title: Combined central venous oxygen saturation and lactate as markers of occult hypoperfusion and outcome following cardiac surgery.
abstract: OBJECTIVE
  To assess the association between postoperative central venous oxygen saturation (ScvO(2)) and arterial lactate with outcome after cardiac surgery.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  University-affiliated tertiary care hospital.
  
  
  METHODS
  Patients after coronary artery bypass and/or valve surgery.
  
  
  METHODS
  None.
  
  
  RESULTS
  Postoperative ScvO(2) and arterial lactate were obtained on arrival to the intensive care unit (ICU). ScvO(2) and lactate were drawn again at 8 and 24 hours, respectively, after ICU admission. Moderate global tissue hypoxia (GTH) was defined as ScvO(2) <70% and lactate ≥2 to <4 mmol/L, and severe GTH was defined as ScvO(2) <70% and lactate ≥4 mmol/L. Occult hypoperfusion was defined as moderate-to-severe GTH with mean arterial pressure ≥65 mmHg, central venous pressure ≥8 mmHg, and urine output ≥0.5 mL/kg/h. ScvO(2) on ICU admission negatively correlated with postoperative 24-hour lactate (p = 0.009), which was a strong predictor of time on mechanical ventilation, total complications, and ICU and hospital lengths of stay (p < 0.001 for all comparisons). On admission to the ICU, 19 patients (32%) exhibited occult hypoperfusion. Patients with severe GTH (n = 8) had longer ICU lengths of stay (p = 0.04) and a trend toward longer length of mechanical ventilation (p = 0.17) and number of complications per patient (p = 0.09) compared with those without GTH (n = 10).
  
  
  CONCLUSIONS
  The incidence of GTH is high after cardiac surgery. Postoperative ScvO(2) and lactate may be valuable measurements to identify patients with occult hypoperfusion and subsequently guide hemodynamic optimization to positively affect postoperative outcomes in patients after cardiac surgery.
authors.affiliation: Department of Pharmacy, St Luke's Episcopal Hospital, Houston, TX 77030, USA. bhu@sleh.com
authors.forename: BeeBee Y
authors.initials: BY
authors.lastname: Hu
authors.forename: Greg A
authors.initials: GA
authors.lastname: Laine
authors.forename: Suwei
authors.initials: S
authors.lastname: Wang
authors.forename: R Thomas
authors.initials: RT
authors.lastname: Solis
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002405:Catheterization, Central Venous / Q000379:methods; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D011183:Postoperative Complications / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D011446:Prospective Studies; D014018:Tissue Distribution / Q000502:physiology; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D019344:Lactic Acid; D010100:Oxygen