Total buffer base

The summed concentration of bicarbonate and non-bicarbonate buffer base ([HC03 ] + [Pr ]) is called the total buffer base or, more usually, the buffer base (Table 4.3A). For blood of normal composition in equilibrium with gas... 

A. Buffer Base (or Total Buffer Base) is ([HCOa ] + [Pr ]) Typical value for normal blood is 48 mM. 

The concentration of total buffer base depends on the overall buffering power of the blood. Since much of the buffering is due to haemoglobin, in an anaemic person the total buffer base is low. An anaemic person with no disturbance of acid-base physiology will normally operate at a normal PCO2 and normal... 

Figure 4.3. A. Normal blood the normal blood line is plotted with axes as indicated below and to the left. The full arrows show the value of the [HCOj j at the relevant PtU2. Above each full arrow is a dashed arrow indicating the concentration of non-bicarbonate buffer base. The two arrows together indicate the magnitude of the total buffer base. B. A similar plot for anaemic blood.

The basic deficiency is the lower-than-normal concentration of non-bicarbonate buffer base. When the PcOj with which the blood is equilibrated is changed, the inferior buffering power of anaemic blood is expressed. The slope of the blood line is less than for non-anaemic blood (Figure 4.3B). This is matched by lower values for non-bicarbonate buffer base at all PcOj values. Correspondingly, the total buffer base is less than 48 mM, because of a relative lack of non-bicarbonate buffer base. 

TOTAL BUFFER BASE OF PLASMA AND OF WHOLE BLOOD... 

The value given for the total buffer base for plasma (taken from Figure 5.2) is (15-1- 24), i.e. typically 39 mM whereas that for whole blood is typically 48 mM. Whole blood is a better buffer than plasma, principally because of the haemoglobin contribution to buffering, which is why it has a larger concentration of total buffer base. It has already been noted that anaemic blood has a reduced amount of buffer base, reflecting the poorer buffering capacity by comparison with normal blood. 

E. At point B, the total buffer base is above normal. 

D. The total buffer base within the erythrocytes falls. 

E. Yes. Any point above the normal blood line has an increased value of total buffer base. 

Explain the analyses needed on a blood sample in order to be able to plot a line on the nomogram and how to use the nomogram to read off standard bicarbonate, base excess, total buffer base. 

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