Does the Rectus Sheath Block Analgesia Reduce the Inflammatory Response Biomarkers' IL-1ra, IL-6, IL-8, IL-10 and IL-1β Concentrations Following Surgery? A Randomized Clinical Trial of Patients with Cancer and Benign Disease

Aim: To evaluate whether the post-surgery placement of the rectus sheath block analgesia (RSB) reduces the inflammatory response following surgery. The main hypothesis of our study was to find any correlation between patients' pain experience, numeric rating scale (NRS) postoperatively and concentrations of inflammatory response biomarkers, such as interleukin-1 receptor antagonist (IL-1ra), IL-6, IL-8, IL-10, IL-1 beta, in patients with benign disease and cancer. Patients and Methods: Initially, 46 patients with midline laparotomy were randomized to the placebo group (n=11) and to one of the three active groups; single-dose (n=12), repeated-dose (n=12) and continuous infusion (n=11) RSB analgesia groups. Plasma concentrations of high-sensitivity C-reactive protein (hs-CRP) and five interleukins (IL-1ra, IL-6, IL-8, IL-10, IL-1 beta) were measured at three time points; just before, immediately after and 24 h after operation. The primary end-point was to compare plasma concentrations of the hs-CRP and five interleukins in the placebo group and in the three different RSB analgesia groups in patients with benign disease and cancer. Results: The placebo group and three active groups were similar in terms of demographic variables and perioperative data. Of the anti-inflammatory cytokines, patients in the continuous infusion group had significantly higher IL-10 median values postoperatively than the three other study groups (p=0.029). In addition, patients in the three active groups combined had significantly higher IL-10 median values immediately after operation than the placebo group (p=0.028; in all patients with benign disease and cancer). There is a significant correlation between the individual values of NRS and IL-10 values postoperatively in the placebo group and the three active groups separately (r=0.40, p=0.03) and also a significant correlation between the individual values of the NRS scale and IL-1 beta values postoperatively in the placebo group and the three active groups separately (r=0.38, p=0.04). Conclusion: Placement of RSB analgesia does not significantly reduce the inflammatory response biomarkers' concentrations in patients with benign disease or cancer patients. A new finding in the present work is a significant correlation in the NRS scale versus plasma concentrations of anti-inflammatory cytokine IL-10 and pro-inflammatory cytokine IL-1 beta postoperatively suggesting that inflammation and pain are related.