Perioperative supplemental oxygen and NT-proBNP concentrations after major abdominal surgery - A prospective randomized clinical trial

2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM Guideline for Perioperative Cardiovascular Management for Noncardiac Surgery: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM Guideline for Perioperative Cardiovascular Management for Noncardiac Surgery" provides recommendations to guide clinicians in the perioperative cardiovascular evaluation and management of adult patients undergoing noncardiac surgery.

METHODS

A comprehensive literature search was conducted from August 2022 to March 2023 to identify clinical studies, reviews, and other evidence conducted on human subjects that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline.

STRUCTURE

Recommendations from the "2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery" have been updated with new evidence consolidated to guide clinicians; clinicians should be advised this guideline supersedes the previously published 2014 guideline. In addition, evidence-based management strategies, including pharmacological therapies, perioperative monitoring, and devices, for cardiovascular disease and associated medical conditions, have been developed.

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.

Preoperative routine measurement of NT-proBNP predicts postoperative morbidity after non-cardiac surgery with intermediate or high surgical risk: an observational study

BACKGROUND

Chronic heart failure (HF) is a common clinical condition associated with adverse outcomes in elderly patients undergoing non-cardiac surgery. This study aimed to estimate a clinically applicable NT-proBNP cut-off that predicts postoperative 30-day morbidity in a non-cardiac surgical cohort.

METHODS

One hundred ninety-nine consecutive patients older than 65 years undergoing elective non-cardiac surgery with intermediate or high surgical risk were analysed. Preoperative NT-proBNP was measured, and clinical events were assessed up to postoperative day 30. The primary endpoint was the composite morbidity endpoint (CME) consisting of rehospitalisation, acute decompensated heart failure (ADHF), acute kidney injury (AKI), and infection at postoperative day 30. Secondary endpoints included perioperative fluid balance and incidence, duration, and severity of perioperative hypotension.

RESULTS

NT-proBNP of 443 pg/ml had the highest accuracy in predicting the composite endpoint; a clinical cut-off of 450 pg/ml was implemented to compare clinical endpoints. Although 35.2% of patients had NT-proBNP above the threshold, only 10.6% had a known history of HF. The primary endpoint was the composite morbidity endpoint (CME) consisting of rehospitalisation, acute decompensated heart failure (ADHF), acute kidney injury (AKI), and infection. Event rates were significantly increased in patients with NT-proBNP > 450 pg/ml (70.7% vs. 32.4%, p < 0.001), which was due to the incidence of cardiac rehospitalisation (4.4% vs. 0%, p = 0.018), ADHF (20.1% vs. 4.0%, p < 0.001), AKI (39.8% vs. 8.3%, p < 0.001), and infection (46.3% vs. 24.4%, p < 0.01). Perioperative fluid balance and perioperative hypotension were comparable between groups. Preoperative NT-proBNP > 450 pg/ml was an independent predictor of the CME in a multivariable Cox regression model (hazard ratio 2.92 [1.72-4.94]).

CONCLUSIONS

Patients with NT-proBNP > 450 pg/ml exhibited profoundly increased postoperative morbidity. Further studies should focus on interdisciplinary approaches to improve outcomes through integrated interventions in the perioperative period.

TRIAL REGISTRATION

German Clinical Trials Register: DRKS00027871, 17/01/2022.

The effect of high perioperative inspiratory oxygen fraction for abdominal surgery on surgical site infection: a systematic review and meta-analysis

Guidelines from the World Health Organization strongly recommend the use of a high fraction of inspired oxygen (FiO2) in adult patients undergoing general anesthesia to reduce surgical site infection (SSI). However, previous meta-analyses reported inconsistent results. We aimed to address this controversy by focusing specifically on abdominal surgery with relatively high risk of SSI. Medline, EMBASE, and Cochrane CENTRAL databases were searched. Randomized trials of abdominal surgery comparing high to low perioperative FiO2 were included, given that the incidence of SSI was reported as an outcome. Meta-analyses of risk ratios (RR) were performed using a fixed effects model. Subgroup analysis and meta-regression were employed to explore sources of heterogeneity. We included 27 trials involving 15977 patients. The use of high FiO2 significantly reduced the incidence of SSI (n = 27, risk ratio (RR): 0.87; 95% confidence interval (CI): 0.79, 0.95; I2 = 49%, Z = 3.05). Trial sequential analysis (TSA) revealed that z-curve crossed the trial sequential boundary and data are sufficient. This finding held true for the subgroup of emergency operations (n = 2, RR: 0.54; 95% CI: 0.35, 0.84; I2 = 0%, Z = 2.75), procedures using air as carrier gas (n = 9, RR: 0.79; 95% CI: 0.69, 0.91; I2 = 60%, Z = 3.26), and when a high level of FiO2 was maintained for a postoperative 6 h or more (n = 9, RR: 0.68; 95% CI: 0.56, 0.83; I2 = 46%, Z = 3.83). Meta-regression revealed no significant interaction between SSI with any covariates including age, sex, body-mass index, diabetes mellitus, duration of surgery, and smoking. Quality of evidence was assessed to be moderate to very low. Our pooled analysis revealed that the application of high FiO2 reduced the incidence of SSI after abdominal operations. Although TSA demonstrated sufficient data and cumulative analysis crossed the TSA boundary, our results should be interpreted cautiously given the low quality of evidence.Registration: https://www.crd.york.ac.uk/prospero (CRD42022369212) on October 2022.

