New Equations to Calculate Temperature Correction Factors for P_O2 in Human Blood

Abstract

Effects of hemoglobin concentration (Hb), pH, and body temperature (T) on the relationships between ΔlogP_O2/ΔT and P_O2 were studied by means of a mathematical model using a Newton-Raphson iteration method. The functions between ΔlogP_O2/ΔT and P_O2 were affected by the above three factors. New equations considering the effects of Hb, pH, and T were proposed by modifying the equation reported by Severinghaus: ΔlogP_O2/ΔT=(L+(U-L)/(A(vP_O237)B+1))(10-2) where U=3.15-0.45(7.4-pH37) L=0.68-0.09(7.4-pH37) A=5.86(exp10(0.074(T)-0.294(7.4-pH37)-11))((Hb)0.913) B=6.33(exp10(-0.0051(T)))((Hb)-0.113)+0.24(7.4-pH37) and vP_O2³⁷ is virtual P_O2³⁷ which may exist when P_O2³⁷ is corrected to standard conditions (pH=7.4, BE=0) by the following equations: vP_O2³⁷=P_O2³⁷(exp₁₀(f_B(7.4-Ph³⁷)-0.0013(BE))) fB=(P_O2³⁷/26.6)^0.08-1.52 where f_B is the Bohr factor. The above equations provided values of ΔlogP_O2/ΔT which fit closely to those obtained by the complex iteration method with maximum differences of less than 1.3×10^-3 at T=27, indicating that maximum % errors for P_O2 at T (P_O2^T) are less than 3.0% at T=27 and that our equations can be applied over a wide range of Hb, Ph37 and T.