title: Low-flow perfusion via the innominate artery during aortic arch operations provides only limited somatic circulatory support.
abstract: BACKGROUND
  Aortic arch operations in pediatric patients using low-flow perfusion techniques have been standardized to a certain degree, but some of the often-stated beneficial effects have never been proven. Especially, the existence or efficacy of any subdiaphragmal perfusion still remains unclear.
  
  
  METHODS
  Twenty-six newborn male piglets (10-15 kg) underwent aortic arch surgery under general anesthesia using either low-flow perfusion via the innominate artery (LF, 30 ml/(kg min), 25 degrees C, n=12) or conventional deep hypothermic circulatory arrest (DHCA, 20 degrees C, n=14). Cortical somatosensory-evoked potentials (SSEPs), carotid, and subdiaphragmal blood flows were measured. The animals of both groups have been randomized to either pH-stat or alpha-stat management on cardiopulmonary bypass (CPB).
  
  
  RESULTS
  During low-flow perfusion via the innominate artery only negligible flows of maximum 1-3 ml/min in the femoral arteries were detected, whereas the right carotid artery flow doubled. During reperfusion, serum-lactate and aspartate amino-transferase (AST) levels were significantly higher compared to the circulatory arrest group, whereas alanine amino-transferase (ALT), gamma-glutamyl transpeptidase (gamma-GT), AP, and creatinine did not show any significant differences. Cortical SSEP returned to preoperative values in all but two low-flow animals. There was no return of SSEP in all piglets operated under deep hypothermic circulatory arrest (p<0.01).
  
  
  CONCLUSIONS
  Compared to DHCA, low-flow perfusion via the innominate artery provides superior neuroprotection despite higher tissue temperatures. Although collateral blood flow via the subclavian artery and the circulus arteriosus willisii has often been presumed, only 'trickle-flow' with some protective potential was detectable in the femoral arteries during low-flow perfusion. Origin of elevated lactate and AST levels seems to be the lower limbs.
authors.affiliation: Department of Cardiothoracic Surgery, University Hospital Erlangen, University of Erlangen-Nuremberg, Krankenhausstrasse 12, 91054 Erlangen, Germany. olaf.roerick@herz.imed.uni-erlangen.de
authors.forename: Olaf
authors.initials: O
authors.lastname: Roerick
authors.forename: Timo
authors.initials: T
authors.lastname: Seitz
authors.forename: Petra
authors.initials: P
authors.lastname: Mauser-Weber
authors.forename: Thomas
authors.initials: T
authors.lastname: Palmaers
authors.forename: Michael
authors.initials: M
authors.lastname: Weyand
authors.forename: Robert
authors.initials: R
authors.lastname: Cesnjevar
mesh_terms: D000137:Acid-Base Imbalance / Q000209:etiology; D000818:Animals; D000831:Animals, Newborn; D001013:Aorta, Thoracic / Q000601:surgery*; D001831:Body Temperature; D016122:Brachiocephalic Trunk / Q000502:physiology*; D001927:Brain Diseases / Q000517:prevention & control; D002560:Cerebrovascular Circulation; D005073:Evoked Potentials, Somatosensory; D006324:Heart Arrest, Induced; D006439:Hemodynamics; D007430:Intraoperative Care / Q000379:methods*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010477:Perfusion; D012039:Regional Blood Flow; D013552:Swine
chemical_list: D019344:Lactic Acid