Quantitative acid–base physiology using the Stewart model. Does it improve our understanding of what is really wrong?

Traditional theories of acid–base balance are based on the Henderson–Hasselbalch equation to calculate proton concentration. The recent revival of quantitative acid–base physiology using the Stewart model has increased our understanding of complicated acid–base disorders, but has also led to several new controversies. With the help of three patient histories, we show that the Henderson–Hasselbalch equation should be regarded as a simplified version of the more general Stewart model and not as something completely different. Therefore, both models may be useful at the bedside.