Pleth'ora (Gr., 'fullness') designates a general excess of blood in the system. It may arise either from too much blood being made or from too little being expended. The persons who become plethoric are usually those in thorough health, who eat heartily and digest readily, but who do not take sufficient bodily exercise, and do not duly attend to the action of the excreting organs. With them the process of blood-making is always on the increase, and the vessels become more and more filled, as is seen in the red face, distended veins, and full pulse. The heart is excited and overworked, and hence palpitation, shortness of breath, and probably a sleepy feeling may arise; but these symptoms, instead of acting as a warning, ence of pneumonia. Although the above-named symptoms, especially when most of them occur together, afford almost certain evidence of the existence of pleurisy, yet to the physician the physical signs are still more valuable, especially those furnished by auscultation and percussion. The friction-sound, characteristic of pleurisy in the dry stage in its most marked form, resembles the creaking of leather: the patient is often himself conscious of the grating sensation produced by the rubbing of the pleural surfaces; and it may sometimes be felt by a hand laid on the affected part. If fluid effusion be present the friction-sound is lost; but dullness on percussion replaces the normal resonance over the area which it occupies.
Pleurisy far more commonly arises from exposure to cold than from any other cause, especially if a poisoned condition of the blood, predisposing to inflammation of the serous membrane, is present; thus it often complicates rheumatic fever and Bright's disease; but it may be occasioned by mechanical violence (as by a penetrating wound of the thorax, by the splintered ends of a broken rib, &c.), or by the accidental extension of disease from adjacent parts. The disease may terminate in resolution and complete recovery; or in adhesion, which often only causes slight embarrassment of breathing; or it may end with such a retraction of one side of the chest as to render the corresponding lung almost or totally useless; or it may cause death either directly by actual suffocation, if the effusion is very copious, and is not removed by tapping, or indirectly, by exhaustion. It is seldom that simple pleurisy proves fatal; but empyema in adults is a very fatal disease.
In the treatment of pleurisy rest in bed, careful nursing, and light diet are essential. In acute cases in the early stage cupping, leeching, or blistering is generally indicated. When effusion has taken place, purgatives, diuretics, and absorbents should be given. But when fluid is present, in large amount and is not diminishing from day to day, it is usually desirable to draw it off by tapping. If the fluid be serous this usually greatly hastens recovery. Even when it is purulent (empyema) aspiration, repeated when necessary, is often successful in the case of children; but more generally, especially in adults, free anti-septic opening and drainage of the cavity alone affords any hope of cure.