Tissue hypercarbic acidosis as a marker of acute circulatory failure (shock).

Measurement of pH of the stomach wall (gastric intramural pH) by the tonometric method has been utilized both experimentally and clinically as an indicator of the capability of the stomach to extract and utilize oxygen. As such, it serves as a metabolic marker of acute perfusion failure (circulatory shock). More recently, researchers have found that increases in the PCO2 accounted for the decline in pH; this was documented in tissues other than the stomach wall, including the esophageal and sublingual mucosa. In this review, tissue PCO2 is identified as a universal indicator of impaired perfusion and contrasted with conventional hemodynamic and metabolic markers of perfusion failure.