title: Microcirculatory imaging in cardiac anesthesia: ketanserin reduces blood pressure but not perfused capillary density.
abstract: OBJECTIVE
  It has become possible to image the human microcirculation at the bedside using sidestream dark field (SDF) imaging. This may help the clinician when correlation between global and microvascular hemodynamics may not be straightforward. Ketanserin, a serotonin and alpha-1 adrenoceptor antagonist, is used in some countries to treat elevated blood pressure after extracorporeal circulation. This might hamper microcirculatory perfusion. Conversely, it is also conceivable that microcirculatory flow is maintained or improved as a result of flow redistribution. In order to introduce SDF imaging in cardiac anesthesia, the authors set out to directly observe the sublingual microcirculation in this setting.
  
  
  METHODS
  An observational study.
  
  
  METHODS
  A large teaching hospital.
  
  
  METHODS
  Mechanically ventilated patients with elevated arterial blood pressure immediately after extracorporeal circulation (ECC).
  
  
  METHODS
  An intravenous bolus of ketanserin, 0.15 mg/kg.
  
  
  RESULTS
  Five minutes before and 10 minutes after ketanserin administration, global hemodynamic variables were recorded. In addition, the authors used SDF imaging to record video clips of the microcirculation. Analysis of these allowed for quantification of microvascular hemodynamics including determination of perfused vessel density (PVD) and microcirculatory flow index (MFI). After ketanserin administration, there was a significant reduction in systolic arterial blood pressure (129 +/- 9 to 100 +/- 15 mmHg, p = 0.0001). At the level of the microcirculation, the mean MFI did not change significantly for small (diameter <20 microm, 2.79 [interquartile range, 1.38-3] to 2.38 [1.88-2.75], p = 0.62) or large (diameter >20 microm, 2.83 [1.4-3] to 2.67 [0.35-2.84] p = 1.0) vessels. There was a significant increase in mean PVD for large vessels (1.23 +/- 0.63 to 1.70 +/- 79 mm(-1), p = 0.017) but not for small vessels (5.59 +/- 2.60 to 5.87 +/- 1.22 mm(-1), p = 0.72) where red blood cell flow was maintained.
  
  
  CONCLUSIONS
  SDF imaging clearly showed a discrepancy between global and microvascular hemodynamics after the administration of ketanserin for elevated blood pressure after ECC. Ketanserin effectively lowers arterial blood pressure. However, capillary perfusion is maintained at a steady value. Both effects may be explained by an increase in shunting in the larger vessels of the microcirculation.
authors.affiliation: Department of Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. info@acidbase.org
authors.forename: Paul W G
authors.initials: PW
authors.lastname: Elbers
authors.forename: Alaattin
authors.initials: A
authors.lastname: Ozdemir
authors.forename: Mat
authors.initials: M
authors.lastname: van Iterson
authors.forename: Eric P A
authors.initials: EP
authors.lastname: van Dongen
authors.forename: Can
authors.initials: C
authors.lastname: Ince
mesh_terms: D000328:Adult; D000368:Aged; D000758:Anesthesia / Q000379:methods*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002196:Capillaries / Q000187:drug effects / Q000502:physiology*; D006348:Cardiac Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D002318:Cardiovascular Diseases / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D007650:Ketanserin / Q000494:pharmacology* / Q000627:therapeutic use; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology*; D008875:Middle Aged; D009060:Mouth Floor / Q000098:blood supply*
chemical_list: D007650:Ketanserin