Blue Ribbon Abstract Award: Aggressive Glycemic Control To Improve Outcomes in Cardiac Bypass Surgery Patients

ISSUE: Post-operative hyperglycemia is a risk factor for deep sternal surgical site infection (DS-SSI) following cardiac bypass (CB) surgery. We identified a DS-SSI rate of 4.3% (8/185) within a one year period. A medical record review of the infected patients supported poor blood glucose (BG) control as a risk factor; Mean BG was 150 mg/dl. PROJECT: Multiple glucose control protocols were examined, none deemed sufficient to attain tight glucose control. An interdisciplinary team developed an automated expert system to improve glycemic control in CB Surgery patients using a narrow target range (80-110). The protocol combines a basal insulin drip with insulin boluses, deploying a sophisticated algorithm to determine appropriate therapy based on current and previous BG level and insulin delivery rate, without immediate physician oversight. The RN-driven computer interface supplies the nurse with directions for insulin therapy that can be immediately implemented resulting in therapy that is both aggressive (38u/hr in one case) and dynamic. All BG levels for up to 5 days were collected on a cohort of CB surgery patients for 6 months pre-intervention and on all patients placed on protocol within the subsequent 15 months to determine protocol effectiveness. Medical records of all CB patients were retrospectively reviewed for 12 months pre-intervention and all protocol patients within the subsequent 15 months to evaluate length of stay, mortality, and SSI data. Costs were calculated based on a mean bed day of care (BDOC) cost. RESULTS: The number of diabetic patients in both groups was similar [38.9% (72/185); 40.7% (72/177)]. The BS target range is 80-110 and despite aggressive therapy only 7.9% (14/177) BG fell to <70 mg/dl, 1.7% (3/177) <50 mg/dl and none <40 mg/dl. The DS-SSI rate decreased from 4.3% (8/185) pre-intervention to 1.1% (2/177) post. The post-operative mortality rate at ≤90 days fell from 6.0% (11/183) to 2.3% (4/177). Surgical interventions for treatment of DS-SSI decreased 50%, from 18 to 9. Mean LOS decreased from 13.2 days to 11.2. Based on the mean BDOC cost, we estimate a cost savings of $1,965,898.00 during the post-intervention period. LESSONS LEARNED: Tight glycemic control improves outcomes in CB surgery patients. It is feasible to use an aggressive approach to maintaining euglycemia with minimal physician oversight, when it is standardized, without compromising patient safety.