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BLOOD PRESSURES IN MAN, NORMAL AND PATHOLOGICAL 325 



sary for the due vigour of the cardiac muscle; otherwise the coronary 

 circulation is apt to be insufficient. Excessively low pressure injures 

 the nutrition of the heart, favouring enlargement, etc. Muhlberg (99) 

 is quoted by Friedlander to the effect that low pressure after the age 

 of 50, unassociated with any organic lesion to account for it, constitutes 

 the best criterion of life beyond the normal expectancy; it is also stated 

 by Friedlander (50) from Fisher's figures that of 3,389 persons (ages 

 16 to 60) with systolic pressures of 100 mm. or less there was only 

 35 per cent of the expected mortality. Symonds (122) considers low 

 pressures after the age of 40 desirable; he also reports that the lowest 

 mortality was found in those subjects who were 15 per cent below the 

 average weight. Pressures not too low seem to favour longevity. 



The general relation of low blood pressure to tuberculosis has been 

 the subject of several inquiries in recent years. Marfan and Vannieu- 

 wenhuyse (94) (700 cases) while finding systolic pressure lowered — 

 more so as the disease was serious or getting worse — do not regard 

 low pressure as excluding improvement or recovery. Normal or raised 

 systolic pressure they regard as a good prognostic. Diastolic pressure 

 falls only in the last stage. These workers emphasise the importance 

 of repeated examinations. De Bloeme (36) in 500 cases by the auscul- 

 tatory method affirmed the existence of an important group at 100 

 to 110 mm. S. where the seriousness of the condition was more recog- 

 nisable by the blood pressure than by other methods, while cases at 

 80 to 100 mm. were recognisable by ordinary diagnostic means. There 

 seemed to be a general relation between the higher pressures and better 

 conditions of the patients. The most favourable cases of both sexes 

 were between 110 and 150 mm. There was apparently an association 

 between low pressures and the tendency to relapse or the occurrence of 

 relapse, even after the local and general symptoms had subsided; 

 blood pressure rose with improvement. 



While regarding blood pressure as being below normal in 60 per cent 

 of early cases, Naucler (101) sometimes found normal or higher pres- 

 sures in early cases and concluded that low pressure is not a reliable 

 sign of early phthisis. The low pressures seemed to depend more on 

 the severity than on the extent of the disease. 



R. J. Cyriac (31) recorded differences in the systolic pressure readings 

 in the two arms in a number of tuberculous cases as E. F. Cyriac (30) 

 did in association with some traumatic conditions. 



That excessive smoking can lower blood pressure has long been 

 known and comes into question when systolic pressures at or below 

 100 mm. are observed. 



