EMPHYSEMA

Emphysema ( Greek : emphysan: inflate Itself composed of en meaning in and physan  meaning breath, blast) 

Emphysema means swelling.
Emphysema is included in a group of the disease called chronic obstructive pulmonary disease (COPD).
It is often caused by long term exposure to air pollution or smoking.
Emphysema causes dilation of air spaces by the destruction of the alveolar wall, leading to the collapse of alveoli during expiration.
Emphysema is a long-term progressive disease of the lungs that primarily causes shortness of breath.
There is the destruction of lung tissue around smaller sacs, called alveoli, which makes their air sacs unable to hold their functional shape upon exhalation. That is why it is called obstructive lung disease.

ETIOLOGY

1)Tobacco smoking

2) Atmospheric pollution
3) Infections
4) Genetic factor
5) Alpha-1 antitrypsin deficiency
6) Inherited diseases (rare) [ Marfan syndrome, Menke's syndrome]

7) Severe cases of Alpha I antitrypsin deficiency may also develop cirrhosis of the liver, where Alpha I antitrypsin gets accumulated and then leads to fibrotic reaction.

8) When persons enter at the age of 20 years, the new alveoli tissue development stops and simultaneously the lung tissue starts to deteriorate. Pulmonary elasticity will also be lost as alveoli die, the number of lung capillaries starts declining and after the breakdown of the lung, elastin begins.

• As the age increases, they will also lose strength along with the mass in their chest muscles and the muscles get weaken.
• With the increasing age, our bone density also gets reduced, and bones start to deteriorate and this will affect the posture of the body.
• Together, if we see all age-related aspects then we conclude that they can cause the development of emphysema. Though it is not necessary, there is a risk of having decreased respiratory function.

9) Second-hand smoke

10) Chemicals and toxins

CLINICAL FEATURES

"Pink puffer"

1) Barrel chest deformity
2) lung volume increases
3) Vital capacity decreases
4) Loss of weight
5) Peptic ulceration
6) Speaks in short, jerky sentences
7) Purse lip breathing
8) Minimal cyanosis
9) Cough with or without expectorant
10) Hyperventilates and less hypoxemia (pink)
11) Prolonged expiratory time
12) Anxious
13) Use of accessory muscles
14) Thin appearance

CLASSIFICATION

1) Centriacinar emphysema :

• Also called as centrilobular emphysema.
• Occurs most commonly in the upper lobes.
• The respiratory bronchiole is expanded.
• There is dilation of the respiratory bronchiole.
• The distal acinus or alveoli are unchanged.
• It can co-exist with chronic bronchitis.
• Invariably occurs in smokers.
• Mostly coal mine workers which exposed more to carbon and dust are affected.

2) Panacinar emphysema:

• Also called as pan lobular emphysema.
• Whole of acinus is uniformly affected.
• The entire respiratory acinus, from respiratory bronchioles to alveoli, is expanded.
• Occurs more commonly in lower lobes(especially basal segments, and anterior margins of the lungs).
• Associated with:
1) Alpha antitrypsin deficiency
2) Cigarette smokers

3) Paraseptal emphysema

• Distal acinar.
• Involves alveolar ducts and sacs at the lung periphery.
• Associated with spontaneous pneumothorax.
• It may also be seen in older patients with centrilobular emphysema.
"Both centrilobular and paraseptal emphysema may progress to bullous emphysema"

~Bulla - Bulla is defined as being atleast1 cm in diameter, and with a wall less than 1 mm thick.

When the air gets trapped inside the emphysematous spaces, there is a local expansion of the structure.

• Least common.
• Localized along pleura- peripheral part of the acinus.

4) Irregular emphysema:

• Most common.
• Least significant.
• Common around scar tissue

• There is congenital extrinsic compression by an abnormally large pulmonary artery. This causes malformation of bronchial cartilage, making them soft and collapsible.

There is a special type of emphysema. congenital lobar emphysema.

CONGENITAL LOBAR EMPHYSEMA

• CLE is potentially reversible.
• CLE cause respiratory distress in the neonates.
• Life-threatening.
• CLE is a severe case of bullous emphysema.
• CLE results in over expansion of a pulmonary lobe and resultant compression of the remaining lobes of the ipsilateral lung, and possibly also the contralateral lung.

