Science review: extracellular acidosis and the immune response: clinical and physiologic implications

Abstract

Metabolic acidosis is among the most common abnormalities seen in patients suffering from critical illness. Its etiologies are multiple and treatment of the underlying condition is the mainstay of therapy. However, growing evidence suggests that acidosis itself has profound effects on the host, particularly in the area of immune function. Given the central importance of immune function to the outcome of critical illness, there is renewed interest in elucidating the effects of this all too common condition on the immune response. In this review we concentrate on the effects of extracellular acids on production and release of inflammatory mediators, and we demonstrate that different acids produce different effects despite similar extracellular pH. Finally, we discuss potential clinical implications.

Figure 1

Mean arterial pressure for septic animals (induced by cecal ligation and puncture) after infusion of 0.1 N HCl acid to reduce the base deficit (BD) by 5–10 mEq/l (white bars) or 10–15 mEq/l (black bars). A control group was given a similar volume of lactated Ringer's (gray bars). Shown are group means (n = 8) ± SEM. *P < 0.05. Adapted from Kellum and coworkers [46].