title: Hypothermic circulatory arrest with "low flow" lower body perfusion: an experimental feasibility study of microcirculatory parameters.
abstract: BACKGROUND
  To avoid extended cardiopulmonary bypass (CPB), moderate temperatures are commonly accepted for hypothermic circulatory arrest (HCA), thereby jeopardizing organ protection. Distal aortic perfusion may be an option, but supportive experimental data is missing.
  
  
  METHODS
  Eight juvenile pigs (36 ± 2 kg) were cooled to 30 °C followed by 60 min of HCA with 50 min of low flow (LF) lower body perfusion. Multimodal monitoring was used to measure overall metabolism, hemodynamics and microcirculation of the terminal ileum. The animals were observed for four hours following reperfusion. Organs were harvested for histopathological evaluation.
  
  
  RESULTS
  During LF perfusion, initially elevated l-lactate levels decreased subsequently ( P < 0.05). Capillary blood flow decreased during cooling to 50 % baseline levels ( P = 0.03), but remained stable under LF conditions. Parameters indicative of reduced liver and kidney function were slightly elevated at the end of the experiment, but still within normal ranges.
  
  
  CONCLUSIONS
  Under moderate hypothermia, low flow perfusion seems to provide adequate protection for the lower body organs. Microcirculatory parameters during perfusion as well as lactate levels within normal ranges throughout the experiments further confirm the concept.
authors.affiliation: Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany. peterss.sven@mh-hannover.de
authors.forename: S
authors.initials: S
authors.lastname: Peterss
authors.forename: N
authors.initials: N
authors.lastname: Khaladj
authors.forename: M
authors.initials: M
authors.lastname: Pichlmaier
authors.forename: K
authors.initials: K
authors.lastname: Hoeffler
authors.forename: R
authors.initials: R
authors.lastname: von Wasielewski
authors.forename: M L
authors.initials: ML
authors.lastname: Shrestha
authors.forename: A
authors.initials: A
authors.lastname: Haverich
authors.forename: C
authors.initials: C
authors.lastname: Hagl
mesh_terms: D000818:Animals; D002315:Cardiopulmonary Bypass; D005240:Feasibility Studies; D005260:Female; D006324:Heart Arrest, Induced; D006439:Hemodynamics; D007036:Hypothermia, Induced; D007082:Ileum / Q000098:blood supply*; D019344:Lactic Acid / Q000097:blood; D017078:Laser-Doppler Flowmetry; D035002:Lower Extremity / Q000098:blood supply*; D008833:Microcirculation; D023421:Models, Animal; D010477:Perfusion / Q000379:methods*; D013552:Swine; D013997:Time Factors; D014781:Viscera / Q000098:blood supply*
chemical_list: D019344:Lactic Acid