Microvascular blood flow alterations including heterogeneity of both the spatial distribution of perfused capillary densities, transit times, and local perfusion pressures are pivotal in the pathogenesis of sepsis. Such alterations are independent of the arterial pressure in animal studies. We designed a study using Orthogonal Polarization Spectral (OPS) imaging to further investigate the extent of the microvascular changes and correlate these to the severity of sepsis.
5 patients with sepsis treated as part of an early goal-directed protocol were compared to 5 healthy volunteers. The sublingual microvasculature was studied serially using a Cytoscan ARII with a 5X objective. 5 - 7 areas were recorded for off-line analysis. Hemodynamic data and SOFA scores were collected for each patient. Fields were assigned a semi-quantitative Microvascular Perfusion Score (MPS) ranging from 0 (no flow) –3 (normal flow). 3 equidistant vertical and horizontal lines were drawn and the vessels were separated into large (> 20 μm) and small (< 20 μm). A Vascular Density Score (VDS) was calculated as the total number of perfused vessels intersecting the lines divided by their length.
VDS was significantly reduced in sepsis (8.01 ± 2.20 vs. 10.93 ± 1.28 vessels/mm, p = 0.0001). MPS was also decreased in patients with sepsis (1.75 ± 0.43 vs. 2.72 ± 0.35). A positive correlation was found between mean arterial pressure (MAP) and VDS for vessels < 20 μm, p = 0.046. No correlation was found between SOFA, cardiac index (CI) or MAP and MPS.
Our study confirms the dysfunction of microvascular perfusion and alterations in its density in humans with sepsis. Perfusion perturbations are independent of hemodynamic variables and SOFA score.
This highlights the need for directly visualizing and studying the microcirculation and exploring the impact of early-goal directed therapy on potentially reversing the alterations in sepsis.
J.S. Bajaj, None.