Evidence from randomized controlled trials and historical series convincingly demonstrates that tight glycemic control in the critical care setting reduces mortality, length of hospital stay, and other morbidities.1-6 Several protocols targeting a range of glucoses have been published.7-10 We modified a protocol used at the University of Washington (Seattle) that targeted glucoses of 80-180 mg/dl to aim for a tighter glycemic goal range of 80-110 mg/dl and effectively lowered blood glucoses in our intensive care unit (ICU) with a low rate of hypoglycemia.9 We share here our protocol and results over the past year.
Methods
Column protocols have the advantage of accommodating rates of insulin infusion adjustment to the individual patient’s degree of insulin resistance. If glucoses are not falling appropriately using one column, a protocol is followed to move to a more aggressive column. If glucoses fall precipitously, a similar process guides the nurse to a less aggressive column. The column format avoids the need for nurses to do calculations, which reduces the possibility of error.
Figure 1. ICU percent glucose readings. Jan. 2005-Aug. 2006.
In August 2005, in our ICU, we piloted a four-column protocol used at the University of Washington. This protocol was designed with an initial target glucose range of 80-180 mg/dl, and during our pilot it did not work well because we were targeting a glucose range of 80-110 mg/dl. Our ICU nursing staff at Southwest Washington Medical Center (SWMC), Vancouver, preferred to revise the column format rather than switch to a different type of protocol such as the Portland Protocol. We therefore created a new six-column protocol targeting the 80-110 mg/dl glucose range. (See Figure 1, above.)
In creating this protocol, we reviewed infusion rates in an unpublished Oregon Health and Sciences University (OHSU), Portland, six-column protocol and the Georgia Hospital Association, Marietta, 10-column protocol.11,12 Our current version includes new glucose ranges of 70-89 mg/dl, 90-99 mg/dl, and 100-109 mg/dl to allow for more rate adjustments within the overall target range, while our previous version had only one glucose category of 70-109 mg/dl within the target range.
Figure 2. CCU percent glucose readings. Jan. 2005-Aug. 2006.
Nursing feedback also led us to modify criteria for moving to the right (more aggressive) column as follows: If blood glucose is lower than 200, algorithm failure is defined as glucose outside of goal range and not decreased since previous reading; if blood glucose is greater than or equal to 200, algorithm failure is defined as glucose outside of goal range and has not decreased by at least 60 mg/dl within one hour. The longest interval we allow between glucometer checks for stable patients is two hours. Automatic triggers for implementing the protocol include two consecutive glucoses over 140 mg/dl or a single glucose over 180 mg/dl.
Our revised protocol succeeded when we intensified nursing education, solicited frequent nursing feedback, and organized the procedure so that ICU nurse managers drove the process with a responsive physician/pharmacist team.
Figure 3. CCU percent glucose readings. Jan. 2005-Aug. 2006.
Results
In March 2006 we instituted the revised six-column insulin infusion protocol in our ICU. The percent of glucometer readings in the ICU between 70-150 mg/dl increased from 58% in February 2006 to 78% in August of 2006. (See Figure 2, above.) In our cardiac care unit (CCU), where an older, non-column insulin infusion protocol continued to be used, glucoses went from 50% in the 70-150 mg/dl range in February 2006 to 61% in that range in July 2006. When we began the six-column ICU insulin infusion protocol in the CCU in August 2006, 66% of glucoses were in the 70-150 range. (See Figure 3, p. 43.)