title: The correlation between peri-operative hyperglycemia and mortality in cardiac surgery patients: a systematic review.
abstract: BACKGROUND
  Hyperglycemia occurs frequently in patients undergoing cardiac surgery. It has been identified as a risk factor for increased peri-operative morbidity and mortality.
  
  
  OBJECTIVE
  To review the evidence of the correlation of peri-operative hyperglycemia with mortality in cardiac surgery patients and to discuss the main results in order to provide evidence-based knowledge for the appropriate glycemic control.
  
  
  METHODS
  We searched the electronic databases MEDLINE, CINAHL and EMBASE in June 2010. The material of our study was articles published between 1 January 1990 and 31 May 2010, which investigated the correlation between peri-operative hyperglycemia and in-hospital and/or 30-day cardiac surgery mortality.
  
  
  RESULTS
  Out of the 16 reviewed articles in our study, 12 (75%) significantly associated hyperglycemia and inadequate blood glucose control with increased mortality. In addition, four of the reviewed articles were controlled randomized trials and among them only one demonstrated strong correlation between poor glycemic control and mortality. No study was multi-centre and the reviewed articles were characterized by different definitions of peri-operative hyperglycemia, different intensity and duration of the applied therapy and heterogeneity of the population.
  
  
  CONCLUSIONS
  It is clear that peri-operative hyperglycemia is harmful for cardiac surgery patients. The significant shortage of randomized controlled trials, the absence of multicentre studies, the different definitions of peri-operative hyperglycemia, the different intensity and duration of the applied insulin therapy protocol and the heterogeneity of the studied population (diabetics and non-diabetics) are significant limitations, which could explain the inconsistent findings of the literature. These limitations indicate the need for further research.
authors.affiliation: Cardiac Surgery Intensive Care Unit, Evangelismos General Hospital of Athens, Greece. kongiakoumidakis@gmail.com
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Giakoumidakis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Nenekidis
authors.forename: Hero
authors.initials: H
authors.lastname: Brokalaki
mesh_terms: D006348:Cardiac Surgical Procedures / Q000401:mortality*; D006331:Heart Diseases / Q000401:mortality* / Q000601:surgery*; D006801:Humans; D006943:Hyperglycemia / Q000401:mortality*; D011184:Postoperative Period; D057234:Preoperative Period; D012307:Risk Factors