Martin et al1 retrospectively studied more than 2000 nontrauma-related surgical ICU admissions and reported that serum bicarbonate (HCO3) might provide information equivalent to the arterial base deficit (BD). This conclusion is a bit surprising, as is their determination that the normal BD of 0 is associated with an HCO3 level of 22 mEq/L rather than the typical level of 24.
There are many formulae2 to calculate the BD, or its negative, the base excess (BE). A positive BE, or a negative BD, is typically associated with an increased serum bicarbonate level, so the authors may have confused these 2 terms. Digital blood gas analyzers today are unlikely to use the standard nomograms, and perhaps the simplest formula for BE is given by the point-of-care blood analyzers (iSTAT Corp, East Windsor, NJ) now used in our hospital: BE = (HCO3) − 24.8 + 16.2 × (pH − 7.4).