title: Central Venous-Arterial pCO2 Difference Identifies Microcirculatory Hypoperfusion in Cardiac Surgical Patients With Normal Central Venous Oxygen Saturation: A Retrospective Analysis.
abstract: OBJECTIVE
  Parameters such as central venous oxygen saturation (ScvO2) are used increasingly to monitor adequate hemodynamic treatment. However, it still remains challenging to identify patients with assumed adequate circulatory status quantified by ScvO2 who suffer from macro- and microcirculatory hypoperfusion. The authors hypothesized that central venous-arterial pCO2 difference (dCO2) could serve as an additional parameter to evaluate the adequacy of perfusion in cardiac surgery patients.
  
  
  METHODS
  Retrospective data analysis of a prospective interventional study.
  
  
  METHODS
  University medical center.
  
  
  METHODS
  Patients undergoing surgery with cardiopulmonary bypass.
  
  
  METHODS
  The dCO2 was measured postoperatively. The patients with an ScvO2≥70% were divided into 2 groups, the high-dCO2 group (≥8 mmHg) and the low-dCO2 group (<8 mmHg).
  
  
  RESULTS
  Sixty patients were included in this analysis. Twenty-five patients had ScvO2≥70%, 4 patients were assigned to the high-dCO2 group. Patients of the high-dCO2 group had significantly longer intensive care unit (ICU) stays (4 d; 1-29 v 1 d; 1-1; p = 0.02), significantly prolonged need for mechanical ventilation (41.5 h; 11-263.5; v 10 h; 7-11; p = 0.03), and higher cardiovascular complication rates in the ICU on postoperative days 3, 4, and 5 (p = 0.02). The mixed venous saturation (SvO2) after 1 hour in the ICU was significantly lower, lactate levels were significantly higher, and the plasma disappearance rate of indocyanine green was significantly lower after 1 hour in the ICU (14.6%/min; 11.6-19.8%/min v 23.6%/min; 22.5-27.3%/min; p = 0.02) in the high-dCO2 group. Cytokines increased significantly postoperatively in the high-dCO2 group.
  
  
  CONCLUSIONS
  The authors described dCO2 as a routinely available tool to detect global and microcirculatory hypoperfusion in postoperative cardiac surgical patients. The authors showed that in patients with an ScvO2≥70%, a high dCO2 (≥8 mmHg) was associated with increased postoperative lactate levels and decreased splanchnic function. These findings were associated with a longer need for mechanical ventilation and longer ICU stay.
authors.affiliation: Department for Anesthesia and Intensive Care Medicine, Charité Universitätsmedizin Berlin. Electronic address: Marit.Habicher@charite.de.
authors.forename: Marit
authors.initials: M
authors.lastname: Habicher
authors.affiliation: Department for Anesthesia and Intensive Care Medicine, Charité Universitätsmedizin Berlin.
authors.forename: Christian
authors.initials: C
authors.lastname: von Heymann
authors.affiliation: Department for Anesthesia and Intensive Care Medicine, Charité Universitätsmedizin Berlin.
authors.forename: Claudia D
authors.initials: CD
authors.lastname: Spies
authors.affiliation: SOSTANA-Sophisticated Statistical Analyses GmbH, Berlin, Germany.
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Wernecke
authors.affiliation: Department for Anesthesia and Intensive Care Medicine, Charité Universitätsmedizin Berlin.
authors.forename: Michael
authors.initials: M
authors.lastname: Sander
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000097:blood*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000639:trends; D002315:Cardiopulmonary Bypass / Q000009:adverse effects* / Q000639:trends; D002405:Catheterization, Central Venous / Q000379:methods* / Q000639:trends; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D010092:Oximetry / Q000379:methods*; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D012189:Retrospective Studies
chemical_list: D002245:Carbon Dioxide
keywords: cardiac surgery; central venous- arterial pCO(2) difference; microcirculatory hypoperfusion; splanchnic hypoperfusion