ASPHYXIA. 



263 



undergo this change, and towards the arterial 

 blood in advance of it in the vessels ; not of 

 the nature of an increased contraction of the 

 vessels themsleves ; and that it is in conse- 

 quence of the failure of this auxiliary power 

 in the circulation, that the stagnation of the 

 blood in the lungs in asphyxia, and the extinc- 

 tion of the organic life, are effected. 



What has been said of the manner in which 

 death is produced in asphyxia, enables us to 

 understand in what circumstances it can hap- 

 pen, that life may be retained, even by a 

 warm-blooded animal, for an unusual length 

 of time, without respiration. As the stop to 

 the circulation is the immediate cause of death, 

 it is obvious that an animal which can exist for 

 a time, in a lowered state of vitality, with 

 little or no circulation, will during that time 

 require no exposure of its blood to air, to 

 maintain that grade of vitality ; and farther 

 that in such an animal, as the brain will not 

 suffer from the afflux of venous blood, and as 

 the lungs will not be hurtfully congested, these 

 organs will retain a condition much better 

 adapted for the recovery of their functions, 

 than they will in those cases where asphyxia 

 is produced at a time when the circulation is 

 vigorous. 



Hence we can easily understand, that per- 

 sons who are in a state of syncope, (from a 

 temporary cause,) in whom the circulation is 

 nearly at a stand before the access of air to 

 their lungs is obstructed, may survive a longer 

 suspension of the acts of respiration than per- 

 sons in health. This has been stated, by Des 

 Granges and Fodere, as the explanation of 

 some cases in which it appears certain, that 

 recovery has taken place after fifteen minutes 

 or more of submersion in water.* 



The case of hybernating animals was, until 

 lately, considered to be of this nature, i. e. it 

 was supposed that circulation is gradually sus- 

 pended in those animals, simultaneously with 

 respiration, and therefore that such animals, 

 although consuming little or no air, did not 

 suffer the noxious influence of venous blood 

 on their solids, and remained susceptible even 

 of sensation. But the experiments of Dr. 

 Marshall Hall f appear to have established that 

 in warm-blooded hybernating animals in the 

 complete state of torpor, when respiration is 

 quite at a stand for many hours, circulation, 

 although slow and feeble, still goes on regu- 

 larly; so that we must suppose the essential 

 peculiarity of these animals, during the state 

 of lowered vitality, to which they are reduced 

 by cold, to be this, that the venous blood has 

 little of the noxious effect, in any part of the 

 system, which it has, on them as on other 

 animals, during the state of activity ; it has 

 neither the same difficulty of making its way 

 through the lungs, nor the same destructive 

 influence on the brain. J 



* Fodere, Med. Legale, $ 613. 



t Phil. Transactions, 1832. 



$ Dr. M. Hall considers the essential peculiarity 

 of these animals to be, that the left side of the 

 heart in them, is irritable by venous blood ; but as 

 it appears from the facts above stated, that the 



The nearest approach to this mode of vita- 

 lity in the human body, is in the case of the 

 new-born child, which has never felt the in- 

 fluence of perfectly arterial blood, and which 

 has been known to live, although its natural 

 respiration was not established for nearly an 

 hour after birth. 



The study of the fatal changes in asphyxia 

 is also of peculiar importance as illustrating 

 the manner in which the circulation, and the 

 organic functions maintained by it, are con- 

 nected with the nervous system. It will be 

 observed, that as the vitality of hybernating 

 animals, during the state of torpor, is inde- 

 pendent of respiration, so it is also, in a great 

 measure at least, independent of the larger 

 masses of the nervous system ; and Dr. M. 

 Hall found, by experiment in a hedgehog in 

 this state, that the circulation went on regu- 

 larly for ten hours after the gradual but com- 

 plete destruction of the brain and spinal cord. 



Indeed, the maintenance of the circulation 

 after the head of an animal has been cut off, 

 by the artificial respiration, i. e. by inflating 

 its lungs in a manner resembling its natural 

 breathing, (which has been so often practised 

 by Fontana, Cruikshanks, Bichat, Brodie, Le 

 Gallois, Wilson Philip, and others,) is in it- 

 self a clear proof that the circulation, and 

 other functions of organic life* in animals, 

 are necessarily and immediately dependent on 

 the animal life, only inasmuch as the natural 

 respiration of animals, and the arterialization of 

 their blood, are dependent on sensation. And ac- 

 cordingly we know, that in that stage of animal 

 existence, where the supply of sufficiently 

 arterialized blood is provided for without the 

 intervention of sensation, i.e. in the foetus in 

 utero, the whole organic life is altogether in- 

 dependent of the animal, and goes on perfectly, 

 not only before sensation is felt, but even in 

 cases where the essential organs of sensation 

 and of voluntary motion, the brain and spinal 

 cord, do not exist. It is not until the moment 

 of birth, when the arterialization of the blood 

 is put in dependence on sensation, that the 

 brain and spinal cord become essential for the 

 maintenance of organic life ; or that we possess 

 any proof of influence being exercised by the 

 nervous system, over that part of the animal 

 ceconomy. 



It seems probable, that if we possessed the 

 means of making the artificial respiration ex- 

 actly similar to the natural, and neither injuring 

 the structure of the lungs, nor introducing 

 more air into them than is useful, in practising 

 it, the circulation, and perhaps all the func- 

 tions of organic life, might be maintained, after 

 the head of an animal is cut off, until nearly 

 the time when it must fail for want of nourish- 

 ment; but it must also be remembered, that 

 in the adult animal, as the experiments of Le 



stop to the circulation in asphyxia is at the lungs, 

 the chief peculiarity of these animals must lie 

 there also. 



* By organic life, we mean those vital acts which 

 take place without the intervention or consciousness 

 of the mind ; by animal life, those in which some 

 mental act is an essential constituent. 



