Insulin resistance plays a potential role in postoperative cognitive dysfunction in patients following cardiac valve surgery

Severe insulin resistance (IR) promotes the development of Alzheimer disease. IR and postoperative cognitive dysfunction (POCD) are a common complication during the cardiac perioperative period. The authors hypothesized that IR of individuals with cardiac valve surgery would have increased the risk of POCD. The purpose of the study was to analyze the association of IR and POCD after cardiac valve surgery. Total 131 patients who underwent valve replacement via cardiopulmonary bypass (CPB) were included. Cognitive function was assessed by a series of neuropsychological measurements at 1 day before and 7 days after the surgery. 40 healthy volunteers as the control group also completed the neuropsychological assessment at the same time point. POCD was identified using the “Z score” method. Fasting blood glucose and insulin levels were detected before anesthesia and at 6 h and 7 days post-operation. Additionally serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) were measured at 6 h post-operation. The insulin resistance index was calculated by “homeostasis model assessment 2” (HOMA2) software. The relationship between IR and POCD or TNF-α, IL-6 was then analyzed. At 7 days after surgery, the incidence of POCD was 43.8%. The levels of HOMA2-IR in patients with POCD were significantly higher than those of patients without POCD at 6 h and 7 days after operation (P < 0.05).The levels of serum IL-6 and TNF- α were positively correlated with HOMA2-IR value at 6 h after operation (RIL-6 = 0.426, P < 0.01; RTNF-a = 0.381, P < 0.01). POCD was correlated with the patients' education age (OR = 1.062), CPB time (OR = 1.018), self-rating depression scale (SDS) score after operation (OR = 1.082), HOMA2-IR at 6 h (OR = 1.110) and 7 days (OR = 13.762) after operation, IL-6 (OR = 1.036) and TNF-α (OR = 1.039) at 6 h after operation. Our study suggests that IR is correlated with the incidence of POCD and the increase of inflammatory factors.