RESPIRATION. 205 



of oxygen, a condition ensues, which passes rapidly from HYPERPXCEA 

 (excessive breathing) to the state of DYSPNCEA (difficult breathing), and 

 afterwards to ASPHYXIA ; and the latter quickly ends in death. 



The ways by which this condition of asphyxia may be produced are 

 very numerous. As, for example, by the prevention of the due entry of 

 oxygen into the blood, either by direct obstruction of the trachea or other 

 part of the respiratory passages, or by introducing instead of ordinary 

 air a gas devoid of oxygen, or by interference with the due interchange 

 of gases between the air and the blood. 



Symptoms, The symptoms of asphyxia may be divided into three 

 groups, which correspond with the stages of the condition which are 

 usually recognized, these are (1), the stage of exaggerated breathing ; 

 (2), the stage of convulsions ; (3), the stage of exhaustion. 



In the first stage the patient breathes more rapidly and at the same 

 time more deeply than usual, the inspirations at first being especially ex- 

 aggerated and prolonged. The muscles of extraordinary inspiration are 

 called into action and the effort to respire is labored and painful. This 

 is soon followed by a similar increase in the expiratory efforts, which be- 

 come excessively prolonged, being aided by all the muscles of extraordi- 

 nary expiration. During this stage, which lasts a varying time, from a 

 minute upwards, according as the deprivation of oxygen is sudden or 

 gradual, the patient's face and lips become blue, his eyes are prominent, 

 and his expression intensely anxious. The prolonged respirations are 

 accompanied by a distinctly audible sound ; the muscles attached to the 

 chest stand out as distinct cords. The stage includes the two conditions 

 hyperpnoea and dyspnoea already spoken of. It is due to the increasingly 

 powerful stimulation of the respiratory centres by the increasingly venous 

 blood. 



In the second stage, which is not marked out by any distinct line of 

 demarcation from the first, the violent expiratory efforts give way to 

 general convulsions (in men and other warm-blooded animals at any rate), 

 which arise from the further stimulation of the centres. The spasms of 

 the muscles are those of the body in general, and not of the respiratory 

 muscles only. The convulsive stage is a short one, and soon passes into 

 the third stage, of exhaustion. In it, the respirations all but cease, the 

 spasms give way to flaccidity of the muscles, the patient is insensible, the 

 conjunctivas are insensitive and the pupils are widely dilated. Every 

 now and then a prolonged sighing inspiration takes place, at longer and 

 longer intervals until they cease altogether, and the patient dies. During 

 this stage the pulse is scarcely to be felt, but the heart may beat for some 

 seconds after respirations have quite ceased. The condition is due to 

 the gradual paralysis of the respiratory centre by the prolonged action 

 of the increasingly venous blood. 



As with the first stage, the duration of the second and third stages 



