The aim of this study was to assess the clinical application of a near-patient testing (NPT) device for capillary blood hydroxybutyrate (HOB) measurement in evaluating a new end-point for intravenous insulin therapy in the treatment of diabetic ketoacidosis (DKA) in children.
Children fulfilling the criteria for DKA were treated according to an integrated care pathway (ICP) with fluid replacement and insulin infusion. We measured capillary HOB hourly by NPT (Abbott Optium meter, analytical range 0-6.0 mmol/L), venous blood gases 4 hourly, and venous HOB 4 hourly by laboratory enzymatic method and tested all urine passed for ketones. Two possible ICP end-points were compared: A, pH > 7.3 followed by two successive NPT HOB measurements <1 mmol/L, and B, pH > 7.3 and urine ketone free (our current end-point).
In 35 patient episodes, the ICP was completed (28 to negative ketonuria) without significant variation. Before treatment, median (range) laboratory HOB was 9.5 mmol/L (4.6-15.70 mmol/L), pH 7.18 (6.98-7.38), and standard bicarbonate 11.5 mmol/L (4.3-18.6 mmol/L). ICP end-point A was reached after 17 h (4-39 h), whereas end-point B was not reached until 28 h (14-64 h) after starting treatment. The median lag was 11 h (1-36 h). For 59 paired venous samples (excluding samples with laboratory HOB >6 mmol/L), the relation between NPT (y) and laboratory (x) HOB was y = 0.92x - 0.05, r(2)= 0.94, mean bias -0.25 mmol/L.
(i) Serial measurement of NPT HOB allows evaluation of a new, simple, earlier end-point for intravenous insulin therapy. (ii) Agreement between NPT and laboratory HOB was clinically acceptable for HOB levels within the meter's analytical range.