Perioperative Oxidative Stress: The Unseen Enemy

Oxygenation during general anesthesia in pediatric patients: A retrospective observational study

STUDY OBJECTIVE

Protocols are used in intensive care and emergency settings to limit the use of oxygen. However, in pediatric anesthesiology, such protocols do not exist. This study aimed to investigate the administration of oxygen during pediatric general anesthesia and related these values to PaO2, SpO2 and SaO2.

DESIGN

Retrospective observational study.

SETTING

Tertiary pediatric academic hospital, from June 2017 to August 2020.

PATIENTS

Patients aged 0-18 years who underwent general anesthesia for a diagnostic or surgical procedure with tracheal intubation and an arterial catheter for regular blood withdrawal were included. Patients on cardiopulmonary bypass or those with missing data were excluded. Electronic charts were reviewed for patient characteristics, type of surgery, arterial blood gas analyses, and oxygenation management.

INTERVENTIONS

No interventions were done.

MEASUREMENTS

Primary outcome defined as FiO2, PaO2 and SpO2 values were interpreted using descriptive analyses, and the correlation between PaO2 and FiO2 was determined using the weighted Spearman correlation coefficient.

MAIN RESULTS

Data of 493 cases were obtained. Of these, 267 were excluded for various reasons. Finally, 226 cases with a total of 645 samples were analyzed. The median FiO2 was 36% (IQR 31 to 43), with a range from 20% to 97%, and the median PaO2 was 23.6 kPa (IQR 18.6 to 28.1); 177 mmHg (IQR 140 to 211). The median SpO2 level was 99% (IQR 98 to 100%). The study showed a moderately positive association between PaO2 and FiO2 (r = 0.52, p < 0.001). 574 of 645 samples (89%) contained a PaO2 higher than 13.3 kPa; 100 mmHg.

CONCLUSIONS

Oxygen administration during general pediatric anesthesia is barely regulated. Hyperoxemia is observed intraoperatively in approximately 90% of cases. Future research should focus on outcomes related to hyperoxemia.

Quantitative Metabolomics and Lipoprotein Analysis of PDAC Patients Suggests Serum Marker Categories for Pancreatic Function, Pancreatectomy, Cancer Metabolism, and Systemic Disturbances

Pancreatic ductal adenocarcinoma (PDAC) is difficult to diagnose in the early stages and lacks reliable biomarkers. The scope of this project was to establish quantitative nuclear magnetic resonance (NMR) spectroscopy to comprehensively study blood serum alterations in PDAC patients. Serum samples from 34 PDAC patients obtained before and after pancreatectomy as well as 83 age- and sex-matched control samples from healthy donors were analyzed with in vitro diagnostics research (IVDr) proton NMR spectroscopy at 600 MHz. Uni- and multivariate statistics were applied to identify significant biofluid alterations. We identified 29 significantly changed metabolites and 98 lipoproteins when comparing serum from healthy controls with those of PDAC patients. The most prominent features were assigned to (i) markers of pancreatic function (e.g., glucose and blood triglycerides), (ii) markers related to surgery (e.g., ketone bodies and blood cholesterols), (iii) PDAC-associated markers (e.g., amino acids and creatine), and (iv) markers for systemic disturbances in PDAC (e.g., gut metabolites DMG, TMAO, DMSO2, and liver lipoproteins). Quantitative serum NMR spectroscopy is suited as a diagnostic tool to investigate PDAC. Remarkably, 2-hydroxybutyrate (2-HB) as a previously suggested marker for insulin resistance was found in extraordinarily high levels only after pancreatectomy, suggesting this metabolite is the strongest marker for pancreatic loss of function.

OXIDATIVE study: A pilot prospective observational cohort study protocol examining the influence of peri-reperfusion hyperoxemia and immune dysregulation on early allograft dysfunction after orthotopic liver transplantation

Early allograft dysfunction (EAD) is a functional hepatic insufficiency within a week of orthotopic liver transplantation (OLT) and is associated with morbidity and mortality. The etiology of EAD is multifactorial and largely driven by ischemia reperfusion injury (IRI), a phenomenon characterized by oxygen scarcity followed by paradoxical oxidative stress and inflammation. With the expanded use of marginal allografts more susceptible to IRI, the incidence of EAD may be increasing. This necessitates an in-depth understanding of the innate molecular mechanisms underlying EAD and interventions to mitigate its impact. Our central hypothesis is peri-reperfusion hyperoxemia and immune dysregulation exacerbate IRI and increase the risk of EAD. We will perform a pilot prospective single-center observational cohort study of 40 patients. The aims are to determine (1) the association between peri-reperfusion hyperoxemia and EAD and (2) whether peri-reperfusion perturbed cytokine, protein, and hypoxia inducible factor-1 alpha (HIF-1α) levels correlate with EAD after OLT. Inclusion criteria include age ≥ 18 years, liver failure, and donation after brain or circulatory death. Exclusion criteria include living donor donation, repeat OLT within a week of transplantation, multiple organ transplantation, and pregnancy. Partial pressure of arterial oxygen (PaO2) as the study measure allows for the examination of oxygen exposure within the confines of existing variability in anesthesiologist-administered fraction of inspired oxygen (FiO2) and the inclusion of patients with intrapulmonary shunting. The Olthoff et al. definition of EAD is the primary outcome. Secondary outcomes include postoperative acute kidney injury, pulmonary and biliary complications, surgical wound dehiscence and infection, and mortality. The goal of this study protocol is to identify EAD contributors that could be targeted to attenuate its impact and improve OLT outcomes. If validated, peri-reperfusion hyperoxemia and immune perturbations could be targeted via FiO2 titration to a goal PaO2 and/or administration of an immunomodulatory agent by the anesthesiologist intraoperatively.

