Background/Aim: The aim of the study was to compare the MDA (malonidialdehyde) plasma concentrations versus CAT (catalase)/NT (nitrotyrosine) plasma concentrations, patient satisfaction and pain score at rest/pressure to the wound area in laparotomy patients with rectus sheath block (RSB) analgesia. Patients and Methods: Initially, 56 patients were randomized to four groups; control group (n=12), single-dose (n=16), repeated-dose (n=12) and continuous infusion (n=16) RSB analgesia groups. The plasma concentrations of CAT, NT and MDA markers were measured just before, immediately after and 24 h after operation. Results: The RSB analgesia enhanced significantly patient satisfaction (p=0.001). The plasma MDA decreased immediately after operation (POP1) and the postoperative decrease between the preoperative and the POP1 values in the MDA marker were statistically significant (p<0.001). In linear mixed model, the time effect in both the single group and in the benign group in plasma NT biomarker was statistically significant (p=0.001, p=0.013, respectively). The median plasma MDA concentrations (ng/ml) following surgery were significantly lower in patients with cancer versus patients with benign disease (589 vs. 852, p=0.021). Jitterplots of the individual plasma NT versus plasma MDA showed that there was significant correlation in benign and cancer patients (r=0.347, p<0.001). Conclusion: Plasma MDA decreased significantly after operation in all patients and cancer patients had significantly lower MDA concentrations following surgery than patients with benign disease.Reactive oxygen species (ROS) degrade polyunsaturated fatty acids (PUFAs) by lipid peroxidation forming malonidialdehyde (MDA) (1). MDA is one of the many ROS that cause oxidative stress in cells attacking the subcellular structures and forming covalent protein adducts (1). The production and plasma concentration of MDA can be measured and used as a biomarker to estimate the degree of oxidative stress and lipid peroxidation in human disease (2). MDA is a toxic substance reacting with deoxyadenosine in DNA and forming DNA adducts, which are mutagenic (3). A schematic representation of the relationship among the formation of ROS/Reactive nitrogen species (RNS) lipid peroxidation, nitrotyrosine (NT), catalase (CAT) and MDA is shown in five recent reviews (1,(4)(5)(6)(7).Our previous study showed that the control group of patients and the rectus sheath block (RSB) groups did not differ in individual pain scores (numeric rating scales, NRS) following surgery (8, 9). However, it seems that plasma CAT levels correlate NRS pain scores following surgery (10) and NT concentration does significantly correlate satisfaction for analgesia (9). There are seven large reviews in the literature available to compare ROS/RNS in clinical trials that investigated the impact of 253 *These Authors contributed equally to this study.

Background/Aim: Our original hypothesis was that the rectus sheath block (RSB) analgesia could enhance patient satisfaction and decrease pain following midline laparotomy. Patients and Methods: Initially, 56 patients were randomized into four groups; control group (n=12), single-dose (n=16), repeated-dose (n=12) and continuous infusion (n=16) RSB analgesia groups. The BPI (Brief Pain Inventory) survey was conducted preoperatively and at one and four weeks and 12 months postoperatively. The patients pain 24 h postoperatively and satisfaction 48 h postoperatively was filled on an 11-point numeric rating scale (NRS). Results: The repeated-dose group had lower BPI severity score (p=0.045) and BPI interference score (p=0.043) mean values postoperatively compared to the three other groups separately. Also, the time effect on the linear mixed model in BPI interference score mean values was statistically significant (p=0.008), which means that in the repeated dose group preoperative BPI severity score [2.7 (3.9)] and interference score [4.3 (4.2)] mean (SD) values were significantly higher than the BPI severity score [1.3 (0.8)] and interference score [1.5 (1.8)] mean (SD) values following surgery. Conclusion: The higher elevation in BPI severity score and decrease in interference score values in the repeated dose group and also the time effect in a linear mixed model in BPI interference score were statistically significant.

Background/Aim: The simultaneous increase of antioxidant CAT (catalase) enzyme and plasma MDA (malonidialdehyde) concentrations versus the numeric rating scale (NRS) pain score following surgery is unknown. Patients and Methods: The study included 114 patients with gallstone disease and 29 patients in the cancer group. Results: Following surgery, the plasma CAT concentrations increased and plasma MDA concentrations decreased in all patients and especially in cancer patients. The linear mixed model time-effect was statistically significant in CAT and MDA (p<0.001 and p=0.02, respectively). In addition, a significant correlation between NRS pain score values and plasma MDA median concentrations in cancer patients was identified (r=0.430, p<0.001). Conclusion: The plasma MDA concentrations decreased and CAT concentrations increased significantly in all patients and especially in cancer patients following surgery. The simultaneous increase of antioxidant CAT enzyme with the decrease of plasma MDA may be an important ROS inhibiting mechanism to help patients return to normal antioxidant-oxidant status. Lipid peroxidation is a process where reactive oxygen species (ROS) attack lipids containing carbon double bonds (C-C), 5701 This article is freely accessible online.