S6 L1 COPD, Brochiectasis, Cystic Fibrosis Flashcards
What is COPD?
- What type of respiratory disease is this?
- What does it affect?
- Is it reversible?
- What ‘diseases’ does it include?
Causes of COPD
Chronic Obstructive Pulmonary Disease (COPD) is characterised by airflow obstruction that is not fully reversible, and is an umbrella term that encompasses both emphysema and chronic bronchitis. The airflow limitation is usually progressive (meaning that it cannot be cured or reversed). It is estimated that 1.2 million people in the UK suffer with COPD.
Aetiology:
The primary cause of COPD is smoking, meaning that most patients diagnosed with COPD will have a significant smoking history.
However, it is important to remember that other causes of COPD do exist, including air pollution, illicit drug use (e.g. smoking cannabis), occupational exposure to certain chemicals, and inherited conditions such as alpha-1 antitrypsin deficiency.
COPD - Pathophysiology
- Emphysema
- Chronic bronchitis
Emphysema:
Emphysema is a condition in which destruction of the terminal bronchioles and distal air spaces occurs, through the breakdown of elastin, a key component in alveolar walls. This breakdown leads to loss of integrity of the alveolar walls, and destruction of the surrounding small airways, meaning that all air spaces distal to the terminal bronchioles are permanently enlarged into useless spaces called bullae.
During expiration, when the pressure outside the airway rises, the smaller airways collapse due to the lack of surrounding elastic tissue keeping them patent, causing airway obstruction. The loss of elastic tissue in the lungs also causes them to hyperinflate, as the elastic recoil of the lungs has been destroyed.
Chornic Bronchitis:
Chronic bronchitis is a condition that occurs frequently in smokers, in which there is hypersecretion of mucus caused by inflammation of the large airways. There is also ciliary dysfunction, meaning that the normal clearance mechanisms for mucus are not effective. This means that patients with chronic bronchitis have a chronic productive cough, and are more prone to have frequent respiratory tract infections. The remodelling and narrowing of the airways caused by the inflammation causes irreversible airflow obstruction.
The airway narrowing and destruction of lung tissue predisposes patients with COPD to hypoxia, particularly during physical activity. This progressive hypoxia causes pulmonary vasoconstriction (to maintain the ventilation:perfusion ratio) and over time, leads to vascular smooth muscle thickening, with subsequent pulmonary hypertension.
A patient with COPD usually has features of both emphysema and chronic bronchitis, list some…
both conditions are progressive and not reversible. To summarise, the changes that occur as a result of COPD to the airways include:
- Enlargement of the mucus-secreting glands of the central airways leading to increased mucus production and a predisposition to infection in the mucus.
- Replacement of ciliated cells with goblet cells, and dysfunction of the ciliary cells that remain leading to stasis of the already increased amount of mucus.
- Breakdown of elastin, causing destruction of alveolar walls and their structure leading to the formation of large air spaces, reducing the total surface area available for gas exchange.
- Vascular bed changes leading to pulmonary hypertension.
- Loss of elastic recoil.
-> Leads to airflow limitation
Pathway to diagnosis
Signs and Symptoms of COPD:
- List
A method of measuring breathlessness?
COPD has a gradual onset and usually presents in older people with a long history of smoking. That being said, it can have other causes, and so a presentation typical of COPD without a smoking history should be investigated for other causes, such as alpha-1 antitrypsin deficiency. A cough is usually the first symptom of COPD, which begins as a morning cough but becomes constant as the disease progresses. It is usually productive, and the sputum quality and quantity may change with exacerbations and superimposed infections.
Shortness of breath usually occurs on exertion at the start of the disease process but may progress to occurring at rest.
The MRC dyspnoea score is used to grade how severe a patient is experiencing breathlessness, ranging from 1 (not troubled by breathlessness unless exercising strenuously) to 5 (too breathless to leave the house, or gets breathless when dressing or undressing).
