title: Preoperative microvascular dysfunction: a prospective, observational study expanding risk assessment strategies in major thoracic surgery.
abstract: BACKGROUND
  Brachial artery reactivity testing (BART)--a surrogate test of microvascular function--predicts cardiac risk in the nonsurgical population and associates it with adverse outcome after vascular surgery. This pilot study investigated BART-derived variables, including flow-mediated dilation (FMD), in preoperative risk stratification for major thoracic surgery.
  
  
  METHODS
  After institutional review board approval, BART was performed in 63 patients before major thoracic surgery. Ultrasonography recorded two-dimensional images and Doppler flow signals of the brachial artery preoperatively at baseline and after induced reactive hyperemia. Variables derived using BART were correlated with preoperative risk factors, established risk scores, and postoperative complications.
  
  
  RESULTS
  The median preoperative FMD value in patients without postoperative complications was 11.5%. This value was used to delineate all patients into two groups: low (FMD < 11.5%) and high (FMD ≥ 11.5%) FMD cohorts. Patients in the low FMD group experienced more postoperative complications: 54% versus 30% had one or more adverse postoperative event, and 11% versus 0% had three or more adverse postoperative events (p < 0.001), respectively. The low FMD group required longer intensive care unit (3.9 ± 2.0 days versus 0.9 ± 0.3 days; p = 0.015) and hospital (14.0 ± 3.3 days versus 6.8 ± 0.6 days; p = 0.007) stays. This cutoff point for FMD accurately predicted 71% of the patients with adverse postoperative events, achieving 71.4% (95% confidence interval, 54.7 to 88.2) sensitivity and 48.6% (95% confidence interval, 32.0 to 65.1) specificity.
  
  
  CONCLUSIONS
  Using BART, preoperative microvascular dysfunction can be identified in patients at increased risk for postoperative complications. These data suggest that larger observational studies and studies exploring preoperative optimization strategies aimed at improving microvascular function are warranted.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Cologne, Cologne, Germany. robert.schier@uk-koeln.de
authors.forename: Robert
authors.initials: R
authors.lastname: Schier
authors.forename: Jochen
authors.initials: J
authors.lastname: Hinkelbein
authors.forename: Hanke
authors.initials: H
authors.lastname: Marcus
authors.forename: Reza
authors.initials: R
authors.lastname: Mehran
authors.forename: Randa
authors.initials: R
authors.lastname: El-Zein
authors.forename: Wayne
authors.initials: W
authors.lastname: Hofstetter
authors.forename: Joseph
authors.initials: J
authors.lastname: Swafford
authors.forename: Bernhard
authors.initials: B
authors.lastname: Riedel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001916:Brachial Artery / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D055806:Microvessels / Q000503:physiopathology*; D008875:Middle Aged; D010865:Pilot Projects; D011183:Postoperative Complications / Q000209:etiology; D011300:Preoperative Care; D011446:Prospective Studies; D018570:Risk Assessment; D019616:Thoracic Surgical Procedures / Q000009:adverse effects*; D014664:Vasodilation