Effects of Carbon Mon-oxide Poisoning, 



69 



(3) the number of respirations per minute, (4) the volume of air 

 respired per minute; in twelve experiments: (i) the physical 

 symptoms, (2) the point of onset of coma, (3) the point of death. 



As soon as the animal begins to breathe the carbon mon-oxide 

 there is an immediate acceleration of the pulse, which steadily 

 gains in frequency until 45-50 per cent, of the hemoglobin is 

 saturated with carbon mon-oxide. Then the pulse rate is at its 

 maximum. After that it declines gradually until a point is reached 

 between 71-74 per cent, of carbon mon-oxide saturation, when 

 the pulse rate falls abruptly and the heart ceases to beat. 



The blood pressure in about half the cases was found to go 

 gradually downward in spite of the markedly increased rate in the 

 heart beat. In the rest of the cases there was a preliminary rise 

 in pressure of about 10-15 mm. of Hg, which reached its maxi- 

 mum when 45—50 per cent, was saturated with carbon mon-oxide. 

 This was followed by a gradual decline, until when about 67 per 

 cent, of the hemoglobin was saturated, there was an abrupt fall in 

 blood pressure. 



The number of respirations per minute, taking two character- 

 istic examples, was found to increase from a normal of 19 and 22 

 to 32 and 45, respectively, when about 50 per cent, of the hemo- 

 globin was saturated with carbon mon oxide. In other cases there 

 was no increase in the rate of respiration at all, but there was a 

 marked increase in the depth of each inspiration. The volume of 

 air respired per minute, however, increased in all cases as soon as 

 the animal began to breathe the carbon mon-oxide. It presented 

 a curve with an ascending and descending limb. The maximum 

 ventilation of the lungs took place when about 45 per cent, of the 

 hemoglobin was combined with carbon mon-oxide. After that it 

 declined gradually. At about 65 per cent, saturation, however, 

 breathing became irregular, sometimes of the Cheyne-Stokes 

 variety. Respiration always stopped about one to three minutes 

 before the heart ceased beating. 



When about 40 per cent, of the dog's hemoglobin is deprived 

 of its oxygen carrying capacity, the animal begins to get weak. 

 It cannot stand on its legs. It is in a state of general indifference. 

 It does not partake of any food or drink, though it may be hungry. 

 It is seized with vomiting and occasionally has convulsive spells. 



