Diseases of the Pleura III - Tumors of the Pleura and Pneumothorax

TUMOURS OF THE PLEURA
Primary tumour (mesothelioma) is rare, whereas secondary tumours are common. Mesothelioma may be benign or more commonly malignant. Pleural malignancy is more common in persons chronically exposed to asbestos. Secondary tumours arise from carcinomas of the bronchus, stomach liver and other structures. Malignant lesions in the pleura give rise to hemorrhagic Pleural effusion.

PNEUMOTHORAX
Presence of air in the Pleural cavity is known as Pneumothorax. Pneumothorax may be spontaneous, traumatic, and iatrogenic (artificial). Another classification is to divide them into open, closed, and valvular pneumothorax (tension pneumothorax). In open penumothorax there is a free rent on the surface of the lung through which air gets in and out of the pleural cavity during inspiration and expiration. In closed Pneumothorax, the Pleura does not communicate with the exterior. In tension Pneumothorax, there is a valvular slit on the surface of the lung through which air enters the pleural cavity, but does not escape. As a result, tension Pneumothorax develops leading to respiratory and Cardiac embarrassment.

Spontaneous Pneumothorax: This result from rupture of a pulmonary lesion leading to escape of air into the pleura. Subpleural blebs or bullae, pulmonary tuberculosis, congenital cystic disease of the bronchi, chronic bronchitis with emphysema, bronchial asthma, Pneumoconiosis and Staphylococcal Pneumonia are the common medical causes. Fracture of a rib, thoracotomy, puncture of the lung at needle biopsy, and rupture of a bronchus are the common surgical causes. Sometimes Pneumothorax is produced artificially fo diagnostic radiology of the lungs or as a therapy to arrest massive nehoptysis. The lung collapses towards the hilium, when air enters the pleura and abolishes the negative pressure.

Clinical features: Onset is with unilateral pleuritis pain and dyspnea. A feeling of something having given way is complained of by many, Shortness of breath and unproductive cough develop soon. In tension Pneumothorax respiratory embarrassment and cyanosis may be evident. The affected side is prominent and it does not move with respiration. Mid-line tructures are shifted to the opposite side. Percussion note is hyper-resonant. Breath sounds are absent in many cases. If air enters the pleural cavity as in tension Pneumothorax and open Pneumothorax amphoric breath sounds may be heard. A special percussion phenomenon is 'coin sound'. A coin kept firmly ove the front of the chest wall is struck with another coin. Auscultation at the back of the chest reveals a metallic note. Adventitous sounds like clicking sounds synchronous with the heart beat may be heard in a left-sided Pneumothorax. Differential diagnosis of Pneumothorax includes other painful conditions associated with dyspnea such as myocardial infarction and pulmonary infarction. Severe emphysema, large bullae and diaphragmatic hernia may cause problems in diagnosis.

Radiological features: The radiological features are diagnostic in a well developed case. The affected side is hypertranslucent due to the collection of free air in the Pleural cavity and absence of normal lung markings. The outer margin of the collapsed Lung is seen as a sharp margin against the background of air. There is shift of the Trachea and mediastinum to the opposite side. Skiagram should be taken in the erect posture so that even small collections of air will not be missed.

Complications: Though in the majority of cases, spontaneous Pneumothorax is uncomplicated, serious complications may develop in some cases. These are:
1. Severe Cardio-respiratory embarrassment due to compression of the normal lung by the displaced mediastinum in cases of tension pneumothorax
2. air embolism
3. surgical emphysema
4. infection of the pleural cavity resulting in the formation of hydro-or pyo-pneumothorax;
5. Penumothorax on the opposite side from pre-existing disease of the lung; and 
6. failure of expansion of the collapsed lung.

HydroPneumothorax
When both air and fluid are present in the pleural cavity, it is known as hydropneumothorax. This is usually the result of rupture of a pulmonary lesion letting in air and exudates into the pleural cavity. In many cases, it is caused by tuberculosis. Other causes include lung abscess, bronchiectasis, bronchogenic carcinoma, and trauma to the Chest. Some cases of Pneumothorax get converted into hydro-Pneumothorax when effusion develops as a result of infection.

In hydro-pneumothorax, a horizontal upper level of dullness cause by the fluid can be demonstrated which shifts when the pateint is made to adopt different positions (shifting dullness). On shaking the patient gently while auscultating on the air-fluid interphase, a succussion splash is heard. Chest readiograph reveals a horizontal upper level of fluid with the findings of Pneumothorax above it.

Management of Pneumothorax
Small closed Pneumothorax which is not severely symptomatic can be left alone with bed rest and analgesics. Since the air will be absorbed within a few days. Tension pneumothorax may present as a life-threatening emergency. Unless the tension is relieved by letting out the air, the patient may die of Cardio-respiratory failure.

Emergency management: The air is let out by inserting a needle into the second intercostal scae 2-3cm outside the lateral border of the sternum and it is connected to a rubber tube which is led under water, to prevent re-entry of air (underwater seal). This procedure may have to be instituted even outside the hospital at times. Frequently, the needle tends to get blocked and the intrapleural pressure goes up. Injury to the Lung surface, bleeding into the pleura, infection and surgical emphysema are other adverse side effects. When the Pneumothorax reaccumulates due to blockages of the needle, it may be replaced by a wider rubber catheter. After removing the patient to a hospital, the ideal procedure is to establish drainage of the pleura by a rubber tubing connected to an underwater seal. The tube may have to be kept in place for a few days or weeks. Antibiotics are given to prevent secondary infection of the Pleura. Any obvious underlying condition is treated with specific drugs. Recovery of pulmonary function is facilitated by starting physiotherapy at an early stage. If the Lungs fail to expand with removal of the air, suction of the Pleural cavity may help. Surgical repair of the pleural surface may be required in intractable cases.