Intraoperative Anesthetic Strategies to Mitigate Early Allograft Dysfunction After Orthotopic Liver Transplantation: A Narrative Review

Orthotopic liver transplantation (OLT) is the most effective treatment for patients with end-stage liver disease (ESLD). Hepatic insufficiency within a week of OLT, termed early allograft dysfunction (EAD), occurs in 20% to 25% of deceased donor OLT recipients and is associated with morbidity and mortality. Primary nonfunction (PNF), the most severe form of EAD, leads to death or retransplantation within 7 days. The etiology of EAD is multifactorial, including donor, recipient, and surgery-related factors, and largely driven by ischemia-reperfusion injury (IRI). IRI is an immunologic phenomenon characterized by dysregulation of cellular oxygen homeostasis and innate immune defenses in the allograft after temporary cessation (ischemia) and later restoration (reperfusion) of oxygen-rich blood flow. The rising global demand for OLT may lead to the use of marginal allografts, which are more susceptible to IRI, and thus lead to an increased incidence of EAD. It is thus imperative the anesthesiologist is knowledgeable about EAD, namely its pathophysiology and intraoperative strategies to mitigate its impact. Intraoperative strategies can be classified by 3 phases, specifically donor allograft procurement, storage, and recipient reperfusion. During procurement, the anesthesiologist can use pharmacologic preconditioning with volatile anesthetics, consider preharvest hyperoxemia, and attenuate the use of norepinephrine as able. The anesthesiologist can advocate for normothermic regional perfusion (NRP) and machine perfusion during allograft storage at their institution. During recipient reperfusion, the anesthesiologist can optimize oxygen exposure, consider adjunct anesthetics with antioxidant-like properties, and administer supplemental magnesium. Unfortunately, there is either mixed, little, or no data to support the routine use of many free radical scavengers. Given the sparse, limited, or at times conflicting evidence supporting some of these strategies, there are ample opportunities for more research to find intraoperative anesthetic strategies to mitigate the impact of EAD and improve postoperative outcomes in OLT recipients.

Protective Effects of Sesamol on Renal Ischemia-Reperfusion Injury Via Regulation of Nuclear Factor Erythroid 2-Related Factor 2 Pathway

BACKGROUND

Sesamol is a natural antioxidant known for its potent antioxidant and free radical scavenging properties. This study aimed to explore the therapeutic effects and underlying mechanisms of sesamol in the development of renal ischemia-reperfusion injury (IRI) in mice.

METHODS

C57BL/6J wild-type mice were divided into 3 groups: IR group, treated with normal saline after undergoing the IRI procedure; Sesamol + IR group, treated with 30 mg/kg/d of sesamol after the IRI procedure; and Sham group, treated with normal saline but not subjected to the IRI process. Renal IRI was induced by performing a right kidney nephrectomy and subjecting the left kidney to 30-minute ischemia, followed by 24-hour reperfusion. Kidney tissues and serum were collected 24 hours post-IRI to assess the impact of sesamol on renal function after IRI. Serum creatinine and blood urea nitrogen levels were assessed, and renal cell apoptosis was detected through terminal deoxynucleotidyl transferase dUTP nick-end labeling staining. The levels of interleukin 1β and interleukin 18 in kidney tissues, as well as indicators of oxidative stress, were also measured. Furthermore, Nrf2-deficient mice were used to examine the protective function of the nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) and NAD(P)H dehydrogenase quinone 1 (NQO1) signaling pathways induced by sesamol, as determined by western blot assay.

RESULTS

Sesamol demonstrated significant improvement in renal function, along with reductions in renal tubular injury, cell necrosis, and apoptosis in mice. It also effectively lowered key inflammatory mediator levels. Sesamol exhibited antioxidant properties by reducing malondialdehyde levels and enhancing superoxide dismutase activities 24 hours after IRI. Western blot assay revealed increased Nrf2, HO-1, and NQO-1 protein levels with sesamol treatment. Notably, Nrf2-deficient mice did not exhibit the beneficial effects of sesamol.

CONCLUSIONS

This study demonstrates that sesamol effectively alleviates renal IRI by enhancing antioxidant defenses and reducing inflammation potentially through the Nrf2/HO-1 and NQO1 signaling pathways.

Innovation and disruptive science determine the future of cardiothoracic surgery

One of the currently most asked questions in the field of medicine is how any specialty in the future will evolve to ensure better health for the patients by using current, unparalleled developments in all areas of science. This article will give an overview of new and evolving strategies for cardiothoracic (CT) surgery that are available today and will become available in the future in order to achieve this goal. In the founding era of CT surgery in the 1950s and 1960s, there was tremendous excitement about innovation and disruptive science, which eventually resulted in a completely new medical specialty, i.e. CT surgery. Entirely new treatment strategies were introduced for many cardiovascular diseases that had been considered incurable until then. As expected, alternative techniques have evolved in all fields of science during the last few decades, allowing great improvements in diagnostics and treatment in all medical specialties. The future of CT surgery will be determined by an unrestricted and unconditional investment in innovation, disruptive science and our own transformation using current achievements from many other fields. From the multitude of current and future possibilities, I will highlight 4 in this review: improvements in our current techniques, bringing CT surgery to low- and middle-income countries, revolutionizing the perioperative period and treating as yet untreatable diseases. These developments will allow us a continuation of the previously unheard-of treatment possibilities provided by ingenious innovations based on the fundamentals of CT surgery.