PerIoperative iNflammatory reSponse assessment In hiGH-risk patienTs undergoing non-cardiac surgery (INSIGHT): study protocol of a prospective non-interventional observational study

INTRODUCTION

Increased inflammatory processes after non-cardiac surgery are very common. The association between postoperative inflammation and the occurrence of cardiovascular complications after non-cardiac surgery are still not entirely clear. Therefore, we will evaluate the association between postoperative inflammation and the occurrence of major cardiovascular complications in patients at-risk for cardiovascular complications undergoing non-cardiac surgery. We will further evaluate the association of postoperative inflammation and days-at-home within 30 days after surgery (DAH₃₀), the incidence of acute kidney injury, postoperative N-terminal probrain natriuretic peptide (NT-proBNP) concentrations and neurocognitive decline.

METHODS AND ANALYSIS

In this multicentre study, we will include 1400 patients at-risk for cardiovascular complications undergoing non-cardiac surgery. Our primary aim is to evaluate the association of postoperative maximum C-reactive protein concentration and the occurrence of a composite of five major cardiovascular complications (myocardial infarction, myocardial injury after non-cardiac surgery, new onset of atrial fibrillation, stroke and death) within 30 days after surgery using a Mann-Whitney-U test as well as a logistic regression model. As our secondary aim, we will evaluate the association of a composite of three inflammatory biomarkers (interleukin 6, procalcitonin and copeptin) on the occurrence of our composite of five cardiovascular complications within 30 days and 1 year after surgery, acute kidney injury, DAH₃₀ and NT-proBNP concentrations using linear or logistic regression models. We will measure inflammatory biomarkers before surgery, and on the first, second, third and fifth postoperative day. We will check medical records and conduct a telephone survey 30 days and 1 year after surgery. We evaluate neurocognitive function, using a Montreal Cognitive Assessment, before and 1 year after surgery.

ETHICS AND DISSEMINATION

This study was approved by the ethics committees at the Medical University of Vienna (2458/2020) and at the Medical University of Graz (33-274 ex 20/21).

TRIAL REGISTRATION NUMBER

NCT04753307.

Hemodynamic effects of intraoperative 30% versus 80% oxygen concentrations: an exploratory analysis

Background

Supplemental oxygen leads to an increase in peripheral vascular resistance which finally increases systemic blood pressure in healthy subjects and patients with coronary artery disease, heart failure, undergoing heart surgery, and with sepsis. However, it is unknown whether this effect can also be observed in anesthetized patients having surgery. Thus, we evaluated in this exploratory analysis of a randomized controlled trial the effect of 80% versus 30% oxygen on intraoperative blood pressure and heart rate.

Methods

We present data from a previous study including 258 patients, who were randomized to a perioperative inspiratory FiO₂ of 0.8 (128 patients) versus 0.3 (130 patients) for major abdominal surgery. Continuous arterial blood pressure values were recorded every three seconds and were exported from the electronic anesthesia record system. We calculated time-weighted average (TWA) and Average Real Variability (ARV) of mean arterial blood pressure and of heart rate.

Results

There was no significant difference in TWA of mean arterial pressure between the 80% (80 mmHg [76, 85]) and 30% (81 mmHg [77, 86]) oxygen group (effect estimate -0.16 mmHg, CI -1.83 to 1.51; p = 0.85). There was also no significant difference in TWA of heart rate between the 80 and 30% oxygen group (median TWA of heart rate in the 80% oxygen group: 65 beats.min^-1 [58, 72], and in the 30% oxygen group: 64 beats.min^-1 [58; 70]; effect estimate: 0.12 beats.min^-1, CI -2.55 to 2.8, p = 0.94). Also for ARV values, no significant differences between groups could be detected.

