title: Time course of central venous-to-arterial carbon dioxide tension difference in septic shock patients receiving incremental doses of dobutamine.
abstract: OBJECTIVE
  To assess the time course of the central venous-arterial carbon dioxide tension difference (∆PCO2)-as an index of the carbon dioxide production (VCO2)/cardiac index (CI) ratio-in stable septic shock patients receiving incremental doses of dobutamine.
  
  
  METHODS
  Twenty-two hemodynamically stable septic shock patients with no signs of global tissue hypoxia, as testified by normal blood lactate levels, were prospectively included. A dobutamine infusion was administered at a dose of up to 15 μg/kg/min in increments of 5 μg/kg/min every 30 min. Complete hemodynamic and gas measurements were obtained at baseline, and at each dose of dobutamine.
  
  
  RESULTS
  Dobutamine induced a significant dose-dependent increase of CI from 0 to 15 μg/kg/min (P < 0.001). Oxygen consumption (VO2) and VCO2 were progressively increased by dobutamine. These increases were more marked between 10 and 15 μg/kg/min (8.3 and 8.6 %, respectively) than between the lower doses. ∆PCO2 and oxygen extraction (EO2) significantly decreased between 0 (8.0 ± 2.0 mmHg and 43.8 ± 13.4 %, respectively) and 10 μg/kg/min of dobutamine (4.2 ± 1.6 mmHg and 28.9 ± 7.9 %, respectively), but remained unchanged from 10 to 15 μg/kg/min (5.4 ± 2.4 mmHg and 29.5 ± 8.2 %, respectively). The central venous oxygen saturation significantly (ScvO2) increased from 0 to 10 μg/kg/min and remained unchanged from 10 to 15 μg/kg/min. Time courses of ∆PCO2, ScvO2, and EO2 were linked therefore to the biphasic changes of VO2 and VCO2.
  
  
  CONCLUSIONS
  ∆PCO2 is a good indicator of the change of VCO2 induced by dobutamine. Measurement of ∆PCO2, along with ScvO2 and EO2, may be presented as a useful tool to assess the adequacy of oxygen supply versus metabolic and oxygen demand.
authors.affiliation: Intensive Care Unit, Centre Hospitalier du Dr. Schaffner de Lens, Service de Réanimation Polyvalente, 99 route de la bassée, 62307, Lens cedex, France, mallatjihad@gmail.com.
authors.forename: Jihad
authors.initials: J
authors.lastname: Mallat
authors.forename: Younes
authors.initials: Y
authors.lastname: Benzidi
authors.forename: Julia
authors.initials: J
authors.lastname: Salleron
authors.forename: Malcolm
authors.initials: M
authors.lastname: Lemyze
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Gasan
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vangrunderbeeck
authors.forename: Florent
authors.initials: F
authors.lastname: Pepy
authors.forename: Laurent
authors.initials: L
authors.lastname: Tronchon
authors.forename: Benoit
authors.initials: B
authors.lastname: Vallet
authors.forename: Didier
authors.initials: D
authors.lastname: Thevenin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D002316:Cardiotonic Agents / Q000008:administration & dosage* / Q000494:pharmacology; D004280:Dobutamine / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D007362:Intensive Care Units / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects; D011446:Prospective Studies; D012772:Shock, Septic / Q000097:blood / Q000188:drug therapy*; D013997:Time Factors; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D002316:Cardiotonic Agents; D002245:Carbon Dioxide; D004280:Dobutamine