5*^6 DISEASES OF THE HEAD. NECK, VEDfS, ETa 



ENTRANCE OF AIR INTO VEINS. 



Air rapidly injected into a vein causes immediate death, but 

 if injected slowly it only causes great distress. The accidental 

 admission of air into the veins has often resulted in a fatal 

 termination, and advantage has been taken of the knowledge so 

 gained, for the purpose of destroying old or otherwise worthless 

 horses by this easy mode of death. An accidental admission of 

 air into a vein, causing death, may ooour after bloedinjij ; for 

 example, if the pressure upon the jugular whidi is maintainea 

 by the finger or vessel containing tho blood be suddenly with- 

 drawn, a vacuum is formed, into which the car: rushes with a 

 hissing, gurgling, or suclcing sound. The animal is suddenly 

 seized with symptoms of faintness and convulsive breathing, 

 falls, and perhaps immediately dies. In other instances the 

 fatal termination is not so rapid, but a great faintness soems to 

 overcome the animal. He may fall and breathe with difficulty ; 

 a churning noise is said to bo heard at the heart, tlie action of 

 which is extremelv feeble. If the quantity of air whicli has 

 entered is but small, the animal may rally ; but more copious 

 entrance causes death by syncope ; in some cases there ai-e 

 convulsions, whilst in others death seems to be due to mere 

 exhaustion. 



The mode of death is as follows : — The blood becoming 

 mingled with air, assumes a frothy cliaracter in the right 

 ventricle ; it is sent through the pulmonary artery, but becomes 

 more or less arrested in the j)ulraonic capillaries, in consequence 

 of tho right ventricle being unable to overcome the mechanicaJ 

 obstacle presented by air-bubbles in these vessels. The quantity 

 of blood transmitted through the lungs for the systemic 

 circulation grows less and less, according to tlieincrease of 

 obstruction and arrest of the blood in the capillaries of the 

 lungs. The supply to the head is inadequate to afford due 

 stimulus to the nervous centres, and syncope results. If circu- 

 lation bo not ro.storcd, tliis continues ; the respiratory move- 

 uicuta then cease, and life becomes extinct; tlie heart last 

 failing in ita action from want of ita necessary stimulus — the 

 blood. 



From some exporimsuts made by me and one of my pupila 

 (ilr. Ilutchcou), it was found that some of the air was eliminated. 