SIGNS AND SYMPTOMS

1. Alpha-1 antitrypsin destruction
2. Smoking
3. Shortness of breath(Dyspnea)
4. Tachypnea(rapid breathing)
5. Anteroposterior diameter of the chest increase(Barrel chest)
6. Hypoxia
7. Cyanosis

PATHOPHYSIOLOGY

• Smoking is the main cause of emphysema.
• In the case of emphysema, the elasticity of the lung is lost.
• Bronchioles gets enlarged and the walls of the alveoli get destructed.
• Alveoli and small distal airways are affected and then the larger airways also get affected by emphysema.
• The stabilizing function of the bronchioles loses and there is collapsing of airways so gases will remain in it and the bronchioles get enlarged.
• Blisters are formed and the walls of the lungs tissue get diminished.
• As smoking is the main cause of emphysema, so the inhaled irritants cause inflammatory cells to release from polymorphonuclear leukocyte(basophils, eosinophils, and neutrophils) and alveolar macrophages to move into the lungs.
• The irritants which released from smoking will affect on Alpha I antitrypsin and reduce its activity. Therefore, emphysema develops.
• As there is a reduction of the alveolar tissue then there is a reduction in the surface area for the exchange of gases.
• It can also lead to Cor pulmonale.
• Cor pulmonale is also called as right-side heart failure. The right ventricle of the heart gets enlarged due to high blood pressure in the lungs and it is usually caused by chronic lung disease. 

SOME IMPORTANT POINTS TO BE REMEMBERED:

Here I'm including some important points about Alpha I antitrypsin and some medical terminologies which are important for understanding emphysema.

If there is a genetic deficiency of Alpha I antitrypsin -

• Non-smokers- its deficiency will not affect that much in non-smokers.
• Smokers- low level of Alpha I antitrypsin increases the risk of emphysema in smokers because it may progress more rapidly in smokers as smoking reduce its activity. If there is a low level of Alpha I antitrypsin then the chances of lung diseases also get increases and the person is more likely develops chances of COPD( chronic obstructive pulmonary disease)

As we find out the deficiency of Alpha I antitrypsin affects our lung as well as leads to COPD, so let's discuss COPD & Alpha I antitrypsin.

COPD( Chronic Obstructive Pulmonary Disease)

• In COPD, there is a blockage in the airflow which leads to breathing problems.
• As airflow blocks so there is difficulty in breathing.
• It gets block by a group of lung diseases.
• Most common conditions involve in COPD-

1. Emphysema
2. Chronic bronchitis

• Damage to both acinar level- emphysema
• Damage at bronchial level- bronchitis.
• Common extrinsic trigger- cigarette smoking.

ALPHA I ANTITRYPSIN :

• Alpha I antitrypsin is a protein made by the liver.
• Its function is to protect the lungs.
• If there is a deficiency of Alpha I antitrypsin then the risk of developing emphysema and other disorders related to AAT deficiency will increase.
• It is a rare hereditary condition.
• Both parents must have at least 1 copy of the abnormal alpha I antitrypsin deficiency gene. If they have a copy of an abnormal gene then the disease will inherit to their child.
• Basically, it is caused by changes in the SERPINA1 gene. This gene gives the instruction to make the alpha 1 antitrypsin protein.
• AAT's main function is to protect the body from another protein called neutrophil elastase.
• Neutrophil elastase is an enzyme that helps the body to fight with infections, but it can also attack the lungs and also to the other healthy tissues of the body if it is not controlled by AAT.
• As there is a deficiency of AAT, then this allows the neutrophil elastase to destroy the lung tissue, and thus lung disease occurs.
• Testing is done by taking blood samples and it is simple, quick, and highly accurate.
• Normal Range- 100-300 mg/dL ; Less than 80 mg/dL- significant risk for lung diseases.

DIAGNOSIS OF EMPHYSEMA

• X-Ray of chest[ lungs are hyper- expanded; coarse bronchovascular markings; increase in anteroposterior diameter; diaphragm has normal contour].
• Atrial Blood Gas analysis[measures how well your lungs transfer oxygen to your bloodstream and how well carbon dioxide removes from the body].

TREATMENT OF EMPHYSEMA

1. Oxygen therapy
2. Bronchodilators
3. Steroids
4. Corticosteroids in an inhaler form
5. Surgery or lung transplant
6. Pulmonary rehabilitation
7. Antibiotics
8. Vaccines ( to prevent the disease, the patient should receive a flu shot annually and pneumonia shot every 5-7 years)
9. Protein therapy.

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