title: Influence of hemodynamics on the performances of intravascular gas exchangers.
abstract: BACKGROUND
  The intravascular gas exchanger is a lung assist device for augmentation of gas exchange in critically ill patients with severe acute respiratory failure. These patients often require inotropic support therapy due to the cardiovascular instability that almost inevitably accompanies severe respiratory failure.
  
  
  METHODS
  We investigated the interaction of vasoactive medication (dopamine, nitroglycerin, and noradrenaline) with the gas exchange performances of the intravascular gas exchanger in a bovine experimental model.
  
  
  RESULTS
  Dopamine administration highly increased cardiac output, caval flow rates, and diameter of vena cava inferior. These effects resulted in a significant increase in oxygen transfer (baseline, 35 +/- 6 mL/min versus 153 +/- 27 mL/min at 20 micrograms.kg-1.min-1 of dopamine, p < 0.001) and carbon dioxide elimination (baseline, 35 +/- 2 mL/min versus 47 +/- 4 mL/min at 20 micrograms.kg-1.min-1 of dopamine, p < 0.001). Administration of nitroglycerin did not cause significant changes of the hemodynamic parameters nor did it affect the oxygen transfer or carbon dioxide elimination. Noradrenaline caused a moderate increase in cardiac output and caval flow, but no changes of caval diameter. hemodynamic changes were accompanied by an increase in oxygen transfer from 38 +/- 5 mL/min to 68 +/- 7 mL/min (p < 0.01) and carbon dioxide elimination from 33 +/- 1 mL/min to 40 +/- 1 mL/min (p = 0.03). The multiple regression analysis showed significant influence of changes in cardiac output on oxygen transfer (p < 0.001) and carbon dioxide elimination (p = 0.004). The administration of vasoactive drugs induced slight changes in caval diameter that did not significantly affect the gas transfer.
  
  
  CONCLUSIONS
  The results from our study reveal the major influence of cardiac output on efficiency of gas transfer of the intravascular oxygenator.
authors.affiliation: Department of Surgery, University Hospital Zurich, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Mihaljevic
authors.forename: L K
authors.initials: LK
authors.lastname: von Segesser
authors.forename: M
authors.initials: M
authors.lastname: Tönz
authors.forename: B
authors.initials: B
authors.lastname: Leskosek
authors.forename: M I
authors.initials: MI
authors.lastname: Turina
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D002302:Cardiac Output / Q000187:drug effects; D002417:Cattle; D004298:Dopamine / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D005996:Nitroglycerin / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010106:Oxygenators; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014682:Vena Cava, Inferior / Q000187:drug effects / Q000502:physiology
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D005996:Nitroglycerin; D004298:Dopamine; D009638:Norepinephrine