Computational augmentation of blood gas measurements

Blood gas analysis provides the physician with powerful tools for both diagnosis and patient management. It is technically and economically expedient to measure pH and the partial pressures of oxygen and carbon dioxide directly. Oxyhemoglobin saturation may then be calculated, and oxygen and carbon dioxide content and arteriovenous differences determined by computation if hemoglobin, hematocrit, and temperature are known. Although the necessary computational techniques are available, they are not commonly used in clinical practice. A computer program called BLOODGAS, which performs these calculations was written in basic FORTRAN IV for an XDS Sigma 3 computer. In addition to the calculations indicated above, it corrects the measured partial pressures for temperature. The oxyhemoglobin saturations which it computes are virtually indistinguishable from those of the standard oxy-hemoglobin dissociation curve. For example, the P50(7.4) of the standard curve is approximately 26.4 while that of the computed curve is 26.834. Its calculated values of carbon dioxide content compare favorably with values published in the literature.