title: Microcirculatory blood flow as a tool to select ICU patients eligible for fluid therapy.
abstract: OBJECTIVE
  The aim of this study is to assess the incidence of sublingual microcirculatory flow alterations, according to a predefined arbitrary cutoff value, in patients with "clinical signs of impaired organ perfusion". Secondary endpoints were the changes in microvascular flow index (MFI), "clinical signs of impaired organ perfusion", and stroke volume (SV) after fluid administration, and the differences between groups.
  
  
  METHODS
  Prospective, single-center, observational study in a 22-bed mixed intensive care unit (ICU). Patients ≥18 years with invasive hemodynamic monitoring and "clinical signs of impaired organ perfusion" as the principal reason for fluid administration were included. Before and after fluid challenge, systemic hemodynamics and direct in vivo observation of the sublingual microcirculation with sidestream dark-field imaging were obtained. Microvascular flow index (MFI) <2.6 was predefined as abnormal.
  
  
  RESULTS
  N = 50. At baseline, MFI <2.6 was present in 66 % of the patients. In these patients, MFI increased from 2.3 (2-2.5) at baseline to 2.5 (2.1-2.8) after fluid challenge (p = 0.003). This was accompanied by a reduction in the number of "clinical signs of impaired organ perfusion" from 2 (1-2) to 1 (0-2) (p < 0.001). However, in patients with MFI >2.6 at baseline, MFI and clinical signs changed insignificantly [2.8 (2.8-2.9) versus 2.8 (2.7-3), p = 0.45, respectively, 1 (1-2) versus 1 (1-2), p < 0.32]. These changes were not restricted to patients with a rise in SV ≥10 %.
  
  
  CONCLUSIONS
  These data add to the understanding that noninvasive assessment of microvascular blood flow may help to identify patients eligible for fluid therapy, and to evaluate its effect.
authors.affiliation: Department of Intensive Care Medicine, Hospital of Lithuanian University of Health Sciences, Kaunas, Lithuania.
authors.forename: Andrius
authors.initials: A
authors.lastname: Pranskunas
authors.forename: Matty
authors.initials: M
authors.lastname: Koopmans
authors.forename: Peter M
authors.initials: PM
authors.lastname: Koetsier
authors.forename: Vidas
authors.initials: V
authors.lastname: Pilvinis
authors.forename: E Christiaan
authors.initials: EC
authors.lastname: Boerma
mesh_terms: D018806:APACHE; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D016638:Critical Illness; D005260:Female; D005440:Fluid Therapy / Q000592:standards*; D006801:Humans; D007362:Intensive Care Units / Q000592:standards; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D009060:Mouth Floor / Q000098:blood supply; D018579:Patient Selection; D011446:Prospective Studies; D062606:Tertiary Care Centers