title: The relationship between blood glucose level and QTc duration in the critically ill.
abstract: OBJECTIVE
  To determine whether hyperglycaemia is associated with prolongation of the corrected QT (QTc) interval on the electrocardiogram (ECG) in critically ill patients.
  
  
  METHODS
  Single-centre, prospective observational study.
  
  
  METHODS
  197 consecutive patients admitted to the adult intensive care unit of a 570-bed teaching hospital over 10 weeks from November 2004.
  
  
  METHODS
  Correlation between QT interval (on standard 12-lead ECG taken on ICU admission, corrected with Bazett's formula) and serum glucose level (BGL) in blood collected at time of ECG; comparison of variables, including BGL, by QTc category (< or = 0.44 s or > 0.44 s); explained variance (R(2)) of QTc, determined by multivariate regression analysis.
  
  
  RESULTS
  Mean patient age was 53.4 years. A moderate, positive correlation was found between QTc and BGL (Pearson's correlation coefficient, r = 0.277, P < 0.001). A standard multivariate regression model explained 32.9% (R(2)) of QTc variance, and revealed four significant, independent predictors of QTc duration: heart rate (explaining 11.4% of QTc variance), use of inotropes (10.1%), BGL (7.3%) and serum magnesium level (4.6%). In the cohort with QTc > 0.44 s, BGL was significantly higher, as were the need for inotropes, APACHE II scores and mortality. QTc was significantly longer in patients with BGL > 8 mmol/L than in those with lower BGL (0.471 v 0.442 s, P < 0.001). The only independent predictors of mortality were APACHE II score and mean arterial pressure.
  
  
  CONCLUSIONS
  There was a moderate, significant correlation between QTc and BGL. Patients with a QTc > 0.44 s had higher BGL, APACHE II score and mortality. BGL was an independent predictor of QTc duration, but neither BGL nor QTc were independent predictors of mortality in this study.
authors.affiliation: Department of Emergency Medicine, Gold Coast Hospital, Gold Coast, QLD.
authors.forename: Ellen
authors.initials: E
authors.lastname: Burkett
authors.forename: Gerben
authors.initials: G
authors.lastname: Keijzers
authors.forename: James
authors.initials: J
authors.lastname: Lind
mesh_terms: D018806:APACHE; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology; D001786:Blood Glucose / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D016638:Critical Illness; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D017052:Hospital Mortality; D006801:Humans; D006943:Hyperglycemia / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D001786:Blood Glucose