Evaluation of the efficacy of simplified Fencl-Stewart equation in analyzing the changes in acid base status following resuscitation with two different fluids

BACKGROUND: Metabolic acid-base disorders in critically ill patients may not be identified by base excess (BE) approach. Anion gap method can detect approximately 1/3 hidden “gap acidosis”. In such conditions, when adjusted for hypoalbuminemia, Fencl-Stewart's approach can reliably detect the hidden abnormal anions. AIM: Evaluate the efficacy of simplified Fencl-Stewart equation in identifying the changes in acid-base status of sepsis patients following resuscitation with two different fluids. SETTINGS AND DESIGN: Intensive care unit, randomized, prospective, interventional study. MATERIALS AND METHODS: Three hundred adult patients of both sexes presenting with abdominal sepsis, requiring fluid resuscitation were randomly assigned into normal saline (NS) and Ringer's lactate (RL) group, each comprising of 150 patients. 20 ml/kg of NS or RL were administered over a period of 30 min. The changes in the acid-base status were calculated applying the simplified Fencl-Stewart equation and was compared with the measured values obtained through arterial blood gas. STATISTICAL METHODS: Paired t-test for intra-group while unpaired t-test for inter-group comparison. RESULTS: Blood pH and standard BE decreased and the serum Na(+) and Cl(-) level increased significantly in NS group. The serum albumin level significantly decreased in both the groups. Sodium chloride effect on BE significantly increased in NS group. Albumin effect on BE significantly increased in both the groups. Unmeasured ion effect on BE did not significantly change in both the groups. Measured standard BE level was significantly less as compared to unmeasured anion effect on BE, in both the groups. CONCLUSION: Simplified Fencl-Stewart equation is effective in identifying a mixed acid-base disorder, which otherwise would remain undetected.