi–> Segmental bronchi–> Terminal bronchioles
Respiratory airway:
Respiratory bronchioles–> Alveolar duct–> alveolar sac
What happens during inspiration?
The diaphragm contracts and flattens and the external intercostal muscles elevate the ribs and sternum.
The volume increases and pressure decreases, meaning the environmental pressure is now greater so air rushes in down a pressure gradient
What happens during expiration?
Relaxation of the diaphragm and external intercostal muscles, decreasing the volume of the thoracic cavity and increasing the pressure, forcing air to move out.
What is airways obstruction and what are the main causes?
When the lungs are unable to expel air properly during exhalation:
COPD, asthma, cystic fibrosis
What is airways restriction and what are the main causes?
When the lungs are unable to fully expand, limiting the amount of O2 taking in:
Pulmonary fibrosis, sarcoid
What is type 1 respiratory failure?
Low oxygen levels in the blood (hypoxaemia) with either a normal or low CO2 level.
What is type 2 respiratory failure?
Low oxygen levels with high carbon dioxide. (2 changes–> low pO2 + high CO2)
What is the most common cause of type 1 respiratory failure?
Pulmonary embolism (that causes a V/Q mismatch)
What is the most common cause of type 2 respiratory failure?
Hypoventilation
What is V/Q mismatch?
When part of the lung receives oxygen without blood flow or vice versa (there is blood flow without oxygen.)
What causes Type 1 respiratory failure?
The lungs being unable to meet the demands of the body due to: V/Q mismatch High altitude Shunting Asthma Pneumonia Diffusion impairment
Why does high altitude cause type 1 respiratory failure?
Low oxygen levels
What is shunting and why does it cause type 1 respiratory failure?
When a hole in the heart
means that deoxygenated blood can mix with oxygenated, reducing the overall pressure of O2 in the blood
What is diffusion impairment?
When O2 is not able to diffuse into the blood
What causes Type 2 respiratory failure?
Pump failure so that CO2 can't be removed quick enough and/or O2 cannot arrive at tissues quick enough (poor ventilation) caused by: Depressed central respiratory drive Neuromuscular dysfunction Mechanical defect COPD asthma
What is the name for increased CO2 in the blood?
Hypercapnia
What are the signs of hypercapnoea?
Racing pulse Flapping tremor Confusion Drowsiness Reduced consciousness
What is the transfer co-efficienct?
The measure of the ability of oxygen to diffuse across the alveolar membrane
How is the transfer co-efficient calculated?
By inspiring a small amount of CO, holding breath for 10 seconds at total lung capacity and measuring the amount of gas transfered.
What test is used to measure lung function?
Spirometry
What does spirometry involve?
Different breathing exercises into a machine that measures volumes of air and flow rates.
What is reversibility testing?
Giving a bronchodilator (salbutamol) prior to repeating spirometry to see the impact it has on results
What is peak flow?
Measure of the fastest point of a persons expiratory flow of air.
How is peak flow measured?
Peak flow meter–> stand tall, take deep breath in, make a good seal around the device and blow as fast and hard as possible. Repeat 3 times.
When is peak flow useful?
In obstructive lung disease (e.g. asthma) to see how well it is controlled and how sever an acute exacerbation is.
What is COPD?
Chronic obstructive pulmonary disease: non-reversible, long term deterioration in air flow through the lungs caused by damage to lung tissue.
What is the most common cause of lung damage in COPD?
Smoking
What triggers exacerbations of COPD? (worsening of lung function)
Infections
What is the typical presentation of suspected COPD?
Long term smoker presenting with: Chronic shortness of breath Cough Sputum production Wheeze Recurrent respiratory infections.
What other diagnoses should be considered during a COPD diagnosis?
Lung cancer, fibrosis, heart failure
How is breathlessness assessed?
MRC Dyspnoea scale:
Grade 1: Breathless on strenuous exercise
Grade 2: Breathless on walking up hill
Grade 3: breathless that slows walking on the flat
Grade 4: Stop to catch breath after walking 100 metres
Grade 5: Unable to leave house due to breathlessness
How is COPD diagnosed?
