title: Brachial artery reactivity in patients with severe sepsis: an observational study.
abstract: BACKGROUND
  Ultrasound measurements of brachial artery reactivity in response to stagnant ischemia provide estimates of microvascular function and conduit artery endothelial function. We hypothesized that brachial artery reactivity would independently predict severe sepsis and severe sepsis mortality.
  
  
  METHODS
  This was a combined case-control and prospective cohort study. We measured brachial artery reactivity in 95 severe sepsis patients admitted to the medical and surgical intensive care units of an academic medical center and in 52 control subjects without acute illness. Measurements were compared in severe sepsis patients versus control subjects and in severe sepsis survivors versus nonsurvivors. Multivariable analyses were also conducted.
  
  
  RESULTS
  Hyperemic velocity (centimeters per cardiac cycle) and flow-mediated dilation (percentage) were significantly lower in severe sepsis patients versus control subjects (hyperemic velocity: severe sepsis = 34 (25 to 48) versus controls = 63 (52 to 81), P < 0.001; flow-mediated dilation: severe sepsis = 2.65 (0.81 to 4.79) versus controls = 4.11 (3.06 to 6.78), P < 0.001; values expressed as median (interquartile range)). Hyperemic velocity, but not flow-mediated dilation, was significantly lower in hospital nonsurvivors versus survivors (hyperemic velocity: nonsurvivors = 25 (16 to 28) versus survivors = 39 (30 to 50), P < 0.001; flow-mediated dilation: nonsurvivors = 1.90 (0.68 to 3.41) versus survivors = 2.96 (0.91 to 4.86), P = 0.12). Lower hyperemic velocity was independently associated with hospital mortality in multivariable analysis (odds ratio = 1.11 (95% confidence interval = 1.04 to 1.19) per 1 cm/cardiac cycle decrease in hyperemic velocity; P = 0.003).
  
  
  CONCLUSIONS
  Brachial artery hyperemic blood velocity is a noninvasive index of microvascular function that independently predicts mortality in severe sepsis. In contrast, brachial artery flow-mediated dilation, reflecting conduit artery endothelial function, was not associated with mortality in our severe sepsis cohort. Brachial artery hyperemic velocity may be a useful measurement to identify patients who could benefit from novel therapies designed to reverse microvascular dysfunction in severe sepsis and to assess the physiologic efficacy of these treatments.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Orren
authors.initials: O
authors.lastname: Wexler
authors.forename: Mary A M
authors.initials: MA
authors.lastname: Morgan
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gough
authors.forename: Sherry D
authors.initials: SD
authors.lastname: Steinmetz
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Mack
authors.forename: Denise C
authors.initials: DC
authors.lastname: Darling
authors.forename: Kathleen P
authors.initials: KP
authors.lastname: Doolin
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Apostolakos
authors.forename: Brian T
authors.initials: BT
authors.lastname: Graves
authors.forename: Mark W
authors.initials: MW
authors.lastname: Frampton
authors.forename: Xucai
authors.initials: X
authors.lastname: Chen
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Pietropaoli
mesh_terms: D019540:Area Under Curve; D001783:Blood Flow Velocity / Q000502:physiology; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D018805:Sepsis / Q000401:mortality / Q000503:physiopathology*; D015996:Survival Rate; D014463:Ultrasonography