How to evaluate the microcirculation: report of a round table conference.
BACKGROUND
Microvascular alterations may play an important role in the development of organ failure in critically ill patients and especially in sepsis. Recent advances in technology have allowed visualization of the microcirculation, but several scoring systems have been used so it is sometimes difficult to compare studies. This paper reports the results of a round table conference that was organized in Amsterdam in November 2006 in order to achieve consensus on image acquisition and analysis.


METHODS
The participants convened to discuss the various aspects of image acquisition and the different scores, and a consensus statement was drafted using the Delphi methodology.


RESULTS
The participants identified the following five key points for optimal image acquisition: five sites per organ, avoidance of pressure artifacts, elimination of secretions, adequate focus and contrast adjustment, and recording quality. The scores that can be used to describe numerically the microcirculatory images consist of the following: a measure of vessel density (total and perfused vessel density; two indices of perfusion of the vessels (proportion of perfused vessels and microcirculatory flow index); and a heterogeneity index. In addition, this information should be provided for all vessels and for small vessels (mostly capillaries) identified as smaller than 20 microm. Venular perfusion should be reported as a quality control index, because venules should always be perfused in the absence of pressure artifact. It is anticipated that although this information is currently obtained manually, it is likely that image analysis software will ease analysis in the future.


CONCLUSIONS
We proposed that scoring of the microcirculation should include an index of vascular density, assessment of capillary perfusion and a heterogeneity index.
De Backer
Daniel
D
Department of Intensive Care, Erasme University hospital, Université Libre de Bruxelles, 808 route de Lennik, B-1070 Brussels, Belgium. ddebacke@ulb.ac.be
Hollenberg
Steven
S
Boerma
Christiaan
C
Goedhart
Peter
P
Büchele
Gustavo
G
Ospina-Tascon
Gustavo
G
Dobbe
Iwan
I
Ince
Can
C
D001794:Blood Pressure; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008833:Microcirculation / Q000503:physiopathology*; D018805:Sepsis / Q000503:physiopathology*; D012720:Severity of Illness Index