Types and Stages of Asbestosis

The Different Types/Stages of Asbestosis

Before we go into the different stages of Asbestosis, it is important that we understand the basics of how our lungs work.

Before the lungs can oxygenate the blood, they need air, which is provided by the airways, starting with the trachea. The trachea is a tube made up of incomplete cartilaginous rings that connects the larynx with the lungs. It terminates in a bifurcation, creating the right and left primary (main) bronchi.

Two primary bronchi run from the bifurcation of the trachea to the hila of the lungs. The bronchi, arteries, and veins are referred to collectively as the root of the lung and reside in the hilar spaces.

The right primary bronchus is wider and shorter than the left primary bronchus. It also runs more vertically. The left primary bronchus passes underneath the arch of the aorta and anterior to the esophagus.
The primary bronchi enter the hila of the lungs and form the bronchial trees by first dividing into the secondary bronchi (one for each lobe of each lung) and then into tertiary bronchi.

In each bronchopulmonary segment, the bronchi form more branches that eventually end in terminal bronchioles. Each terminal bronchiole divides into many respiratory bronchioles that lead to outpouchings for the exchange of gases. Each respiratory bronchiole has up to 11 alveolar ducts. Each duct has up to six outpouchings called alveolar sacs surrounded with capillaries. Each alveolar sac contains alveoli where gas exchange between the air and the blood takes place.

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In order to describe the differing levels of damage within an infected person’s lungs, doctors use a grading system for its severity which goes from Grade 0 to Grade 4, along with a grading system for extent, which goes from either 1 to 3, or A to C. these stages are broken down as follows:

Severity of Asbestosis:

• Grade 0 – No fibrosis (scarring) associated with bronchioles.
• Grade 1 – Early fibrosis involving the walls of at least one respiratory bronchiole, fibrosis is confined to alveolated walls of respiratory bronchioles and ducts, not present in more distant alveoli. Alveolitis and inflammation is at a similar level to that caused by cigarette smoking.
• Grade 2 – There is more severe fibrosis in the alveolar ducts and / or two or more layers of adjacent alveoli.
• Grade 3 – Fibrosis is advanced and all of the lung between two affected bronchioles is affected, some alveoli are completely obliterated.
• Grade 4 – Honeycomb remodelling and large (up to 1cm) dilated spaces are clearly visible within the functional tissue of the lung.

Extent of Asbestosis:

• Grade A (1) – Only occasional bronchioles are involved – most appear normal.
• Grade B (2) – More than occasional, but less than half of the bronchioles are involved.
• Grade C (3) – More than half the bronchioles are involved.

If you have any concerns about the health of your lungs you should discuss them straight away with your doctor – early diagnosis gives you a far greater chance of dealing with any issues that may be discovered.