SÉANCE DU 19 OCTOBRE 851 



G Daiuof^'C lo llie circulatory control. — If a low blood pressure bas 

 lasted a long lime, nothing will cause a permanent rise of blood pres- 

 sure (Dijon experimeats, clinical observations). 



7. A marked sensitiveness of sbocked men to ether or chloroform 

 anseslhesia, wbich induces a dangerous réduction of an already low 

 pressure (Bétbune observations and Dijon experiments). 



8. A tolérance of nitrous oxide and oxygen as an aneeslbetic with- 

 out fall of blood pressure (Bétbune observations and Dijon experi- 

 ments). 



EXPLANATION OF THESE FaCTS. - 



j . Low arterial pressure. — This is not due to cardiac weakness ; for 

 if arterial pressure is raised by adrenalin or by cérébral compression, 

 the heart works effectively against Ihe high pressure (Mann, Dijon 

 experiments). It is not due primarily to lack of vasoconstrictor tone ; 

 for, raising the blood pressure by aortic compression, in a rablsit with 

 cervical sympathelic eut on one side, results in flushing of the dener- 

 vated ear but not of the ear still co.nnected with the medulla (Seelig and 

 Joseph). 



2. The low pressure is explicable as a conséquence of blood being 

 out of circulation or stagnant in some part of the vascular System 

 (excemia). The exîemic blood is not in the abdominal veins as 

 commonly supposed (see testimony of British surgeons, Lancet^ 1917, 

 2, p. 727). It is not in the arteries, for in that case arterial pressure 

 would not be low. 



3. Concentration of blood in capillaries. — The observation suggests 

 that the " lost blood " of shock may be largely stagnant in capillaries, 

 concenlrated there by extravasation of lymph. Concentration is seen 

 also in shock produced by injection of histamine (Dale and Laidlaw). 



4. Variation of shock with body température. — Cold causes an 

 accumulation and concentration of corpuscles in the capillaries. The 

 blood count is higher in a cold Ihan in a corresponding warna part ot 

 the skin. Cold, therefore, would augmeut the exsemia of shock and 

 warmth would diminish it. 



.5. Réduction of the alkali reserve. — This results from too great 

 lowering of arterial pressure. If the pressure is lowered to 80 mm., of 

 mercury by lessening cardiac inflow through increased intrapericardial 

 pressure, Ihere is no réduction of the alkali reserve ; if lowered to 

 70 mm. the reserve begins to decrease; and if lowered to 60 mm, it 

 decreases more rapidly (Dijon experiments). Records of human eases 

 made at Bétbune confirm thèse expérimental observations. A " eritical 

 level " in a falling blood pressure lies at about 80 mm. of mercury 

 systolic pressure. 



