32 POISONING BY CARBONIC OXIDE. 



17. Phenomena of Poisoning by Carbonic Oxide. Other 

 Compounds of Haemoglobin. 



Carbonic oxide is formed during incomplete combustion of coal or coke, and 

 passes into the air of the room, provided there is not a free outlet for the 

 products of combustion. It occurs to the extent of 12-28 per cent, in ordinary 

 gas, which largely owes its poisonous properties to the presence of CO. If the 

 be gradually displaced from the blood by the respiration of air containing CO, life 

 can only be maintained as long as sufficient can be obtained from the blood to 

 support the oxidations necessary for life. Death occurs befoi-e all the is dis- 

 placed from the blood. CO has no effect when directly applied to muscle and 

 nerve. When it is inhaled, there is first stimulation and afterwards paralysis of 

 the nervous system, as shown by the symptoms induced, e.g., violent headache, 

 great restlessness, excitement, increased activity of the heart and respiration, 

 salivation, tremors, and spasms. Later, unconsciousness, weakness, and paralysis 

 occur, laboured respiration, diminished heart-beat, and lastly, complete loss of 

 sensibility, cessation of the respiration and heart-beat, and death. At first 

 the temperature rises several tenths of a degree, but it soon falls 1 or more. The 

 pulse is also increased at first, but afterwards it becomes very small and frequent. 



In poisoning with pure CO there is 110 dyspnoea, but sometimes muscular spasms 

 occur, the coma not being very marked. There is also temporary but pronounced 

 paralysis of the limbs, followed by violent spasms. After death the heart and 

 brain are congested with intensely florid blood. lu poisoning with the vapour of 

 charcoal, where CO and C0 2 both occur, there is a varying degree of coma ; pro- 

 nounced dyspnrea, muscular spasms which may last several minutes, gradual 

 paralysis and asphyxia, moniliform contractions and subsequent dilatation of the 

 blood-vessels, with congestion of various organs, occur, accompanied by a fall of the 

 blood-pressure (Klebs), indicating initial stimulation and subsequent paralysis of 

 the vaso-motor centre. This also explains the variations in the temperature and 

 the occasional occurrence of sugar in the urine after poisoning with CO. After 

 death, the blood-vessels are found to be filled with fluid blood of an exquisitely 

 bright cherry-red colour, while all the muscles and viscera and exposed parts of 

 the body (such as the lips) have the same colour. The brain is soft and friable, 

 there are catarrh of the respiratory organs and degeneration of the muscles, and 

 great congestion and degeneration of the liver, kidneys, and spleen. The spots of 

 lividity, post-mortem, are bright red. After recovery from poisoning with CO, 

 there may be paraplegia and (although more rarely) disturbances of the cerebral 

 activity. The poisonous action of the vapours of combustion was known to 

 Aristotle. 



(4.) Nitric Oxide -Haemoglobin (NO-Hb) is formed when NO is 

 brought into contact with Hb (L. Hermann). 



As NO has a great affinity for 0, red fumes of nitrogen peroxide (NOo) being 

 formed whenever the two gases meet, it is clear that, in order to prepare NO-Hb, 

 the O must first be removed. This may be done by passing H through it, [or 

 ammonia may be added to the blood, and a stream of NO passed through it ; the 

 ammonia combines with all the acid formed by the union of the NO with the 

 O of the blood]. NO-Hb is a more stable chemical compound than CO-Hb, 

 which, as we have seen, is again more stable than OjHb. It has a bluish-violet 

 tint, and also gives two absorption -bands in the spectrum similar to those of the 

 other two compounds, but not so intense. These bands are not abolished by the 

 action of reducing agents. 



The three compounds of Hb, with 0, CO, and NO, are crystalline; 

 like Hb, they are isomorphous, and their solutions are not dichroic. One 



