NEET MDS Lessons
General Pathology
Emphysema
Emphysema is a chronic lung disease. It is often caused by exposure to toxic chemicals or long-term exposure to tobacco smoke.
Signs and symptoms
loss of elasticity of the lung tissue
destruction of structures supporting the alveoli
destruction of capillaries feeding the alveoli
The result is that the small airways collapse during expiration, leading to an obstructive form of lung disease
Features are: shortness of breath on exertion
hyperventilation and an expanded chest.
As emphysema progresses, clubbing of the fingers may be observed, a feature of longstanding hypoxia.
Emphysema patients are sometimes referred to as "pink puffers". This is because emphysema sufferers may hyperventilate to maintain adequate blood oxygen levels. Hyperventilation explains why emphysema patients do not appear cyanotic as chronic bronchitis (another COPD disorder) sufferers often do; hence they are "pink" puffers (adequate oxygen levels in the blood) and not "blue" bloaters (cyanosis; inadequate oxygen in the blood).
Diagnosis
spirometry (lung function testing), including diffusion testing
X-rays, high resolution spiral chest CT-scan,
Bronchoscopy, blood tests, pulse oximetry and arterial blood gas sampling.
Pathophysiology :
Permanent destructive enlargement of the airspaces distal to the terminal bronchioles without obvious fibrosis
Oxygen is inhaled in normal breathing
When toxins such as smoke are breathed into the lungs, the particles are trapped by the hairs and cannot be exhaled, leading to a localised inflammatory response. Chemicals released during the inflammatory response (trypsin, elastase, etc.) are released and begin breaking down the walls of alveoli. This leads to fewer but larger alveoli, with a decreased surface area and a decreased ability to take up oxygen and loose carbon dioxide. The activity of another molecule called alpha 1-antitrypsin normally neutralizes the destructive action of one of these damaging molecules.
After a prolonged period, hyperventilation becomes inadequate to maintain high enough oxygen levels in the blood, and the body compensates by vasoconstricting appropriate vessels. This leads to pulmonary hypertension. This leads to enlargement and increased strain on the right side of the heart, which in turn leads to peripheral edema (swelling of the peripherals) as blood gets backed up in the systemic circulation, causing fluid to leave the circulatory system and accumulate in the tissues.
Emphysema occurs in a higher proportion in patient with decreased alpha 1-antitrypsin (A1AT) levels
Prognosis and treatment
Emphysema is an irreversible degenerative condition
Supportive treatmentis by supporting the breathing with anticholinergics, bronchodilators and (inhaled or oral) steroid medication, and supplemental oxygen as required
Lung volume reduction surgery (LVRS) can improve the quality of life for only selected patients.
Congestive heart failure (CHF)
A. Left-sided CHF
1. May result from nearly any heart disease affecting the left ventricle (e.g., ischemic heart disease, hypertension, valvular disease).
2. Common signs and symptoms include:
a. Dyspnea (shortness of breath) exacerbated by exertion.
b. Paroxysmal nocturnal dyspnea.
c. Orthopnea.
d. Tachypnea.
e. Pleural effusion.
f. Consequences include pulmonary edema.
B. Right-sided CHF
1. The most common cause of right heart failure is left heart failure. It uncommonly occurs in isolation. Other causes include left-sided lesions (mitral stenosis), pulmonary hypertension, cardiomyopathy, and tricuspid or pulmonary valvular disease.
2. Frequently presents with peripheral edema, especially in the ankles and feet (i.e., dependent edema), enlarged liver or spleen, and distention of the neck veins.
Acne vulgaris is a chronic inflammatory disorder usually present in the late teenage years characterized by comedones, papules, nodules, and cysts.
- subdivided into obstructive type with closed comedones (whiteheads) and open comedones (blackheads) and the inflammatory type consisting of papules, pustules, nodules, cysts and scars.
- pathogenesis of inflammatory acne relates to blockage of the hair follicle with keratin and sebaceous secretions, which are acted upon by Propionibacterium acnes (anaerobe) that causes the release of irritating fatty acids resulting in an inflammatory response.
- pathogenesis of the obstructive type (comedones) is related to plugging of the outlet of a hair follicle by keratin debris.
- chocolate, shellfish, nuts iodized salt do not aggravate acne.
- obstructive type is best treated with benzoyl peroxide and triretnoin (vitamin A acid)
- treatment of inflammatory type is the above plus antibiotics (topical and/or systemic; erythromycin, tetracycline, clindamycin).
Cor pulmonale
a failure of the right side of the heart. It is caused by prolonged high blood pressure in the right ventricle of the heart, which in turn is most often caused by pulmonary hypertension - prolonged high blood pressure in the arteries or veins of the lungs. People with heart disease, or lung diseases such as cystic fibrosis, are at greater risk.
Pathophysiology
There are several mechanisms leading to pulmonary hypertension and cor pulmonale:
Pulmonary vasoconstriction
Anatomic changes in vascularisation
Increased blood viscosity
Primary pulmonary hypertension
Causes
Acute:
• Massive pulmonary embolization
• Exacerbation of chronic cor pulmonale
Chronic:
• COPD
• Loss of lung tissue following trauma or surgery
Bronchitis
Bronchitis is an obstructive pulmonary disease characterized by inflammation of the bronchi of the lungs
Signs and symptoms
persistent cough that produces sputum
shortness of breath (dyspnea) on exertion
hypercapnia
insufficient oxygenation of the blood hypoxemia leading to cynosis
Severe chronic bronchitis will commonly lead to cor pulmonale and heart failure.
Pathology
an increase in the number of goblet cells with mucus blocking the airway clusters of pigmented alveolar macrophages
the presence of inflammatory cells (e.g. neutrophils) scarring (fibrosis) of the walls of the bronchioles
Diagnosis
- decreased intensity of breath sounds (rhonchi) and extended expiration.
- a sputum culture has pathogenic microorganisms
- a chest x-ray that reveals hyperinflation and increased bronchovascular markings
- a pulmonary function test that shows an increase in the lung's residual volume and a decreased vital capacity
Pathophysiology
- The initiating event in developing bronchitis appears to be chronic irritation due to inhalation of certain chemicals
- earliest clinical feature of bronchitis is increased secretion of mucus by submucousal glands of the trachea and bronchi
- Damage caused by irritation of the airways leads to inflammation and infiltration of the lung tissue by neutrophils
- The neutrophils release substances that promote mucousal hypersecretion
- As bronchitis persists to become chronic bronchitis, a substantial increase in the number of goblet cells in the small airways is seen
- The role of infection in the pathogenesis of chronic bronchitis appears to be secondary.
Treatment
Quit smoking, Oxygen therapy, bronchodilator drugs
Prognosis
Pulmonary hypertension, cor pulmonale, and chronic respiratory failure are possible complications of chronic bronchitis
In severe chronic bronchitis is poor