Signs and Symptoms of COPD:
- Physical signs
- Late COPD…
The physical signs of COPD include:
- Tachypnoea, as the patient tries to compensate for the hypoxia
- Visible use of accessory muscles (e.g. sternocleidomastoid or trapezius) as the patient experiences difficulty moving air in and out of the lungs
- Barrel chest, an increased diameter of the chest due to hyperinflation and incomplete expiration
- Hyper-resonance on percussion of the chest due to hyperinflation
- Decreased breath sounds and reduced air entry
- Pursed-lip breathing
- Potential wheeze
Signs of late COPD include:
- Flapping tremor of the hands, caused by hypercapnia
- Central cyanosis, due to hypoxia
- Signs of right-sided heart failure, such as distended neck veins and ankle oedema, secondary to pulmonary hypertension
Investigations when investigating COPD
When investigating COPD, spirometry is used. It will show an obstructive pattern, where the forced expiratory volume in one second (FEV1) compared to the forced vital capacity (FVC), the FEV1/FVC ratio, is less than 70%, due to the reduced FEV1. This is the same pattern as seen in patients with asthma, however, in patients with COPD this cannot be reversed following treatment with bronchodilators. A vitalograph (or flow volume loop) will show the typical obstructive pattern of scalloping.
How well a patient performs on spirometry can be used to grade their severity of airway obstruction:
- Mild airflow obstruction = FEV1 50-80% of their predicted.
- Moderate airflow obstruction = FEV1 30-49% of their predicted.
- Severe airflow obstruction = FEV1 <30% of their predicted.
The predicted value for spirometry is based on a patient’s gender, age and height.
The most useful piece of imaging to diagnose someone with COPD is a chest x-ray. The chest radiograph will show signs of hyperinflation, such as a flattened diaphragm and an increased antero-posterior diameter of the chest, which is present if more than 8 ribs can be seen clearly within the lung fields on the lateral sides of the radiograph.
A chest x-ray may also be signs of complications, such as the presence of infiltrates consistent with pneumonia or a pneumothorax. A chest x-ray is also useful for excluding other diagnoses in patients with a chronic cough, such as lung cancer.
A high-resolution CT scan is useful for providing an accurate assessment of the alveolar destruction caused in emphysema, which may be useful if there is uncertainty surrounding the diagnosis, or if surgical intervention is required, but is not routinely used in diagnosing COPD.
Pulse oximetry and/or arterial blood gas analysis can be carried out in an acutely unwell patients to assess for hypoxia, respiratory failure and hypercapnia.
Alpha-1 antitrypsin level may be checked if there is high suspicion of deficiency, such as a positive family history and atypical COPD history, such as a young, non-smoker presenting with COPD symptoms.
Management of COPD
The treatment for COPD is mainly focused on managing symptoms, and is achieved through a mixture of making lifestyle changes and medication. These are the mainstay of treatments, because the disease process of COPD involves destruction of alveolar walls, and scarring of the airways, neither of which can be reversed.
Stopping smoking is the main lifestyle change a patient can make to reduce their symptoms. This is because smoking can irritate the already-inflamed lining of the lungs, and can further contribute to ciliary dysfunction, which increases the risk of exacerbations of COPD.
They can also attend pulmonary rehabilitation, a supervised exercise program which aims to increase the patient’s exercise tolerance, educate them on the disease and give them nutritional advice. This helps to slow the progression of COPD, so patients can live with fewer symptoms for longer.
Stable COPD therapy includes a range of medication, such as bronchodilators (relax airways smooth muscle, increase airway calibre making it easier for air flow to reduce breathlessness), anticholinergics, inhaled steroids (reduce neutrophils and lymphocyte counts) and antimuscarinics. These medications aim to reduce the day-to-day symptoms that a patient experiences.
Patients with COPD should also be given annual flu vaccines and a single pneumococcal vaccine to help prevent further infections. Patients may also be given prophylactic antibiotics to help prevent recurrent infective exacerbations.
Long term oxygen therapy at home for at least 16 hours a day has been shown to improve survival by reducing hypoxia, but this is a very intense undertaking for the patient, and for the patient to be safe to have oxygen tanks in their home they must meet certain criteria.
The last step in treatment for COPD is surgical intervention, with procedures such as removal of bullae, lung volume reduction and lung transplants. They are used to improve lung dynamics, exercise adherence, and quality of life. However, these surgeries are not often performed, as patients are often not well enough with other co-morbidities to undergo surgery.
COPD Acute Exacerbations
- What is this
- Risk of having this
- Management of these
An acute exacerbation of COPD is an event characterised by a sustained increase in the patient’s day-to-day symptoms, that is beyond normal variants and acute in onset. These can be infectious or non-infectious, and present with acute, severe shortness of breath, fever and chest pain.
Risk of Acute Exacerbations?
• Previous exacerbations – Always strongest risk factor – “Frequent exacerbator” phenotype
• Disease severity – Airflow obstruction – MRC dyspnoea score
• Gastro-oesophageal reflux
• Pulmonary hypertension
• Respiratory Failure
Management of acute COPD exacerbation includes:
- Monitoring for hypoxia and hypercapnia using pulse oximetry and arterial blood gas analysis.
