SUMMARY

Much of the confusion regarding acid-base chemistry reflects the attempt to apply observational approaches, such as that of Henderson and Hasselbalch as well as Schwartz and Brackett, to the entire spectrum of pathophysiologic processes. The use of physical chemistry principles has provided improved explanations of acid-base balance and superior tools to apply in a wide variety of clinical situations. This does not suggest that the traditional approach is incorrect, merely that it looks at a mirror image of that proposed by Stewart, Fencl, and others. All acid-base disorders can be explained in terms of the SID, A_TOT , and PCO₂ . This is important to anesthesiologists, who may significantly affect the acid-base balance by their choice of fluids and strategy for mechanical ventilation.