Role of buccal PCO2 to manage fluid resuscitation during hemorrhagic shock

Arterial pressure is a widely used measurement for estimating the severity of hemorrhagic shock and to guide its management. However, this capability is reduced when very low arterial pressure values cannot be reliably measured by noninvasive methods. Moreover, hypoperfusion may be masked by compensatory hemodynamic changes, and therefore, in the presence of near normal blood pressure, tissue hypoperfusion may progress undetected. Accordingly, hypercarbia is a general phenomenon of perfusion failure, which occurs in coincidence of the onset of hypotension and is promptly reversed with restoration of normal blood flows. Increases in buccal mucosa PCO2 are highly correlated with increases in gastric wall and sublingual mucosa PCO2 and decreases in tissue blood flows during hemorrhagic shock. In both clinical and experimental settings, tissue PCO2 measured in the oral mucosa proved to be a practical and reliable measurement for the diagnosis of circulatory failure states and an indicator of its severity. In contrast to intraarterial pressure, buccal PCO2 discriminated between short- and long-term survival after large-volume blood loss. Buccal PCO2 measurement therefore emerges as a useful predictor for survival and outcome and a useful guide to manage fluid resuscitation during hemorrhagic shock.