Perioperative redox changes in patients undergoing hepato-pancreatico-biliary cancer surgery

BACKGROUND

Tissue injury induces inflammation and the surgical stress response, which are thought to be central to the orchestration of recovery or deterioration after surgery. Enhanced formation of reactive oxygen and nitrogen species accompanies the inflammatory response and triggers separate but integrated reduction/oxidation (redox) pathways that lead to oxidative and/or nitrosative stress (ONS). Quantitative information on ONS in the perioperative period is scarce. This single-centre exploratory study investigated the effects of major surgery on ONS and systemic redox status and their potential associations with postoperative morbidity.

METHODS

Blood was collected from 56 patients at baseline, end of surgery (EoS) and the first postoperative day (day-1). Postoperative morbidity was recorded using the Clavien-Dindo classification and further categorised into minor, moderate and severe. Plasma/serum measures included markers of lipid oxidation (thiobarbituric acid-reactive substances; TBARS, 4-hydroxynonenal; 4-HNE, 8-iso-prostaglandin F_2⍺; 8-isoprostanes). Total reducing capacity was measured using total free thiols (TFTs) and ferric-reducing ability of plasma (FRAP). Nitric oxide (NO) formation/metabolism was measured using cyclic guanosine monophosphate (cGMP), nitrite, nitrate and total nitroso-species (RxNO). Interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-⍺) were measured to evaluate inflammation.

RESULTS

Both oxidative stress (TBARS) and nitrosative stress (total nitroso-species) increased from baseline to EoS (+14%, P = 0.003 and +138%, P < 0.001, respectively), along with an increase in overall reducing capacity (+9%, P = 0.03) at EoS and protein-adjusted total free thiols (+12%, P = 0.001) at day-1 after surgery. Nitrite, nitrate and cGMP concentrations declined concomitantly from baseline to day-1. Baseline nitrate was 60% higher in the minor morbidity group compared to severe (P = 0.003). The increase in intraoperative TBARS was greater in severe compared to minor morbidity (P = 0.01). The decline in intraoperative nitrate was more marked in the minor morbidity group compared to severe (P < 0.001), whereas the cGMP decline was greatest in the severe morbidity group (P = 0.006).

CONCLUSION

In patients undergoing major HPB surgery, intraoperative oxidative and nitrosative stress increased, with a concomitant increase in reductive capacity. Baseline nitrate was inversely associated with postoperative morbidity, and the hallmarks of poor postoperative outcome include changes in both oxidative stress and NO metabolism.

Avoiding implant-related complications in medically compromised patients with or without unhealthy lifestyle/Elevated oxidative stress

Increased human life expectancy broadens the alternatives for missing teeth and played a role in the widespread use of dental implants and related augmentation procedures for the aging population. Though, many of these patients may have one or more diseases. These systemic conditions may directly lead to surgical complications, compromise implant/bone healing, or influence long-term peri-implant health and its response to biologic nuisances. Offering patients credible expectations regarding intra- and postoperative complications and therapeutic prognosis is an ethical and legal obligation. Clear identification of potential types of adverse effects, complications, or errors is important for decision-making processes as they may be related to different local, systemic, and technical aspects. Therefore, the present review structures the underlying biological mechanisms, clinical evidence, and clinical recommendations for the most common systemic risk factors for implant-related complications.

Oxidative Stress and Inflammation Biomarkers in Postoperative Pain Modulation in Surgically Treated Patients with Laryngeal Cancer-Pilot Study

(1) Background: Surgical treatment of laryngeal carcinoma includes different types of laryngectomies with neck dissection. Surgical tissue damage triggers an inflammatory response, leading to the release of pro-inflammatory molecules. This increases reactive oxygen species production and decreases antioxidant defense mechanisms, leading to postoperative oxidative stress. The aim of this study was to assess the correlation between oxidative stress (malondialdehyde, MDA; glutathione peroxidase, GPX; superoxide dismutase, SOD) and inflammation (interleukin 1, IL-1; interleukin-6, IL-6; C-reactive protein, CRP) parameters and postoperative pain management in patients surgically treated with laryngeal cancer. (2) Methods: This prospective study included 28 patients with surgically treated laryngeal cancer. Blood samples were taken for the analysis of oxidative stress and inflammation parameters before the operative treatment and after the operative treatment (1st postoperative day and 7th postoperative day). The concentrations of MDA, SOD, GPX, IL-1, IL-6, and CRP in the serum were determined by coated enzyme-linked immunosorbent assay (ELISA). The visual analog scale (VAS) was used for pain assessment. (3) Results and conclusion: There was a correlation between oxidative stress and inflammation biomarkers and postoperative pain modulation in surgically treated patients with laryngeal cancer. Age, more extensive surgery, CRP values, and use of tramadol were predictors for oxidative stress parameters.

