﻿ Pleura - A Membrane Around the Lungs, Conditions, Treatment
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Pleura: A Membrane Around the Lungs

Dr.Surya Rao Poodipeddi profile Authored by Dr.Surya Rao Poodipeddi on 23 Dec 2014 - 13:44.

The covering of both the lungs is called Pleura.

Anatomy: The pleura is a two layered structure namely the parietal and the visceral layers. The parietal layer lines the walls of the bony cage in the thorax and the upper surface of the big muscle called diaphragm that divides the chest cavity and the abdominal cavity. The visceral layer also called the pulmonary pleura covers tightly the entire surface of the lungs. The two layers which are in fact one continuous sheet of tissue are separated by a thin space in which a slight amount of watery fluid circulates within the pleural cavity that helps in lubricating the pleural surfaces and facilitates the lungs to slide freely over the inner surface of the thoracic wall during breathing.

Conditions affecting pleura:

However, when the lungs collapse or develop an infection, a condition known as pleurisy can develop. The pleura become inflamed and the pleural cavity becomes noticeably enlarged. When present pleurisy can be extremely painful but can be medically eradicated in many cases.

Pleural mesothelioma is a cancer of the pleura (Cancer of the lining of the lungs) affecting mostly persons employed in asbestos industry. Because this condition is uncommon, some doctors misdiagnose the disease as lung cancer. Lung cancer is totally different from pleural mesothelioma in that the former is a malignant condition affecting the substance of the lungs where as the latter condition involves the lining of the lungs.

The common symptoms of pleural mesothelioma include

  • Pain in the lower back or the side of the chest
  • Shortness of breath
  • A persistent cough
  • Difficulty in swallowing food
  • Fatigue
  • Fever with sweating and loss of weight

These symptoms being common to many minor ailments may misguide a doctor from proper diagnosis. Under normal circumstances there is a thin layer of fluid that separates the two layers of the pleura. There are several reasons which lead to excessive accumulation of fluid within the two layers namely heart failure,pneumonia and cirrhosis of the liver. In some cases blood, pus or high cholesterol fluids may also accumulate within the two layers.

Blood in the pleural cavity can be caused by a chest injury or impaired clotting mechanism or a condition called aneurysm of the aorta.

Pus in the pleural cavity can be due to pneumonia, lung abscess, infected wounds in the chest, any surgical procedure and an abdominal abscess.

High cholesterol fluids may accumulate in the pleural cavity in conditions where pleural effusion was present for some time and caused by such conditions like rheumatoid arthritis or tuberculosis.

Whatever be the cause for accumulations, be it blood, pus or fluid, such fluids can be drained out with the use of a long needle. Drainage of pus should be followed by administration of appropriate antibiotics.

Pleurisy is the commonest condition affecting the linings of the lungs. An inflammation of the pleura is known as pleurisy. The condition occurs when a virus or bacteria irritates the pleura leading to inflammation. Pleurisy may present itself as dry or wet variety. In dry pleurisy there is only inflammation of the linings of the lungs where as in wet pleurisy there is accumulation of fluid in addition to inflammation. The wet variety is known as pleurisy with effusion. Tuberculosis is the commonest culprit presenting, as pleurisy be it dry or wet variety.

In either case, there will be severe pain in the chest. The two inflamed layers of the pleura, when rubbed against each other, the victim experiences pain. This rub if heard by the examining doctor through his stethoscope is the classical sign to diagnose pleurisy. Other concomitant signs and symptoms like evening rise of temperature, axillary sweating, loss of appetite, loss of weight, increased ESR reading, positive Mantoux test help as corroborative evidence to suspect tuberculosis as the cause coupled with changes in the X-ray of the chest. Positive sputum for AFB settles the issue.

Treatment depends on the cause like tubercular, viral or other bacterial infections.Accumulation of air in the pleura is known as pnemothorax, which is often due to injury. Accumulation of pus is known as pyothorax. Accumulation of blood in the pleural cavity is known as hemothorax which is also mostly due to injury to the chest wall. Treatment for each depends on the cause.

When the inflammation subsides, the pleura may go back to its normal condition. However, in some cases adhesions may form leading to sticking together of the pleural layers that can be seen in X-rays.
