A variety of disorders can cause pleuritic chest pain, often with a pleural rub, but without a pleural effusion. Some of these conditions remain ‘dry’ but in most fluid may accumulate, and therefore many of the causes of a pleural effusion must be considered in the differential diagnosis of dry pleurisy.
Pleuritic pain is a common feature of many radiologically obvious pneumonias, but can also occur with minorbacterial and viral pulmonary infections not radiologically apparent. Epidemic myalgia (Bornholm’s disease), mostcommonly due to the Coxsackie B virus, is primarily an infection of intercostal muscle but occasionally the pleura is involved. The intercostal muscles are tender. There maybe associated pericarditis, myocarditis or orchitis. Pain may relapse and remit several times before finally settling.
PNEUMOTHORAX
Pneumothorax is air in the pleural space, as a consequence of which there is partial or complete collapse of the lung. Owing to the recoil of the chest wall and the lung, the pressure within the pleural space is normally negative. When the pleural membrane (visceral or parietal) is breached, air is sucked into the pleural cavity and the lung collapses. When the defect in the pleura seals, the pneumothorax is closed and there is no movement of air in or out of the pleural cavity. When there is a persistent defect in the pleura the pneumothorax is open. When this defect is of the visceral pleura there is then a bronchopleural fistula, and air moves in and out of the pleural space during breathing. Occasionally the damaged visceral pleura acts as a valve, permitting air to enter the pleural space on inspiration but not to leave it on expiration, leading to atension pneumothorax.
A pneumothorax may be spontaneous, or follow chest trauma, mechanical ventilation, ruptured oesophagus, orartificial induction. Causes of traumatic pneumothorax include blunt trauma to the chest, commonly external cardiac massage, and penetrating chest injuries (e.g. stabwounds or needle aspiration biopsies that breach the visceral pleura and transbronchial biopsy and positive-pressure ventilation that breach the visceral pleura from within.
Characteristically, there is a sudden onset of chest pain laterally, sometimes radiating to the shoulder. With substantial collapse of the lung there is associated breathlessness, and a dry, irritating cough is common. Sometimes the patient is aware of the partially collapsed lung flopping about within the thorax. On examination the most striking findings are of reduced breath sounds and hyperresonant percussion.
A small left-sided pneumothorax may be associated with a clicking noise with each heartbeat, noted by the patient and on occasions loud enough to be heard by others. A large pneumothorax in a normal person causes breathlessness, and in the presence of pre-existing pulmonary disease a small one may cause severe respiratory distress. Tension pneumothorax is a medical emergency.
The valve action of the pleural tear results in a progressive increase in the size and pressure of the pneumothorax. The underlying lung is totally collapsed. The mediastinum is shifted to the contralateral side, compromising the function of the opposite lung, and the high intrathoracic pressure elevates the jugular venous pressure, reduces venousreturn and causes tachycardia, low cardiac output, and eventually circulatory collapse and death.