Fluro-Protein C-Phycocyanin Docked Silver Nanocomposite Accelerates Cell Migration through NFĸB Signaling Pathway

Currently, there is a great demand for the development of nanomedicine aided wound tissue regeneration via silver doped nanoceuticals. Unfortunately, very little research is being carried out on antioxidants-doped silver nanometals and their interaction on the signaling axis during the bio-interface mechanism. In this study, c-phycocyanin primed silver nano hybrids (AgcPCNP) were prepared and analyzed for properties such as cytotoxicity, metal decay, nanoconjugate stability, size expansion, and antioxidant features. Fluctuations in the expression of marker genes during cell migration phenomena in in vitro wound healing scenarios were also validated. Studies revealed that physiologically relevant ionic solutions did not exhibit any adverse effects on the nanoconjugate stability. However, acidic, alkali, and ethanol solutions completely denatured the AgcPCNP conjugates. Signal transduction RT²PCR array demonstrated that genes associated with NFĸB- and PI3K-pathways were significantly (p < 0.5%) altered between AgcPCNP and AgNP groups. Specific inhibitors of NFĸB (Nfi) and PI3K (LY294002) pathways confirmed the involvement of NFĸB signaling axes. In vitro wound healing assay demonstrated that NFĸB pathway plays a prime role in the fibroblast cell migration. In conclusion, the present investigation revealed that surface functionalized AgcPCNP accelerated the fibroblast cell migration and can be further explored for wound healing biomedical applications.

Effect of Supplemental Oxygen on von Willebrand Factor Activity and Ristocetin Cofactor Activity in Patients at Risk for Cardiovascular Complications Undergoing Moderate-to High-Risk Major Noncardiac Surgery-A Secondary Analysis of a Randomized Trial

Increased von Willebrand Factor (vWF) activity mediates platelet adhesion and might be a contributor to the development of thrombotic complications after surgery. Although in vitro studies have shown that hyperoxia induces endovascular damage, the effect of perioperative supplemental oxygen as a possible trigger for increased vWF activity has not been investigated yet. We tested our primary hypothesis that the perioperative administration of 80% oxygen concentration increases postoperative vWF activity as compared to 30% oxygen concentration in patients at risk of cardiovascular complications undergoing major noncardiac surgery. A total of 260 patients were randomly assigned to receive 80% versus 30% oxygen throughout surgery and for two hours postoperatively. We assessed vWF activity and Ristocetin cofactor activity in all patients shortly before the induction of anesthesia, within two hours after surgery and on the first and third postoperative day. Patient characteristics were similar in both groups. We found no significant difference in vWF activity in the overall perioperative time course between both randomization groups. We observed significantly increased vWF activity in the overall study population throughout the postoperative time course. Perioperative supplemental oxygen showed no significant effect on postoperative vWF and Ristocetin cofactor activity in cardiac risk patients undergoing major noncardiac surgery. In conclusion, we found no significant influence of supplemental oxygen in patients undergoing major non-cardiac surgery on postoperative vWF activity and Ristocetin cofactor activity.

β-Carotene Protects Mice against Lipopolysaccharide and D-Galactosamine Induced Acute Liver Injury via Regulation of NF-κB, MAPK, and Nrf2 Signaling

Acute liver injury (ALI), posing a serious threaten to our life, has emerged as a public health issue around the world. β-carotene has plenty of pharmacologic effects, such as anti-inflammatory, antioxidant, and antitumor activities. In this study, we focused on studying the protective role and potential molecular mechanisms of β-carotene against D-galactosamine (D-GalN) and lipopolysaccharide (LPS) induced ALI. Our results indicated that β-carotene pretreatment effectively hindered abnormal changes induced by LPS/D-GalN in liver histopathology. Meanwhile, serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were downgraded with β-carotene pretreatment. β-carotene pretreatment also decreased malondialdehyde content and myeloperoxidase activity, increased glutathione peroxidase and superoxide dismutase levels, and reduced the levels of tumor necrosis factor-a (TNF-α) and interleukin 6 (IL-6) in liver tissues. Further investigations found that β-carotene mediated multiple signaling pathways in LPS/D-GalN-induced ALI, inhibiting NF-κB and MAPK signaling and upregulating the expression of Nrf2 and HO-1 proteins. All findings indicate that β-carotene appears to protect mice against LPS/D-GalN induced ALI by reducing oxidative stress and inflammation, possibly via regulating NF-κB, MAPK, and Nrf2 signaling.

Study on the protective mechanism of dexmedetomidine on the liver of perioperative diabetic patients: A randomized controlled trial

BACKGROUND

Although several studies have reported that dexmedetomidine is a highly selective α2-adrenergic receptor agonist that protects liver function in perioperative patients by inhibiting oxidative stress (OS) and inflammatory response, patients with type 2 diabetes mellitus (T2DM) have not been included in the previous studies. The purpose of this study was to investigate the effects of perioperative low-dose dexmedetomidine on perioperative liver function in T2DM patients.

METHODS

This was a single-center, placebo-controlled randomized trial. Fifty-four T2DM patients scheduled for debridement of lower extremity ulcers were included in this study and randomly divided into 2 groups (n = 27 per group): the dexmedetomidine group (DEX group) and the control group (CON group). Continuous intravenous infusion of dexmedetomidine (DEX group) or normal saline (CON group) was administered from the completion of monitoring to the end of surgery. All participants received femoral and sciatic nerve block with 0.33% ropivacaine. The main result was the activity of liver enzymes (AST, ALT) reflecting liver function. The secondary results included variables reflecting blood glucose (Glu), blood lipids (TG, HDL, LDL, total cholesterol), biomarkers of OS (MDA, SOD), and systemic inflammatory response (TNF-α, IL-6).

RESULTS

Compared with CON group, DEX group exhibited a reduction in hemodynamic parameters, Glu, systemic inflammatory response, and liver injury indicators. OS response MDA activity was lower in DEX group than in CON group, while SOD was higher than that in CON group. The variables reflecting lipid metabolism function showed no differences between the groups.

