Pharmacy Management of Postoperative Blood Glucose in Open Heart Surgery Patients: Evaluation of an Intravenous to Subcutaneous Insulin Protocol

Insulin resistance and elevated blood glucose (BG) levels are commonly seen in hospitalized patients irrespective of a history of diabetes mellitus (DM).1 These issues arise in almost all critically ill patients, especially those who have undergone open heart surgery (OHS), coronary artery bypass graft (CABG), and/or valve replacement (VR). Hyperglycemia and insulin resistance increase morbidity, specifically the incidence of sternal wound infections, and mortality.1–3 Hyperglycemia and increased insulin resistance may be due to many factors, but they are highly associated with the release of inflammatory substances, such as cytokines, and stress hormones, such as cortisol.4 To help reduce morbidity and mortality, guidelines and recommendations regarding BG goals have been put forth by the Society of Thoracic Surgeons (STS) and the Surgical Care Improvement Project (SCIP). Though these guidelines and recommendations have similar objectives, their BG goals differ slightly. The STS recommends maintaining BG levels <180 mg/dL throughout the entire hospitalization (pre, peri, and post operative), whereas SCIP focuses on meeting a BG goal of <200 mg/dL at 6:00 a.m. on postoperative day (POD) 1 and 2.1,5 At St. Elizabeth’s Hospital (SEH), a 500-bed facility located in Belleville, Illinois, an increase in sternal wound infections was seen within the OHS patient population during the spring months of 2010 compared to previous months. After an analysis of other factors affecting infection rates such as preoperative antibiotic administration, surgeon, surgical technicians, and operating rooms showed no association with the increase in sternal wound infections, pharmacy was consulted to evaluate postoperative BG control. An initial pilot study of 7 patients was conducted in June 2010 to evaluate current BG control throughout the identified patients’ entire stay. The data collected showed that patients post OHS were meeting the POD 1 goal of <200 mg/dL, but in many cases they were not meeting the POD 2 goal (43%). Additionally, the data collected from this small sample identified conversion from intravenous (IV) to subcutaneous (SC) insulin as a major area needing improvement. To help meet SCIP measures and potentially reduce the incidence of sternal wound infections, the pharmacy implemented a new IV to SC insulin protocol.