PLEURAL SHOCK
The patient develops vasomotor collapse when puncturing the pleura. Inadequate local anesthesia may be a predisposing factor. Urgent resuscitative measures include epinephrine injection, parenteral steroids, and intravenous fluids. Pleural shock can be fatal, if not recognized early.
Bleeding into the pleural cavity comes from vessels on the pleural surface. Bleeding should be suspected when the aspirated fluid progressively stains with blood. In severe cases, hypovolemic shock may occur. When bleeding is evident, it is advisable to stop the procedure. Inadvertent entry of air during aspiration converts a simple pleural effusion into hydropenumomothorax. Rarely, subcutaneous emphysema or gas embolism may develop.
Pulmonary edema occurs in some cases of chronic effusion when the lung expands with the removal of fluid. Slow aspiration and limiting the volume of fluid aspirated in one session to 1 liter help reduce these complications. The onset of pulmonary edema is heralded by a bothersome cough with frothy sputum. Auscultation reveals the presence of rales. The appearance of pulmonary edema is an indication to stop aspiration. Subsequent management follows the same lines as for acute pulmonary edema. The pleural effusion, which is part of the generalized edema, disappears when the underlying condition is treated. Unless there are respiratory problems, paracentesis is required for diagnostic purposes only.
TUBERCULOUS PLUEURAL EFFUCTION
Among the known causes of pleural effusion in Africa and Asia, tuberculosis still tops the list. The pleura may be directly affected 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 lung lesion. Sometimes a caseous subpleural focus may rupture into the pleural cavity, or the pleura may be the seat of military lesions. In most cases, the classic adolescent pleural effusion is a postprimary tuberculous phenomenon, although it may rarely occur in primary tuberculosis. The effusion can develop rapidly or insidiously. Most cases reveal a strongly positive tuberculin skin test. The liquid is an exudate. The cells are mainly lymphocytes. Tuberculosis bacilli are difficult to demonstrate in serous effusions. Culture and animal inoculation may be positive. In tuberculous empyema, the organisms are more easily demonstrable. Needle biopsy is helpful but not necessary in the ordinary case.
Management: Standard tuberculosis treatment is started. Pleural aspiration is performed electively. Repeated aspiration may be necessary to allow the pleural cavity to dry out. Respiratory physiotherapy is essential to quickly restore function. The use of corticosteroids (Prednisolone 15-20 mg/day) helps speed recovery and prevent pleural thickening.
empyema
The accumulation of pus in the pleural cavity is called empyema. The pus may be free in the pleural space or loculated. Empyema may be due to extension of infection from the underlying lung or may complicate chest injuries, thoracentesis, or generalized pyaemia. Pneumonia, lung abscess, bronchiectasis, tuberculous cavities, hepatopulmonary amebiasis, bronchogenic carcinoma, rib osteomyelitis, fungal infections, and actinomycosis are common causes. Thoracic and upper abdominal surgery can cause empyema. Common bacterial flora include streptococci, staphylococci, pneumococci, Pseudomonas, Klebsiella, H. influenzae, anaerobes, M. tuberculosis, and actinomycetes.
Clinical features: All ages can be affected, but children suffer more. Onset is characterized by high fever, pleurisy or dull chest pain, and dry cough. Physical signs of a pleural effusion may be obvious. Unlike a simple pleural effusion, the chest wall becomes edematous (bronchopleural fistula). In this case, the postural cough is a bothersome symptom and the findings are those of a pyopneumothorax. The pus can work its way to the outside and target the chest wall. This is called empyema necessitans. Left-sided empyema may pulsate due to pulsation transmitted from the heart: “pulsating empyema.”
Radiologically, the findings closely resemble those of a 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 a cystic empyema or pyopneumothorax, and these two conditions must be differentiated. Both present with fever, toxemia, and digital palpitations. Displacement of the mediastinum to the opposite side and stony dullness to percussion favor empyema. Special radiological techniques may be necessary to differentiate them. In a loculated pyopneumothorax, the air-fluid interface may transgress the anatomical limits of the lobes, whereas a lung abscess is limited by the interlobular fissures.
Complications of empyema include severe toxemia, cachexia, anemia, pulmonary fibrosis, pleural fibrosis, metastatic brain abscesses, and, in prolonged cases, secondary amyloidosis. Overall mortality is 10-11%.
Treatment: After determining the infecting organism, antimicrobial treatment is instituted. The liquid has to be removed by aspiration and this measure is essential to relieve fever and toxaemia. When the pus is too thick to be aspirated. or if it reaccumulates rapidly, a drain should be established under the water tube after rib resection. Clearance of the pleural space and full re-expansion of the lung may take several weeks to complete. Although antibiotics used to be instilled locally into the pleural cavity with appropriate systemic chemotherapy, this measure is not essential. Thick pus that is difficult to aspirate can be liquefied by instilling proteolytic enzymes such as streptokinase and streptodornase. In most cases, chemotherapy and surgical drainage are adequate to eliminate the empyema. Rarely, an intractable empyema may have to be removed surgically.