Clinical presentation + Spirometry
What will spirometry show in a patient with COPD?
An obstructive picture: Overall lung capacity is not as bad as their ability to quickly blow air out of the lungs.
What will the FEV1/FVC ratio look like in COPD?
<0.7 as it is obstructive. (Low FEV1)
How is the severity of airflow obstruction graded?
Using FEV1--> Stage 1: >80% of predicted Stage 2: 50-79% Stage 3: 30-49% Stage 4: <30%
What investigations other than spirometry can help with diagnosis/ management of COPD?
CXR (excludes cancer) FBC (for polycythamia/ anaemia) BMI (to check changes in future) Sputum culture (to assess for infection) ECG/ Echo (assess heart function) CT thorax (to check for alternate diagnosis) Serum alpha-1 antitrypsin TLCO
What is TLCO and what happens to its levels in COPD?
Transfer factor for carbon monoxide–> decreased in COPD.
What is the essential management of COPD to prevent it getting worse?
Stop smoking
What is the first step in COPD treatment?
Short acting bronchodilator inhalers:
Beta-2 agonists or antimuscarinics
What are the most commonly used short acting bronchodilators?
Salbutamol or terbutaline (beta-2 agonists)
What is the action of beta-2 agonists?
Act directly on beta-2 receptors, causing smooth muscle relaxation and dilation of the airways.
What are antimuscarinics?
Block acetylcholine at muscarnic receptor sites, causing bronchodilation
When should short acting inhalers be used and how often can they be?
Should be used when you feel breathless, up to 4 times a day.
How quickly do short-acting bronchodilators work and how long do they last?
Usually within a few minutes, and last 4-5 hours
When would you move on to step 2 of COPD treatment?
If the patient is experiencing symptoms regularly throughout the day
What is the second step in COPD management?
Long-acting bronchodilators
What are the 2 types of long acting bronchodilators (with examples) and how long do they last?
LABA: Beta-2 antagonists (salmeterol, formoterol)
LAMA: Antimuscarinics (Tiotropium)
What would be added if a patient on a long acting bronchodilator was still becoming breathless or having frequent flare ups?
A steroid inhaler- usually in a combination inhaler with a long-acting medicine
What is the action of steroid inhalers ?
Reduced inflammation in the airways
What is the 4th line in COPD managment?
Trio inhaler: LABA, LAMA and ICS (Inhaled corticosteroid) combination
What other medications can be added in severe cases of COPD?
Nebulisers Oral theophylline Oral mucolytic therapy (breaks down sputum) Long term prophylactic antibiotics Long term home oxygen therapy
What is a nebuliser?
A machine that helps you breathe in a medicine through a mask or mouthpiece
When is long term home oxygen therapy used ?
In severe COPD that is causing problems such as chronic hypoxia, polycythaemia, cyanosis or heart failure secondary to pulmonary hypertension.
How does an exacerbation of COPD present?
Acute worsening of symptoms such as cough, SOB, sputum production and wheeze
How does CO2 make the blood acidotic?
Breaks down into carbonic acid.
What does a low pH with a raised pCO2 indicate is happening in the body?
Respiratory acidosis: They are acutely retaining (not able to get rid of CO2)
What does raised bicarbonate in the blood indicate?
Chronic retention of CO2
Why is there raised bicarbonate in chronic CO2 retention?
Because the kidneys respond to high levels of CO2 by producing more bicarbonate to maintain normal pH.
What happens to the acid levels in an acute COPD exacerbation?
The kidneys can’t keep up with rising levels of CO2 so the patient becomes acidotic despite having higher bicarbonate than normal.
What test would be done to check pO2, pCO2 and bicarbonate levels?
ABG
What are the two main COPD diseases?
Chronic bronchitis
Emphysema
(usually both)
What is emphysema?
Damage to the alveoli, causing loss of elastic recoil, with collapse of the small airways during expiration and enlarged air spaces.
What is usually the cause of early onset COPD?
Alpha-1 antitrypsin deficiency
What is Alpha-1 antitrypsin deficiency?
Condition caused by an abnormality in the gene for the protease inhibitor alpha-1-antitrypsin
What is the pathophysiology of alpha-1 antitrypsin deficiency?
