• Xavier Monnet, Florence Julien, Nora Ait-Hamou, Marie Lequoy, Clément Gosset, Mathieu Jozwiak, Romain Persichini, Nadia Anguel, Christian Richard, and Jean-Louis Teboul.
• AP-HP, Hôpitaux Universitaires Paris-Sud, Hôpital de Bicêtre, Service de Réanimation Médicale, Le Kremlin-Bicêtre, France. xavier.monnet@bct.aphp.fr
• Crit. Care Med.. 2013 Jun 1;41(6):1412-20.

ObjectivesDuring 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.DesignProspective study.SettingICU.PatientsFifty-one patients with an acute circulatory failure (78% of septic origin).MeasurementsBefore and after a volume expansion (500 mL of saline), we measured cardiac index, o2- and Co2-derived variables and lactate.Main ResultsVolume 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.ConclusionsIn 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.

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