title: A simple method for computing acid-base state.
abstract: Simple methods are described for computing the variables derived from the Siggaard-Andersen nomogram, where the in vitro buffer line is either established by direct measurement or calculated from measurements of pH, Pco2 and haemoglobin. Calculations are performed using the equation of the pH-log Pco2 buffer line, the Henderson-Hasselbalch equation, and the polynomials: BE=-38.402+1.8970 (SB)-0.013342 (SB)-2 m-equiv/litre; SL=-69.046+17.377 (pH40)-1.1121 (pH40)-2; SH=-123.30+31.357 (pH40)-2.0143 (pH40)-2. Then haemoglobin=7.5 (1+(S-SL)/(SH-SL)) G/100 ml, where S is the slope of the buffer line. Results are sufficiently accurate for clinical purposes.
mesh_terms: D000136:Acid-Base Equilibrium; D002245:Carbon Dioxide / Q000097:blood; D006454:Hemoglobins; D006863:Hydrogen-Ion Concentration; D008433:Mathematics; D008954:Models, Biological; D010313:Partial Pressure
chemical_list: D006454:Hemoglobins; D002245:Carbon Dioxide