Table 1

Stewart's six simultaneous equations

[H⁺] × [OH^-] = K'w

[H⁺] × [A^-] = Ka × HA

[HA] + [A^-] = A_TOT

[H^+-] × [HCO₃^-] = Kc × PCO₂]

[H⁺] × [CO₃^2-] = Kd × [HCO₃

SID + [H⁺] - [HCO₃^-] - [CO₃^2-] - [A^-] - [OH^-] = 0

All K values are known dissociation constants. PCO₂, partial CO₂tension; SID, strong ion difference.

Morgan Critical Care 2005 9:204 doi:10.1186/cc2946