title: Influence of intravenous thiamine supplementation on blood lactate concentration prior to cardiac surgery: A double-blinded, randomised controlled pilot study.
abstract: BACKGROUND
  Stress related to surgery and critical illness depletes thiamine, essential in energy metabolism, and might result in high blood lactate concentrations and higher mortality.
  
  
  OBJECTIVE
  We hypothesised that thiamine supplementation would increase blood concentration of thiamine and reduce blood lactate concentration postoperatively. Moreover, we aimed to identify the prevalence of, and risk factors for, high blood lactate concentrations.
  
  
  METHODS
  This was a double-blind, randomised controlled pilot study from February to July 2012 including 30 patients scheduled for cardiac surgery with cardiopulmonary bypass.
  
  
  METHODS
  Patients were assigned randomly to receive thiamine (300 mg in 0.9% Normal saline solution) or placebo (0.9% Normal saline) preoperatively.
  
  
  METHODS
  One arterial blood sample was taken preoperatively and another postoperatively to measure thiamine concentration, and multiple samples were taken during surgery and ICU stay to determine lactate concentrations. Twenty-four hour urine samples were collected to measure urinary thiamine concentration. Preoperatively, we assessed extracellular mass to body cell mass ratio (ECM/BCM).
  
  
  RESULTS
  The mean (SD) age of the patients was 58 (12) years, 73% were overweight, 10% were malnourished and the prevalence of thiamine deficiency was 10%. Patients in the thiamine group had significantly higher blood thiamine concentrations 2 days postoperatively [805.2 ± 289.8 ng g(-1) haemoglobin (Hb)] than those in the placebo group (591.2 ± 100.7 ng g(-1) Hb, P < 0.01). The mean blood lactate concentration changed significantly over time, but did not differ significantly between the groups. Patients with ECM/BCM more than 1 had higher lactate concentrations on admission to ICU than those with ECM/BCM less than 1 (2.1 ± 0.7 vs. 1.7 ± 0.6, P = 0.09) and were at a significantly greater risk of having a higher lactate concentration on ICU admission [odds ratio (OR) 13.5, 95% confidence interval (95% CI) 1.0 to 179.4, P < 0.05]. On the basis of these results, a sample size calculation for a larger study has been facilitated.
  
  
  CONCLUSIONS
  Thiamine supplementation caused normalisation of blood and urine concentrations postoperatively but without a significant reduction in lactate concentration or clinical outcome. Body composition played an important role in lactate formation. Further research focusing on preoperative screening and optimal treatment of high lactate concentrations in this specific population is warranted.
  
  
  BACKGROUND
  Clinicaltrials.gov identifier: NCT01524315.
authors.affiliation: From the Department of Internal Medicine III, Division of Endocrinology and Metabolism, Medical University of Vienna, Vienna (ML, PK, RK, BL, KS), Special Institute for Preventive Cardiology and Nutrition SIPCAN, Salzburg (ML), Division Cardiac Thoracic Vascular Anaesthesia and Intensive Care Medicine, Medical University of Vienna (MH, PK, BS, IR, CW), Department of Nutritional Sciences, University of Vienna (JK), and Institute of Social Medicine, Centre for Public Health, Medical University of Vienna, Vienna, Austria (EL).
authors.forename: Maria
authors.initials: M
authors.lastname: Luger
authors.forename: Michael
authors.initials: M
authors.lastname: Hiesmayr
authors.forename: Pamina
authors.initials: P
authors.lastname: Köppel
authors.forename: Beatrix
authors.initials: B
authors.lastname: Sima
authors.forename: Ines
authors.initials: I
authors.lastname: Ranz
authors.forename: Christian
authors.initials: C
authors.lastname: Weiss
authors.forename: Jürgen
authors.initials: J
authors.lastname: König
authors.forename: Eva
authors.initials: E
authors.lastname: Luger
authors.forename: Renate
authors.initials: R
authors.lastname: Kruschitz
authors.forename: Bernhard
authors.initials: B
authors.lastname: Ludvik
authors.forename: Karin
authors.initials: K
authors.lastname: Schindler
mesh_terms: D000328:Adult; D000368:Aged; D002315:Cardiopulmonary Bypass / Q000379:methods*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013831:Thiamine / Q000008:administration & dosage*
chemical_list: D019344:Lactic Acid; D013831:Thiamine