title: Uncertainties in the measurement of blood glucose in paediatric intensive care: implications for clinical trials of tight glycaemic control.
abstract: OBJECTIVE
  In preparation for a tight glycaemic control (TGC) clinical trial we assessed the agreement between methods used to measure blood glucose in critically ill children.
  
  
  METHODS
  Service evaluation comparing blood gas and main laboratory analysers with point-of-care (POC) devices PCX, ACCU-Chek and Hemocue.
  
  
  RESULTS
  Two hundred forty-five samples from 157 children measured on 2-4 devices provided 790 values. Marked variation was evident in glucose values between devices, time between tests, sample (whole blood/plasma) and source; 39% of paired values had >20% difference. The decision to start insulin at 7 mmol/L differed depending on the device used for 33% of samples. At low glucose values (<4 mmol/L), differences up to 1.8 mmol/L were evident. The blood gas analyser read lower than all POC models and the laboratory analyser (less risk of undetected hypoglycaemia). An inverse relationship was evident between haematocrit (Hct) and glucose error using POC devices. PCX values for samples with Hct <30% were higher (85%), whereas those for Hct values >38% were lower (66%). Glycolysis occurred during transfer of samples to the laboratory. Using the PCX at the bedside resulted in 0.5 mmol/L mean difference higher than laboratory values; locating the PCX in the laboratory reduced this to 0.2 mmol/L.
  
  
  CONCLUSIONS
  Discrepancies between measurements may mask hypoglycaemia, and the potential benefits of controlling hyperglycaemia may not be achieved. Variation introduced by different devices, sample or source may have led to misclassification of treatment decisions contributing to the conflicting results of TGC studies.
authors: Alder Hey Children's NHS FT, Liverpool, UK. hhill@liv.ac.uk
authors: Helen
authors: H
authors: Hill
authors: Paul
authors: P
authors: Baines
authors: Paul
authors: P
authors: Barton
authors: Paul
authors: P
authors: Newland
authors: Dianne
authors: D
authors: Terlouw
authors: Mark
authors: M
authors: Turner
mesh_terms: D001784:Blood Gas Analysis; D001786:Blood Glucose / Q000032:analysis*; D002986:Clinical Trials as Topic; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007328:Insulin / Q000008:administration & dosage; D015278:Intensive Care Units, Pediatric; D035501:Uncertainty
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin