title: N-acetylcysteine is associated with increased blood loss and blood product utilization during cardiac surgery.
abstract: OBJECTIVE
  When used to prevent perioperative inflammation and ischemia-reperfusion injury, N-acetylcysteine may inadvertently impair hemostasis. We, therefore, performed a post hoc analysis of a recent randomized controlled trial in cardiac surgery to determine whether N-acetylcysteine was associated with increased blood loss and blood product transfusion.
  
  
  METHODS
  Blinded (patients, caregivers, outcome assessors) placebo-controlled parallel group randomized trial (www.ClinicalTrials.gov ID NCT00188630).
  
  
  METHODS
  Tertiary care hospital in Toronto, Ontario, Canada (September 2003 to October 2005).
  
  
  METHODS
  A total of 177 patients with preexisting moderate renal insufficiency (estimated glomerular filtration rate <or=60 mL/min) and undergoing cardiac surgery.
  
  
  METHODS
  Eighty-nine patients were randomized to receive intravenous N-acetylcysteine (100 mg/kg bolus; 20 mg.kg.hr infusion until 4 hours after cardiopulmonary bypass), and 88 were randomized to receive placebo.
  
  
  RESULTS
  We used laboratory markers (hemoglobin, platelets, coagulation), chest-tube blood loss, and blood product transfusion to evaluate hemostasis. Compared with placebo, patients who received N-acetylcysteine arm experienced a mean 24-hour chest-tube blood loss that was 261 mL higher (95% confidence interval [CI] 93-488 mL, p = 0.008), and were transfused 1.6 more units of red blood cells (95% CI 0.4-3.1 units, p = 0.02) during hospitalization. The risk of receiving >or=5 units of red blood cells within 24 hours of surgery was significantly higher with N-acetylcysteine (relative risk 1.85, 95% CI 1.06-3.21, p = 0.03; adjusted relative risk 2.09, 95% CI 1.24-3.83, p = 0.005).
  
  
  CONCLUSIONS
  In patients who have preexisting moderate renal insufficiency and are undergoing cardiac surgery, N-acetylcysteine was associated with important effects on blood loss and blood product transfusion. Clinicians and researchers should, therefore, consider the potential for impaired hemostasis when using N-acetylcysteine in the perioperative setting. Further research is needed to elucidate mechanisms by which N-acetylcysteine may impair hemostasis, and the risk-benefit profile of N-acetylcysteine for perioperative organ protection.
authors.affiliation: Department of Anesthesia, Toronto General Hospital and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Duminda N
authors.initials: DN
authors.lastname: Wijeysundera
authors.forename: Keyvan
authors.initials: K
authors.lastname: Karkouti
authors.forename: Vivek
authors.initials: V
authors.lastname: Rao
authors.forename: John T
authors.initials: JT
authors.lastname: Granton
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Chan
authors.forename: Roshan
authors.initials: R
authors.lastname: Raban
authors.forename: Jo
authors.initials: J
authors.lastname: Carroll
authors.forename: Humara
authors.initials: H
authors.lastname: Poonawala
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
mesh_terms: D000111:Acetylcysteine / Q000009:adverse effects* / Q000627:therapeutic use; D000368:Aged; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data*; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D002315:Cardiopulmonary Bypass; D004311:Double-Blind Method; D005260:Female; D006487:Hemostasis / Q000187:drug effects; D006801:Humans; D008297:Male
chemical_list: D000111:Acetylcysteine