Elastase is an enzyme secreted by neutrophils that digests connective tissues. Alpha-1-antitrypsin is protein produced in the liver that offers protection from elastase enzyme. In deficiency, the protection is no longer there so elastase can digest connective tissue
What is the cause of alpha-1 antitrypsin deficiency?
Autosomal recessive defect in the gene for A1T1 on chromosome 14
What are the two main organs affected by alpha-1 antitrypsin deficiency and what does it cause?
Liver–> Liver cirrhosis
Lungs–> Bronchiectasis and emphysema (COPD)
What is bronchiectasis?
Long term condition where the airways become abnormally widened, leading to excess mucus build up that can make the lungs more vulnerable to infection
What happens to the lung in the lack of a normal, functioning alpha-1-antitrypsin protein?
Excess protease enzymes attack the connective tissue leading to COPD (bronchiectasis and emphysema.)
How is alpha-1 antitrypsin deficiency diagnosed?
Low serum-alpha-1-antitrypsin
Liver biopsy
Genetic testing
High resolution CT thorax
What is chronic bronchitis?
Infection of the bronchi, causing them to become irritated and inflamed, and resulting in excess mucus production
How is chronic bronchitis classified?
Daily productive cough that lasts for 3 months of the year, and for at least 2 years in a row
What is the epithelium of the respiratory tract?
Ciliated, pseudostratified columnar epithelium with goblet cells.
What is underneath the epithelium?
Lamina propria:
Basement membrane
Loose connective tissue
What is the mucosa and what is it composed of?
The membrane lining the respiratory tract:
Epithelium + Lamina propria (basement membrane, loose connective tissue)
What is underneath the mucosa and what does it consist of?
Submucosa:
Smooth muscle
Connective tissue
Where are the bronchial mucinous glands located and what do they do?
In the submucosa
Secrete the majority of the mucus in the lumen of the bronchi
What layer is in the bronchi but not the bronchioles (underneath the submucosa)?
Layer of cartilage
What does exposure to irritants/ chemicals (e.g. smoking) do to mucus production and why?
Causes hypertrophy and hyperplasia of the bronchial mucinous glands in the bronchi, and goblet cells in the bronchioles increasing mucus production
Why is even a small increase in mucus a problem in the bronchioles?
It causes obstruction, leading to air trapping
What does smoking do to cilia?
Makes them shorter and less mobile, meaning its harder for them to move mucus
Why do people with bronchitis have a productive cough?
There is excess mucus and reduced cilia function, meaning they have to rely on coughing to move mucus plugs.
Why do patients with chronic bronchitis wheeze?
Due to narrowing of the passageway for the air to move in and out
Why do patients with chronic bronchitis have crackles (Rales)?
Caused by popping open of small airways
Why is there hypoxemia and hypercapnia in chronic bronchitis?
Mucus plugs block airflow, increasing the pCO2. This decreases pO2, meaning less oxygen gets to the blood and makes it harder for CO2 to get out of the blood.
What can increased CO2 levels in the blood called?
Cyanosis- blue discolouration of skin
What can patients with chronic bronchitis be referred as and why?
Blue bloaters:
as they may get cyanosis due to high CO2 levels.
What do blood vessels do in response to poor ventilation?
Vasoconstrict to try and move blood to somewhere where there is better ventilation- doesn’t work when large portion of the lung is affected
What does vasoconstriction of a large proportion of the lung lead to?
Increased pulmonary vascular resistance, leading to pulmonary hypertension
What can pulmonary hypertension cause
Right sided heart failure:
Cor pulmonale
What can mucus plugging in the airways also cause?
Lung infections behind the blockages
What damage to irritants (e.g. cigarette smoke) cause in emphysema?
Trigger an inflammatory reaction, attracting immune cells to the alveoli.
What do immune cells release that damage the alveoli in emphysema?
Release inflammatory chemicals and proteases (elastases and collegeaenases)
What is Bernoulli’s principle?
That air moving at high velocity must be at low pressure
What does loss of elastin do to the alveoli?
Weakens the walls, allowing them to be pulled inwards and collapse during exhalation.