CONCLUSION SUBSECTIONS

Dexmedetomidine administered perioperatively can reduce Glu levels and protect the liver by attenuating OS injury and inflammatory response in T2DM patients without any potential risk.

The Janus-faced role of TRPM2-S in retroperitoneal liposarcoma via increasing ROS levels

BACKGROUND

Retroperitoneal liposarcoma (RPLS) is a specific soft tissue sarcoma with a high recurrence rate. The short isoform of transient receptor potential cation channel subfamily M member 2 (TRPM2-S) plays an important role in the regulation of reactive oxygen species (ROS). However, the association between TRPM2-S and RPLS and its underlying mechanisms remains unclear.

METHODS

The expression of both TRPM2-S and TRPM2-L in RPLS tissues was verified by kimmunohistochemistry (IHC). The regulation on Ca²⁺ influx by TRPM2-S was evaluated by Fluo-4 AM staining. The effect of TRPM2-S on cell proliferation and apoptosis was tested by 5-Ethynyl-2'-deoxyuridine (EdU) staining and Flow cytometry respectively. The level of cellular ROS was assessed by the DCFH-DA probe. Different concentrations of H₂O₂ were used to provide oxidative stress on RPLS cells. The underlying mechanisms were further explored by Western blotting.

RESULTS

The IHC assays showed that TRPM2-S, but not TRPM2-L, was prognostic in RPLS. Low TRPM2-S level was associated with poor disease-free survival (DFS). Calcium influx signal intensity was significantly decreased under TRPM2-S overexpression, which resulted in a decrease in the levels of FOXO3a and PTEN. Correspondingly, the levels of pERK, pAKT, pP65, pGSK-3β, Bcl-2, and β-catenin were upregulated, and cellular ROS was gently increased under TRPM2-S overexpression. Moreover, TRPM2-S slightly promoted cell proliferation and inhibited apoptosis of RPLS cell lines under normoxia, but largely increased apoptosis rates under oxidative stress. The cleaved caspase3 was significantly upregulated by TRPM2-S overexpression under oxidative stress. N-Acetyl-L-cysteine (NAC), a small molecule antioxidant, could largely rescue RPLS cells from the apoptosis induced by H₂O₂.

CONCLUSION

TRPM2-S exerts Janus-faced effects in RPLS by increasing the ROS levels via inhibition on FOXO3a, which promotes cell proliferation under normoxia but induces apoptosis under oxidative stress. Video abstract.

Induced blood oxidation in myocardial revascularization

Background: The use of artificial circulation in surgical myocardial revascularization is one of the key pathogenetic factors in the development of the oxidative stress and systemic inflammatory response in the postoperative period. Aims: the purpose of the study was to describe the dynamics of the induced blood oxidation parameters during coronary artery bypass surgery in the conditions of artificial circulation and on the working heart. Methods: The study included 64 patients who underwent coronary bypass surgery, with 31 (48.4%) on-pump patients and 33 (51.6%) off-pump patients. The oxidative stress simulations were conducted under the in vitro conditions. The blood oxidation-induced values were studied using a biological oxygen monitor. Results: In patients with coronary heart disease, regardless of the choice of the revascularization method (on-pump / off-pump), we observed statistically significantly (p 0.05) higher initial and maximum blood oxidation rates, the oxidative activity factor, and a shorter initiation period than those in healthy volunteers. No significant differences were found by the inter-group comparison analysis both 10 days and 6 months post-surgery. Conclusion: The indicators of induced blood oxidation do not depend on the method of revascularization during coronary bypass grafting (artificial circulation or a working heart). The changes in the parameters indicating activation of the oxidative and antioxidant blood systems may be transient by their nature and occur in the early postoperative period.

Assessment of the effect of perineural dexmedetomidine on oxidative stress during peritoneal dialysis catheter insertion: a randomized, controlled trial

Purpose

This study aimed to evaluate the effect of the addition of dexmedetomidine to ropivacaine on oxidative stress during transversus abdominis plane (TAP) and rectus sheath (RS) blockades for patients with end-stage renal disease (ESRD) undergoing peritoneal dialysis (PD) catheter insertion.

Methods

Sixty patients with ESRD undergoing PD catheter insertion to receive left ultrasound-guided TAP and RS blockades were randomly divided into two groups: the dexmedetomidine plus ropivacaine group (25 mL of 0.3% ropivacaine + 1 μg/kg dexmedetomidine) and the ropivacaine group (25 mL of 0.3% ropivacaine). Primary outcomes were oxidative stress marker levels during the procedure.

Results

A total of 60 patients (30 patients in each group) were evaluated. Compared with the ropivacaine group, the dexmedetomidine plus ropivacaine group had significantly lower serum malondialdehyde levels (P < 0.05) and increased glutathione peroxidase (P < 0.01) and superoxide dismutase levels at 24 h after the procedure (P < 0.01).

Conclusion

The addition of 1 μg/kg of dexmedetomidine to ropivacaine for ultrasound-guided TAP and RS blockades could inhibit oxidative stress in patients with ESRD undergoing PD catheter insertion.

Trial registration This study was registered at www.chictr.org.cn on June 7, 2021 (ChiCTR2100047050).

Effect of dexmedetomidine administration on analgesic, respiration and inflammatory responses in patients undergoing percutaneous endoscopic lumbar discectomy: a prospective observational study

Background

Local anesthesia has been recommended for percutaneous endoscopic lumbar discectomy (PELD) in recent years; however, the efficacy, including oxidative stress, inflammatory reactions and ventilation effects, when intravenous dexmedetomidine (DEX) is administered during PELD has not been described.

