title: Lactate and venoarterial carbon dioxide difference/arterial-venous oxygen difference ratio, but not central venous oxygen saturation, predict increase in oxygen consumption in fluid responders.
abstract: OBJECTIVE
  During circulatory failure, the ultimate goal of treatments that increase cardiac output is to reduce tissue hypoxia. This can only occur if oxygen consumption depends on oxygen delivery. We compared the ability of central venous oxygen saturation and markers of anaerobic metabolism to predict whether a fluid-induced increase in oxygen delivery results in an increase in oxygen consumption.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  ICU.
  
  
  METHODS
  Fifty-one patients with an acute circulatory failure (78% of septic origin).
  
  
  METHODS
  Before and after a volume expansion (500 mL of saline), we measured cardiac index, o2- and Co2-derived variables and lactate.
  
  
  RESULTS
  Volume expansion increased cardiac index ≥ 15% in 49% of patients ("volume-responders"). Oxygen delivery significantly increased in these 25 patients (+32% ± 16%, p < 0.0001). An increase in oxygen consumption ≥ 15% concomitantly occurred in 56% of these 25 volume-responders (+38% ± 28%). Compared with the volume-responders in whom oxygen consumption did not increase, the volume-responders in whom oxygen consumption increased ≥ 15% were characterized by a higher lactate (2.3 ± 1.1 mmol/L vs. 5.5 ± 4.0 mmol/L, respectively) and a higher ratio of the veno-arterial carbon dioxide tension difference (P(v - a)Co2) over the arteriovenous oxygen content difference (C(a - v)o2). A fluid-induced increase in oxygen consumption greater than or equal to 15% was not predicted by baseline central venous oxygen saturation but by high baseline lactate and (P(v - a)Co2/C(a - v)o2 ratio (areas under the receiving operating characteristics curves: 0.68 ± 0.11, 0.94 ± 0.05, and 0.91 ± 0.06). In volume-nonresponders, volume expansion did not significantly change cardiac index, but the oxygen delivery decreased due to a hemodilution-induced decrease in hematocrit.
  
  
  CONCLUSIONS
  In volume-responders, unlike markers of anaerobic metabolism, central venous oxygen saturation did not allow the prediction of whether a fluid-induced increase in oxygen delivery would result in an increase in oxygen consumption. This suggests that along with indicators of volume-responsiveness, the indicators of anaerobic metabolism should be considered instead of central venous oxygen saturation for starting hemodynamic resuscitation.
authors: AP-HP, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Service de Réanimation Médicale, Le Kremlin-Bicêtre, France. xavier.monnet@bct.aphp.fr
authors: Xavier
authors: X
authors: Monnet
authors: Florence
authors: F
authors: Julien
authors: Nora
authors: N
authors: Ait-Hamou
authors: Marie
authors: M
authors: Lequoy
authors: Clément
authors: C
authors: Gosset
authors: Mathieu
authors: M
authors: Jozwiak
authors: Romain
authors: R
authors: Persichini
authors: Nadia
authors: N
authors: Anguel
authors: Christian
authors: C
authors: Richard
authors: Jean-Louis
authors: JL
authors: Teboul
mesh_terms: D000208:Acute Disease; D000368:Aged; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood* / Q000378:metabolism; D005440:Fluid Therapy; D006439:Hemodynamics; D006801:Humans; D007362:Intensive Care Units; D019344:Lactic Acid / Q000097:blood* / Q000378:metabolism; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D012769:Shock
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid