title: Changes in hemodynamics and acid-base balance during cross-clamping of the descending thoracic aorta. A study in patients operated on for thoracic and thoracoabdominal aortic aneurysm.
abstract: OBJECTIVE
  In the clinical situation there is discrepancy between various investigations regarding the cardiac response of thoracic aortic cross-clamping. The aim was therefore to investigate the hemodynamic response and blood gases during proximal aortic cross-clamping (XC) in patients operated for descending thoracic and thoracoabdominal aortic aneurysm without circulatory support.
  
  
  METHODS
  Altogether 51 patients operated on for thoracoabdominal (n=31) or descending thoracic aortic aneurysm (n=20) were included in the investigation. All patients were operated with aortic XC, but no circulatory support was applied. Hemodynamic variables and blood gases were recorded before and during XC.
  
  
  RESULTS
  A significant increase in cardiac output during XC from 4.7 to 6.0 liters/min was observed (p<0.01). There was a similar percentual increase in heart rate and also the proximal systolic blood pressure increased. A metabolic acidosis occurred during XC.
  
  
  CONCLUSIONS
  Cardiac output was significantly increased during XC in patients operated on for thoracoabdominal or descending thoracic aneurysm using direct aortic XC without circulatory support. Simultaneously, the heart rate was increased and there was a hyperdynamic circulatory state proximal to the aortic clamp. Redistribution of the blood volume in addition to catecholamine release may be responsible for the observed changes. These observations may influence the selection of operative strategy for some of these patients.
authors.affiliation: Department of Surgery, St. Olavs Hospital, University Hospital of Trondheim, Trondheim, Norway.
authors.forename: T O
authors.initials: TO
authors.lastname: Eide
authors.forename: J
authors.initials: J
authors.lastname: Aasland
authors.forename: P
authors.initials: P
authors.lastname: Romundstad
authors.forename: R
authors.initials: R
authors.lastname: Stenseth
authors.forename: O D
authors.initials: OD
authors.lastname: Saether
authors.forename: P
authors.initials: P
authors.lastname: Aadahl
authors.forename: H O
authors.initials: HO
authors.lastname: Myhre
mesh_terms: D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000209:etiology; D000142:Acidosis, Respiratory / Q000209:etiology; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000601:surgery*; D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology* / Q000601:surgery*; D017545:Aortic Aneurysm, Thoracic / Q000503:physiopathology* / Q000601:surgery*; D002302:Cardiac Output; D003250:Constriction; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D014656:Vascular Surgical Procedures / Q000009:adverse effects