RENAL FUNCTION IN RESPIRATORY FAILURE 



D. A. K. Black 



Departmeyit of Medicine, Royal Infirmary, University of Manchester 



With increasing age, the functional capacity of the lungs 

 and of the kidneys declines. Respiration is embarrassed by 

 increasing rigidity of the chest wall, and there is also an 

 increase in the respiratory dead space of the lung itself in 

 older subjects (Comroe et al., 1955). The kidneys lose efficiency 

 in consequence of a progressive loss of nephrons, which may 

 reduce the nephron population to 60 per cent of the original 

 number; the impairment of renal function is indicated by a 

 fall in the clearance of inulin and of ^^-aminohippurate, and in 

 the maximal reabsorptive capacity for glucose (Tm(j) (Shock, 

 1952). The blood pH in old people is a little lower, and their 

 plasma returns more slowly to its previous level after imposed 

 loads of either acid or alkali. These various encroachments 

 on functional reserve are probably of no great moment in 

 healthy old folk leading a normal life; but they are brought 

 into prominence when respiratory function is pathologically 

 impaired by the related changes of chronic bronchitis, 

 bronchospasm, and emphysema. In an urban population, the 

 incidence of chronic bronchitis in old people has been found 

 to be 40 per cent (Sheldon, 1948); this common illness leads 

 in time to gross respiratory failure, with the patient afflicted 

 by anoxia, hypercapnia, and increased pulmonary vascular 

 resistance in varying degrees. There are several ways in which 

 advanced respiratory failure can increase the demands on 

 the kidneys, and also diminish their functional capacity. 

 This communication outlines the effects on renal function of 

 chronic hypercapnia and of cardiac failure secondary to 

 emphysema (cor pulmonale). 



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