OH. XXIV.] ASPHYXIA. 369 



extraordinary inspiration are called into action, and the effort 

 to respire is laboured and painful. This is soon followed by a 

 similar increase in the expiratory efforts, which become exces- 

 sively prolonged, being aided by all the muscles of extraordinary 

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

 a minute upwards, according as the deprivation of oxygen is 

 sudden or gradual, the lips become blue, the eyes are prominent, 

 and the expression intensely anxious. The prolonged respira- 

 tions are accompanied by a distinctly audible sound ; the muscles 

 attached to the chest stand out as distinct cords. This stage 

 includes the two conditions hyperpnoea (excessive breathing) and 

 dyspnoea (difficult breathing) which follows later. It is due to the 

 increasingly powerful stimulation, of the respiratory centre by the 

 increasingly venous blood. 



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

 line of demarcation from the first, the violent expiratory efforts 

 become convulsive, and then give way, in men and other warm- 

 blooded animals, to general convulsions, which arise from ' the 

 further stimulation of the centres. Spasms of the muscles of the 

 body in general occur, and not of the respiratory muscles only. The 

 convulsive stage is a short one, and lasts less than a minute. 



The third stage, or stage of exhaustion. In it the respirations 

 all but cease, the spasms give way to flaccidity of the muscles, 

 there is insensibility, the conjunctives are insensitive and the 

 pupils are widely dilated. Every now and then a prolonged 

 sighing inspiration takes place, at longer and longer intervals, 

 until breathing ceases altogether, and death ensues. During this 

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

 some seconds after the respiration has stopped. The condition is 

 due to the gradual paralysis of the respiratory centre by the 

 prolonged action of the increasingly venous blood. This stage 

 may last three minutes and upwards. 



The conditions of the vascular system in asphyxia are : 

 ( i i More or less interference with the passage of the blood through 

 tin- systemic and pulmonary blood-vessels; (2) Accumulation of 

 blood in the right side of the heart and in the systemic veins ; 

 (3) Circulation of impure (non-aerated) blood in all parts of the 

 body. 



After death from asphyxia it is found in the great majority of 

 cases that the right side of the heart, the pulmonary arteries, and 

 the systemic veins are gorged with dark, almost black, blood, and 

 the left side of the heart, the pulmonary veins, and the arteries 

 are empty. The explanation of these appearances may be thus 

 summarised : when oxygenation ceases, veuous blood at first 



K.I'. B B 



