In medicine, Beecf refers to the residual alkalinity of the interstitial fluid, which is the main indicator of metabolic acid-base imbalance, with a standard value of -3 to +3 mmol/L. If the value is greater than +3 mmol/L, then metabolic alkalosis may be indicated, while if the value is less than -3 mmol/L, then metabolic acidosis may be indicated. Beecf refers to extracellular fluid residual alkalinity and is a metabolic indicator calculated by measuring the concentration of bicarbonate ions in the serum. The normal value of this indicator is around -3 to +3 mmol/L. If the actual value exceeds +3 mmol/L, then it indicates an increase in base residuals and possible metabolic alkalosis. Alternatively, if the actual value is negative and less than -3mmol/L, then there is a decrease in base residual, which is associated with the development of metabolic acidosis. However, this is not absolute, and to confirm the diagnosis, it is necessary to take into account other indicators in the blood gas analysis, such as pH, oxygen level and standard bicarbonate, and to actively cooperate with the doctor.