Also makes them more compliant, so they expand and hold air in during inhalation.
Causes breakdown of septa, meaning alveoli merge to form large air spaces.
What does the loss of septa (alveolar walls) cause?
Neighbouring alveoli to merge and form a large air space, reducing the available surface for gas exchange.
Why does emphysema cause shortness of breath?
Because there is decreased gas exchange due to air trapping and reduced surface area.
What are emphysema patients sometimes referred to as and why?
Pink puffers:
Often exhale slowly through pursed lips to increase the pressure in the airways and stop them collapsing. Pink because they are oxygenated.
What symptoms occur after prolonged emphysema?
Hypoxemia
Cough (with some spitum caused by inflammation of bronchioles)
Barrel shaped chest
What are the X-ray findings in a patient with emphysema?
Increased anterior-posterior diameter
Increased lung field lucency
Flattened diaphragm
What are the 3 types of emphysema?
Centriacinar
Panacinar
Paraseptal
What is centriacinar emphysema and what is the most common cause?
Damage to the central/ proximal alveoli. Most common in smoking as smoke is not able to reach the most distal alveoli
What is panacinar emphysema and what is the most common cause?
Entire acinus is affected. Usually caused by alpha-1-antitrypsin deficiency
What is paraseptal emphysema and what can it cause?
Emphysema affecting the distal alveoli on the peripheries of the lungs. If these rupture, it can cause a pneomothroax.
Why does alpha-1-antitrypsin cause emphysema?
Elastase damages the elastin (as alpha-1-antitrypsin isn’t there to stop it) and so the alveolar walls are damages and collapse.
What do the blood vessels of the lungs do to try to counteract the poor ventilation and why doesn’t this work?
Vasoconstrict to try to divert the blood to somewhere with better ventilation, but the majority of the lung is affected so it doesn’t work
What can COPD do to the heart and how?
Cause Cor Pulmonale: right sided heart failure as the lungs vasoconstrict, leading to pulmonary hypertension.
What does the loss of elastic recoil in emphysema cause?
Expiratory airflow limitation and air trapping
What is the most common form of emphysema?
Centri-acinar emphysema
What does the combination of emphysema and chronic bronchitis lead to?
Severe airflow limitation
What are the causes of V/Q mismatch in COPD?
Air trapping: Caused by mucus plugging/ rapid collapse during expiration.
Small airways
What type of respiratory failure does COPD cause?
Both types (more commonly type 2)
What are the main signs and symptoms of COPD?
Dyspnoea, tachypnoea, barrel chest, SOB, chronic cough, recurrent chest infection.
Why is excess oxygen a bad idea when treating a COPD excacerbation?
It can depress their respiratory drive, slowing down the breathing rate and effort, leading to more CO2 retention.
How is oxygen given to treat COPD and under guidance from what?
Given through venturi masks (designed to deliver specific percentage concentration of oxygen) under the guidance of oxygen saturations and repeat ABG’s to ensure the optimum pO2 without increasing pCO2.
What is the target oxygen saturations in a patient retatining CO2?
88-92%
What is the target oxygen saturation in a patient not retaining Co2 with normal bicarb?
> 94%
How is a COPD exacerbation treated at home?
Prednisolone - anti-inflammatory (30mg o.d. 7-14 days)
Regular inhalers/ nebulisers
Antibiotics if signs of infection
How is a COPD exacerbation treated in hospital?
Nebulised bronchodilators (e.g. salbutamol, ipratropium)
Steroids
Antibiotics
Physiotherapy to clear sputum
What are the COPD treatment options in severe exacerbations not responding to first line treatment?
IV aminophylline
Non-invasive ventilation
Intubation/ ventilation
Doxapram (resp stimulant)
What is asthma?
Chronic inflammation of the airways that causes episodic exacerbations of bronchoconstriction
Does asthma cause airways restriction or airways obstruction?
Airways obstruction (caused by narrowing of airways)
What causes bronchoconstriction in asthma?
hypersensitivity of the airways (usually triggered by environmental factors)
What type of hypersensitivity reaction is asthma?
Type 1
What happens in a type 1 hypersensitivity reaction?
