Methods of Raising a Low Arterial Pressure. 389 



were more effective than pure Einger's solution, the rise in arterial pressure 

 did not remain at any considerably raised level for more than 5 mins. or 

 so. It appears from Boycott's experiments (11) that increase in the total 

 volume of blood, at least in rabbits, is apt to lead to heart failure, presumably 

 from over-distension. The cat's heart does not so readily suffer in this way, 

 and it is to be expected that a rise in venous pressure would be found to 

 occur if the falling blood pressure were due to this cause. I have made 

 several observations by connecting a cannula in the vena cava end of the renal 

 vein with a small indiarubber recording tambour filled with half-saturated 

 sodium sulphate solution. The results obtained were rather contrary to my 

 expectation, in that signs of heart failure were not obvious. For example, in 

 a small cat, the arterial pressure after section of the cord was 40 mm. of 

 mercury, and the venous pressure -47 to 50 mm. of sodium sulphate solution 

 of a density of T047. The injection of 50 c.c. of Einger's solution containing 

 6 per cent, of gum and 3 per cent, of soluble starch raised the arterial 

 pressure to 110 mm. of mercury, but it fell again in 18 mins. to 80 mm. The 

 immediate effect of the injection was to raise the venous pressure to 100 mm. 

 of !N"a 2 S04. But, as the arterial pressure fell, the venous pressure also fell 

 along with it, and when the former was 80 mm. of mercury the latter had 

 returned to its original value. Moreover, the heart beats were no smaller 

 than the initial ones, and even greater than those before the injection of the 

 gum. In experiments in which a membrane manometer was used to record 

 the arterial pressure, it was clear that the fall of blood pressure was not 

 accompanied by any decrease in the vigour of the cardiac contractions. On 

 two occasions on which oedema of the lungs came on in the course of the 

 experiment, a rise in venous pressure up to 160 mm. or more of sodium 

 sulphate solution occurred, as would be expected. In the spinal cat, the rise 

 of arterial pressure produced by injection of gum solutions appears to last 

 for a shorter time than when the cord is merely cut. But here again, 

 although the pressure may have fallen to its original value, the heart beats 

 were larger. There was no considerable rise of venous pressure, but by 

 repetition of injections a permanent rise in it could be produced, and sooner 

 or later heart failure came on. The general impression one obtains from 

 these experiments is that the failure of gum injections to maintain for any 

 considerable length of time the temporary rise of blood pressure is not to be 

 accounted for by heart failure resulting from over-distension of the vascular 

 system. 



Some experiments were made to discover whether an increase of the 

 viscosity of the blood, without increasing its volume, would be more effective. 

 This was done by removing a portion of the blood, defibrinating, centrifuging, 



