RESPIRATORY PHYSIOLOGIC STUDIES DURING 

 HYPOTHERMIA 



JOHN W. SKVERINGHAUS and M. STUPFEL 



Methods. The major physicocheniical effects of changing temperature on hlood 

 gas transport mechanisms have heen summarized l)y UiH and Forl)es^ and Rosen- 

 hain and Penrod.- Briefly, the sokibihty of l)oth oxygen and caribou dioxide in blood 

 is increased more than 50 per cent at 20° C. For each degree fall in temperature 

 the serum pK' rises .005 pH units (see below) and the whole blood pH [in vitro) 

 rises 0.0147 pH units. The changes in oxygen dissociation curves have been dis- 

 cussed. These changes invalidate the usual nomograms used for computing gas 

 tensions, or pH. 



The direct determination of blood gas tensions using the Roughton-Scholander 

 syringe technique will provide the correct tension if the equilibration and absorp- 

 tion procedures are carried out at body temperature. Since it is difficult to adjust 

 baths to exact and rapidly varying body temperatures, it was desirable to be able 

 to apply corrections for small temperature differences. These corrections may be 

 computed from the standard curves for oxygen dissociation, CO2 solubility, and the 

 known pH and pK' changes. The assumption is made, and has been verified experi- 

 mentally, that plasma CO^ content and whole blood oxygen content are not altered 

 by in vitro changes in temperature. For oxygen, the fact that temperature alters 

 blood pH, and this in turn alters the dissociation curve in addition to the alteration 

 due to the temperature change at constant pH, must be included. Over small ranges 

 of temperature it is sufficiently accurate to reduce the observed tension, per degree 

 difference between body and equilibration bath, by 6 per cent for oxygen and by 

 4.7 per cent for COo. An accurate expression for these relations is given as follows : 



P,, = P„X10'^^^'>-T"'-^^ 



where Pb and Po are the gas tensions in mm. Hg at body and water bath tempera- 

 tures respectively, Ti, and T,. The factor "f" varies with temperature and i)H, values 

 being given in Table I for oxygen and carl)on dioxide. 



These calculated temperature corrections have been subjected to experimental 

 confirmation using the Riley modification of the direct tension technique. The aver- 

 age change for oxygen tension found on reducing blood temperature from ?)7 to 24° 

 was 54 per cent, which is 6.1 per cent per degree when converted by the above 



TABLE I 



Factors iou Coruixtinc IIlood Oxvi.en and Cardox Dioxide Tension ero:m tue 

 Temi'eratuke ok Measurement to the TE^rl'ERAT^■RE or the Subject 



Factors 

 Factors "f" for oxygen "f" for 



^ J- , C'tr. at 



at pH at pH at pTI at pH all pH 



Temp. (C.) 7.0 7.2 7.4 7.6 values 



2,7° 02349 .02410 .02475 .02542 .0192 



30° 02435 .024% .()25(.l .02628 .0200 



23° 02523 .02584 .02049 .02716 .0219 



52 



