title: Hemodilution on cardiopulmonary bypass as a determinant of early postoperative hyperlactatemia.
abstract: OBJECTIVE
  The nadir hematocrit (HCT) on cardiopulmonary bypass (CPB) is a recognized independent risk factor for major morbidity and mortality in cardiac surgery. The main interpretation is that low levels of HCT on CPB result in a poor oxygen delivery and dysoxia of end organs. Hyperlactatemia (HL) is a marker of dysoxic metabolism, and is associated with bad outcomes in cardiac surgery. This study explores the relationship between nadir HCT on CPB and early postoperative HL.
  
  
  METHODS
  Retrospective study on 3,851 consecutive patients.
  
  
  RESULTS
  Nadir HCT on CPB and other potential confounders were explored for association with blood lactate levels at the arrival in the Intensive Care Unit (ICU), and with the presence of moderate (2.1 - 6.0 mMol/L) or severe (> 6.0 mMol/L) HL. Nadir HCT on CPB demonstrated a significant negative association with blood lactate levels at the arrival in the ICU. After adjustment for the other confounders, the nadir HCT on CPB remained independently associated with moderate (odds ratio 0.96, 95% confidence interval 0.94-0.99) and severe HL (odds ratio 0.91, 95% confidence interval 0.86-0.97). Moderate and severe HL were significantly associated with increased morbidity and mortality.
  
  
  CONCLUSIONS
  Hemodilution on CPB is an independent determinant of HL. This association, more evident for severe HL, strengthens the hypothesis that a poor oxygen delivery on CPB with consequent organ ischemia is the mechanism leading to hemodilution-associated bad outcomes.
authors.affiliation: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese (Milan), Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Ranucci
authors.affiliation: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese (Milan), Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Carboni
authors.affiliation: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese (Milan), Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Cotza
authors.affiliation: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese (Milan), Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Bianchi
authors.affiliation: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese (Milan), Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Di Dedda
authors.affiliation: Department of Cardiothoracic-Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese (Milan), Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Aloisio
mesh_terms: D000368:Aged; D015415:Biomarkers; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D005260:Female; D006400:Hematocrit; D006438:Hemodilution / Q000009:adverse effects*; D006801:Humans; D065906:Hyperlactatemia / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D011183:Postoperative Complications; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers