• Armand Mekontso-Dessap, Vincent Castelain, Nadia Anguel, Mabrouk Bahloul, Franck Schauvliege, Christian Richard, and Jean-Louis Teboul.
• Service de Réanimation Médicale, Centre Hospitalier Universitaire de Bicêtre, Assistance Publique, Hôpitaux de Paris, Faculté de Médecine Paris-Sud, Université Paris XI, 78 rue du Général Leclerc, 94275 le Kremlin-Bicetre Cedex, France.
• Intensive Care Med. 2002 Mar 1;28(3):272-7.

ObjectiveUnder conditions of tissue hypoxia total CO2 production (VCO2) should be less reduced than O2 consumption (VO2) since an anaerobic CO2 production should occur. Thus the VCO(2)/VO(2) ratio, and hence the venoarterial CO2 tension difference/arteriovenous O2 content difference ratio (DeltaPCO2/C(a-v)O2), should increase. We tested the value of the DeltaPCO2/C(a-v)O2 ratio in detecting the presence of global anaerobic metabolism as defined by an increase in arterial lactate level above 2 mmol/l (Lac+).Design And SettingRetrospective study over a 17-month period in medical intensive care unit of a university hospital.PatientsWe obtained 148 sets of measurements in 89 critically ill patients monitored by a pulmonary artery catheter.ResultsThe DeltaPCO2/C(a-v)O2 ratio was higher in those with increased ( n=73) than in the normolactatemic group (2.0+/-0.9 vs. 1.1+/-0.6, p<0.0001). Among all the O2- and CO2-derived parameters the DeltaPCO2/C(a-v)O2 ratio had the highest correlation with the arterial lactate level ( r=0.57). Moreover, for a threshold value of 1.4 the DeltaPCO2/C(a-v)O2 ratio predicted significantly better than the other parameters (receiver operating characteristic curves) the presence of hyperlactatemia (positive and negative predictive values of 86% and 80%, respectively). The overall survival estimate at 1 month was greater when the DeltaPCO2/C(a-v)O2 ratio was less than 1.4 on the first set of measurements (38+/-10% vs. 20+/-8%, p<0.01).ConclusionThe DeltaPCO2/C(a-v)O2 ratio seems a reliable marker of global anaerobic metabolism. Its calculation would be helpful for a better interpretation of pulmonary artery catheter data.

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