Methods

Sixty adult patients undergoing PELD were randomly allocated to either an intravenous DEX sedation group (Group A) or a normal saline group (Group B). Respiratory data, including minute ventilation (MV), tidal volume (TV), and respiratory rate (RR), were recorded using a respiratory volume monitor (RVM), and peripheral oxygen saturation (SpO₂) was monitored by pulse oximetry. The visual analog score (VAS) was used to assess the level of pain. The serum levels of inflammatory biomarkers including interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were to assess inflammatory reactions. The serum levels of oxidative stress biomarkers including malondialdehyde (MDA) and glutathione peroxidase (GSH-PX) were also recorded to evaluate oxidative stress.

Results

There were no significant differences in RR, MV, TV and SpO₂ between the two groups at any time point (P > 0.05). Group B exhibited lower serum levels of GSH-PX (P < 0.0001) and higher serum levels of MDA (p < 0.0001) than Group A at the end of surgery. Twenty-four hours after surgery, Group B exhibited higher serum levels of IL-6 (P = 0.0033), TNF-α (P = 0.0002), and MDA (P < 0.0001) and lower serum levels of GSH-PX (P < 0.0001) than Group A. In addition, Group A exhibited lower VAS (P < 0.0001) than Group B during surgery.

Conclusions

DEX administration using RVM not only provides analgesia without ventilatory depression but also alleviates oxidative stress and inflammatory reactions in patients undergoing PELD.

Neonatal Anesthesia and Oxidative Stress

Neonatal anesthesia, while often essential for surgeries or imaging procedures, is accompanied by significant risks to redox balance in the brain due to the relatively weak antioxidant system in children. Oxidative stress is characterized by concentrations of reactive oxygen species (ROS) that are elevated beyond what can be accommodated by the antioxidant defense system. In neonatal anesthesia, this has been proposed to be a contributing factor to some of the negative consequences (e.g., learning deficits and behavioral abnormalities) that are associated with early anesthetic exposure. In order to assess the relationship between neonatal anesthesia and oxidative stress, we first review the mechanisms of action of common anesthetic agents, the key pathways that produce the majority of ROS, and the main antioxidants. We then explore the possible immediate, short-term, and long-term pathways of neonatal-anesthesia-induced oxidative stress. We review a large body of literature describing oxidative stress to be evident during and immediately following neonatal anesthesia. Moreover, our review suggests that the short-term pathway has a temporally limited effect on oxidative stress, while the long-term pathway can manifest years later due to the altered development of neurons and neurovascular interactions.

Hyperoxia and Antioxidants for Myocardial Injury in Noncardiac Surgery: A 2 × 2 Factorial, Blinded, Randomized Clinical Trial

BACKGROUND

Hyperoxia and oxidative stress may be associated with increased risk of myocardial injury. The authors hypothesized that a perioperative inspiratory oxygen fraction of 0.80 versus 0.30 would increase the degree of myocardial injury within the first 3 days of surgery, and that an antioxidant intervention would reduce degree of myocardial injury versus placebo.

METHODS

A 2 × 2 factorial, randomized, blinded, multicenter trial enrolled patients older than 45 yr who had cardiovascular risk factors undergoing major noncardiac surgery. Factorial randomization allocated patients to one of two oxygen interventions from intubation and at 2 h after surgery, as well as antioxidant intervention or matching placebo. Antioxidants were 3 g IV vitamin C and 100 mg/kg N-acetylcysteine. The primary outcome was the degree of myocardial injury assessed by the area under the curve for high-sensitive troponin within the first 3 postoperative days.

RESULTS

The authors randomized 600 participants from April 2018 to January 2020 and analyzed 576 patients for the primary outcome. Baseline and intraoperative characteristics did not differ between groups. The primary outcome was 35 ng · day/l (19 to 58) in the 80% oxygen group; 35 ng · day/l (17 to 56) in the 30% oxygen group; 35 ng · day/l (19 to 54) in the antioxidants group; and 33 ng · day/l (18 to 57) in the placebo group. The median difference between oxygen groups was 1.5 ng · day/l (95% CI, -2.5 to 5.3; P = 0.202) and -0.5 ng · day/l (95% CI, -4.5 to 3.0; P = 0.228) between antioxidant groups. Mortality at 30 days occurred in 9 of 576 patients (1.6%; odds ratio, 2.01 [95% CI, 0.50 to 8.1]; P = 0.329 for the 80% vs. 30% oxygen groups; and odds ratio, 0.79 [95% CI, 0.214 to 2.99]; P = 0.732 for the antioxidants vs. placebo groups).

CONCLUSIONS

Perioperative interventions with high inspiratory oxygen fraction and antioxidants did not change the degree of myocardial injury within the first 3 days of surgery. This implies safety with 80% oxygen and no cardiovascular benefits of vitamin C and N-acetylcysteine in major noncardiac surgery.

EDITOR’S PERSPECTIVE

Contribution of oxidative stress in the mechanisms of postoperative complications and multiple organ dysfunction syndrome

BACKGROUND

The extent of the damage following surgery has been subject of study for several years. Numerous surgical complications can impact postoperative quality of life of patients and even can cause mortality. Although these complications are generally due to multifactorial mechanisms, oxidative stress plays a key pathophysiological role. Moreover, oxidative stress could be an unavoidable effect derived even from the surgical procedure itself.

