CHLORAL 337 



pose chloral, and that chloroform is not found in the blood, tissues or 

 excretions, except in the case of the urine, when it is strongly alkaline. 

 Moreover, chloral acts as usual upon a frog when the blood of the batrach- 

 iau is replaced by a neutral saline solution. 



Heart and Blood Vessels. — Chloral in large doses depresses the 

 action of the heart muscle and the vasomotor centres. It also produces 

 local paralysis of the vascular walls. Elood pressure is therefore low- 

 ered. In small medicinal doses the circulation is not influenced mate- 

 rially, but in poisoning the pulse at first is accelerated and then becomes 

 slow, weak and irregular, and the heart is arrested in diastole. 



Nervous System. — The salient action of chloral is exerted upon the 

 byain and cord. Like other narcotics, the depressing effect may be pre- 

 ceded by a transient and unimportant excitation of the brain and cord; 

 but this commonly passes unnoticed, and the prominent action of chloral 

 consists, in ordinary doses, in depressing the sensory and motor centres 

 of the brain, and in larger doses, the spinal reflex activity and the motor 

 tract of the cord. Moderate therapeutic doses cause, therefore, dulness 

 and sleepiness (with contracted pupils) in the lower animals, while doses 

 approaching the toxic point produce insensibility, coma, paralysis of the 

 inferior cornua, with loss of reflex action and muscular power, so that the 

 animal falls with paraplegia, dilated pupils and anesthesia. These 

 symptoms may occur and be followed by recovery. The anesthesia is of 

 spinal origin. Neither the sensory nerves, motor nerves, nor muscles 

 are affected except in the' later stages of poisoning. 



Insensibility to pain is said, by Brunton, to follow the action of 

 chloral upon the gray matter of the cord, by preventing the transmission 

 of painful sensations through this tract. It is uncertain whether chloral 

 acts as an hypnotic by its direct depressing influence upon the brain tis- 

 sue, or by inducing cerebral anemia in causing the blood to be withdrawn 

 from the cerebrum into the dilated peripheral arterioles. 



Respiration. — The respiration is not interfered with by modeirate 

 medicinal doses of chloral but toxic quantities depress and paralyze the 

 respiratory centre. The respiratory movements become deep, regular, 

 accelerated and fuU, with large therapeutic doses, but with toxic doses, 

 slow, irregular and shallow. Death occurs more commonly from arrest 

 of respiration, yet primary heart failure, or both combined, may lead to 

 a fatal result. 



Temperature. — The temperature may be elevated at first, but soon 

 falls, owing to diminished heat production and increased loss, through 

 heart failure and vascular dilatation. 



Elimination. — Chloral is eliminated by the urine, in part unchanged 

 and in part as urochloralic acid. 



Metabolism. — Chloral in large doses leads to increased destruction 

 of the proteids of the body and imperfect oxidation of their products, 

 together with fatty degeneration of the internal organs. These tissue 

 changes are caused by the production of urochloralic acid in the tissues. 



Summary. — Chloral is a local anesthetic, stimulant and antiseptic. 



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