IgE mediated immediate hypersensitivity triggered by re-exposure to a specific allergen.
What are some allergens that trigger asthma?
Air pollution (smoke, car exhaust) Dust Pollen Animal hair Mites Mould Medications (aspirin)
What happens on subsequent exposure to an allergen in asthma?
The allergen binds to primed mast cells, stimulating them to degranulate and release pro-inflammatory mediators which cause an allergic reaction.
What is the main pro-inflammatory mediator and what is its action?
Histamine:
- Binds to H1 receptors on smooth muscle and causes bronchoconstriction
- Causes blood vessel dilation and increased permeability of cell walls, increasing blood flow to the area but also causing fluid to leak into the interstitium, causing oedema and urtica (hives)
What are the typical triggers of bronchoconstriction in asthma?
Infection Night/ early morning Exercise Animals Cold/ damp Dust Strong emotions
What happens when you come into contact with a trigger in asthma?
The hypersensitivity reaction causes smooth muscle spasms and increased mucus secretion, resulting in narrowing of the airways.
What happens after many years of having asthma?
Irreversible changes begin to take place–> permenant narrowing of the airways.
What are the key presentations of asthma?
Episodic symptoms which are typically worse at night. Dyspnoea Dry cough Chest tightness Wheezing Sputum
What do patients with asthma also commonly have?
Other atopic conditions: eczema, hayfever, food allergies
How is asthma diagnosed?
Clinical diagnosis based on history/ effectiveness of treatment
Fractional exhaled nitric oxide test (FeNO)
Spirometry
Peak flow test
In what different ways can asthma be classified?
Frequency of symptoms
FEV1
PEFR
Frequency of medication use
What is the stepwise process by which asthma managed?
- SABA (blue reliever inhaler)
- SABA + ICS (reliever + brown preventer inhaler)
- SABA + ICS + LABA/ LAMA
- Leukotriene receptor antagonist/ MART inhaler
What are the symptoms of an acute asthma attack?
Progressively worse shortening of breath
Tachypnoea
Use of accessory muscles
Symmetrical expiratory wheeze and tight chest sounds
What is the PEFR in a: - Moderate -Severe -Life threatening asthma attack?
M: 50-75% of predicted
S: 33-50% of predicted
Life threatening: <33% predicted
What are the stats in a severe asthma attack?
PEFR 33-50%
Resp rate >25
Heart rate >110
Unable to complete sentences
How do you know it is a life threatening asthma attack?
Oxygen saturation <92%
No wheeze (silent chest: no air entry at all)
Confusion/ exhaustion
Haemodynamic instability (shock)
How is a severe acute asthma attack treated?
Oxygen therapy to maintain O2 sats Nebulised salbutamol Prednisolone Aminophylline Magnesium sulphate infusion
How are sever asthma attacks monitored?
ABGs Respiratory rate Respiratory effort Peak flow Oxygen sats Chest auscultation
What is bronchiectasis?
Chronic inflammation of the bronchi and bronchioles, leading to permenant dilation of the airways.
What are the main causes of bronchiectasis?
Post infection (pneumonia, whooping cough, TB e.t.c.)
Ciliary dysfunction (Ciliary dyskinesia)
Cystic fibrosis
Airway obstruction (e.g. tumour, foreign body)
Allergic bronchopulonary aspergillosis
What happens in bronchioectasis?
The mucociliary elevators malfunctions, leading to mucus plugs forming. This allows bacteria to multiply and cause infection, damaging the bronchi and causing them to dilate and more mucus to be present, making it more vulnerable to infection. (viscious cycle)
What does chronic infection do to bronchi walls?
Causes immune cells to release cytokines that damage the ciliated epithelial cells and destroy the elastin in the walls, meaning over time they become dilated and filled with mucus.
Why does fibrosis occur in bronchioectasis?
Fibroblasts enter to try and repair the damage, depositing collagen which in the absence of elastin, makes the lungs stiff.
What are the key presentations of bronchiectasis?
Productive cough (lots of smelly mucus)
Shortness of breath
Wheezing
How is bronchiectasis diagnosed?
HRCT–> dilated bronchi
Lung function test (indicated obstruction)