- Appropriate antibiotics, particularly to cover Haemophilus influenzae and Streptococcus pneumoniae.
- Nebulised bronchodilators.
- Oral steroids – a short course of high dose oral prednisolone.
- Controlled oxygen therapy while keeping under review for CO2 retention.’
- Possible escalation to non-invasive ventilation (e.g. BI-PAP) for worsening type 2 respiratory failure.
- Intensive treatment unit (ITU) referral for invasive ventilation may be considered if repeated ABG shows no signs of improvement with inpatient management.
- Wider therapy e.g. smoking cessation, action plan for future….
COPD - Complications
COPD is a condition that is not reversible, and the progressive damage to the lungs predisposes the patients to a number of conditions:
- Recurrent infection, possibly progressing to pneumonia
- Pneumothorax
- Respiratory failure
- Right sided heart failure
- *Bronchiectasis**
- What is this?
- Process of this disease
- Why can it predispose us to infections?
Bronchiectasis is lung condition characterised by the chronic dilation of one or more bronchi. These bronchi exhibit poor mucus clearance, this to infection which leads to inflammation which paradoxically causes airway narrowing. People with bronchiectasis are therefore predisposed to recurrent or chronic bacterial infection.
Bronchioectasis
- Causes
Remember in three headings:
- Genetics e.g. CF, primary ciliary dykinesia
- Infection e.g. whooping cough, TB
- Immunodeficiencies (e.g. PID, SID…)
There are many different causes of bronchiectasis, although in many patients no obvious cause can be found:
- Post-infection – most commonly seen following whooping cough or tuberculosis infections.
- Immunodeficiencies – such as hypogammaglobulinemia (a condition characterised by low IgG levels), or secondary immunodeficiency (such as HIV infection).
- Mucociliary Clearance Defects – conditions such as cystic fibrosis or primary ciliary dyskinesia.
- Obstruction – by things such a foreign body, tumour or an extrinsic lymph node.
- Toxic Insult – aspiration of acidic gastric contents or occupational smoke inhalation.
- Allergic Bronchopulmonary Aspergillosis – a mixed type I (IgE eosinophilic) and type III (IgG) hypersensitivity reaction that occurs when aspergillus species are breathed in. Unusually, bronchiectasis causes by aspergillosis causes peripheral and central airway dilation.
- Autoimmune Disease – such as rheumatoid arthritis or Sjogren’s Syndrome.
It is important to note that tobacco smoking has not been proven as a cause of bronchiectasis. However, tobacco smoking can worsen pulmonary function, encourage obstruction (e.g. lung cancers) and accelerate the progression of established bronchiectasis.
Bronchioectasis
- Presentation
The most common symptoms of bronchiectasis include:
- Chronic cough
- Daily sputum production which can vary in quantity, consistency, and colour (green foul-smelling sputum – purulent)
- Intermittent fever
- Losing weight
- Breathlessness on exertion
- Fine cracklets (rales)
- Intermittent haemoptysis commonly presenting as red streaks in the sputum
- Chest pain
- Fatigue
- Patients may also experience a wheeze, but this is less common
Bronchiectases
- Investigations
The gold standard diagnostic investigation for bronchiectasis is a high resolution CT scan, which will show bronchial dilation to the point where the bronchus is more dilated than the adjacent blood vessel, and bronchial wall thickening. Classically, CT scans of bronchiectasis patients also show the ‘Signet Ring sign’, a term used to describe the shape that a very dilated bronchus and smaller pulmonary artery are seen in very close association. On the image below, it can be seen in the right middle and lower lobes. In normal healthy lungs – the airway is smaller than the blood vessel.
Bronchiectasis
- Management
Differentiating bronchiectasis from chronic bronchitis
- How are they different, think about: Anatomic site pathology, etiology, main symptoms
- *Cystic Fibrosis**
- What is this?
- What is affected?
- What does this lead to (process)?
Cystic fibrosis (CF) is an autosomal recessive disease, that causes a mutation in the long arm of chromosome 7. This mutation is named the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutation and causes ineffective cell surface chloride transport, making thick, dehydrated body fluids in organs with the mutation. The mucous is thick and sticky and impairs muco-ciliary clearance. This causes multisystem disease primarily in the respiratory and gastrointestinal system as this is where the CFTR mutation is present.
Cystic Fibrosis:
Complications
Cystic Fibrosis:
- Chest x-ray
- CT scan
GW:
- Pack years…
