Emphysema

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Diagnosis: Emphysema

Definition:

• abnormal permanent enlargement of air spaces distal to the terminal bronchioles, accompanied by the destruction of the walls and without obvious fibrosis

Types:

1.Centriacinar(centrilobular)

• begins in the respiratory bronchioles and spreads peripherally
• associated with long-standing cigarette smoking
• predominantly involves the upper half of the lungs

2.Panacinar(Panlobular)

• destroys the entire alveolus uniformly
• generally is observed in patients with homozygous alpha1-antitrypsin (AAT) deficiency
• Among smokers,focal panacinar emphysema at the lung bases may accompany centriacinar emphysema.
• predominant in the lower half of the lungs

3.Distal acinar emphysema(paraseptal ephysema)

• preferentially involves the distal airway structures, alveolar ducts, and alveolar sacs
• process is localized around the septae of the lungs or pleura
• apical bullae may lead to spontaneous pneumothorax
• Giant bullae occasionally cause severe compression of adjacent lung tissue.

Causes:

• Tobacco smoking (mainly)
• Toxic chemicals
• alpha-1-antrypsin deficiency
• air pollution
• genetic
• abnormal airway reactivity
• old age

Differential diagnosis:

• Chronic bronchitis
• Bronchitis
• Bronchiectasis
  

Pathophysiology:

1.neutrophil and macrophage activation and retention in the lung parenchyma

• neutrophils produce serine proteinases
• Macrophages synthesize various metalloproteinases and cysteine proteinases.
• neutrophils and macrophages release elastase
• these enzymes can break down the walls of alveoli which leads to significant modifications of lung architecture.

2. alpha-1-antitrypsin deficiency

• AAT is a glycoprotein member of the serine protease inhibitor family that is synthesized in the liver and is secreted into the blood stream
• main function is to neutralize neutrophil elastase in the lung interstitium and to protect the lung parenchyma from elastolytic breakdown
• AAT deficiency predisposes to unopposed elastolysis with clinical sequela of early onset of panacinar emphysema.

Symptoms:

• productive cough or acute chest illness-cough usually is worse in the morning and produces small amounts of colorless sputum
• Breathlessness
• Wheezing may occur in some patients, particularly during exertion and exacerbations

Signs:

• cyanosis
• wheeze
  
• tachpnoea
• hyperinflation
• cricosternal distance <3cm
• reduce chest expansion
• resonant or hyper-resonant percussion
• quite breath sounds
  

Test:

Routine:

• FBC=PCV increase

Imaging:

• Chest X-ray=

-hyperinflation(> 6 ribs anterior above diaphragm,mid-clavicular line)
-Flat hemidiaphragms
-large central pulmonary arteries (due to pulmonary hypertension)
-reduce pulmonary vascular markings
-bullae
-hyperlucency of the lungs

• CT scan

Special test:

• Pulmonary function test

-FEV1<80%
-FEV1:FVC ration <70%
-TLC-increase
-DLCO-reduce
-RV-increase

• ABG - PaO2 reduce±hypercapnia
• ECG- right atrial and ventricular hypertrophy (cor pulmonale)