Introduction
The term stress hyperglycemia describes transient increases in blood sugar in patients without a history of diabetes mellitus (DM) that occur during acute illness or stress. Hyperglycemia seen in cardiac surgery patients is important in terms of its severity and its relationship with postoperative complications.1-3 Intraoperative hyperglycemia has been associated with increased morbidity in diabetic patients.4 Mortality has also increased in diabetic and non-diabetic hyperglycemic patients who underwent cardiac surgery with cardiopulmonary bypass (CPB).5 Approximately 30% of patients undergoing cardiac surgery have a history of DM and approximately 60-80% of patients without DM have stress hyperglycemia, which is defined as blood glucose value above 140 mg / dL.6-8 It is thought that certain disorders in glucose metabolism such as increased levels of insulin resistance, cortisol, adrenocorticotropic hormone (ACTH), growth hormone (GH), epinephrine and norepinephrine during cardiac surgery and CPB in patients with and without DM contribute to hyperglycemia.9
The key determinants to maintain of tissue perfusion and cellular integrity are adequacy of macrocirculation and delivery of oxygen at values exceeding the current rate of consumption.10Oxygen extraction rate (O2ER) is the ratio of the body’s oxygen consumption (VO2) to systemic oxygen delivery (VO2 / DO2), which is a practical way to describe the adequacy of systemic oxygen delivery.11
To our knowledge, there are no previous studies focusing on tissue perfusion-related outcomes with the degree of hyperglycemia that may occur in cardiac surgery patients with and without a history of DM. We hypothesized that stress hyperglycemia may be correlated (or associated) with reduced tissue perfusion during cardiac surgery, therefore, we closely examined a series of consecutive cases undergoing cardiac surgery to determine the presence of stress hyperglycemia and its relationship to tissue perfusion. Primary outcome measures were associated with stress hyperglycemia and tissue perfusion parameters in non-diabetic patients undergoing cardiac surgery and patients with non-insulin-dependent diabetes mellitus (NIDDM). Data may be relevant for tailored intervention and proper management.