1908.] 



Composition of the Blood in Cholera. 



301 



The Relationship of Blood-pressure to Post-choleraic Uraemia. 



One result of tiding so many severe cases of cholera over the collapse stage 

 hy large hypertonic saline transfusions, is to accentuate the importance of 

 uraemia in the later stages of the disease. This very serious complication is 

 especially seen in two distinct classes of cases : — Firstly, in patients brought 

 to hospital more than 48 hours after the onset of the symptoms, which not 

 infrequently have been comparatively mild at the onset, and whose treatment 

 has been neglected. Secondly, the other extreme of patients admitted early 

 on account of the great severity of the affection, who have been supported 

 by repeated transfusions to the stage of reaction, when it is found to be 

 extremely difficult to restore the renal secretory activity, which has been in 

 abeyance during the prolonged period of very low blood-pressure. 



On cutting sections of the kidneys of patients who had died in the uraemic 

 stage of cholera, I was much struck by the amount of effused blood in and 

 around the convoluted and straight tubules and the tense state of the capsule 

 enclosing the extremely congested organ : all suggesting an actual mechanical 

 difficulty in the re-establishment of an efficient circulation through the organ. 

 In order to test if this was the case or not, I tried perfusion of normal saline 

 solution through the renal artery from different heights, so as to measure 

 the actual pressure required to obtain a fairly full outflow from the renal 

 veins. For this purpose I used both healthy kidneys, got from the bodies 

 of patients dying of other diseases, and also several from those who had 

 succumbed to the uraemia of cholera. In the former, a pressure equivalent 

 to 20 or 30 mm. of mercury sufficed to obtain a good flow through the 

 kidney circulation. On the other hand, in the cholera ones no flow at all 

 was got under a pressure of about 60 mm., and then only drop by drop, and 

 it was not until 90 or 100 mm. was reached that anything like a full stream 

 was observed. In one experiment, subsequent slitting of the capsule of the 

 organ reduced the pressure required by about 20 mm. In a case of cholera 

 in which the patient died of late complication with empyema, after the 

 secretion of the urine had been freely established a pressure equivalent to 

 30 mm. of mercury sufficed for the free perfusion of normal saline through 

 the kidneys, showing that it was only in uraemic cases that obstruction of 

 the renal circulation existed in such a marked degree. 



Since the above observations were made, the blood-pressure has been 

 carefully watched day by day after the termination of the collapse stage, and 

 it has been found that the uraemic symptoms are more common in those 

 whose blood-pressures do not rise above 100 mm. For example, two very 

 severe cases of cholera were admitted to hospital at about the same time, 

 both of whom received two saline transfusions of 4 pints each, and 