Conclusion

In contrast to previous results, we did not observe a significant increase in blood pressure or a significant decrease in heart rate in patients, who received 80% oxygen as compared to patients, who received 30% oxygen during surgery and for the first two postoperative hours. Thus, hemodynamic effects of supplemental oxygen might play a negligible role in anesthetized patients.

Clinical Trail Registration

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

Effects of Combined Use of Salbutamol/Budesonide in Thoracic Surgery on Postoperative Myocardial Injury (MINS) – A Prospective Randomized Clinical Trial

Purpose

This study aims to investigate whether the administration of salbutamol/budesonide reduced the incidence of myocardial injury in thoracic surgery.

Methods

The randomized controlled trial included 298 patients over 45 and at high-risk for cardiovascular complications after lobectomy. Patients in the experimental group were treated with salbutamol/budesonide after anesthesia induction with fiberoptic bronchoscope. The primary outcome was the incidence rates of myocardial injury, assessed before and three days after the operation. The secondary outcome was respiratory function at each time point during the operation, including lung compliance and arterial partial pressure of oxygen, postoperative pulmonary and cardiovascular complications, hospital stay, pain score, and analgesic dosage.

Results

In the control group, the incidence of myocardial injury was 57/150 (38%), while that in the experimental group was 33/148 (22%); compared between the two groups, the difference in the incidence of myocardial injury was statistically significant. The dynamic compliance and static compliance at half an hour after the start of surgery in the experimental group were significantly improved. Before leaving the operating room, the difference in arterial oxygen partial pressure between the two groups was statistically significant.

Conclusion

Intraoperative administration of salbutamol/budesonide reduced the incidence of myocardial injury after thoracic surgery, improved lung function, and reduced the incidence of postoperative pulmonary complications.

Perioperative strategies to reduce risk of myocardial injury after non-cardiac surgery (MINS): A narrative review

Myocardial injury is a frequent complication of surgical patients after having non-cardiac surgery that is strongly associated with perioperative mortality. While intraoperative anesthesia-related deaths are exceedingly rare, about 1% of patients undergoing non-cardiac surgery die within the first 30 postoperative days. Given the number of surgeries performed annually, death following surgery is the second leading cause of death in the United States. Myocardial injury after non-cardiac surgery (MINS) is defined as an elevation in troponin concentrations within 30 days postoperatively. Although typically asymptomatic, patients with MINS suffer myocardial damage and have a 10% risk of death within 30 days after surgery and excess risks of mortality that persist during the first postoperative year. Many factors for the development of MINS are non-modifiable, such as preexistent coronary artery disease. Preventive measures, systematic approaches to surveillance and treatment standards are still lacking, however many factors are modifiable and should be considered in clinical practice: the importance of hemodynamic control, adequate oxygen supply, metabolic homeostasis, the use of perioperative medications such as statins, anti-thrombotic agents, beta-blockers, or anti-inflammatory agents, as well as some evidence regarding the choice of sedative and analgesic for anesthesia are discussed. Also, as age and complexity in comorbidities of the surgical patient population increase, there is an urgent need to identify patients at risk for MINS and develop prevention and treatment strategies. In this review, we provide an overview of current screening standards and promising preventive options in the perioperative setting and address knowledge gaps requiring further investigation.

Updated meta-analysis on intraoperative inspired fraction of oxygen and the risk of surgical site infection in adults undergoing general and regional anesthesia

This updated meta-analysis aims at exploring whether the use of systematic high vs low intraoperative oxygen fraction (FiO2) may decrease the incidence of postoperative surgical site infection during general (GA) or regional anesthesia (RA). PubMed, Cochrane CENTRAL, ClinicalTrials.gov databases were searched from January 1st, 1999 and July, 1st 2022, for randomized and quasi-randomized controlled trials that included patients in a high and low FiO2 groups and reported the incidence of SSI. The meta-analysis was conducted with a DerSimonian and Laird random-effects model. Thirty studies (24 for GA and 6 for RA) totaling 18,055 patients (15,871 for GA and 2184 for RA) were included. We have low-to-moderate-quality evidence that high FiO2 (mainly 80%) was not associated with a reduction of SSI incidence compared to low FiO2 (mainly 30%) in all patients (RR 0.90, 95%CI 0.79-1.03). Moderate inconsistency existed between studies (I2 = 38%). Subgroup analyses showed a moderate protective effect in patients undergoing GA (RR 0.86, 95%CI 0.75-0.99) (low level of evidence), while high FiO2 was not associated with a reduction of SSI in patients undergoing RA (RR 1.17, 95%CI 0.90-1.52) (moderate level of evidence). Sensitivity analyses restricted to patients ventilated without nitrous oxide (n = 20 studies), to patients operated from abdominal surgeries (n = 21 studies), and to patients suffering from deep SSI (n = 13 studies), all showed the absence of any significant effect of high FiO2. As a conclusion there is no compelling evidence that high FiO2 can improve postoperative patient's outcome on its own when good SSI prevention practices are properly applied. Recent well-designed and adequately powered randomized controlled trials add further weight to these results.

