title: Evaluation of the use of lower body perfusion at 28°C in aortic arch surgery.
abstract: OBJECTIVE
  Although hypothermic circulatory arrest (HCA) and selective cerebral perfusion (SCP) are widely used for cerebral protection during aortic arch surgery, these strategies offer no protection for mesenteric ischaemia during prolonged circulatory arrest. This study explored mesenteric haemodynamics, metabolism, oxidative stress and inflammatory response levels during isolated SCP and combined cerebral and lower body perfusion (CLBP) in pigs.
  
  
  METHODS
  Fourteen pigs (35-45 kg) were cooled on CPB to 28°C. After 10 min of HCA, they were randomized to 60 min of isolated SCP (n = 7) and CLBP (n = 7) at low-flow pump rates: 10 ml/kg/min (SCP) and 20 ml/kg/min (LBP). Microspheres were injected at baseline, 5 and 60 min of SCP/CLBP and 5 and 60 min off CPB, to calculate mesenteric regional blood flow (RBF). Lactate levels and Oxy-DNA expression [fluorescence activated cell sorting (FACS)] in the portal venous blood were determined at the same time points. Semi-quantitative assessment of inflammatory cytokines was performed using real-time polymerase chain reaction (PCR) and immunhistochemical analyses.
  
  
  RESULTS
  At baseline mesenteric, RBF was 61 ± 31 ml/min/100 g in the jejunum and 78 ± 43 ml/min/100 g in the colon. Whereas SCP provided a residual mesenteric RBF of 5%, CLBP offered 47% of the baseline jejunal (34 ± 10 ml/min/100 g) and 68% of the colonic RBF (52 ± 34 ml/min/100 g; P = 0.001). Lactate levels were significantly higher in then SCP group (15 ± 2 vs. 11 ± 3 mmol/l; P = 0.01). Oxy-DNA increased, reaching 137% of baseline (SCP) and 129% (CLBP) at 60 min SCP/CLBP, but recovered promptly during reperfusion. Real-time PCR revealed a massive increase in early cytokine expression vs. baseline, showing significant higher interleukin (IL) -6 (29 vs.2; P = 0.027) and COX-relative expression (7 vs. 3, P = 0.016) in the SCP group. Immunhistochemical analysis confirmed a higher immunological activity in the SCP group, showing more intensive signal for tumour necrosis factor-α, IL-6 and p38 when compared with the CLBP group.
  
  
  CONCLUSIONS
  Low-flow CLBP provides a diminished but considerable mesenteric RBF, leading to lower lactate and oxidative stress levels and a diminished local inflammatory response reaction than isolated SCP.
authors.affiliation: Department of Cardiothoracic Surgery, Ruhr-University of Bochum, Bochum, Germany. peter.haldenwang@bergmannsheil.de
authors.forename: Peter L
authors.initials: PL
authors.lastname: Haldenwang
authors.forename: Tobias
authors.initials: T
authors.lastname: Klein
authors.forename: Klaus
authors.initials: K
authors.lastname: Neef
authors.forename: Tobias
authors.initials: T
authors.lastname: Riet
authors.forename: Anja
authors.initials: A
authors.lastname: Sterner-Kock
authors.forename: Hildegard
authors.initials: H
authors.lastname: Christ
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wahlers
authors.forename: Justus T
authors.initials: JT
authors.lastname: Strauch
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000601:surgery*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000502:physiology; D003106:Colon / Q000098:blood supply; D016207:Cytokines / Q000097:blood; D005260:Female; D007036:Hypothermia, Induced / Q000379:methods*; D018836:Inflammation Mediators / Q000378:metabolism; D007430:Intraoperative Care / Q000379:methods*; D007511:Ischemia / Q000517:prevention & control; D007583:Jejunum / Q000098:blood supply; D019344:Lactic Acid / Q000097:blood; D065666:Mesenteric Ischemia; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D010477:Perfusion / Q000379:methods; D019990:Perioperative Care / Q000379:methods; D012039:Regional Blood Flow / Q000502:physiology; D013152:Splanchnic Circulation / Q000502:physiology*; D034421:Sus scrofa; D013696:Temperature; D014652:Vascular Diseases / Q000517:prevention & control
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen