Objective: To describe the main findings of the Portland Diabetic Project, which elucidates the adverse relationship between hyperglycemia and outcomes of cardiac surgical procedures in patients with diabetes and delineates the protective effects of intravenous insulin therapy in reducing those adverse outcomes.
Results: In this ongoing 17-year prospective, nonrandomized, interventional study of 4,864 patients with diabetes who underwent an open-heart surgical procedure, we investigated the effects of hyperglycemia, and its subsequent reduction by continuous intravenous insulin (CII) therapy, on in-hospital outcomes. Increasing blood glucose levels were found to be directly associated with increasing rates of death, deep sternal wound infections (DSWI), length of hospital stay (LOS), and hospital cost. In separate multivariate analyses, increasing hyperglycemia was found to be independently predictive of increasing mortality (P<0.0001), DSWI (P = 0.017), and LOS (P<0.002). Conversely, CII therapy, designed to achieve predetermined target blood glucose levels, independently reduced the risks of death and DSWI by 57% and 66%, respectively (P<0.0001 for both). Target blood glucose levels of less than 150 mg/dL and a 3-day postoperative duration of CII therapy are both important variables that determine the effect of the CII therapy on improved outcomes. Coronary artery bypass grafting-related mortality (2.5%) and DSWI rates (0.8%) in patients with diabetes were normalized to those of the nondiabetic population by the use of the Portland CII Protocol.
Conclusion: Perioperative hyperglycemia in patients undergoing a cardiac surgical procedure affects biochemical and physiologic functions, which, in turn, adversely alter mortality, LOS, and infection rates. The Portland CII Protocol is a cost-efficient method that effectively eliminates hyperglycemia and reduces postoperative morbidity and mortality in patients with diabetes undergoing an open-heart operation. CII protocols should be the standard care for glycometabolic control in all patients undergoing cardiac surgical procedures.