Stewart's approach is a mathematically coherent explanation of acid-base balance, which allows one to make precise predictions regarding the interactions of the numerous interacting variables which affect pH. Laws governing the behaviour of aqueous solutions can be used to create equations which describe these interactions. In their model answer for Question 24 from the first paper of 2014, the college examiners commented that they only expected "an overall understanding of the principles involved". Most trainees possess this understanding; however, the pass rate was only 5.7%. The main problem was therefore a failure to articulate this knowledge into a coherent answer. This chapter ambitiously compacts a concept requiring a 504-page book to explain into a 10-minute SAQ answer or a sixty-second viva.
In its briefest form:
Thus, acid-base disorders can be classified as:
Advantages of the Stewart method:
Disadvantages of the Steward method:
Morgan, T. J. "What exactly is the strong ion gap, and does anybody care?" Critical Care and Resuscitation (2004) 6: 155-166.
Sirker, A. A., et al. "Acid− base physiology: the ‘traditional’and the ‘modern’approaches." Anaesthesia 57.4 (2002): 348-356.
Story, D. A., S. Poustie, and R. Bellomo. "Quantitative physical chemistry analysis of acid− base disorders in critically ill patients." Anaesthesia 56.6 (2001): 530-533.