Pathophysiology of the Respiratory system Flashcards
What are the major genetic causative factors of the respiratory system?
Cystic fibrosis
Asthma
What are the major environmental causative factors in respiratory disease?
Smoking- Lung cancer, Chronic bronchitis (inflammation of the bronchus), emphysema (destruction of alveoli) and susceptibility to infection
Air pollution- Chronic bronchitis and susceptibility to infection
What are the major environmental causative factors in respiratory disease?
Smoking- Lung cancer, Chronic bronchitis (inflammation of the bronchus), emphysema (destruction of alveoli) and susceptibility to infection
Air pollution- Chronic bronchitis and susceptibility to infection
What are the major occupational causative factors in respiratory disease?
Pneumoconiosis (lung disease caused by dust inhalation), asbestosis, mesothelioma (type of lung cancer) and lung cancer
What are the major infectious causative factors in respiratory disease?
Influenza, measles, pneumonia and TB
What is cystic fibrosis (CF)?
> Most common inherited metabolic disease
More common in white people
Abnormal genes carried by approx. 1/20
Affects 1/2000 births
Gene found on chromosome 7 and results in abnormal water and electrolyte transport across cell membranes- makes substances really thick (any substances that sit can cause infection)
What are the 2 ways a foetus can be tested for CF?
Amniocentesis and chronic villus sampling
What is amniocentesis?
> 16 wks+
> When a sample of amniotic fluid is taken and tested
What is chronic villus sampling?
> Newer method
Can be performed much earlier on in pregnancy
Needle into abdomen and a sample of placenta is taken
What is chronic villus sampling?
> Newer method
Can be performed much earlier on in pregnancy
Needle into abdomen and a sample of placenta is taken
What abnormalities may predispose to infection?
1) Loss of cough reflex- coma, anaesthesia, neuromuscular disorders, surgery, stroke
2) Ciliary defects- loss of cilia due to smoking, tumours
3) Mucus disorders- CF, chronic bronchitis
4) Immunosuppression- loss of B/T lymphocytes
5) Macrophage function damage- smoking or hypoxia
6) Pulmonary oedema with flooding of the alveoli (flooding of the lungs with fluid)
What is a primary respiratory infection?
No underlying predisposing conditions in a healthy individual
What is a secondary respiratory infection?
When local/systemic defences are weakened
What is bronchitis?
> Where the bronchial tubes become inflamed and irritated
Characterised by cough, dyspnoea (shortness of breath), tachypnoea and excessive production of sputum
Usually viral but can be bacterial (haemophilus influenzae and streptococcus pneumoniae)
Exacerbations are common in COPD
Affects trachea, larynx and lungs- ‘laryngotracheobronchitis’ or ‘croup’ in infants
More severe in children
Acute bronchitis can be caused by direct chemical injury from air pollutants (smoke, sulphur dioxide and chlorine)
What is pneumonia?
> Alveolar inflammation
Large numbers of lymphocytes and macrophages in the blood
Usually due to infection affecting distal airways, especially alveoli
Causes formation of exudate (fluid)
Streptococcus pneumoniae, streptococcus aureus, mycobacterium tuberculosis, etc
What are the symptoms of pneumonia?
> High fever > Chills > Low BP > High BPM > Cough with sputum > Dyspnoea > Chest pain
What is bronchopneumonia?
> Characterised by a patchy presentation on the chest x-ray
Centred on inflamed bronchioles and bronchi and spreads to alveoli
Occurs mostly in old age, infants and in patients with debilitating diseases such as cancer, heart failure and stroke
Patients often become septicaemic (sepsis in the blood) with fever and reduced consciousness
Crackles on auscultation
What is Legionnaires’ disease
> Caused by Legionella pneumophilia, transmitted in water droplets from contaminated air humidifiers and water cisterns
Some have underlying illnesses such as heart failure or carcinoma
Cough, dyspnoea, chest pain, myalgia (muscle pain), headache, confusion, nausea, vomiting and diarrhoea
5-20% of cases are fatal, depending on age and condition
Treated by erythromycin group of antibiotics
What is pulmonary TB?
