title: Combination of venoarterial PCO2 difference with arteriovenous O2 content difference to detect anaerobic metabolism in patients.
abstract: OBJECTIVE
  Under 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+).
  
  
  METHODS
  Retrospective study over a 17-month period in medical intensive care unit of a university hospital.
  
  
  METHODS
  We obtained 148 sets of measurements in 89 critically ill patients monitored by a pulmonary artery catheter.
  
  
  RESULTS
  The 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).
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: 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.
authors.forename: Armand
authors.initials: A
authors.lastname: Mekontso-Dessap
authors.forename: Vincent
authors.initials: V
authors.lastname: Castelain
authors.forename: Nadia
authors.initials: N
authors.lastname: Anguel
authors.forename: Mabrouk
authors.initials: M
authors.lastname: Bahloul
authors.forename: Franck
authors.initials: F
authors.lastname: Schauvliege
authors.forename: Christian
authors.initials: C
authors.lastname: Richard
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Teboul
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D001424:Bacterial Infections / Q000097:blood / Q000378:metabolism*; D015415:Biomarkers; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood / Q000378:metabolism*; D002407:Catheterization, Swan-Ganz; D003422:Critical Care; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007773:Lactates / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D012372:ROC Curve; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D007773:Lactates; D002245:Carbon Dioxide