title: Acute hypercapnia improves indices of tissue oxygenation more than dobutamine in septic shock.
abstract: BACKGROUND
  Hypercapnia has similar hemodynamic effects to those of a dobutamine infusion and may have relevance in the management of septic shock.
  
  
  OBJECTIVE
  To compare the effects induced by hypercapnia with those of dobutamine in a clinically relevant model of septic shock.
  
  
  METHODS
  Fecal peritonitis was induced in 21 anesthetized, invasively monitored, mechanically ventilated female sheep. A combination of Ringer's lactate and 6% hydroxyethyl starch solution was titrated to maintain constant cardiac filling throughout the experiments. Two hours after feces spillage, animals were randomized to one of three groups (each, n = 7): (1) hypercapnia: carbon dioxide given to maintain partial pressure of carbon dioxide between 55 and 65 mm Hg throughout the experiment; (2) dobutamine: dobutamine infused intravenously (7 microg/kg/min); (3) control: no treatment. In the dobutamine and control groups, the partial pressure of carbon dioxide was kept between 35 and 45 mm Hg. All animals were monitored until spontaneous death.
  
  
  RESULTS
  The animals in the hypercapnia group had significantly lower arterial pH than the other two groups (P < 0.05). Hypercapnic and dobutamine-treated animals developed significantly higher heart rate, cardiac index, and oxygen delivery, and lower lactate concentrations than control animals (P < 0.05). Hypercapnic animals had lower post mortem lung wet/dry ratio than the control animals (P < 0.05). The alveolar-arterial oxygen partial pressure difference and shunt fraction were significantly lower in hypercapnic animals than in the other groups (P < 0.05).
  
  
  CONCLUSIONS
  In this clinically relevant ovine model of septic shock, hypercapnia had similar effects to dobutamine on hemodynamic variables and lactic acidosis. Hypercapnia improved tissue oxygenation and reduced lung edema formation more than dobutamine administration.
authors.affiliation: Department of Intensive Care, Erasme Hospital, Route de Lennik 808, 1070-B Brussels, Belgium. jlvincen@ulb.ac.be.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Fuhong
authors.initials: F
authors.lastname: Su
authors.forename: Alejandro
authors.initials: A
authors.lastname: Bruhn
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Vincent
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002302:Cardiac Output; D004195:Disease Models, Animal; D004280:Dobutamine / Q000627:therapeutic use*; D005260:Female; D006339:Heart Rate; D006935:Hypercapnia; D010100:Oxygen / Q000378:metabolism*; D012756:Sheep; D012772:Shock, Septic / Q000188:drug therapy / Q000378:metabolism / Q000628:therapy*
chemical_list: D000318:Adrenergic beta-Agonists; D002245:Carbon Dioxide; D004280:Dobutamine; D010100:Oxygen