METHODS

A systematic review was performed following an electronic search of Pubmed and ScienceDirect databases. Keywords such as sepsis, oxidative stress, organ dysfunction, antioxidants, outcomes in postoperative complications, among others, were used. Review articles were preferably used between the years 2015 onwards, not excluding older ones.

RESULTS

The vast majority point to the role of oxidative stress in generating greater damage and worse prognosis in postoperative patients without the necessary care and precautions, taking importance on the use of antioxidants to prevent this problem.

DISCUSSIONS

Oxidative stress represents a common final pathway related to pathological processes such as inflammation or ischemia-reperfusion, among others. The expression of greater severity of these complications can result in multiple organ dysfunction or sepsis. The aim of this study was to present an update of the role of oxidative stress on surgical postoperative complications.

Perioperative supplemental oxygen and oxidative stress in patients undergoing moderate- to high-risk major abdominal surgery - A subanalysis of randomized clinical trial

STUDY OBJECTIVE

Oxidative stress plays a pivotal role in the development and aggravation of cardiovascular diseases. The influence of intraoperative inspired oxygen concentrations on oxidative stress is still not entirely known. Therefore, we evaluated in this sub-study if supplemental oxygen affects the oxidation-reduction potential in patients at-risk for cardiovascular complications undergoing moderate- to high-risk major abdominal surgery.

DESIGN

Sub-study of a prospective parallel-arm double-blinded single-center superiority randomized trial.

SETTING

Operating room and postoperative recovery area.

INTERVENTION

Administration of 0.8 FiO₂ versus 0.3 FiO₂ throughout surgery and for the first two postoperative hours.

MEASUREMENTS

The primary outcome was the static oxidation-reduction potential (sORP) and the oxidation-reduction potential capacity (cORP) between both groups. The secondary outcome was the trend of sORP and cORP in the overall study population. We assessed sORP and cORP before induction of anesthesia, 2 h after induction of anesthesia, within 2 h after surgery and on the first and third postoperative day.

MAIN RESULTS

258 patients were analyzed. 128 patients were randomly assigned to the 80% oxygen group and 130 patients were randomly assigned to the 30% oxygen group. Postoperative sORP values did not differ significantly between the 80% and 30% oxygen group (effect estimate: -1.162 mV,95% CI: -2.584 to 0.260; p = 0.109). On average, we observed a change in sORP of 5.288 mV (95% CI:4.633 to 5.913, p < 0.001) per day. cORP values did not differ significantly between the 80% and 30% oxygen group (effect estimate: -0.015μC, (95%CI: -0.062 to 0.032; p = 0.524). On average, we observed a change in cORP values of -0.170μC (95%CI: -0.194 to -0.147, p < 0.001) per day.

CONCLUSION

In contrast to previous reports, we could not find any evidence of an association between intraoperative supplemental oxygen and perioperative oxidative stress assessed by sORP and cORP.

TRIAL REGISTRATION

clinicaltrials.gov: NCT03366857https://clinicaltrials.gov/ct2/show/NCT03366857?term=vienna&cond=oxygen&draw=2&rank=1.

Activation of Nrf2 Pathway by Dimethyl Fumarate Attenuates Renal Ischemia-Reperfusion Injury

BACKGROUND

Dimethyl fumarate (DMF) is a novel antioxidant that selectively reduces hydroxyl radicals. This study aimed to investigate the potential role of DMF in the pathogenesis of renal ischemia-reperfusion injury (IRI) and the mechanisms involved.

METHODS

C57BL/6 wild-type mice were treated with DMF or a vehicle. Subsequently, renal IRI was induced in mice by a model of right kidney nephrectomy and left renal ischemia for 30 minutes followed by reperfusion for 24 hours. Sham operation and phosphate-buffered saline were used as controls. Serum and renal tissues were collected at 24 hours after IRI to evaluate the influence of DMF on the recovery of renal function after IRI. Blood urea nitrogen and serum creatinine levels were measured. Kidney cell apoptosis was evaluated using terminal deoxynucleotidyl transferase dUTP nick end labeling-positive staining. Interleukin 6 and tumor necrosis factor α cytokines in the kidney tissues were measured. Indicators of oxidative stress in the kidneys were detected. Finally, Nrf2-deficient mice were used to determine the protective role of the nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) and NAD(P)H dehydrogenase quinone 1 (NQO1) signaling pathways induced by DMF using western blot assay.

RESULTS

DMF significantly attenuated renal dysfunction in mice and showed reductions in the severity of renal tubular injury, cell necrosis, and apoptosis. Moreover, DMF significantly reduced the amount of key inflammatory mediators. Additionally, DMF attenuated the malondialdehyde levels 24 hours after IRI but upregulated the superoxide dismutase activities. Western blot assay showed that DMF significantly increased the protein levels of Nrf2, HO-1, and NQO-1. Importantly, these DMF-mediated beneficial effects were not observed in Nrf2-deficient mice.

CONCLUSIONS

DMF attenuates renal IRI by reducing inflammation and upregulating the antioxidant capacity, which may be through Nrf2/HO-1and NQO1 signaling pathway.

Lifting the lid on perioperative goal-directed therapy

The complex cellular interactions that underlie pathologies related to reduced oxygen delivery after surgery are poorly defined and difficult to measure. Heywood and colleagues explored the patterns of protein expression in skin biopsies taken from a subgroup of patients enrolled in a randomised trial designed to evaluate perioperative goal-directed therapy. One of their key findings was that a failure of participants to maintain preoperative systemic oxygen delivery was associated with an upregulation of intracellular proteins involved in counteracting oxidative stress. Their study highlights the importance of oxidative stress in the perioperative setting and suggests that maintenance of baseline oxygen delivery might be an important regulator of redox balance.

