Dyspncea is of various kinds. Sometimes it is due to obstruction in the air-passages because of swelling, the formation of false membranes, dropsy of the larynx (p. 363), the presence of foreign bodies or tumours, or accumulation of secretion, as in bronchitis, or blocking of the lungs, as in pneumonia (p. 368) and consump tion, &c. It is a common symptom of valvular disease of the heart (p. 319). It may be of nervous origin, as in asthma ; and it must not be forgotten that it may be associated with a cause quite outside of the chest, owing, for instance, to tumours or accumulated fluid in the belly pressing up the diaphragm (p. 345), and thus interfering with expansion of the chest. In this way an overloaded stomach, or a stomach distended with gas, or a dilated stomach, or a congested liver, will cause short ness of breath.
Suffocation (Asphyxia, Greek, asphuxia, a stopping of the pulse) is an advanced stage of dyspncea. It is the result of want of oxygen in the blood. Usually this want is the result of the exchange between the gases of the blood and those of the external air (p. 349) being interfered with, so that not only does the deficiency of oxy gen become marked, but there is an accumula tion of carbonic acid gas in the blood. Excess of the latter gas in the blood would not, how ever, produce suffocation, provided sufficient oxygen were at the same time supplied ; but it would produce the signs of narcotic poisoning, namely, profound sleep, and complete insensi bility that might end in death. It is the lack of oxygen that produces the results to be de scribed.
It is evident that asphyxia may be brought on in two ways: (1) either by the person being in an atmosphere incapable of supplying any thing like the due amount of oxygen, or, (2) while the atmosphere is of a proper kind, some obstacle exists to the admission of the air to the blood. The latter event may happen because the air cannot be introduced to the lungs be cause of paralysis of the respiratory movements, because the lungs have become blocked up and cannot admit it, or because some obstruction exists in the- air-passages. Thus some foreign body may have fallen into the windpipe, or the windpipe may be closed by strangulation, or the chest may be prevented moving, as, for instance, happens when a mass of earth falls upon a per son, burying him up to the neck.
Asphyxia may occur suddenly by sudden com plete interruption to the breathing, or may came on more slowly, as it does in some diseases, difficulty of breathing becoming worse and worse till it passes into a state of suffocation.
However it occurs its symptoms are the same. Symptoms.—Three stages are recognized in the progress of the process of suffocation. In the first stage there is great difficulty of breathing, in which every muscle is exerted in the effort to get air into the lungs, the veins of the surface of the body becoming distended and livid. This laboured breathing passes into general convulsions, in which nearly all the muscles of the body partake, the faeces and urine being passed by the convulsive move ments.
Then follows the second stage, in which the animal or person lies quiet and insensible, the pupils being widely dilated, the muscles all relaxed, and no movement is capable of being called forth.
Following this is the third and final stage, when long and slow efforts to breathe in are made at long intervals, and become gradually like convulsive gasps, until with one final gasp, head being thrown back, back arched, nostrils dilated, and mouth widely open, death occurs. The heart ceases only after all other movements have stopped.
If the obstruction to the breathing be sudden and complete the stages are all passed through in the course of three to five minutes, and the heart stops in between seven and eight minutes after deprivation of air. In experiments per formed to ascertain after what lapse of time recovery could occur, it was found that a dog, simply deprived of air for four minutes, re covered ; but if deprived of air by submersion in water, recovery was impossible after one and a half minutes, apparently because the entrance of water had prevented the restoration of the lung's function.
Treatment of suffocation consists in remov ing, if possible, any obstacle to the entrance of air. If that has been accomplished the next thing is to cause air to enter the chest. When the case has not gone too far, movements of respiration may be excited by dashing cold water over the chest, or by lashing the chest with towels dipped in cold water. If no move ments can be excited in this way air can still be caused to enter the lungs by artificial res piration (see ACCIDENTS AND EMERGENCIES). Sometimes breathing can be induced by electric shocks properly applied to the nerves of breath ing. Recovery need not be despaired of unless the heart has ceased to beat.