continuing education Acid-Base Review

In the normal, healthy individual the acid-base balance within the body is remarkably constant. For example, arterial blood, drawn from healthy individuals at sea level, will show that, in over 95% of the individuals, the pH of the blood is between 7.35 and 7.45. Furthermore, the pC02 will be maintained between 35 and 48 mmHg while the bicarbonate concentration will be between 23 and 28 mEq/L. This homeostasis is not accidental but essential to the functioning of most life processes. Any drastic change in pH results in failure of the multiple enzyme systems which require constant conditions in order to mediate life processes. A pH below 7.0 or above 7.8 is not compatible with life for any length of time. The circulatory system, including lungs and kidneys, is the primary homeostatic mechanism. Since it is the aim of extracorporeal technology to substitute for the circulation; in part as in dialysis, or in total as in heart-lung bypass, it is important that we who deliver extracorporeal technology service understand acid-base balance, disturbances in this balance, and corrective actions in the case of disturbances.