High postoperative blood levels of macrophage migration inhibitory factor are associated with less organ dysfunction in patients after cardiac surgery

Abstract

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that exerts protective effects during myocardial ischemia/reperfusion injury. We hypothesized that elevated MIF levels in the early postoperative time course might be inversely associated with postoperative organ dysfunction as assessed by the simplified acute physiology score (SAPS) II and sequential organ failure assessment (SOFA) score in patients after cardiac surgery. A total of 52 cardiac surgical patients (mean age [± SD] 67 ± 10 years; EuroScore: 7) were enrolled in this monocenter, prospective observational study. Serum levels of MIF and clinical data were obtained after induction of anesthesia, at admission to the intensive care unit (ICU), 4 h after admission and at the first and second postoperative day. To characterize the magnitude of MIF release, we compared blood levels of samples from cardiac surgical patients with those obtained from healthy volunteers. We assessed patient outcomes using the SAPS II at postoperative d 1 and SOFA score for the first 3 d of the eventual ICU stay. Compared to healthy volunteers, patients had already exhibited elevated MIF levels prior to surgery (64 ± 50 versus 13 ± 17 ng/mL; p < 0.05). At admission to the ICU, MIF levels reached peak values (107 ± 95 ng/mL; p < 0.01 versus baseline) that decreased throughout the observation period and had already reached preoperative values 4 h later. Postoperative MIF values were inversely correlated with SAPS II and SOFA scores during the early postoperative stay. Moreover, MIF values on postoperative d 1 were related to the calculated cardiac power index (r = 0.420, p < 0.05). Elevated postoperative MIF levels are inversely correlated with organ dysfunction in patients after cardiac surgery.

Figure 1

Flowchart according to the STROBE-recommendations (41). From the initially included 55 patients, 3 were excluded from further analysis because of an intraoperative switch of the surgical technique.

Figure 2

(A) Perioperative time course of serum MIF levels in cardiac surgical patients (n = 52 until first POD). The dashed line indicates the mean value of MIF as obtained in a healthy control group. (B) Comparison of perioperative time course of serum MIF values between male (n = 35) and female (n = 17) patients. (C) Comparison of perioperative time course of serum MIF values between young (age 46 ± 8 years; n = 12) and old patients (age 71 ± 6 years; n = 40). Data are presented as mean ± SEM. *p < 0.05, **p < 0.01 versus baseline.

Figure 3

Correlations of MIF_AUC with SAPS II score on the first POD. Data are depicted as linear regression (black line) with 95% confidence intervals (long dashed line).

Figure 4

Correlation between MIF values and cardiac power index on the first POD. Insertion of the pulmonary artery catheter was performed intraoperatively as deemed necessary by the attending physician. In these patients (n = 14), the CPI was calculated after induction of anesthesia, after admission to the ICU and at the morning of the first POD with the following formula: CPI = mean arterial pressure × cardiac index/451 (W/m²) (23). Data are depicted as linear regression (black line) with 95% confidence interval (long dashed line).

Figure 5

Perioperative release of myocardial specific troponin T. **p < 0.05 versus baseline.