• Ellen Burkett, Gerben Keijzers, and James Lind.
• Department of Emergency Medicine, Gold Coast Hospital, Gold Coast, QLD.
• Crit Care Resusc. 2009 Mar 1;11(1):8-13.

ObjectiveTo determine whether hyperglycaemia is associated with prolongation of the corrected QT (QTc) interval on the electrocardiogram (ECG) in critically ill patients.DesignSingle-centre, prospective observational study.Participants And Setting197 consecutive patients admitted to the adult intensive care unit of a 570-bed teaching hospital over 10 weeks from November 2004.Main Outcome MeasuresCorrelation 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.ResultsMean 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.ConclusionsThere 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.

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