Figure 2.

Plot of pH versus strong ion difference (SID). For this plot,total weak acid concentration (A_TOT) and partial carbon dioxidetension (pCO₂) were held constant at 18 mmol/l and 40 mmHg,respectively. Assumes a water dissociation constant for blood of 4.4 ×10–14 (mol/l). Note how steep the pH curve becomes at SID <20 mmol/l.Adapted from Kellum and Kellum [10].