Please see Bibliography of References for a list of abstracts, manuscripts and posters.

Sepsis

Is there a correlation between near infrared spectroscopy and side dark field imaging?

Favory, Ospina-Tascon G, Donadello K, Simion D, Neves AP, Occhipinti G, Oliveira T, Fonseca A, Creteur J, Vincent JL, De Backer D. Int Care Med. 2009;35(Suppl 1):S205.

Background: A growing body of evidence suggests implication of microcirculatory dysfunction in numerous diseases. The use of sidedark field (SDF) imaging and near infrared spectroscopy (NIRS) associated with a vascular occlusion test (VOT) have been proposed to assess microcirculation at the bedside. In sepsis, alterations in both types of measures are associated with a poor outcome [1, 2]. However these techniques may provide different information: SDF provides a direct look of the microvascular network whereas VOT gives more dynamic informations. We evaluated whether data obtained simultaneously with NIRS and SDF imaging in critically ill patients may be related.

Materials and Methods: For NIRS (Inspectra, Hutchinson Technology, Hutchinson, MN, USA) we performed a 3 min VOT using a tourniquet, and we recorded: descending slope of StO₂, ascending slope, StO₂ at baseline and at its maximal value after the tourniquet release. To visualize the microcirculation in the sublingual area we used a SDF imaging device (MicroScan; MicroVision Medical, Amsterdam, The The Netherlands) with emphasis on the FCD calculated as the number of small vessels (<20 µm) crossing lines of the grid divided by the total length of the grid and the proportion of small vessels perfused (PPV). Linear correlation was used.

Results: We analyzed a total of 95 concomitant measures of NIRS and SDF in 51 patients (41 with severe sepsis or septic shock). We found no significant correlation between basal StO₂ and FCD (r² = 0.01, P = 0.44) or PPV (r² = 0.02, P = 0.11), StO₂ max and FCD (r2 = 0.02, P = 0.23) and PPV (r2 = 0.02, P = 0.15), descending slope and FCD (r² = 0.01, P = 0.96) or PPV (r² = 0.01, P = 0.28), ascending slope and FCD (r² = 0.03, P = 0.08) and PPV (r² = 0.01, P = 0.44). See figure for point cloud of ascending slope and PPV for the 95 measures.

Conclusion: We failed to demonstrate any significant correlation between data obtained with NIRS and SDF in critically ill patients. These two techniques explore different variables in different regions of the body. Both have prognostic implications and can provide complementary information.