DROPSY. 241 



"When the fluid accumulates in the membrane which lines the chest or thorax and 

 covers the surface of the lung, the condition is known as " hydrothorax ; " and when 

 it Collects in the pericardium, or membrane of the heart, it is called " hydroperi- 

 cardium. Sometimes the liquid accumulates in the belly, and then we speak of it 

 as " ascites." When the limbs and body are distinctly swollen from the accumulation 

 of dropsical fluid beneath the skin, the patient is sometimes said to be suffering from 

 " anasarca." By " general dropsy " is usually meant a combination of anasarca with 

 dropsy of one or more of the large cavities to which we have referred. 



Dropsy may be due to many different causes. Thus, it may arise from disease of 

 the heart, or from disease of the liver, or from disease of the kidneys more especially 

 from the form of kidney disease which we have already described under the name 

 of " Blight's." The way in which these complaints produce effusion of fluid is in all 

 probability by increasing the pressure of blood in the vessels the arteries, and veins, 

 and smaller vessels called capillaries ; so that its more fluid portion infiltrates or is 

 squeezed through their walls. It is easily understood that if the kidneys are diseased 

 they cannot throw off the water from the system, and the blood-vessels get too full. 

 The same thing happens in disease of the heart, for that organ may be so weakened 

 and may perform its functions so imperfectly as to be unable to push on the blood, 

 and an obstruction with increased pressure is the result. In disease of the liver, 

 dropsy usually begins in the form of ascites, or effusion into the belly, and the 

 explanation of this is that the liver contracts and narrows the calibre of the blood- 

 vessels, so as to increase the pressure of the blood and squeeze out the fluid. 



The influence of obstruction to the circulation in producing dropsy is well seen 

 in the case of the complaint known as " white leg," which is common in women soon 

 after child-birth. The foot, leg, and thigh become enormously distended. The 

 essence of the complaint is inflammation of the vein of the thigh, precluding or 

 retarding the return of blood from the limb. Again, in pregnancy, the womb some- 

 times presses upon some of the large veins in the belly, obstructing the current of 

 blood in them, and in this way giving rise to dropsy of the lower extremities. It 

 is but a temporary condition, and soon disappears after the confinement. Sometimes 

 effusion of fluid is so strictly localised as to be confined to one joint, as the knee or 

 elbow, but then it is nearly always due to some injury to the part, as a blow or 

 sprain, and is not the result of any constitutional disease. 



It is quite conceivable that we may get dropsy without any increased pressure in 

 the blood-vessels, and this undoubtedly does sometimes occur. Thus, in cases of 

 marked anaemia, the blood may become so thin that its fluid part filters through the 

 blood-vessels independently of any unusual pressure, and in this way gives rise to 

 dropsy. It is, we think, not generally known that very extensive dropsy may be 

 dependent solely on the presence of anaemia. Many women suddenly become drop- 

 sical as the result of flooding, and this condition rapidly disappears when the quality 

 of the blood improves. A sharp attack of diarrhoea has been known to give rise to 

 a temporary dropsical effusion. 



There is seldom any difficulty in recognising the presence of dropsy. The limbs 

 are commonly increased in size ; they are soft and inelastic, and when they are 

 pressed upon with the finger a little mt or depression is left. Usually there is 

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