75. 



O^ PRESSURE GRADIENT BETWEEN FETAL AND MATERNAL BLOOD: 



MAN 



III MpOz = partial pressure of O2 in maternal circulation; FpGz = partial pressure of O2 in fetal circulation. 



Contributor : Nesbitt, R. E. L.. Jr. 



Reference : Prystowsky, H., Bull. Johns Hopkins Hosp. \OVA&, 1957. 



7b. 0-, DISSOCIATION RELATIONSHIPS OF FETAL AND MATERNAL BLOOD: MAN, COW. SHEEP 



An approximate curve can be drawn for the range of values from 15-80 mm Hg pOz, based upon the pO^ at half 

 saturation, but the curve is not necessarily valid above and below these pressures. The half saturation pOz is, 

 therefore, a satisfactory approximation. Inflections of the curves around this point have not been investigated in 

 sufficient detail as yet. In man, separation of hemoglobin from the corpuscle results in a decrease of half satura- 

 tion pO^ of 9 mm Hg for maternal blood and 2 ram for fetal at pH 6.8 and 370C; this may reverse their relative 

 positions [ 1] . Values in parentheses are ranges, estimate "b" or "c" of the 95% range (cf Introduction). 



Animal 



No. 



Age 



pO^. ram Hg 

 Half Saturation 



Maternal 



Fetal 



pCOz 

 ram Hg 



Reference 



(A) 



(B) 



(C) 



m 



31(30-35)c2 



333 



27. 27(26. 37-28.17)b5 



29.08(28.02-30. 14)b5 



34 



33 



32 



31.5 



(42-49)c 



(E) 



(F) 



(G) 



1 

 2 

 3 

 4 

 5 

 6 

 7 

 8 

 9 

 10 



Man 



Cow 



Sheep 



1 



224 



224 



3 

 2 

 7 



6 



Term 



Terra 



3.5 mo gestation 



5.5 mo gestation 



7 and 8 mo gestation 



At birth 



50 to HI da 



139 and 140 da gestation 



25(22-29)c2 



255 



21. 86(21. 26-22. 46)b5 



23.94(23. 10-24. 78)b5 



18 



23 



20 



22.5 



(17-19)c 



(25-26)c 



40 



40 



pH = 7.4 



40 



43(41-45)b 



43(41-45)^ 



43(41-45)t' 



43(41-45)b 



40(36-44)b 



40(38-42)1" 



III Temperature, 

 published curve. 



380C. /2/ Derived from graphic approximations corrected to pCOz ■■ 

 111 b maternal, 16 fetal. /5/ Corrected for A log pOz = -0.048 A pH. 



40. in Estimated from 



Contributor: Kaiser, I. H. 



References : [ l) McCarthy, E. F 

 Sax, M. G., ibid 87:97, 1936. [3] 

 Hosp. 53:246, 1933. [4] Darling, 

 1941. [5] Roos, J., and Romijn, 

 Yale J. Biol. 24:169, 1951. 



, J. Physiol., Lond. 1^:55, 1943. [2] Leibson, R. G., Likhnitzky, I. I., and 

 Eastman, N. J., Gelling, E. M., and De Lawder, A. M., Bull. Johns Hopkins 

 R. C, Smith, C. A., Asmussen, E., and Cohen, F. M., J. Clin. Invest. 20:739, 

 C, Proc. Koninkl. Ned. Akad. Wetenschap. 43:1212, 1940. [6] Barron, D. H., 



83 



