Topic 4—Dysfunction of the respiratory system Flashcards
What are the major dysfunctions of the respiratory system?
The major dysfunctions of the respiratory system are
- obstructive pulmonary disease,
- infections
- neoplasms.
The almost inevitable consequences of severe respiratory disease are reduced clearance of carbon dioxide from the blood, causing hypercapnia (excess levels of blood CO2) and reduced oxygenation(hypoxaemia).
What are the Symptoms of respiratory disease?
- Dyspnea is the feeling of being ‘short of breath’ and is an extremely common symptom of respiratory disease.
- Cough needs no definition. A persistent cough may indicate respiratory disease and the condition of any sputum produced may indicate the cause—clear sputum usually only indicates irritation while purulent (pus containing) sputum indicates infection by foreign organisms (e.g. bacteria or fungi).
- Haemoptysis is the presence of blood in sputum or coughing up blood, and indicates damage that has resulted in rupture of blood vessels within the lungs. The blood is usually bright red, frothy and mixed with sputum. It can occur in severe inflammation or digestion of blood vessels by a growing tumour.
- Pain is frequently more pronounced after a cough that produces haemoptysis.
- Clubbing of digits is an unusual symptom of respiratory disease. It is the bulbous enlargement of the very endsof fingers or toes and occurs when blood is poorly oxygenated. The mechanism for clubbing is not known.
Describe Obstructive Pulmonary disorder
Obstructive Pulmonary disorders refers to conditions that cause obstruction of the airways (of alveoli,
bronchioles, bronchi).
What is Chronic bronchitis
Chronic bronchitis is the long term inflammation of the inner lining of the bronchi. There is usually
excessive mucus production, together with thickening and scarring of the airways.
Symptoms
- productive persistent cough,
- breathlessness (dyspnea) and wheezing.
Contributing factors
- cigarette smoking,
- atmospheric pollution and
- repeated or chronic infection.
The consequence of chronic bronchitis is that the airways are narrowed, making breathing difficult.
Describe Emphysema
Emphysema is essentially the breakdown of the walls of the alveoli, resulting in a reduction of the
internal surface area of the lung and thereby reducing the capacity for gas exchange.
Emphysema is frequently
associated with cigarette smoking, but the condition is also associated with chronic bronchitis.
Describe Asthma
Asthma is used to describe obstruction of airflow due to widespread narrowing of the airways.
The most important aspect of airway narrowing in asthmatics is bronchospasm—intermittent narrowing caused by contraction of smooth muscle surrounding the airways.
Frequently this is an allergic response, so treatments may include corticosteroids to inhibit the immune response, as well as bronchodilators.
What are the Complications of obstructive lung disease?
- pulmonary hypertension—high blood pressure in the pulmonary artery. This increased afterload may eventually lead to right handed heart failure (cor pulmonale).
- The reason why people with obstructive lung disease oftensuffer from hypertension in the pulmonary artery is that the disease results in scarring and occlusion of thecapillaries in the lungs, thereby increasing peripheral resistance to blood flow through the lungs.
What neoplasms are involve the lungs?
Lung cancer. Cigarette smoking appears to be the cause of about 80–90% of lung cancer
PEOPLE AT RISK
- heavy smokers .
- Asbestos workers
SYMPTOMS
- include airway obstruction,
- stridor (harsh sounds whilst exhaling)
- blood tinged sputum caused by destruction of blood vessels within the lung by the growing neoplasm.
Cancer of the larynx
PEOPLE AT RISK
- cigarette smokers;
- consumes alcohol, especially spirits.
Infections of the lungs
Pneumonia means infection of the lung, and may be caused by bacteria, viruses, fungi or protozoans. Several of the conditions described above may increase the risk of pneumonia.
Conditions of the lungs caused by injury
Acute respiratory distress syndrome
Postoperative respiratory failure
Pulmonary oedema.
Aspiration.
Pneumothorax
Describe Pulmonary vascular disease
If there is a restriction of blood flow through the capillaries of the lungs, the supply of oxygen to the rest of the
body (and the removal of carbon dioxide) may be affected.
A pulmonary embolism occurs when the supply of deoxygenated blood to an area of lung tissue is obstructed
by an embolus or thromboembolus. Any condition that increases the tendency of blood to clot, especially
sluggish flow in veins, may cause the formation of a thrombus. This can detach and become a thromboembolus that travels via the vena cava, right hand side of the heart and pulmonary artery to the lung. For example, deep vein thrombosis (this was described in topic 2) can cause a pulmonary embolism.
The consequences of a pulmonary embolism depend on location and size of the vessels affected. Blockage of a large arteriole supplying deoxygenated blood to the lung can be life threatening because it greatly reduces gas exchange in the lung, but blockage of a small arteriole may not even be detected.
Describe Acute respiratory distress syndrome (ARDS)
- is life-threatening
- general inflammation of the lung.
There may not be any infection: ARDS can occur following damage to the lung
from a variety of causes, including near-drowning, smoke, noxious gases and radiation therapy.
Essentially, one
or more of these stimulates a massive inflammatory response within the lungs, causing fluid (and white blood cells) to leak into the alveoli and seriously impair gas exchange. The clinical course of this condition followingthe initial injury is (a) hyperventilation to increase oxygen availability (b) respiratory alkalosis (due to low CO2
levels), (c) a feeling of shortage of breath as the lungs become progressively more compromised, (d) respiratory acidosis as the lungs can no longer clear sufficient CO2 from the body, (e) hypoxemia and (f) death. Treatment includes oxygen therapy and mechanical ventilation.
Describe Pneumothorax
is the presence of air or gas in the thorax.
that the lungs are essentially in an airtight box (the thoracic cavity) with inflation and deflation controlled by
pressure changes. An open pneumothorax is when an opening in the chest wall prevents pressure changes
occurring so the lung remains collapsed. This is common if an accident causes penetration of the chest wall (the sucking chest wound). Spontaneous pneumothorax occurs when an opening develops between the airway and thoracic cavity. Here too, any movement of the chest wall or diaphragm doesn’t have an effect on lung expansion.
Describe Aspiration
This is the entry of fluid and/or solid particles into the lung.
Often this term is only used in
relation to food or stomach contents. The consequences can be severe.
Large particles can block major airways
and the fluid (especially if it is low pH stomach acid) can cause inflammation of the lung.
Bacterial pneumonia
may also occur. The death rate from aspiration induced ARDS is high (50–60%).
Describe Pulmonary oedema
‘water on the lung’ and is the accumulation of fluid within the alveoli,
which normally contain very little fluid.
Causes
left hand heart disease. When the
left ventricle fails to pump sufficient blood to the body, fluid accumulates in the pulmonary vein and begins to
leak out of the capillaries in the lung.
Symptoms
cough and dyspnea.
Postoperative respiratory failure
is similar but less severe than ARDS.
Many patients experience
post-operative pulmonary problems, including accumulation of fluid in their alveoli and collapse of alveoli (atelectasis) which impairs gas exchange. Treatment includes turning, deep breathing and encouraging ambulation (walking by the patient) as soon as possible.
Absorption atelectasis also often occurs after surgery. Anaesthetic agents and post‑operative shallow breathing
means that alveoli may become blocked with mucus. Air is absorbed from the blocked alveoli which then
collapse. Deep breathing can help reopen and re-inflate collapsed alveoli.
