Determination of base excess in umbilical cord blood at birth: accessory or excess?

Validation of the Siggaard–Andersen Acid–Base Nomogram for Hemoglobin F: Implications for Fetal Cord Blood Gas Analysis

“…In contrast, metabolic acidemia is much less common but reflects longer standing hypoxia and may be associated with newborn encephalopathy and long-term neurologic impairment. [1][2][3][4][5][6][7][8][9] In 1960, Siggaard-Andersen published a nomogram facilitating the evaluation of blood acid-base disturbances using the concept of base excess, defined as the number of milliequivalents of acid or base required to bring the pH of 1 L of blood to 7.40 at 37°C with a constant pCO 2 of 40 mm Hg. 10,11 The Siggaard-Andersen nomogram is essentially a simultaneous solution of two equations, the Henderson-Hasselbalch equation ( 12 As such, it allows calculation of base excess (BE in the latter equation) based on the measurement of pCO 2 , pH, and hemoglobin concentration.…”

“…Recent data based on empiric observations have demonstrated a poor correlation between calculated umbilical cord base excess values and newborn outcomes linked to tissue hypoxia and metabolic acidosis. [5][6][7][8][9] The most obvious explanation for such observations involves the well-established fact that most cases of in utero neurologic impairment predate labor and are unrelated to intrapartum hypoxia or acid-base disturbance. 8,18 However, there are two additional physiological possibilities for the limited correlation between HCO 3 , and base excess assessment, intrapartum events, and newborn condition.…”

Neonatal metabolic acidosis at birth: In search of a reliable marker

“…Older [19] and more recent studies [20][21][22][23] discount any value of in vivo BD over and above knowledge of the pH, which they consider as the best marker of fetal status at birth, but their conclusions on pH value at birth address ''total'' acidity, because they do not take into account the hypercapnic portion that contributes substantially to acidemia (information on PCO 2 values is lacking in the majority of articles). Our goal is to obtain a reliable method of diagnosing NMA that would be a true instantaneous picture at time zero (T0) of the metabolic part of newborn acid-base status, to measure fetal response to labor, and to identify any potential abnormalities that may result from labor, because this knowledge may help identify term infants at risk of morbidity, or later may have a recognized medical-legal importance in case of CP [4].…”

Sensors for Fetal Hypoxia and Metabolic Acidosis: A Review

“…The base deficit (BD) is indicative of the fetal reserves and represents the number of bases that would neutralize the blood to a pH value ranging between 7.2 and 7.4. The carbonic acid (H 2 CO 3 ) −bicarbonate (HCO 3 − ) buffer is represented by Equation (1) [ 36 ]. …”