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.

Optimal anesthetic conduct regarding immediate and short-term outcomes after liver transplantation - Systematic review of the literature and expert panel recommendations

BACKGROUND

In the era of enhanced recovery after surgery, there is significant discussion regarding the impact of intraoperative anesthetic management on short-term outcomes following liver transplantation (LT), with no clear consensus in the literature.

OBJECTIVES

To identify whether or not intraoperative anesthetic management affects short-term outcomes after liver transplantation.

DATA SOURCES

Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central.

METHODS

A systematic review following PRISMA guidelines was undertaken. The systematic review was registered on PROSPERO (CRD42021239758). An international expert panel made recommendations for clinical practice using the GRADE approach.

RESULTS

After screening, 14 studies were eligible for inclusion in this systematic review. Six were prospective randomized clinical trials, three were prospective nonrandomized clinical trials, and five were retrospective studies. These manuscripts were reviewed to look at five questions regarding anesthetic care and its impact on short term outcomes following liver transplant. After review of the literature, the quality of evidence according to the following outcomes was as follows: intraoperative and postoperative morbidity and mortality (low), early allograft dysfunction (low), and hospital and ICU length of stay (moderate).

CONCLUSIONS

For optimal short term outcomes after liver transplantation, the panel recommends the use of volatile anesthetics in preference to total intravenous anesthesia (TIVA) (Level of Evidence: Very low; Strength of Recommendation: Weak) and minimum alveolar concentration (MAC) versus bispectral index (BIS) for depth of anesthesia monitoring (Level of Evidence: Very low; Strength of Recommendation: Weak). Regarding ventilation and oxygenation, the panel recommends a restrictive oxygenation strategy targeting a PaO₂ of 70-120 mmHg (10-14 kPa), a tidal volume of 6-8 ml/kg ideal body weight (IBW), administration of positive end expiratory pressure (PEEP) tailored to patient intraoperative physiology, and recruitment maneuvers. (Level of evidence: Very low; Strength of Recommendation: Strong). Finally, the panel recommends the routine use of antiemetic prophylaxis. (Level of evidence: low; Strength of Recommendation: Strong).

Fraction of Inspired Oxygen During General Anesthesia for Non-Cardiac Surgery: Systematic Review and Meta-Analysis

Background

Controversy exists regarding the effects of a high versus a low intraoperative fraction of inspired oxygen (FiO₂) in adults undergoing general anesthesia. This systematic review and meta‐analysis investigated the effect of a high versus a low FiO₂ on postoperative outcomes.

Methods

PubMed and Embase were searched on March 22, 2022 for randomized clinical trials investigating the effect of different FiO₂ levels in adults undergoing general anesthesia for non‐cardiac surgery. Two investigators independently reviewed studies for relevance, extracted data, and assessed risk of bias. Meta‐analyses were performed for relevant outcomes, and potential effect measure modification was assessed in subgroup analyses and meta‐regression. The evidence certainty was evaluated using GRADE.

Results

This review included 25 original trials investigating the effect of a high (mostly 80%) versus a low (mostly 30%) FiO₂. Risk of bias was intermediate for all trials. A high FiO₂ did not result in a significant reduction in surgical site infections (OR: 0.91, 95% CI 0.81–1.02 [p = .10]). No effect was found for all other included outcomes, including mortality (OR = 1.27, 95% CI: 0.90–1.79 [p = .18]) and hospital length of stay (mean difference = 0.03 days, 95% CI −0.25 to 0.30 [p = .84). Results from subgroup analyses and meta‐regression did not identify any clear effect modifiers across outcomes. The certainty of evidence (GRADE) was rated as low for most outcomes.

Conclusions

In adults undergoing general anesthesia for non‐cardiac surgery, a high FiO₂ did not improve outcomes including surgical site infections, length of stay, or mortality. However, the certainty of the evidence was assessed as low.

