Pathology Flashcards
What is an obstructive lung disease?
Restricted airflow especially on expiration
What is a shunt?
When blood passes through the lungs without participating in gas exchange.
What is dead space?
Air in the respiratory system that is not participating in gas exchange
Name the types of dead space
Anatomical, alveolar and physiologic (total) dead space
What are the differences between asthma and COPD
COPD is almost all smokers, this is not significant in asthma.
COPD is rare in <35 yo but asthma is very common in <35yo.
COPD has a productive cough which is very uncommon in asthma.
COPD breathlessness is persistent and progressive while breathlessness is asthma is variable.
COPD rarely wakes patents up with breathlessness/wheeze and variability in symptoms in uncommon however these are both very common in asthma.
What is COPD?
The combination of chronic bronchitis and emphysema.
Is COPD obstructive or restrictive ?
Obstructive
Risk factors for COPD
Smoking, pollution, dust,
Do chronic bronchitis and emphysema always occur together?
No not in the case of Alpha 1-antiprotease deficiency which causes emphysema alone.
What is chronic bronchitis ?
Chronic bronchitis is a cough which produces sputum most days for three consecutive months for two or more consecutive years
What does chronic bronchitis sometimes look like?
chronic bronchial asthma
What is emphysema?
Loss of alveolar tissue causing dilation in distal airways.
Types of emphysema
Centriacinar emphysema starts with bronchiolar dilation and then alveolar tissue is lost. It is found at the top of the lobes.
Panacinar emphysema infects all the alveoli in a whole area of lung.
Scar emphysema is no clinical effects and is just the formation of emphysema next to scars.
Periacinar empyema causes tissue loss at the edge of acini and if it leaks air into the pleural cavity then it causes a pneumothorax to develop.
What causes emphysema
Build up of elastase enzymes.
What deficiency causes a lack of anti-elastase enzymes?
alpha 1 antitrypsin deficiency
What are the main effects of emphysema?
Hypoxia throughout the body.
High blood pressure - Blood is diverted from the damaged areas, which creates more resistance in the lungs, which means your heart has to pump harder.
Cor-pulmonale (failure of the right side of the lung) which leads to hypertrophy and oedema.
Fibrosis - Forms from long term vasoconstriction makes the constriction even worse.
Secondary polycythaemia - Increase in erythropoietin makes blood thicker and makes heart pump even harder.
Symptoms of COPD
COPD presents with a cough, breathlessness, production of sputum, chest infections, wheezing, weight loss, loss of muscle mass, fatigue, swollen ankles, continued worsening of symptoms, cyanosis, raised JVP, cachexia, pursed lip breathing, hyperinflated chest (seen on X-ray), use of accessory muscles, peripheral oedema and acute exacerbations.
How is COPD diagnosed ?
COPD is diagnosed with a combination of symptoms, history and spirometry. A FEV1/FVC ratio of <0.7 is key to diagnosis. Chest X-rays, and mMRC breathlessness scale results, lung volume or transfer factors tests (Low results may indict COPD) and CT scans can all also be used to help diagnose it. Many people with COPD are not diagnosed.
What is a COPD acute exacerbation?
Worsening symptoms, chest tightening, temperature, fatigue, systematic upset (eating etc). Sometimes it can be fatal if the patient goes into respiratory failure.
A COPD acute exacerbation can be caused by a … or …. infection?
Viral or bacterial.
How is COPD managed?
Non-pharmacological (Most effective) = Smoking cessation, pulmonary rehabilitation, vaccination.
Pharmacological = SABA, LAMA, ICS and LABA.
How are COPD acute exacerbations managed?
Short acting bronchodilators, Steroids (Prednisolone 40mg per day for 5-7 days) and Antibiotics.
Is Asthma obstructive or restrictive ?
Obstructive
What causes/triggers asthma?
Asthma is a type I hypersensitivity reaction. Exacerbations are triggered by a large range of things i.e. perfume, pollen, dust, exercise etc
Risk factors for asthma
Genetics - Atopic gene, where hay fever, eczema, asthma and allergic rhinitis are all common.
Maternal or grandmaternal Smoking - Causes smaller lungs in offspring giving a higher chance of lung conditions.
