BLAIR 



per cent mortality to 60 percent — 75 per cent in coliform or staph- 

 ylococcus shock (Altmeier and Cole, 1958;Smithand Vickers, 1960). 

 Ps. aeroguinosa continues to claim a 100 per cent death rate (Mon- 

 crief). 



Failure to control satisfactorily the staggering losses prompted 

 exploration for help in another direction. While the complex pattern 

 from infection to shock and death is yet to evolve, the underlying 

 problem appears to be hypoxemia. Cellular metabolic requirements 

 (MROo) in febrile states accelerate. This calls for a proportionate 

 increase in circulation to assure adequate delivery of oxygen (CDO2). 

 At any given metabolic level, the ratio of CDO2 to MRO2 determines 

 the presence or absence of hypoxemia and its degree. As long as the 

 circulation meets the requirements, there is no hypoxemia. In the 

 case of septic shock characterized by circulatory failure, the re- 

 duced perfusion results in a proportionate decrease in tissue oxygen 

 tension. The disparity lies with CDO2 (assuming alveolar oxygen 

 tension is maintained). When the ratio falls below a critical level for 

 a given metabolic state, the cell dies. Current treatment is aimed at 

 CDO2 in the form of transfusions, oxygen inhalation and vasopres- 

 sors. This line of attack is inadequate as indicated by the high rate 

 of death. The next obvious step is to attempt modification of MRO2 

 in order to bring it more in line with the reduced CDO2 and restore 

 the normal ratio. Hypothermia is a means of doing this. With pro- 

 gressive lowering of core temperature of the homeotherm, there is 

 an exponential fall in oxygen uptake in the absence of shivering 

 (Spurr etal., 19 54), At 32° C uptake is reduced by one- third, at 30° C 

 by one- half, at 25° C two- thirds, and four-fifths at 20° C (Blair, 

 1960). Reduction in blood flow is roughly proportional to that in oxy- 

 gen consumption. Thus, in septic shock with an already diminished 

 flow, it appeared possible that with a lowering of MRO2 by hypo- 

 thermia, a more favorable metabolic environment may supervene. 



In addition to the significant decrease in metabolism at 32° C, 

 other features at this level provide additional physiological benefits. 

 Cold pressor effect restores and sustains the arterial blood pres- 

 sure. The heart rate is slowed and its work allayed; the central ner- 

 vous system is stimulated and reflex mechanisms are augmented; 

 ventilation is improved, and renal flow is enhanced. This has been 

 termed the augmented level (Blair, 1960). The thesis for hypothermia 



420 