> Lung is the most common place
Predisposing conditions include chronic alcoholism, diabetes mellitus, immunosuppression (HIV/AIDS)
Often reactivation of primary or secondary lesions
1/3 in the world’s population have it
What are the clinical features of TB?
> Sudden weight loss with night sweats, mild chronic cough
Rampant bronchopneumonia with fever, dyspnoea and respiratory distress
Early stages usually silent
Lesions (10mm diameter) will appear in the lungs which destroy lung tissue, leaving a calcified nodule
May recur, depending on health and environment
What is a pulmonary embolism?
> Clot in the lung
Can be due to DVT- leads to formation of a clot
DVT starts in the lower limbs where it will travel to the right side of heart, then lungs where it causes a blockage
Can also be due to air, fat, cancer cells or bony fragments following a trauma
Blockage may lead to pulmonary infarct
What are risk factors for a thrombo-embolism?
> Immobilisation > Pregnancy > Oral contraceptives > Malignancies (particularly pancreatic) > Cardiac failure > Post op recovery phase > Long haul flights
How can a PE be prevented?
> Early ambulation (movement) post op to improve venous flow
TED (thrombo-embolic deterrent) stockings and leg exercises
Prophylactic anticoagulation (drugs) given to high risk patients
What is the treatment of a PE?
> Fibrinolytic agents and surgical embolectomy
> Have a 30% chance of developing another if you have one
What is COPD?
> Reversible and intermittent (can change with treatment) or irreversible and persistent
Centred on bronchi and bronchioles
Significant respiratory impairment causing airway limitation - reduced vital capacity
The more major diseases of COPD are chronic bronchitis, emphysema and asthma
What is chronic bronchitis?
> Defined as chronic cough and sputum for at least 3 months each year for 2 consecutive years
Mucus hypersecretion with bronchial mucous gland hypertrophy (enlargement)
Respiratory bronchiolitis
In UK, almost all cases caused by cigarette smoking
Typically middle-aged men
Episodes associated with recurrent, low grade bronchial infections caused by bacteria such as Haemophilus influenzae or Streptococcus pneumoniae
What is the treatment for chronic bronchitis?
> Antibiotics
Chest therapy
Sometimes, short-term use of oxygen therapy
Bronchodilators such as Salbutamol can also be used
What can chronic bronchitis lead to?
> Over time it becomes progressively more severe and is accompanied withy hypercapnia (high co2) , hypoxaemia (low O2) and cyanosis
Patients hyperventilate, using accessory respiratory muscles in order to produce relatively normal blood gas profile
Eventually, right-sided heart failure or respiratory failure
What are the symptoms of right-sided heart failure?
> Fatigue > Increased peripheral venous pressure > Enlarged liver and spleen > Distended jugular veins > Oedema
What is emphysema?
> Enlargement and dilation of alveolar airspaces with destruction of elastin in their walls, resulting in inability to take part in gaseous exchange
Associated with chronic bronchitis
1/3 of lung capacity is destroyed before clinical symptoms appear
Progressive dyspnoea, weight loss and right-sided heart failure
Cough and sputum
Recurrent infections with purulent sputum
What is asthma?
> Increased irritability of the bronchial tree with paroxysmal narrowing (occuring often) of the airways which may resolve by itself, or after treatment
5 clinical causes- atopic, non-atopic, aspirin-induced, occupational or allergic bronchopulmonary aspergillosis
What is a carcinoma of the lung?
> Most common primary malignant tumour with the worst survival rate (4-7%)
Directly related to smoking cigarettes
Only 10% are operable at diagnosis
Typically 40-70 yrs old
What are the symptoms of a carcinoma of the lung?
> Severe weight loss
Cough
Haemoptysis (coughing blood)
Dyspnoea and chest pain (often pleuric in nature)
May present with metastases, commonly lymph nodes, bone, brain, liver and adrenals
What is the treatment of a carcinoma of the lung?
> Depends on the stage of the tumour
Surgical resection is the best option but only possible with small tumourswith no metastases
Combination chemotherapy can induce remission
