title: Oscillation frequency of skin microvascular blood flow is associated with mortality in critically ill patients.
abstract: BACKGROUND
  Microcirculatory dysfunction has been hypothesized to play a key role in the pathophysiology of multiple organ failure and, consequently, patient outcome. The objective of this study was to investigate the differences in reactive hyperemia response and oscillation frequency in surviving and non-surviving patients with multiple organ dysfunction syndrome.
  
  
  METHODS
  Twenty-nine patients (15 survivors; 14 non-survivors) with two or more organ failures were eligible for study entry. All patients were hemodynamically stabilized, and demographic and clinical data were recorded. A laser Doppler flowmeter was used to measure the cutaneous microcirculatory response. Reactive hyperemia and oscillatory changes in the Doppler signal were measured during 3 min before and after a 5-min period of forearm ischemia.
  
  
  RESULTS
  Non-survivors demonstrated a significantly higher multiple organ dysfunction score when compared with survivors (P= 0.004). Norepinephrine administration was higher in non-survivors (P= 0.018). Non-survivors had higher arterial lactate levels (P= 0.046), decreased arterial pH levels (P= 0.001) and decreased arterial Po(2) values (P= 0.013) when compared with survivors. A higher oscillation frequency of the skin microvasculature at rest (P= 0.033) and after an ischemic stimulus (P= 0.009) was observed in non-survivors. The flow motion frequency observed in reactive hyperemia was associated with the severity of multiple organ dysfunction (P= 0.009) and, although not statistically significant, with the arterial lactate concentration (P= 0.052).
  
  
  CONCLUSIONS
  Increased skin microvascular oscillation frequency at rest and in the hyperemic state after an ischemic stimulus is associated with increased mortality in patients suffering from multiple organ dysfunction. The underlying mechanism could be a response of the skin microvasculature to an impaired oxygen utilization of the skin tissue.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University, Innsbruck, Austria. johann.knotzer@uki.at
authors.forename: H
authors.initials: H
authors.lastname: Knotzer
authors.forename: S
authors.initials: S
authors.lastname: Maier
authors.forename: M
authors.initials: M
authors.lastname: Dünser
authors.forename: K H
authors.initials: KH
authors.lastname: Stadlbauer
authors.forename: H
authors.initials: H
authors.lastname: Ulmer
authors.forename: W
authors.initials: W
authors.lastname: Pajk
authors.forename: W R
authors.initials: WR
authors.lastname: Hasibeder
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D016638:Critical Illness / Q000401:mortality*; D006801:Humans; D006940:Hyperemia / Q000209:etiology; D008833:Microcirculation / Q000473:pathology / Q000503:physiopathology*; D008875:Middle Aged; D012039:Regional Blood Flow; D012121:Respiration, Artificial; D018805:Sepsis; D012772:Shock, Septic; D012867:Skin / Q000098:blood supply*; D016019:Survival Analysis; D017741:Survivors