Occupation - i.e. bakers or painters.
What is Asthma?
Difficulty breathing as a result of airway narrowing. Narrowing is caused by smooth muscle contraction, increased mucus, inflamed and thickened wall.
How do you diagnose asthma?
There is no clear test. However asthma will respond to treatment.
Symptoms of asthma
Wheeze (in all children and most adults), variability of symptoms through the day, cough (especially in the mornings or at night), chest tightness, shortness of breath.
What to look for in the history of a potential asthmatic?
Atopic conditions, triggers (i.e. pets, occupations)
Investigations for asthma
Spirometry. May be normal in an asthmatic (because they are not currently having an exacerbation),
FeNO
Bronchodilator reversibility test.
Peak flow monitoring - variability suggests Asthma.
CXR - May show hyperinflation or hyperlucent
How to diagnose a child with asthma
Spirometry (before and after medication), bronchodilator response test, then a responsive spirometry test.
Asthma differential diagnosis
COPD
Bronchiectasis
Cystic fibrosis
Tumour or foreign body (indicated by stridor)
Cardiac cause
Lung cancer (Indicted by finger clubbing or cervical lymphadenopathy)
Collapsed lung (Asymmetrical expansion or dull percussion)
Bronchiectasis (Crackles)
Management of asthma
Action plan
Inhalers. Metered dose inhalers (pMDI) are used with spacers and medicine is released in combination with inhalation. Dry / Powder inhalers (DPI) relies on sucking. There are Short acting B2 agonists (SABA) which are relievers i.e. salbutamol (MDI and DPI) and terbutaline (DPI).
Oral therapy i.e. leukotriene receptor antagonists, theophylline, prednisolone
Specialist treatment include omalizumab and mepolizumab and bronchial thermoplastic. These can only be delivered by very high specialists.
Treating children with suspected asthma
As a rule of thumb in children especially if quality of life is effected then give a trial of treatment and see if it relieves symptoms and if quality of life is not effected then watch and see.
In children ICS course is given for 2 months. The over the Easter (While coughs and colds are less) a holiday from the inhaler is given to check that the symptoms do come back. Treatment in children may cause the child’s total height to be 0.5-1cm less than would be otherwise.
Step up/step down approach in children
Step 1 - very low dose ICS Step 2 - very low dose ICS + SABA Step 3 - very low dose ICS + SABA + LABA Step 4 - low dose ICS + SABA or Low dose ICS + SABA + LABA or very low dose ICS + SABA + LTRA Step 5 -Refer to specialist care
Considerations before stepping up or down asthma treatment
Is the medication effective? If not is it because they don’t have asthma? or they aren’t taking the medication? or they aren’t taking the medication properly
What does a mild asthma exacerbation look like?
Use inhalers, oral steroids, treatment of trigger, establish early follow up plana and a back up plan with these patients. Management is done using SABA via spacer or SABA via spacer + pred
What does a moderate asthma exacerbation look like?
Increased symptoms but able to speak and complete sentences, heart rate is less than 110. Respiratory rate is less than 25. Here patients should be brought into hospital and any patients admitted to hospital should have a blood gas test done. Management is done using SABA via neb +pred or SABA + ipra via neb + pred.
What does a severe asthma exacerbation look like?
The inability to complete sentences in one breath, HR ≥110 and respiratory rate ≥25. Here Nebulizers (Salbutamol/Ipratropium), Oral/IV Steroid, Magnesium, Aminophylline, Triggers – infection/allergen, CXR, possibly Level 2/3 care. Management is done using IV salbutamol, IV aminophylline, IV magnesium (neb), IV hydrocortisone, finally Intubate and ventilation in last case resort.
What does a life threatening asthma exacerbation look like?
Is one of any of the following Grunting, Impaired consciousness, confusion, exhaustion, Bradycardia/ arrhythmia/ hypotension, PEF < 33% predicted or best, Cyanosis, Silent chest, Poor respiratory effort, SaO2 < 92%, PaO2 < 8kPa, PaCO2 normal (4.6 - 6.0kPa because you should have blown off a lot of CO2 and therefore have a low PaCo2)