Perioperative Supplemental Oxygen and Postoperative Copeptin Concentrations in Cardiac-Risk Patients Undergoing Major Abdominal Surgery-A Secondary Analysis of a Randomized Clinical Trial

Noncardiac surgery is associated with hemodynamic perturbations, fluid shifts and hypoxic events, causing stress responses. Copeptin is used to assess endogenous stress and predict myocardial injury. Myocardial injury is common after noncardiac surgery, and is often caused by myocardial oxygen demand-and-supply mismatch. In this secondary analysis, we included 173 patients at risk for cardiovascular complications undergoing moderate- to high-risk major abdominal surgery. Patients were randomly assigned to receive 80% or 30% oxygen throughout surgery and the first two postoperative hours. We evaluated the effect of supplemental oxygen on postoperative Copeptin concentrations. Copeptin concentrations were measured preoperatively, within two hours after surgery, on the first and third postoperative days. In total, 85 patients received 0.8 FiO2, and 88 patients received 0.3 FiO2. There was no significant difference in postoperative Copeptin concentrations between both study groups (p = 0.446). Copeptin increased significantly within two hours after surgery, compared with baseline in the overall study population (estimated effect: −241.7 pmol·L−1; 95% CI −264.4, −219.1; p < 0.001). Supplemental oxygen did not significantly attenuate postoperative Copeptin release. Copeptin concentrations showed a more immediate postoperative increase compared with previously established biomarkers. Nevertheless, Copeptin concentrations did not surpass Troponin T in early determination of patients at risk for developing myocardial injury after noncardiac surgery.

Perioperative Supplemental Oxygen and Plasma Catecholamine Concentrations after Major Abdominal Surgery-Secondary Analysis of a Randomized Clinical Trial

Perioperative stress is associated with increased sympathetic activity that leads to increases in heart rate and blood pressure, which are associated with the development of perioperative myocardial ischemia. In healthy volunteers, it was shown that the administration of supplemental oxygen attenuated sympathetic nerve activity and subsequently led to lower plasma catecholamine concentrations. We therefore tested the hypothesis that perioperative supplemental oxygen attenuates sympathetic nerve in patients at risk for cardiovascular complications undergoing major abdominal surgery. We randomly assigned 81 patients to receive either 80% or 30% inspired oxygen concentration throughout surgery and the first two postoperative hours. We assessed noradrenaline, adrenaline, and dopamine plasma concentrations before the induction of anesthesia, two hours after surgery and on the third postoperative day. There was no significant difference in postoperative noradrenaline (effect estimated: −41.5 ng·L⁻¹, 95%CI −134.3, 51.2; p = 0.38), adrenaline (effect estimated: 11.2 ng·L⁻¹, 95%CI −7.6, 30.1; p = 0.24), and dopamine (effect estimated: −1.61 ng·L⁻¹, 95%CI −7.2, 3.9; p = 0.57) concentrations between both groups. Based on our results, it seems unlikely that supplemental oxygen influences endogenous catecholamine release in the perioperative setting.

Effect of perioperative levosimendan administration on postoperative N-terminal pro-B-type natriuretic peptide concentration in patients with increased cardiovascular risk factors undergoing non-cardiac surgery: protocol for the double-blind, randomised, placebo-controlled IMPROVE trial

INTRODUCTION

Elevated N-terminal pro-brain natriuretic peptide (NT-pro-BNP) after non-cardiac surgery is a strong predictor for cardiovascular complications and reflects increased myocardial strain. NT-pro-BNP concentrations significantly rise after non-cardiac surgery within the first 3 days. Levosimendan is a potent inotropic drug that increases calcium sensitivity to cardiac myocytes, which results in improved cardiac contractility that last for approximately 7 days. Thus, we will test the effect of a pre-emptive perioperative administration of levosimendan on postoperative NT-pro-BNP concentration as compared with the administration of a placebo in patients undergoing moderate-risk to high-risk major abdominal surgery.

METHODS AND ANALYSIS

We will conduct a double-blinded prospective randomised trial at the Medical University of Vienna, Vienna, Austria (and potentially a second centre in Germany), including 230 patients at-risk for cardiovascular complications undergoing moderate- to high-risk major abdominal surgery. Patients will be randomly assigned to receive a single dose of 12.5 mg levosimendan versus placebo after induction of anaesthesia. The primary outcome will be the postoperative maximum NT-pro-BNP concentration between both group within the first three postoperative days. Our secondary outcomes will be the incidence of myocardial ischaemia, myocardial injury after non-cardiac surgery and a composite of myocardial infarction and death within 30 days and 1 year after surgery between both groups. Our further secondary outcome will be stratification of NT-pro-BNP values according to previously thresholds to predict mortality of myocardial infarction after surgery.

ETHICS AND DISSEMINATION

The study was approved by the Ethics Committee of the Medical University of Vienna on 14 July 2020 (EK 2187/2019). Written informed consent will be obtained from all patients a day before surgery. Results of this study will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04329624.

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.