Multicenter validation of a computer-based clinical decision support tool for glucose control in adult and pediatric intensive care units

Abstract

Introduction: Hyperglycemia during critical illness is common, and intravenous insulin therapy (IIT) to normalize blood glucose improves outcomes in selected populations. Methods differ widely in complexity, insulin dosing approaches, efficacy, and rates of hypoglycemia. We developed a simple bedside-computerized decision support protocol (eProtocol-insulin) that yields promising results in the development center. We examined the effectiveness and safety of this tool in six adult and five pediatric intensive care units (ICUs) in other centers.

Methods: We required attending physicians of eligible patients to independently intend to use intravenous insulin to normalize blood glucose. We used eProtocol-insulin for glucose control for a duration determined by the clinical caregivers. Adults had an anticipated length of stay of 3 or more days. In pediatric ICUs, we also required support or intended support with mechanical ventilation for greater than 24 hours or with a vasoactive infusion. We recorded all instances in which eProtocol-insulin instructions were not accepted and all blood glucose values. An independent data safety and monitoring board monitored study results and subject safety. Bedside nurses were selected randomly to complete a paper survey describing their perceptions of quality of care and workload related to eProtocol-insulin use.

Results: Clinicians accepted 93% of eProtocol-insulin instructions (11,773/12,645) in 100 adult and 48 pediatric subjects. Forty-eight percent of glucose values were in the target range. Both of these results met a priori-defined efficacy thresholds. Only 0.18% of glucose values were < or =40 mg/dl. This is lower than values reported in prior IIT studies. Although nurses reported eProtocol-insulin required as much work as managing a mechanical ventilator, most nurses felt eProtocol-insulin had a low impact on their ability to complete non-IIT nursing activities.

Conclusions: A multicenter validation demonstrated that eProtocol-insulin is a valid, exportable tool that can assist clinicians in achieving control of glucose in critically ill adults and children.

Keywords: computerized decision support; critical care; glucose control; intensive insulin therapy.

Figure 1.

eProtocol-insulin screen. Single screen displayed to the bedside intensive care unit clinician (usually a nurse). The clinician enters patient-specific data [current blood glucose measurement (mg/dl or mmol/liter) and whether the patient is receiving at least 50% of predicted caloric intake]. eProtocol-insulin generates a patient-specific recommendation with a white background that turns gray when the clinician checks the “Accept” box, at which time the recommended insulin infusion rate is automatically entered in the “Insulin drip” box [Units/kg/h for children (as shown) and Units/h for adults]. A large countdown timer starts and indicates the time remaining until the next eProtocol-insulin mandated blood glucose measurement (1 hour, 56 minutes, and 0 second in the illustration). Past data are listed in the table on the bottom of the display (only the first two lines of the table are shown for clarity).

Figure 2.

Distributions of on-study blood glucose values (a) and insulin doses (b) are shown for adult and pediatric patients. Use of eProtocol-insulin resulted in a similar distribution of blood glucose, although the distribution of insulin infusion rates (normalized to body weight) differed between adults and children.

Figure 3.

The range of intravenous insulin infusion rates (in units of insulin per hour) over 9 hours for 12 protocols is shown in gray. The patient was managed by the Van den Berghe protocol (dashed line). Wilson and colleagues then plotted the starting insulin dose and subsequent dose adjustments for a dozen published protocols to demonstrate the wide variability in insulin dosing recommendations. eProtocol-insulin values are plotted using a solid line for a 70-kg adult (initial infusion rate for a blood glucose of 459 mg/dl = 5.6 units per hour). Figure modified from Wilson et al.