Year in Review in Intensive Care Medicine, 2006. III. Circulation, ethics, cancer, outcome, education, nutrition, and pediatric and neonatal critical care

Excerpt

Microcirculation has become a major topic of interest. Several studies have shown that microcirculatory alterations frequently occur in patients with septic shock, and that these alterations are correlated with the development of organ failure and death. Although direct visualization is now feasible, indirect measurements are more commonly used at the bedside. Among the indirect measurements, measurements of tissue carbon dioxide pressure can be used. These measurements can be obtained non-invasively either in the stomach (gastric tonometry) or in the sublingual area. Creteur et al. [1] investigated in 18 patients with septic shock the relationship between sublingual microvascular perfusion, assessed using an orthogonal polarization spectral imaging device, and sublingual and gastric carbon dioxide pressure. They observed an inverse relationship between microvascular perfusion and sublingual to arterial carbon dioxide pressure gap. Dobutamine administration, at a dose of 5 μg/kg min⁻¹, increased microvascular perfusion and decreased sublingual carbon dioxide. In addition, measurements of carbon dioxide pressure in the gastric and sublingual areas were highly related. These findings suggest that regional microcirculatory flow is the main determinant of sublingual carbon dioxide pressure. In addition, these findings suggest that the sublingual area can be used as a surrogate of other microvascular beds, including the splanchnic area. The accompanying editorial by Ince [2] discussed the determinants of a raised tissue carbon dioxide pressure. Although mitochondrial dysfunction may be evoked, the inverse relationship between perfusion and carbon dioxide pressure suggest that the altered flow, rather than mitochondrial dysfunction, was responsible for the elevated carbon dioxide. …