Fatal neuroglycopaenia after accidental use of a glucose 5% solution in a peripheral arterial cannula flush system

A patient on an Intensive Care Unit who was recovering from multiple organ failure was being given an intravenous infusion of insulin to maintain normoglycaemia. On her 20th day in the unit, she suddenly became unresponsive. A cerebrovascular accident was suspected as other clinical and laboratory parameters remained normal apart from a blood glucose value of 20.6 mmol.l(-1). The insulin infusion rate had been increased to treat hyperglycaemia. Subsequent bedside finger prick blood testing suggested that the blood sugar was low but no numerical reading was provided. Repeat blood glucose analysis using a further sample drawn from the arterial line and measured in the blood gas analyser gave a value of 10.1 mmol.l(-1). Confirmatory laboratory blood tests revealed severe hypoglycaemia (0.1 mmol.l(-1)) and intravenous glucose 50% was given immediately. Examination showed that a glucose 5% solution had been inadvertently used in the arterial cannula flush system rather than saline, contaminating earlier samples drawn from the arterial line and giving falsely high blood glucose values. The prolonged period of severe hypoglycaemia led to neuroglycopaenia and irreversible brain injury. The patient died 9 days later without regaining consciousness. Such a complication has not previously been reported in this context and has particular significance given the increasing use of insulin therapy to maintain normoglycaemia in critically ill patients.