We conducted the study in an 18-bed medical/surgical ICU in a teaching hospital (Onze Lieve Vrouwe Gasthuis Hospital, Amsterdam, the Netherlands). This unit admits approximately 1,900 patients annually; approximately 1,100 of these patients had recent cardiothoracic surgery. The medical staff has sole direct supervisory responsibility for patients admitted to the unit. This staff includes five permanent intensivists and six intensive care fellows (who work for as long as two years in the unit). A physician is always present on the unit. The nursing staff consists of 93 nurses working in eight-hour shifts. The patient-to-nurse ratio is normally 1:2 but varies with the severity of the patient's illness.
The hospital unit achieved full CIS implementation on April 1, 2001. The staff uses the CIS to complete all patient charting and documentation, such that no information has paper as its primary storage mechanism. The system is connected to the bedside monitor (Siemens SC8000; Siemens-Elema, Solna, Sweden), the ventilator (Siemens Servo 300, Dräger Evita II, Dräger Evita IV; Dräger, Lübeck, Germany), the medication pumps (P1000; Alaris Medical, San Diego, CA), and the Hospital Information System (HIS). Each bed is equipped with a CIS workstation. Every patient room (containing two beds) has an additional CIS workstation. The central desk and the physicians' room also contain workstations.
Prior to the study, health care workers performed glucose regulation ad hoc; “acceptable” glucose levels were between 10 and 12 mmol/L. The compelling and growing body of evidence in the literature regarding the adverse effects of this practice made it imperative to develop a guideline for strictly regulating patient glucose levels. We analyzed existing guidelines, consensus methods, and published evidence to develop the guideline. The guideline recommends the timing between glucose measurements and the administration of insulin doses. The guideline does so uniformly in both diabetic and nondiabetic patients. Guideline activation occurs for any patient with an expected length of stay (LOS) longer than 24 hours and for all patients with a preexisting diagnosis of diabetes mellitus. Exclusion (or deactivation) criteria for guideline usage included induced hypothermia, administration of glucose-insulin-potassium infusions, and normal eating. The guideline could be reactivated when exclusion criteria no longer applied. The nursing staff has responsibility for executing the guideline. Further details on the guideline and its development are beyond the scope of this article ( shows the first page of the guideline).
Sample guideline segment (page 1 of 4).
To prevent disparities caused by different glucose measuring methods (laboratory versus handheld devices, whole blood sampling versus plasma sampling), clinical staff performed all measurements with the Accu-check, a handheld glucose measurement device. The laboratory computer interface conveys Accu-check results to the CIS. Consequently, the CIS can display and process all values directly after their measurement with a maximum delay, introduced by the interface, of 1 minute. The Institutional Ethics Committee reviewed the study protocol. The committee waived requirements for informed consent because the study involved different methods of introducing the same guideline for the same treatment in all study groups.
The study included three distinct periods with an off-on-off design. The design allows for estimation of bias through crossover and learning effects. After extensive training and the initial introduction of the guideline, there was a two-week prestudy period (with no data collection). During this period, researchers fine-tuned the guideline, and staff continued to familiarize themselves with the new guideline. The actual first study period then lasted six weeks and involved continued use of the paper-based guideline (paper implementation group [group A]). A ten-week second study period followed during which patients were randomly assigned to either the computerized- or the paper-based version of the guideline (computerized [B1] and control [B2] groups, respectively). During the third and final four-week study period, treatment reverted to paper-based guideline utilization (postintervention group [group C]). Additionally, we collected data over an eight-week period directly prior to the guideline introduction. These data provided baseline characteristics for the level of glucose measurements (preimplementation period [group R]). The duration of the third (postintervention) study period was limited because the study was performed as part of a master's thesis project.
During the second study (intervention) period, all patients admitted to the ICU were randomly assigned to a study group based on their “internal” patient number. The CIS automatically generates the number, which is not visible to the user. Researchers did not reveal the randomization method to the staff. Only after a patient was admitted to the CIS would the study group (paper-based vs. computerized guideline utilization) be displayed. Authors only used data from those patients and periods when the guideline was activated for study analyses (see activation and exclusion criteria in the Setting section).
During the second study period, clinicians treating patients randomized to the computerized group (B1) received guideline-based advice via the CIS decision support software module (Event Manager) and a custom-made Visual Basic application integrated within the CIS. The application displayed glucose and insulin data and suggested current treatment and the interval to the next glucose measurement (). During this study period, for the intervention group (B1) the Event Manager continuously ensured that guideline activation occurred for eligible patients (based on physiological data within the system). These data included LOS, ventilation status, and body temperature (LOS was monitored because this was the main inclusion criterion; other exclusion criteria were ventilation status to exclude that patients were eating and body temperature to exclude hypothermia). The Event Manager also monitored the time interval between glucose measurements and alerted the staff if a measurement was overdue. Furthermore, the Event Manager checked whether guideline-based insulin infusion rate changes occurred properly. For group B1, each noncompliant event triggered a pop-up window to appear on top of the active CIS screen, alerting clinical staff members. This window appeared on bedside workstations and at any workstation where the patient's record was activated. (). If the staff took no action, the alert would again pop up within a few minutes. For patients in the control group (B2), treatment was based solely on the paper-based version of the guideline, a four-page flowchart that directs the nurse to the relevant guideline advice. No automated support from the CIS was given in any form. A copy of the guideline was available at every workstation and on the unit's Intranet.
Event alerting the staff to the late glucose measurement.
The CIS automatically collected and processed all study data. To do so, the CIS utilized interfaces with the laboratory (as part of the HIS), the vital signs monitor, mechanical ventilator data, and medication infusion pump data.
For the third study period (postintervention) group (C), computerized implementation of the guideline was discontinued, and we blocked end-user access to computer-based guideline-related data. Clinical staff treated all patients in this group using the paper guideline in a manner similar to that of the first study period.
Data Collection and Analysis
After the third study period, an automated script retrieved all relevant data from the MetaVision database. To determine adherence to the time (of glucose measurement) advice of the guideline, we verified the time at which a sample was taken, calculated the guideline-recommended time interval to the next measurement, and then compared this interval with the actual time interval.
The recommended interval between measurements could range from 15 to 180 minutes depending on the patient's measured glucose level and its rate of change since the last measurement. Therefore, the study calculated the deviation between advised and actual measurement times as the percentage and minutes of elapsed time between measurements compared with the advice. A deviation of 5% was allowed, with a minimum of 2 minutes, before a measurement was considered to be taken too early or too late. We determined adherence to the advised insulin infusion rate by retrieving the actual insulin infusion rates along with the rate recommended by the guideline.
To assess the guideline's impact on glucose regulation, we calculated the amount of time that patients' glucose levels fell within predefined ranges using the trapezoidal rule, assuming a linear progression between two measurements.22
Based on clinical relevance, we chose to measure the amount of time glucose measurements fell within the target range and not the number of measurements (data points) that fell within the target range. The time between measurements differed significantly (as determined by the guideline). The recommended time between measurements in the lowest glucose range (hypoglycemia) was 15 minutes; in the normal and high ranges, it was two or three hours. The guideline calls for oversampling when lower glucose values occur (for patient safety because hypoglycemia is potentially harmful), so that any analysis of “glucose control” based on data points being weighted equally (independent of timing) would skew the results because more low than normal or high values would be obtained per protocol.
We used Student's t-test, nonparametric tests, and analysis of proportions and their differences. Because the data for the glucose measurements were not normally distributed, we performed log transformation before statistical analysis. Results include 95% confidence intervals (CIs) for the values.