title: Microcirculatory perfusion shift in the gut wall layers induced by extracorporeal circulation.
abstract: OBJECTIVE
  Extracorporeal circulation (ECC) is regularly applied to maintain organ perfusion during major aortic and cardiovascular surgery. During thoracoabdominal aortic repair, ECC-driven selective visceral arterial perfusion (SVP) results in changed microcirculatory perfusion (shift from the muscularis toward the mucosal small intestinal layer) in conjunction with macrohemodynamic hypoperfusion. The underlying mechanism, however, is unclear. Therefore, the aim of this study was to assess in a porcine model whether ECC itself or the hypoperfusion induced by SVP is responsible for the mucosal/muscular shift in the small intestinal wall.
  
  
  METHODS
  A thoracoabdominal aortic approach was performed in 15 healthy pigs divided equally into three groups: group I, control; group II, thoracic aortic cross-clamping with distal aortic perfusion; and group III, thoracic aortic cross-clamping with distal aortic perfusion and SVP. Macrocirculatory and microcirculatory blood flow was assessed by transit time ultrasound volume flow measurement and fluorescent microspheres. In addition, markers for metabolism and intestinal ischemia-reperfusion injury were determined.
  
  
  RESULTS
  ECC with a roller pump induced a significant switch from the muscularis and mucosal layer of the small intestine, even with adequate macrocirculation (mucosal/muscular perfusion ratio: group I vs II, P = .005; group I vs III, P = .0018). Furthermore, the oxygen extraction ratio increased significantly in groups II (>30%) and III (>40%) in the beginning of the ECC compared with the control (group I vs II, P = .0037; group I vs III, P = .0062). Lactate concentrations and pH values did not differ between groups I and II; but group III demonstrated a significant shifting toward a lactate-associated acidosis (lactate: group I vs III, P = .0031; pH: group I vs III, P = .0001).
  
  
  CONCLUSIONS
  We demonstrated a significant shifting between the small intestinal gut wall layers induced by roller pump-driven ECC. The shift occurs independently of macrohemodynamics, with a significant effect on aerobic metabolism in the gut wall. Consequently, an optimal intestinal perfusion cannot be guaranteed by a roller pump; therefore, perfusion techniques need to be optimized.
authors.affiliation: European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Kalder
authors.affiliation: European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Dieudonne
authors.initials: D
authors.lastname: Ajah
authors.affiliation: European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Paula
authors.initials: P
authors.lastname: Keschenau
authors.affiliation: Department of Medical Statistics, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Lieven N
authors.initials: LN
authors.lastname: Kennes
authors.affiliation: Institute for Laboratory Animal Science and Experimental Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Rene
authors.initials: R
authors.lastname: Tolba
authors.affiliation: European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Kokozidou
authors.affiliation: European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany; Department of Surgery, Maastricht University Medical Center, Maastricht, The Netherlands. Electronic address: m.jacobs@mumc.nl.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Jacobs
authors.affiliation: European Vascular Center Aachen-Maastricht, Department of Vascular Surgery, Rheinisch-Westfaelische Technische Hochschule (RWTH) University Hospital Aachen, Aachen, Germany.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Koeppel
mesh_terms: D000140:Acidosis, Lactic / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology / Q000601:surgery; D001783:Blood Flow Velocity; D003250:Constriction; D005112:Extracorporeal Circulation / Q000009:adverse effects; D005260:Female; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000098:blood supply* / Q000378:metabolism; D007421:Intestine, Small / Q000098:blood supply* / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood; D065666:Mesenteric Ischemia / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D008833:Microcirculation; D023421:Models, Animal; D009130:Muscle, Smooth / Q000098:blood supply* / Q000378:metabolism; D012039:Regional Blood Flow; D015427:Reperfusion Injury / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D013152:Splanchnic Circulation; D013552:Swine; D013997:Time Factors
chemical_list: D019344:Lactic Acid