The patient develops vasomotor collapse on puncturing the pleura. Inadequate local anesthesia may be a predisposing factor. Urgent resuscitatory measures include the injection of adrenaline, parenteral steroid, and intravenous fluids. Pleural shock may be fatal, if not recognized in time.
Bleeding into the pleural cavity is from vessels on the Pleural surface. Bleeding should be suspected when the aspirated fluid becomes progressively blood-stained. In sever cases, hypovolemic shock may ensue. When bleeding is evident, it is advisable to stop the procedure. Entry of air inadvertently during aspiration converts a simple pleural effusion into hydropenumothorax. Rarely subcutaneous emphysema or air embolism may develop.
Pulmonary edema occurs in some cases of chronic effusion when the lung expands with removal of the fluid. Slow aspiration and restricting the volume of fluid aspirated at one sitting to 1 liter helps in reducing these complications. Onset of pulmonary edema is heralded by troublesome cough with frothy expectoration. Auscultation reveals the presence of rales. Onset of pulmonary edema is an indication for stopping aspiration. Further management is on the same lines as for acute pulmonary edema. Pleural effusion which is a part of generalized edema, clears up when the underlying condition is treated. Unless there is respiratory embarrassment, paracentesis is required only for diagnostic purposes.
TUBERCULOUS PLEURAL EFFUSION
Among the known causes of pleural effusion in Africa and Asian subjects, tuberculosis still tops the list. The pleura may be directly involved by the tuberculous process. In most cases it spreads from an underlying pulmonary focus and the effusion is almost always on the side of the pulmonary lesion. Sometimes a caseous subpleural focus may rupture into the pleural cavity or the pleura may be the seat of military lesions. In the majority of cases the classic adolescent pleural effusions is a postprimary tuberculous phenomenon though rarely it may occur in primary tuberculosis. The effusion may develop rapidly or insidiously. Most cases reveal strongly positive tuberculin test. The fluid is an exudate. The cells are mainly lymphocytes. Tubercula bacilli are difficult to demonstrate in serous effusions. Culture and animal inoculation may be positive. In tuberculous empyema, the organisms are most easily demonstrable. Needle biopsy is helpful, but this is not required in the ordinary case.
Management : Standard antituberculosis treatment is started. Pleural aspiration is done electively. Repeated aspiration may be required to make the Pleural cavity dry. Respiratory physiotherapy is essential to restore function promptly. Use of corticosteroids (Prednisolone 15-20 mg / day) helps in hastening recovery and preventing pleural thickening.
Collection of pus in the pleural cavity is called empyema. Pus may be free in the pleural space or loculated. Empyema may result from the extension of infection from the underlying lung, or it may complicate chest injuries, thoracentesis, or generalized pyemia. Pneumonia, lung abscess, bronchiectasis, tuberculous cavities, hepatopulmonary amoebiasis, bronchogenic carcinoma, osteomyelitis of the ribs, fungal infections and actinomycosis are all common causes. Thoracic and upper abdominal surgery may lead to empyema. Common bacterial flora include streptococcus, staphylococcus, Pneumococcus, Pseudomonas, Klebsiella, H.influenzae, anaerobes, M. tuberculosis, and actinomycetes.
Clinical features : All ages may be affected, but children suffer more. Onset is marked by high fever, pleuritis or dull chest pain and dry cough. Physical signs of pleural effusion may be evident. Unlike as in simple pleural effusion, the chest wall becomes edematous (broncho-pleural fistula). In this case, postural cough is a troublesome symptom and the findings are those of pyopneumothorax. The pus may work its way outside and point on the Chest wall. This is called empyema necessitans. Left-sided empyema may pulsate due to transmitted pulsation from the heart- "pulsating empyema".
Radiologically, the findings closely resemble those of pleural effusion. Demonstration of pus in the pleural cavity by aspiration confirms the diagnosis. The causative organism can be identified by examination of the pus. Clinically, a large lung abscess may resemble an empyema or encysted pyopneumothorax and these two conditions have to be differentiated. Fever, toxemia and digital clubbing occur in both. Shift of the mediastinum to the opposite side and stony dullness on percussion are in favor of empyema. Special radiological techniques may be necessary to differentiate them. In a loculated pyopneumothorax, the air-fluid interphase may transgress anatomical boundaries of lobes, whereas a Lung abscess is limited by the interlobar fissures.
Complications of empyema include severe toxemia, cachexia, anemia, pulmonary fibrosis, pleural fibrosis, metastatic brain abscesses and in longstanding cases, secondary amyloidosis. The overall mortality is 10-11%.
Treatment : After determining the infecting organism, antimicrobial treatment is instituted. The fluid has to be removed by aspiration and this measure is essential to allay fever and toxemia. When the pus is too thick to be aspirated. or if it re-accumulates rapidly, under water tube drainage has to be established after rib resection. Clearance of the pleural space and full re-expansion of the lung may take several weeks to complete. Though antibiotics used to be instilled locally into the pleural cavity with adequate systemic chemotherapy, this measure is not essential. Thick pus which is difficult to be aspirated can be liquefied by the instillation of proteolytic enzymes like streptokinase and streptodornase. In most cases, chemotherapy and surgical drainage are adequate to clear the empyema. Rarely an intractable empyema may have to be excised surgically.