title: The Use of the Ratio between the Veno-arterial Carbon Dioxide Difference and the Arterial-venous Oxygen Difference to Guide Resuscitation in Cardiac Surgery Patients with Hyperlactatemia and Normal Central Venous Oxygen Saturation.
abstract: BACKGROUND
  After cardiac surgery, central venous oxygen saturation (ScvO 2 ) and serum lactate concentration are often used to guide resuscitation; however, neither are completely reliable indicators of global tissue hypoxia. This observational study aimed to establish whether the ratio between the veno-arterial carbon dioxide and the arterial-venous oxygen differences (P(v-a)CO 2 /C(a-v)O 2 ) could predict whether patients would respond to resuscitation by increasing oxygen delivery (DO 2 ).
  
  
  METHODS
  We selected 72 patients from a cohort of 290 who had undergone cardiac surgery in our institution between January 2012 and August 2014. The selected patients were managed postoperatively on the Intensive Care Unit, had a normal ScvO 2 , elevated serum lactate concentration, and responded to resuscitation by increasing DO 2 by >10%. As a consequence, 48 patients responded with an increase in oxygen consumption (VO 2 ) while VO 2 was static or fell in 24.
  
  
  RESULTS
  At baseline and before resuscitative intervention in postoperative cardiac surgery patients, a P(v-a)CO 2 /C(a-v)O 2 ratio ≥1.6 mmHg/ml predicted a positive VO 2 response to an increase in DO 2 of >10% with a sensitivity of 68.8% and a specificity of 87.5%.
  
  
  CONCLUSIONS
  P(v-a)CO 2 /C(a-v)O 2 ratio appears to be a reliable marker of global anaerobic metabolism and predicts response to DO 2 challenge. Thus, patients likely to benefit from resuscitation can be identified promptly, the P(v-a)CO 2 /C(a-v)O 2 ratio may, therefore, be a useful resuscitation target.
authors.forename: Wei
authors.initials: W
authors.lastname: Du
authors.forename: Yun
authors.initials: Y
authors.lastname: Long
authors.forename: Xiao-Ting
authors.initials: XT
authors.lastname: Wang
authors.affiliation: Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D006348:Cardiac Surgical Procedures; D005260:Female; D006801:Humans; D065906:Hyperlactatemia / Q000097:blood* / Q000628:therapy; D007362:Intensive Care Units / Q000706:statistics & numerical data; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011446:Prospective Studies; D012151:Resuscitation
chemical_list: D002245:Carbon Dioxide; D019344:Lactic Acid