Serum and Erythrocyte Antioxidant Defense in Colorectal Cancer Patients during Early Postoperative Period: Potential Modifiers and Impact on Clinical Outcomes

A better understanding of antioxidant status, its modifiers, and its effect on clinical outcomes in patients undergoing colorectal cancer surgery is needed for effective antioxidant-based interventions. The objectives of this cohort study were: to determine baseline serum (total antioxidant capacity (TAC) and ferric reducing antioxidant power (FRAP); n = 72) and erythrocyte (superoxide dismutase (SOD) and glutathione peroxidase (GPx); n = 47) antioxidant capacity and time-course during the 72 h postoperative period, to identify potential modifiers, and to establish impact on clinical outcomes. Older patients with comorbidities had lower baseline FRAP. TAC was inversely and SOD directly correlated with inflammatory markers. Cancer pathology affected GPx (lower in advanced and more aggressive cancers) and SOD (higher in advanced cancers). Surgical intervention induced a transient increase in FRAP and TAC with greater FRAP elevation in older, obese patients with several comorbidities. SOD activity significantly increased while GPx non-significantly decreased between 8 and 24 h post-incision. Poorer health status was associated with an increase in SOD and a decrease in GPx at 72 h. Clinical manifestation of postoperative ileus was preceded by decreased TAC at 24 h and an increase in SOD between 8 and 24 h and anastomotic leak was manifested by diminished SOD at 72 h compared to activities at 8 and 24 h. The time-frame between 8 and 24 h post-incision might be the most critical regarding oxidant/antioxidant balance and therefore the best suited for antioxidant-based intervention.

A meta-analysis of randomized clinical trials on the impact of oral vitamin C supplementation on first-year outcomes in orthopedic patients

This meta-analysis aimed at investigating the impact of oral vitamin C supplementation on the post-procedural recovery of orthopedic patients, including functional outcomes and complex regional pain syndrome type I (CRPS I). Literature search using the Medline, Cochrane Library, and Embase databases from inception till March 2021 identified seven eligible randomized controlled trials with 1,361 participants. Forest plot revealed no significant difference in the functional outcomes at 6–12 months [standardized mean difference (SMD) = −0.00, 95% CI − 0.19 to 0.18, 467 patients], risk of overall complications (RR = 0.98, 95% CI 0.68 to 1.39, 426 patients), and pain severity at 3–6 months (SMD = − 0.18, 95% CI − 0.49 to 0.12, 486 patients) between patients with and without oral vitamin C supplementation. Pooled analysis showed that vitamin C treatment reduced the risk of CRPS I regardless of dosage (RR = 0.46, 95% CI 0.25 to 0.85, 1143 patients). In conclusion, the current meta-analysis demonstrated that oral vitamin C supplementation may reduce the risk of complex regional pain syndrome type I but did not improve the functional outcomes in orthopedic patients. Nevertheless, because of the small number of trials included in the present study, further large-scale clinical studies are warranted to support our findings.

Effects of perioperative oxygen concentration on oxidative stress in adult surgical patients: a systematic review

Background

The fraction of inspired oxygen (FiO₂) administered during general anaesthesia varies widely despite international recommendations to administer FiO₂ 0.8 to all anaesthetised patients to reduce surgical site infections (SSIs). Anaesthetists remain concerned that high FiO₂ administration intraoperatively may increase harm, possibly through increased oxidative damage and inflammation, resulting in more complications and worse outcomes. In previous systematic reviews associations between FiO₂ and SSIs have been inconsistent, but none have examined how FiO₂ affects perioperative oxidative stress. We aimed to address this uncertainty by reviewing the available literature.

Methods

EMBASE, MEDLINE, and Cochrane databases were searched from inception to March 9, 2020 for RCTs comparing higher with lower perioperative FiO₂ and quantifying oxidative stress in adults undergoing noncardiac surgery. Candidate studies were independently screened by two reviewers and references hand-searched. Methodological quality was assessed using the Cochrane Collaboration Risk of Bias tool.

Results

From 19 438 initial results, seven trials (n=422) were included. Four studies reported markers of oxidative stress during Caesarean section (n=328) and three reported oxidative stress during elective colon surgery (n=94). Risk of bias was low (four studies) to moderate (three studies). Pooled results suggested high FiO₂ was associated with greater malondialdehyde, protein-carbonyl concentrations and reduced xanthine oxidase concentrations, together with reduced antioxidant markers such as superoxide dismutase and total sulfhydryl levels although total antioxidant status was unchanged.

Conclusions

Higher FiO₂ may be associated with elevated oxidative stress during surgery. However, limited studies have specifically reported biomarkers of oxidation. Given the current clinical controversy concerning perioperative oxygen therapy, further research is urgently needed in this area.

New techniques and recommendations in the management of free flap surgery for head and neck defects in cancer patients

Free flap surgery is the gold standard surgical treatment for head and neck defects in cancer patients. Outcomes have improved considerably, probably due to recent advances in surgical techniques. In this article, we review improvements in the parameters traditionally used to optimize hematocrit levels and body temperature and to prevent vasoconstriction, and describe the use of cardiac output-guided fluid management, a technique that has proved useful in other procedures. Finally, we review other parameters used in free flap surgery, such as clotting/platelet management and nutritional optimization.